Sample records for mn ia mo

  1. Charge and magnetic states of Mn-, Fe-, and Co-doped monolayer MoS{sub 2}

    SciTech Connect (OSTI)

    Lin, Xianqing [State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023 (China); Ni, Jun, E-mail: junni@mail.tsinghua.edu.cn [State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China)

    2014-07-28T23:59:59.000Z

    First-principles calculations have been performed to investigate the electronic and magnetic properties of monolayer MoS{sub 2} substitutionally doped with Mn, Fe, and Co in possible charge states (q). We find that the Mn, Fe, and Co dopants substituting for a Mo atom in monolayer MoS{sub 2} (Mn@Mo, Fe@Mo, and Co@Mo) are all magnetic in their neutral and charge states except in the highest positive charge states. Mn@Mo, Fe@Mo, and Co@Mo have the same highest negative charge states of q=?2 for chemical potential of electron just below the conduction band minimum, which corresponds to the electron doping. In the q=?2 state, Mn@Mo has a much larger magnetic moment than its neutral state with the antiferromagnetic coupling between the Mn dopant and its neighboring S atoms maintained, while Fe@Mo and Co@Mo have equal or smaller magnetic moments than their neutral states. The possible charge states of Mn@Mo, Fe@Mo, and Co@Mo and the variation of the magnetic moments for different dopants and charge states are due to the change of the occupation and energy of the anti-bonding defect levels in the band gap. The rich magnetic properties of the neutral and charge states suggest possible realization of the substitutionally Mn-, Fe-, and Co-doped monolayer MoS{sub 2} as dilute magnetic semiconductors.

  2. Supercapacitor behavior of ?-MnMoO{sub 4} nanorods on different electrolytes

    SciTech Connect (OSTI)

    Purushothaman, K.K., E-mail: purushoth_gri@yahoo.co.in [Department of Physics, TRP Engineering College (SRM Group), Irungalur, Trichy, Tamilnadu (India); Cuba, M. [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India)] [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India); Muralidharan, G., E-mail: muralg@rediffmail.com [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India)

    2012-11-15T23:59:59.000Z

    Graphical abstract: SEM image of ?-MnMoO{sub 4} nanorods on FTO substrate. Highlights: ? Synthesis of ?-MnMoO{sub 4} nanorods by spin coating method. ? First study on the effect of electrolyte on the pseudocapacitance behavior. ? ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g. ? At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior. -- Abstract: ?-MnMoO{sub 4} nanorods were prepared on conducting glass substrate via sol–gel spin coating method at the optimum doping level. The effect of electrolyte on the pseudocapacitance behavior of the ?-MnMoO{sub 4} nanorods was studied using para toluene sulfonic acid (p-TSA), sulfuric acid (H{sub 2}SO{sub 4}) and hydrochloric acid (HCl) as electrolytes. X-ray diffraction analysis reveals the formation of ?-MnMoO{sub 4} in monoclinic phase. FTIR spectra contain vibrational bands associated with Mo=O, M–O and Mo–O–Mo bonds. SEM image reveals the formation of nanorods. Supercapacitor behavior has been studied using cyclic voltammetry (CV) analysis. ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g at a scan rate of 5 mV/s in H{sub 2}SO{sub 4} electrolyte while a specific capacitance of 784 F/g and 530 F/g have been obtained using p-TSA and HCl electrolytes, respectively. At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior than H{sub 2}SO{sub 4}.

  3. Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past water-column

    E-Print Network [OSTI]

    Wehrli, Bernhard

    Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past online 22 June 2013 Abstract Here, we present sedimentological, trace metal, and molecular evidence underscores the value of combining sedimentological, geochemical, and microbiological approaches

  4. Magnetic cluster excitations in the antiferromagnetic phase of a-MnMoO4 

    E-Print Network [OSTI]

    Ochsenbein, Stefan T; Chaboussant, Gregory; Sieber, Andreas; Gudel, Hans U; Janssen, Stefan; Furrer, Albert; Attfield, J. Paul

    2003-01-01T23:59:59.000Z

    The tetramer-based compound a-MnMoO4 exhibits four prominent peaks in the inelastic neutron scattering (INS) spectrum between 0.5 and 2.0 meV below 10 K. They are assigned to magnetic excitations of the (Mn2+)4 rhombus ...

  5. Transmission electron microscopy of RSP Fe/Cr/Mn/Mo/C alloy. [Fe-3 wt % Cr-2 wt % Mn-0. 5 wt % Mo, -0. 3 wt % C

    SciTech Connect (OSTI)

    Rayment, J.J.; Thomas, G.

    1982-03-01T23:59:59.000Z

    Rapid solidification processing (RSP) has been carried out on an Fe/Cr/Mn/Mo/C alloy using both electron-beam melting and piston-and-anvil techniques. Preliminary TEM results show RSP produces a refined duplex microstructure of ferrite and martensite, with a typical ferrite grain size of 0.50 - 3.0 microns. This RSP microstructure is significantly different from that observed in the conventionally austenitized and quenched alloys - a lath martensitic microstructure with thin films of retained interlath austenite. The morphological change produced by RSP is accompanied by an increase in hardness from 48R/sub c/ to 61R/sub c/ (approx. 480 to 720 VHN). It is intended to use electron-beam specimens to examine the potential beneficial effect of RSP upon sliding wear resistance and, by careful TEM studies, it will be possible to characterize the microstructure and its role in the hardness and wear behavior of the RSP alloy.

  6. The p-Process in the Carbon Deflagration Model for Type Ia Supernovae and Chronology of the Solar System Formation

    SciTech Connect (OSTI)

    Kusakabe, Motohiko [Department of Astronomy, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Iwamoto, Nobuyuki [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Nomoto, Ken'ichi [Department of Astronomy, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2006-07-12T23:59:59.000Z

    We study nucleosynthesis of p-nuclei in the carbon deflagration model for Type Ia supernovae (SNe Ia) by assuming that seed nuclei are produced by the s-process in accreting layers on a carbon-oxygen white dwarf during mass accretion from a binary companion. We find that about 50 % of the p-nuclides are synthesized in proportion to the solar abundance and that p-isotopes of Mo and Ru which are significantly underproduced in Type II supernovae (SNe II) are produced up to a level close to other p-nuclei. Comparing the yields of iron and p-nuclei in SNe Ia we find that SNe Ia can contribute to the galactic evolution of the p-nuclei. Next, we consider nucleochronology of the solar system formation by using four radioactive nuclides and apply the result of the p-process nucleosynthesis to simple galactic chemical evolution models. We find that when assumed three phases of interstellar medium are mixed by the interdiffusion with the timescale of about 40 Myr 53Mn/55Mn value in the early solar system is consistent with a meteoritic value. In addition, we put constraints to a scenario that SNe Ia induce the core collapse of the molecular cloud, which leads to the formation of the solar system.

  7. Dust around Type Ia supernovae

    E-Print Network [OSTI]

    Wang, Lifan

    2005-01-01T23:59:59.000Z

    Dust around Type Ia supernovae Lifan Wang 1,2 LawrenceIa. Subject headings: Supernovae: General, Dust, Extinctionline) bands for Type Ia supernovae. (a), upper panel, shows

  8. Electronic Phase Separation in Pr sub 1 sub x (Ca, Sr) sub x MnO sub 3 subdelta and Tunneling Magnetoresistance in Sr sub 2 FeMoO sub 6

    E-Print Network [OSTI]

    Niebieskikwiat, D G

    2003-01-01T23:59:59.000Z

    In this work, we approach two aspects of the physics of magnetic perovskites presenting colossal magnetoresistance (CMR). Firstly, we go deeply into the phase separation (PS) between the ferromagnetic (FM) metallic state and the antiferro-magnetic (AFM) charge ordered (CO) insulating state, in manganites of the type Pr sub 1 sub x (Ca,Sr) sub x MnO sub 3 subdelta. Secondly, and more briefly, we analyze the problem of the influence of the grain boundary insulating barriers on the tunneling magnetoresistance in the Sr sub 2 FeMoO sub 6 double perovskite.The use of different measurement techniques allowed us to make a complete characterization of the PS state in the compounds Pr sub 0.65Ca sub 0 sub . sub 3 sub 5 sub - sub y Sr sub y MnO sub 3 for 0 ) keeping constant the carrier concentration (x = 0.35). This material presents an evolution from a CO insulating phase for small (y =0), towards the FM metallic phase for large (y = 0.20). In t

  9. DIVERSITY OF TYPE Ia SUPERNOVAE IMPRINTED IN CHEMICAL ABUNDANCES

    SciTech Connect (OSTI)

    Tsujimoto, Takuji [National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan); Shigeyama, Toshikazu, E-mail: taku.tsujimoto@nao.ac.jp [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2012-12-01T23:59:59.000Z

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit an SN-Ia-like elemental feature including a very low [Mg/Fe] ( Almost-Equal-To - 1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr, Mn, Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth and give a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nicely explains the different [Cr, Mn, Ni/Fe] features between the two galaxies as well as the puzzling feature seen in the LMC stars exhibiting very low Ca but normal Mg abundances. Furthermore, the corresponding channel of slow SN Ia is exemplified by performing detailed nucleosynthesis calculations in the scheme of SNe Ia resulting from a 0.8 + 0.6 M{sub Sun} white dwarf merger.

  10. HIGH VOLTAGE TERMINAL IN COSY ELECTRON COOLER V.A. Chekavinskiy, E.A. Bekhtenev, I.A. Gusev, M.N. Kondaurov, V.R. Kozak, E.A. Kuper, V.R.

    E-Print Network [OSTI]

    Kozak, Victor R.

    HIGH VOLTAGE TERMINAL IN COSY ELECTRON COOLER V.A. Chekavinskiy, E.A. Bekhtenev, I.A. Gusev, M acceleration system ­ high voltage terminal. All power and control electronics were placed in a single isolated Voltage Terminal (HVT) in electron cooler is intended for generating of electron cooling beam

  11. Diversity of Type Ia Supernovae Imprinted in Chemical Abundances

    E-Print Network [OSTI]

    Tsujimoto, Takuji

    2012-01-01T23:59:59.000Z

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit a SN Ia-like elemental feature including a very low [Mg/Fe] (~-1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr,Mn,Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth, and gives a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nice...

  12. New approaches for modeling type Ia supernovae

    E-Print Network [OSTI]

    Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

    2007-01-01T23:59:59.000Z

    runaway in Type Ia supernovae: How to run away? oIgnition in Type Ia Supernovae. II. A Three- dimensionalnumber modeling of type Ia supernovae. I. hydrodynamics.

  13. New approaches for modeling type Ia supernovae

    E-Print Network [OSTI]

    Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

    2007-01-01T23:59:59.000Z

    ich and J. Stein. On the thermonuclear runaway in Type IaSmall-Scale Stability of Thermonuclear Flames o in Type IaS. E. Woosley. The thermonuclear explosion of chandrasekhar

  14. MO. REV. MO. MAGNETIC CLEANLINESS GUIDELINES

    E-Print Network [OSTI]

    Rathbun, Julie A.

    MO. REV. MO. ATM-865 MAGNETIC CLEANLINESS GUIDELINES PAGE 1 Of 3 DATE 4/6/70 The purpose of this ATM is to update the ALSEP Magnetic Cleanliness Guidelines as delineated in A TM-294, dated 1 June. ATM-865 MAGNETIC CLEANLINESS GUIDELINES PAGE 2 OF 3 DATE 4/6/70 A review of the ALSEP Magnetic

  15. Corrosion Resistance of Amorphous Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 coating - a new criticality-controlled material

    SciTech Connect (OSTI)

    Farmer, J C; Choi, J S; Saw, C K; Rebak, R; Day, S D; Lian, T; Hailey, P; Payer, J H; Branagan, D J; Aprigliano, L F

    2007-03-28T23:59:59.000Z

    An iron-based amorphous metal with good corrosion resistance and a high absorption cross-section for thermal neutrons has been developed and is reported here. This amorphous alloy has the approximate formula Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} and is known as SAM2X5. Chromium (Cr), molybdenum (Mo) and tungsten (W) were added to provide corrosion resistance, while boron (B) was added to promote glass formation and the absorption of thermal neutrons. Since this amorphous metal has a higher boron content than conventional borated stainless steels, it provides the nuclear engineer with design advantages for criticality control structures with enhanced safety. While melt-spun ribbons with limited practical applications were initially produced, large quantities (several tons) of gas atomized powder have now been produced on an industrial scale, and applied as thermal-spray coatings on prototypical half-scale spent nuclear fuel containers and neutron-absorbing baskets. These prototypes and other SAM2X5 samples have undergone a variety of corrosion testing, including both salt-fog and long-term immersion testing. Modes and rates of corrosion have been determined in various relevant environments, and are reported here. While these coatings have less corrosion resistance than melt-spun ribbons and optimized coatings produced in the laboratory, substantial corrosion resistance has been achieved.

  16. Type Ia Supernova Explosion Models

    E-Print Network [OSTI]

    W. Hillebrandt; J. C. Niemeyer

    2000-06-21T23:59:59.000Z

    Because calibrated light curves of Type Ia supernovae have become a major tool to determine the local expansion rate of the Universe and also its geometrical structure, considerable attention has been given to models of these events over the past couple of years. There are good reasons to believe that perhaps most Type Ia supernovae are the explosions of white dwarfs that have approached the Chandrasekhar mass, M_ch ~ 1.39 M_sun, and are disrupted by thermonuclear fusion of carbon and oxygen. However, the mechanism whereby such accreting carbon-oxygen white dwarfs explode continues to be uncertain. Recent progress in modeling Type Ia supernovae as well as several of the still open questions are addressed in this review. Although the main emphasis will be on studies of the explosion mechanism itself and on the related physical processes, including the physics of turbulent nuclear combustion in degenerate stars, we also discuss observational constraints.

  17. Turbulence-Flame Interactions in Type Ia Supernovae

    E-Print Network [OSTI]

    Aspden, Andrew J; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (Authors 1, 2 & 3); Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (Author 4); Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (Author 5)

    2008-01-01T23:59:59.000Z

    Interactions in Type Ia Supernovae A. J. Aspden 1 , J. B.involved in type Ia supernovae (SN Ia) requires the use of ?generated by RT in type Ia supernovae should obey Bolgiano-

  18. Ideal bandpasses for type Ia supernova cosmology

    E-Print Network [OSTI]

    Davis, Tamara M.; Schmidt, Brian P.; Kim, Alex G.

    2005-01-01T23:59:59.000Z

    diversity of type Ia Supernovae, in preparation. Kim, A.error in measurements of supernovae depends on a periodicABSTRACT To use type Ia supernovae as standard candles for

  19. Rates and progenitors of type Ia supernovae

    E-Print Network [OSTI]

    Wood-Vasey, William Michael

    2004-01-01T23:59:59.000Z

    Supernovae . . . . . . . . . . . . . . . . . . . .Supernovae Found 5.1 Introduction . . . . . . . . . . . .1.2 Non-Type Ia Supernovae . . . . . . . . . . . . . . . 1.3

  20. Appendix 14-Ia Coach's Employment

    E-Print Network [OSTI]

    Swaddle, John

    Appendix 14-Ia Coach's Employment Non Institutional Camp/Clinic Revised August 2010 ATHLETICS STAFF MEMBERS' EMPLOYMENT AT A NON-WILLIAM & MARY CAMP/CLINIC Coach's Name: ______ Sport) No athletics department staff member may be employed (salary or volunteer) in any capacity by a camp or clinic

  1. Subclasses of Type Ia Supernovae as the origin of [\\alpha/Fe] ratios in dwarf spheroidal galaxies

    E-Print Network [OSTI]

    Kobayashi, Chiaki; Hachisu, Izumi

    2015-01-01T23:59:59.000Z

    Recent extensive observations of Type Ia Supernovae (SNe Ia) have revealed the existence of a diversity of SNe Ia, including SN 2002cx-like objects (also called SN Iax). We introduce two possible channels in the single degenerate scenario: 1) double detonations in sub-Chandrasekhar (Ch) mass CO white dwarfs (WDs), where a thin He envelope is developed with relatively low accretion rates after He novae even at low metallicities, and 2) carbon deflagrations in Ch-mass possibly hybrid C+O+Ne WDs, where WD winds occur at [Fe/H] ~ -2.5 at high accretion rates. These subclasses of SNe Ia are rarer than `normal' SNe Ia and do not affect the chemical evolution in the solar neighborhood, but can be very important in metal-poor systems with stochastic star formation. In dwarf spheroidal galaxies in the Local Group, the decrease of [\\alpha/Fe] ratios at [Fe/H] ~ -2 to -1.5 can be produced depending on the star formation history. SNe Iax give high [Mn/Fe], while sub-Ch-mass SNe Ia give low [Mn/Fe], and thus a model inclu...

  2. Type Ia Supernova Carbon Footprints

    E-Print Network [OSTI]

    Thomas, R C; Aragon, C; Antilogus, P; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Hsiao, E Y; Kerschhaggl, M; Kowalski, M; Loken, S; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Rubin, D; Runge, K; Scalzo, R; Smadja, G; Tao, C; Weaver, B A; Wu, C; Brown, P J; Milne, P A

    2011-01-01T23:59:59.000Z

    We present convincing evidence of unburned carbon at photospheric velocities in new observations of 5 Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 d relative to maximum. Detections are based on the presence of relatively strong C II 6580 absorption "notches" in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the 5 SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibits high-velocity (v > 20,000 km/s) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broad band light curve/color behavior: Three of the 5 have relatively narrow light curves but also blue colors, and a fourth may be a dust-reddened member of this family. Accounting for signal-to-noise and phase, we ...

  3. Rates and Progenitors of Type Ia Supernovae

    E-Print Network [OSTI]

    William Michael Wood-Vasey

    2005-05-30T23:59:59.000Z

    The remarkable uniformity of Type Ia supernovae (SNe Ia) has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, SNe Ia exhibit intrinsic variation in both their spectra and observed brightness. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in SNe Ia. Toward this end, the Nearby Supernova Factory (SNfactory) has been designed to discover hundreds of SNe Ia in a systematic and automated fashion and study them in detail. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of SNe Ia. This dissertation presents a new method for analyzing the true sensitivity of a multi-epoch supernova search and finds a SN Ia rate from $z\\sim0.01$--0.1 of $r_V = 4.26 (+1.39 -1.93) (+0.10 - 0.10)$ SNe Ia/yr/Mpc$^3$ from a preliminary analysis of a subsample of the SNfactory prototype search. Several unusual supernovae were found in the course of the SNfactory prototype search. One in particular, SN 2002ic, was the first SN Ia to exhibit convincing evidence for a circumstellar medium and offers valuable insight into the progenitors of SNe Ia.

  4. Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution

    E-Print Network [OSTI]

    Almgren, Ann S.; Bell, John B.; Rendleman, Charles A.; Zingale, Mike

    2006-01-01T23:59:59.000Z

    Number Modeling of Type Ia Supernovae. II. Energy EvolutionIa. Subject headings: supernovae: general — white dwarfs —the ignition of Type Ia supernovae (SNe Ia) is critical to

  5. Turbulent Combustion in Type Ia Supernova Models

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt

    2006-09-15T23:59:59.000Z

    We review the astrophysical modeling of type Ia supernova explosions and describe numerical methods to implement numerical simulations of these events. Some results of such simulations are discussed.

  6. Evidence for ? c <mo stretchy="false">(mo> <mn>2mn> S <mo stretchy="false">)mo> in ? <mo stretchy="false">(mo> <mn>3686mn> <mo stretchy="false">)mo> <mo>?> ? K S <mn>0mn> K <mo>±> ? <mo>?> ? <mo>+> ? <mo>?>

    SciTech Connect (OSTI)

    Ablikim, M.; Achasov, M. N.; Albayrak, O.; Ambrose, D. J.; An, F. F.; An, Q.; Bai, J. Z.; Baldini Ferroli, R.; Ban, Y.; Becker, J.; Bennett, J. V.; Bertani, M.; Bian, J. M.; Boger, E.; Bondarenko, O.; Boyko, I.; Briere, R. A.; Bytev, V.; Cai, H.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, X.; Chen, Y. B.; Cheng, H. P.; Chu, Y. P.; Cronin-Hennessy, D.; Dai, H. L.; Dai, J. P.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; Ding, W. M.; Ding, Y.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Fang, J.; Fang, S. S.; Fava, L.; Feng, C. Q.; Friedel, P.; Fu, C. D.; Fu, J. L.; Gao, Y.; Geng, C.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, T.; Guo, Y. P.; Han, Y. L.; Harris, F. A.; He, K. L.; He, M.; He, Z. Y.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, J. F.; Hu, T.; Huang, G. M.; Huang, G. S.; Huang, J. S.; Huang, L.; Huang, X. T.; Huang, Y.; Huang, Y. P.; Hussain, T.; Ji, C. S.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, L. L.; Jiang, X. S.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Jing, F. F.; Kalantar-Nayestanaki, N.; Kavatsyuk, M.; Kopf, B.; Kornicer, M.; Kuehn, W.; Lai, W.; Lange, J. S.; Leyhe, M.; Li, C. H.; Li, Cheng; Li, Cui; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, K.; Li, Lei; Li, Q. J.; Li, S. L.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, X. R.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Liao, X. T.; Lin, D.; Liu, B. J.; Liu, C. L.; Liu, C. X.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H.; Liu, H. B.; Liu, H. H.; Liu, H. M.; Liu, H. W.; Liu, J. P.; Liu, K.; Liu, K. Y.; Liu, Kai; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H.; Lu, G. R.; Lu, H. J.; Lu, J. G.; Lu, Q. W.; Lu, X. R.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lv, M.; Ma, C. L.; Ma, F. C.; Ma, H. L.; Ma, Q. M.; Ma, S.; Ma, T.; Ma, X. Y.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, Y. J.; Mao, Z. P.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Morales Morales, C.; Muchnoi, N. Yu.; Muramatsu, H.; Nefedov, Y.; Nicholson, C.; Nikolaev, I. B.; Ning, Z.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Park, J. W.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Ping, J. L.; Ping, R. G.; Poling, R.; Prencipe, E.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, L. Q.; Qin, X. S.; Qin, Y.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Rong, G.; Ruan, X. D.; Sarantsev, A.; Schaefer, B. D.; Shao, M.; Shen, C. P.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, X. Y.; Spataro, S.; Spruck, B.; Sun, D. H.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Toth, D.; Ullrich, M.; Uman, I. U.; Varner, G. S.; Wang, B. Q.; Wang, D.; Wang, D. Y.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, Q. J.; Wang, S. G.; Wang, X. F.; Wang, X. L.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. Y.; Wei, D. H.; Wei, J. B.; Weidenkaff, P.; Wen, Q. G.; Wen, S. P.; Werner, M.; Wiedner, U.; Wu, L. H.; Wu, N.; Wu, S. X.; Wu, W.; Wu, Z.; Xia, L. G.; Xia, Y. X.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, G. M.; Xu, Q. J.; Xu, Q. N.; Xu, X. P.; Xu, Z. R.; Xue, F.; Xue, Z.; Yan, L.; Yan, W. B.; Yan, Y. H.; Yang, H. X.; Yang, Y.; Yang, Y. X.; Ye, H.; Ye, M.; Ye, M. H.; Yu, B. X.; Yu, C. X.; Yu, H. W.; Yu, J. S.; Yu, S. P.; Yuan, C. Z.; Yuan, Y.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, LiLi; Zhang, R.; Zhang, S. H.; Zhang, X. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhang, Zhenghao; Zhao, G.; Zhao, H. S.; Zhao, J. W.; Zhao, K. X.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, Q. Z.; Zhao, S. J.; Zhao, T. C.; Zhao, X. H.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, Y. H.; Zhong, B.; Zhong, Z.; Zhou, L.; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhu, C.; Zhu, K.; Zhu, K. J.; Zhu, S. H.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. M.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zou, B. S.; Zou, J. H.

    2013-03-01T23:59:59.000Z

    We search for the M1 radiative transition ?(3686)???c(2S) by reconstructing the exclusive ?c(2S)?K?SK±?????? decay using 1.06×10? ?(3686) events collected with the BESIII detector. The signal is observed with a statistical significance of greater than 4 standard deviations. The measured mass of the ?c(2S) is 3646.9±1.6(stat)±3.6(syst) MeV/c², and the width is 9.9±4.8(stat)±2.9(syst) MeV/c². The product branching fraction is measured to be B(?(3686)???c(2S))×B(?c(2S)?K0SK±??????)=(7.03±2.10(stat)±0.70(syst))×10??. This measurement complements a previous BESIII measurement of ?(3686)???c(2S) with ?c(2S)?K?SK±?? and K?K???.

  7. Theoretical cosmic Type Ia supernova rates

    E-Print Network [OSTI]

    R. Valiante; F. Matteucci; S. Recchi; F. Calura

    2009-03-16T23:59:59.000Z

    The aim of this work is the computation of the cosmic Type Ia supernova rates at very high redshifts (z>2). We adopt various progenitor models in order to predict the number of explosions in different scenarios for galaxy formation and to check whether it is possible to select the best delay time distribution model, on the basis of the available observations of Type Ia supernovae. We also computed the Type Ia supernova rate in typical elliptical galaxies of different initial luminous masses and the total amount of iron produced by Type Ia supernovae in each case. It emerges that: it is not easy to select the best delay time distribution scenario from the observational data and this is because the cosmic star formation rate dominates over the distribution function of the delay times; the monolithic collapse scenario predicts an increasing trend of the SN Ia rate at high redshifts whereas the predicted rate in the hierarchical scheme drops dramatically at high redshift; for the elliptical galaxies we note that the predicted maximum of the Type Ia supernova rate depends on the initial galactic mass. The maximum occurs earlier (at about 0.3 Gyr) in the most massive ellipticals, as a consequence of downsizing in star formation. We find that different delay time distributions predict different relations between the Type Ia supernova rate per unit mass at the present time and the color of the parent galaxies and that bluer ellipticals present higher supernova Type Ia rates at the present time.

  8. An APFIM and TEM study of Ni{sub 4}Mo precipitation in a commercial Ni-28% Mo-1.4% Fe-0.4% Cr wt. % alloy

    SciTech Connect (OSTI)

    Thomson, R.C.; Brown, N.; Bates, J.S. [Loughborough Univ. (United Kingdom). Inst. of Polymer Technology and Materials Engineering; Russell, K.F.; Miller, M.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1998-02-01T23:59:59.000Z

    Ni-Mo alloys containing at least 26 wt.% Mo have a negligible corrosion rate in boiling 10% hydrochloric acid and are therefore used in corrosive environments. A series of commercial Ni-Mo alloys has been developed with subtle variations in chemical composition. These alloys usually contain {approximately} 28 wt.% Mo with additions of up to 5% Fe and Cr. A significant amount of research has been performed to understand the microstructure and properties of these alloys, although most of the effort has concentrated on the Ni-Mo binary system. In some alloys with low Fe and Cr contents, a severe embrittlement problem has been observed due to the formation of the Ni{sub 4}Mo (D1{sub a}-ordered) phase within the microstructure. This research focuses on a commercial alloy with nominal composition Ni-28% Mo-1.4% Fe-0.4% Cr-0.1% Mn-0.003 wt.% C. The material supplied was a heat treatment coupon which had been attached to a large vessel during fabrication. Assessment of the chemical analysis of the alloy suggested that detrimental phases could be present or might appear during subsequent repair work. Therefore, it was important to assess the microstructural condition of the vessel, and in particular the kinetics of precipitation of Ni{sub 4}Mo.

  9. Supersoft Sources as SN Ia Progenitors

    E-Print Network [OSTI]

    Greiner, Jochen

    of the existence of supersoft X­ray sources. It is argued that SNe Ia are thermonuclear explosions of accreting C is that they represent thermonuclear disruptions of mass accreting white dwarfs (WDs). Thus, the basic ingredient

  10. Nucleosynthesis in Type Ia Supernovae

    E-Print Network [OSTI]

    K. Nomoto; K. Iwamoto; N. Nakasato; F. -K. Thielemann; F. Brachwitz; T. Tsujimoto; Y. Kubo; N. Kishimoto

    1997-06-03T23:59:59.000Z

    Among the major uncertainties involved in the Chandrasekhar mass models for Type Ia supernovae are the companion star of the accreting white dwarf (or the accretion rate that determines the carbon ignition density) and the flame speed after ignition. We present nucleosynthesis results from relatively slow deflagration (1.5 - 3 % of the sound speed) to constrain the rate of accretion from the companion star. Because of electron capture, a significant amount of neutron-rich species such as ^{54}Cr, ^{50}Ti, ^{58}Fe, ^{62}Ni, etc. are synthesized in the central region. To avoid the too large ratios of ^{54}Cr/^{56}Fe and ^{50}Ti/^{56}Fe, the central density of the white dwarf at thermonuclear runaway must be as low as \\ltsim 2 \\e9 \\gmc. Such a low central density can be realized by the accretion as fast as $\\dot M \\gtsim 1 \\times 10^{-7} M_\\odot yr^{-1}$. These rapidly accreting white dwarfs might correspond to the super-soft X-ray sources.

  11. Survey gives clues to origin of Type Ia supernovae | EurekAlert! Science News

    E-Print Network [OSTI]

    ... to origin of Type Ia supernovae ... Type Ia supernovae still not understood despite their ... s behind the Type Ia supernovae they use to measure distances ...

  12. New findings show some Type Ia supernovae linked to novae | EurekAlert! Science News

    E-Print Network [OSTI]

    ... findings show some Type Ia supernovae linked to novae ... least some thermonuclear (Type Ia) supernovae come from a recurrent nova ... originators of other Type Ia supernovae . ...

  13. Verifying the Cosmological Utility of Type Ia Supernovae: Implications of a Dispersion in the Ultraviolet Spectra

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    Utility of Type Ia Supernovae: Implications of a Dispersionheadings: surveys – supernovae: general – cosmologicalparameters Introduction Supernovae of Type Ia (SNe Ia) are

  14. Type Ia Supernova Intrinsic Magnitude Dispersion and the Fitting of Cosmological Parameters

    E-Print Network [OSTI]

    Kim, Alex G

    2011-01-01T23:59:59.000Z

    Applied to Type Ia supernovae, my strategy provides adata sets. Subject headings: Supernovae: Data Analysis andhomogeneous nature of Type Ia supernovae (SNe Ia) makes them

  15. Nebular spectra and abundance tomography of the type Ia supernova SN 2011fe: a normal SN Ia with a stable Fe core

    E-Print Network [OSTI]

    Mazzali, P A; Filippenko, A V; Garnavich, P M; Clubb, K I; Maguire, K; Pan, Y -C; Shappee, R; Silverman, J M; Benetti, S; Hachinger, S; Nomoto, K; Pian, E

    2015-01-01T23:59:59.000Z

    A series of optical and one near-infrared nebular spectra covering the first year of the Type Ia supernova SN 2011fe are presented and modelled. The density profile that proved best for the early optical/ultraviolet spectra, "rho-11fe", was extended to lower velocities to include the regions that emit at nebular epochs. Model rho-11fe is intermediate between the fast deflagration model W7 and a low-energy delayed-detonation. Good fits to the nebular spectra are obtained if the innermost ejecta are dominated by neutron-rich, stable Fe-group species, which contribute to cooling but not to heating. The correct thermal balance can thus be reached for the strongest [FeII] and [FeIII] lines to be reproduced with the observed ratio. The 56Ni mass thus obtained is 0.47 +/- 0.05 Mo. The bulk of 56Ni has an outermost velocity of ~8500 km/s. The mass of stable iron is 0.23 +/- 0.03 Mo. Stable Ni has low abundance, ~10^{-2} Mo. This is sufficient to reproduce an observed emission line near 7400 A. A sub-Chandrasekhar exp...

  16. Ethanol Conversion on Cyclic (MO3)3 (M = Mo, W) Clusters. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Conversion on Cyclic (MO3)3 (M Mo, W) Clusters. Ethanol Conversion on Cyclic (MO3)3 (M Mo, W) Clusters. Abstract: Oxides of molybdenum and tungsten are an important class of...

  17. Visualizing Buoyant Burning Bubbles in Type Ia Supernovae at...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Burning in Supernovae Buoyant Burning Bubbles in Type Ia Supernovae bubble-s.jpeg Flame ignition in type Ia supernovae leads to isolated bubbles of burning buoyant fluid. As a...

  18. Closest Type Ia Supernova in Decades Solves a Cosmic Mystery

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    PTF 11kly as it appeared in the nearby M101 galaxy. (Images: Peter Nugent) Type Ia supernovae (SN Ia's) are the extraordinarily bright and remarkably similar "standard candles"...

  19. High Mn austenitic stainless steel

    DOE Patents [OSTI]

    Yamamoto, Yukinori (Oak Ridge, TN) [Oak Ridge, TN; Santella, Michael L (Knoxville, TN) [Knoxville, TN; Brady, Michael P (Oak Ridge, TN) [Oak Ridge, TN; Maziasz, Philip J (Oak Ridge, TN) [Oak Ridge, TN; Liu, Chain-tsuan (Knoxville, TN) [Knoxville, TN

    2010-07-13T23:59:59.000Z

    An austenitic stainless steel alloy includes, in weight percent: >4 to 15 Mn; 8 to 15 Ni; 14 to 16 Cr; 2.4 to 3 Al; 0.4 to 1 total of at least one of Nb and Ta; 0.05 to 0.2 C; 0.01 to 0.02 B; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1W; up to 3 Cu; up to 1 Si; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale including alumina, nanometer scale sized particles distributed throughout the microstructure, the particles including at least one of NbC and TaC, and a stable essentially single phase FCC austenitic matrix microstructure that is essentially delta-ferrite-free and essentially BCC-phase-free.

  20. China Today IAS 2123.001

    E-Print Network [OSTI]

    Oklahoma, University of

    China Today IAS 2123.001 Kevin Carrico Tuesdays & Thursdays 10:30 am -11:45 am Approved for Non-Western culture credit Everyone knows that China today is a "rising superpower," but the real story of China's modern history is considerably more complex. This course looks beyond the headlines to rediscover China

  1. Probing Cosmological Isotropy With Type IA Supernovae

    E-Print Network [OSTI]

    Bengaly, C A P; Alcaniz, J S

    2015-01-01T23:59:59.000Z

    We investigate the validity of the Cosmological Principle by mapping the cosmological parameters $H_0$ and $q_0$ through the celestial sphere. In our analysis, performed in a low-redshift regime to follow a model-independent approach, we use two compilations of type Ia Supernovae (SNe Ia), namely the Union2.1 and the JLA datasets. Firstly, we show that the angular distributions for both SNe Ia datasets are statistically anisotropic at high confidence level ($p$-value $<$ 0.0001), in particular the JLA sample. Then we find that the cosmic expansion and acceleration are mainly of dipolar type, with maximal anisotropic expansion [acceleration] pointing towards $(l,b) \\simeq (326^{\\circ},12^{\\circ})$ [$(l,b) \\simeq (174^{\\circ},27^{\\circ})$], and $(l,b) \\simeq (58^{\\circ},-60^{\\circ})$ [$(l,b) \\simeq (225^{\\circ},51^{\\circ})$] for the Union2.1 and JLA data, respectively. Secondly, we use a geometrical method to test the hypothesis that the non-uniformly distributed SNe Ia events could introduce anisotropic imp...

  2. Models of Type Ia Supernova Explosions

    E-Print Network [OSTI]

    J. C. Niemeyer; M. Reinecke; W. Hillebrandt

    2002-03-21T23:59:59.000Z

    Type Ia supernovae have become an indispensable tool for studying the expansion history of the universe, yet our understanding of the explosion mechanism is still incomplete. We describe the variety of discussed scenarios, sketch the most relevant physics, and report recent advances in multidimensional simulations of Chandrasekhar mass white dwarf explosions.

  3. Models of Type Ia Supernova Explosions

    E-Print Network [OSTI]

    Niemeyer, J C; Hillebrandt, W

    2002-01-01T23:59:59.000Z

    Type Ia supernovae have become an indispensable tool for studying the expansion history of the universe, yet our understanding of the explosion mechanism is still incomplete. We describe the variety of discussed scenarios, sketch the most relevant physics, and report recent advances in multidimensional simulations of Chandrasekhar mass white dwarf explosions.

  4. The Outermost Ejecta of Type Ia Supernovae

    E-Print Network [OSTI]

    Masaomi Tanaka; Paolo A. Mazzali; Stefano Benetti; Ken'ichi Nomoto; Nancy Elias-Rosa; Rubina Kotak; Giuliano Pignata; Vallery Stanishev; Stephan Hachinger

    2007-12-17T23:59:59.000Z

    The properties of the highest velocity ejecta of normal Type Ia supernovae (SNe Ia) are studied via models of very early optical spectra of 6 SNe. At epochs earlier than 1 week before maximum, SNe with a rapidly evolving Si II 6355 line velocity (HVG) have a larger photospheric velocity than SNe with a slowly evolving Si II 6355 line velocity (LVG). Since the two groups have comparable luminosities, the temperature at the photosphere is higher in LVG SNe. This explains the different overall spectral appearance of HVG and LVG SNe. However, the variation of the Ca II and Si II absorptions at the highest velocities (v >~ 20,000 km/s) suggests that additional factors, such as asphericity or different abundances in the progenitor white dwarf, affect the outermost layers. The C II 6578 line is marginally detected in 3 LVG SNe, suggesting that LVG undergo less intense burning. The carbon mass fraction is small, only less than 0.01 near the photosphere, so that he mass of unburned C is only <~ 0.01 Msun. Radioactive 56Ni and stable Fe are detected in both LVG and HVG SNe. Different Fe-group abundances in the outer layers may be one of the reasons for spectral diversity among SNe Ia at the earliest times. The diversity among SNe Ia at the earliest phases could also indicate an intrinsic dispersion in the width-luminosity relation of the light curve.

  5. A threat-based definition of IA- and IA-enabled products.

    SciTech Connect (OSTI)

    Shakamuri, Mayuri; Schaefer, Mark A.; Campbell, Philip LaRoche

    2010-07-01T23:59:59.000Z

    This paper proposes a definition of 'IA and IA-enabled products' based on threat, as opposed to 'security services' (i.e., 'confidentiality, authentication, integrity, access control or non-repudiation of data'), as provided by Department of Defense (DoD) Instruction 8500.2, 'Information Assurance (IA) Implementation.' The DoDI 8500.2 definition is too broad, making it difficult to distinguish products that need higher protection from those that do not. As a consequence the products that need higher protection do not receive it, increasing risk. The threat-based definition proposed in this paper solves those problems by focusing attention on threats, thereby moving beyond compliance to risk management. (DoDI 8500.2 provides the definitions and controls that form the basis for IA across the DoD.) Familiarity with 8500.2 is assumed.

  6. A threat-based definition of IA and IA-enabled products.

    SciTech Connect (OSTI)

    Shakamuri, Mayuri; Schaefer, Mark A.; Campbell, Philip LaRoche

    2010-09-01T23:59:59.000Z

    This paper proposes a definition of 'IA and IA-enabled products' based on threat, as opposed to 'security services' (i.e., 'confidentiality, authentication, integrity, access control or non-repudiation of data'), as provided by Department of Defense (DoD) Instruction 8500.2, 'Information Assurance (IA) Implementation.' The DoDI 8500.2 definition is too broad, making it difficult to distinguish products that need higher protection from those that do not. As a consequence the products that need higher protection do not receive it, increasing risk. The threat-based definition proposed in this paper solves those problems by focusing attention on threats, thereby moving beyond compliance to risk management. (DoDI 8500.2 provides the definitions and controls that form the basis for IA across the DoD.) Familiarity with 8500.2 is assumed.

  7. The resistance to cavitation erosion of CrMnN stainless steels

    SciTech Connect (OSTI)

    Fu, W.T. [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering] [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering; [Harbin Inst. of Tech. (China); Jing, T.F.; Zheng, Y.Z. [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering] [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering; Yang, Y.B. [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering] [Yanshan Univ., Qinhuangdao (China). Dept. of Materials Engineering; [Bohai Aluminum Industries Co., Ltd., Qinhuangdao (China); Yao, M. [Harbin Inst. of Tech. (China)] [Harbin Inst. of Tech. (China)

    1998-12-01T23:59:59.000Z

    The resistance to cavitation erosion (CE) was measured using a magnetostrictive device and a rotating disk device for some CrMnN stainless steels (Chinese patent ZL 90 1 02197.0). The microstructural changes in the surface layer before and after CE were analyzed by use of Mossbauer spectra. Results show that the resistance to CE of duplex austenitic-martensitic CrMnN stainless steels is much better than that of ZG0Cr13Ni4-6Mo and ZG0Cr16Ni5Mo steel, which are in common use for hydraulic turbine runners. The metastable austenite and its changes in the process of CE are the key factors why the CrMnN stainless steels have excellent resistance to cavitation erosion.

  8. SHOCK BREAKOUT FROM TYPE Ia SUPERNOVA

    SciTech Connect (OSTI)

    Piro, Anthony L.; Chang, Philip; Weinberg, Nevin N., E-mail: tpiro@astro.berkeley.ed, E-mail: pchang@astro.berkeley.ed, E-mail: nweinberg@astro.berkeley.ed [Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States)

    2010-01-01T23:59:59.000Z

    The mode of explosive burning in Type Ia supernovae (SNe Ia) remains an outstanding problem. It is generally thought to begin as a subsonic deflagration, but this may transition into a supersonic detonation (the delayed detonation transition, DDT). We argue that this transition leads to a breakout shock, which would provide the first unambiguous evidence that DDTs occur. Its main features are a hard X-ray flash (approx20 keV) lasting approx10{sup -2} s with a total radiated energy of approx10{sup 40} erg, followed by a cooling tail. This creates a distinct feature in the visual light curve, which is separate from the nickel decay. This cooling tail has a maximum absolute visual magnitude of M{sub V} approx -9 to -10 at approx1 day, which depends most sensitively on the white dwarf radius at the time of the DDT. As the thermal diffusion wave moves in, the composition of these surface layers may be imprinted as spectral features, which would help to discern between SN Ia progenitor models. Since this feature should accompany every SNe Ia, future deep surveys (e.g., m = 24) will see it out to a distance of approx80 Mpc, giving a maximum rate of approx60 yr{sup -1}. Archival data sets can also be used to study the early rise dictated by the shock heating (at approx20 days before maximum B-band light). A similar and slightly brighter event may also accompany core bounce during the accretion-induced collapse to a neutron star, but with a lower occurrence rate.

  9. Type Ia Supernova Hubble Residuals and Host-Galaxy Properties

    E-Print Network [OSTI]

    Kim, A. G.

    2014-01-01T23:59:59.000Z

    magnitudes of type Ia supernovae from multi-band lightsuch an analysis on the supernovae of the Nearby Supernovaheadings: distance scale, supernovae: general 1 Physics

  10. K-corrections and spectral templates of Type Ia supernovae

    E-Print Network [OSTI]

    Hsiao, E. Y.

    2008-01-01T23:59:59.000Z

    templates of Type Ia supernovae E. Y. Hsiao 1 , A. Conleyobservations of low-redshift supernovae are less a?ected byobservations, stars: supernovae Department of Physics and

  11. Constraining Cosmic Evolution of Type Ia Supernovae

    SciTech Connect (OSTI)

    Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

    2008-02-13T23:59:59.000Z

    We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

  12. IA Blog Archive | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page onYouTube YouTube Note: Since the.pdfBreaking of Blythe SolarContaminationCurrentHydronic71 IA Blog Archive en DOE andBlog

  13. IA News Archive | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page onYouTube YouTube Note: Since the.pdfBreaking of Blythe SolarContaminationCurrentHydronic71 IA Blog Archive en DOENews

  14. Steamboat IA Geothermal Facility | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to:Ezfeedflag JumpID-f < RAPID‎SolarCityInformation Glass Buttes AreaSteaI GeothermalIA

  15. First Evidence of Globular Cluster Formation from the Ejecta of Prompt Type Ia Supernovae

    E-Print Network [OSTI]

    Tsujimoto, Takuji

    2012-01-01T23:59:59.000Z

    Recent spectroscopic observations of globular clusters (GCs) in the Large Magellanic Cloud (LMC) have discovered that one of the intermediate-age GC, NGC 1718 with [Fe/H]=-0.7 has an extremely low [Mg/Fe] ratio of ~-0.9. We propose that NGC 1718 was formed from the ejecta of type Ia supernovae (SNe Ia) mixed with very metal-poor ([Fe/H] <-1.3) gas about ~ 2 Gyr ago. The proposed scenario is shown to be consistent with the observed abundances of Fe-group elements such as Cr, Mn, and Ni. In addition, compelling evidence for asymptotic giant branch stars playing a role in chemical enrichment during this GC formation is found. We suggest that the origin of the metal-poor gas is closely associated with the efficient gas-transfer from the outer gas disk of the Small Magellanic Cloud to the LMC disk. We anticipate that the outer part of the LMC disk contains field stars exhibiting significantly low [Mg/Fe] ratios, formed through the same process as NGC 1718.

  16. Type Ia Supernova Explosion: Gravitationally Confined Detonation

    E-Print Network [OSTI]

    Tomasz Plewa; Alan Calder; Don Lamb

    2004-05-08T23:59:59.000Z

    We present a new mechanism for Type Ia supernova explosions in massive white dwarfs. The proposed scenario follows from relaxing the assumption of symmetry in the model and involves a detonation created in an unconfined environment. The explosion begins with an essentially central ignition of stellar material initiating a deflagration. This deflagration results in the formation of a buoyantly-driven bubble of hot material that reaches the stellar surface at supersonic speeds. The bubble breakout forms a strong pressure wave that laterally accelerates fuel-rich outer stellar layers. This material, confined by gravity to the white dwarf, races along the stellar surface and is focused at the location opposite to the point of the bubble breakout. These streams of nuclear fuel carry enough mass and energy to trigger a detonation just above the stellar surface. The flow conditions at that moment support a detonation that will incinerate the white dwarf and result in an energetic explosion. The stellar expansion following the deflagration redistributes stellar mass in a way that ensures production of intermediate mass and iron group elements consistent with observations. The ejecta will have a strongly layered structure with a mild amount of asymmetry following from the early deflagration phase. This asymmetry, combined with the amount of stellar expansion determined by details of the evolution (principally the energetics of deflagration, timing of detonation, and structure of the progenitor), can be expected to create a family of mildly diverse Type Ia supernova explosions.

  17. Dark matter ignition of type Ia supernovae

    E-Print Network [OSTI]

    Bramante, Joseph

    2015-01-01T23:59:59.000Z

    Recent studies of low redshift type Ia supernovae (SNIa) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SNIa progenitors. We show that $0.1-10$ PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SNIa. We combine data on SNIa masses with data on the ages of SNIa-adjacent stars. This combination reveals a $ 3 \\sigma$ inverse correlation between SNIa masses and ignition ages, which could result from increased capture of dark matter in 1.4 versus 1.1 solar mass white dwarfs. Future studies of SNIa in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SNI...

  18. Plasma Redshift, Time Dilation, and Supernovas Ia

    E-Print Network [OSTI]

    Ari Brynjolfsson

    2004-07-20T23:59:59.000Z

    The measurements of the absolute magnitudes and redshifts of supernovas Ia show that conventional physics, which includes plasma redshift, fully explains the observed magnitude-redshift relation of the supernovas. The only parameter that is required is the Hubble constant, which in principle can be measured independently. The contemporary theory of the expansion of the universe (Big Bang) requires in addition to the Hubble constant several adjustable parameters, such as an initial explosion, the dark matter parameter, and a time adjustable dark energy parameter for explaining the supernova Ia data. The contemporary Big Bang theory also requires time dilation of distant events as an inherent premise. The contention is usually that the light curves of distant supernovas show or even prove the time dilation. In the present article, we challenge this assertion. We document and show that the previously reported data in fact indicate that there is no time dilation. The data reported by Riess et al. in the Astrophysical Journal in June 2004 confirm the plasma redshift, the absence of time dilation, dark matter, and dark energy.

  19. Three-dimensional numerical simulations of Rayleigh-Taylor unstable flames in type Ia supernovae

    E-Print Network [OSTI]

    Zingale, M.; Woosley, S.E.; Rendleman, C.A.; Day, M.S.; Bell, J.B.

    2005-01-01T23:59:59.000Z

    Unstable Flames in Type Ia Supernovae M. Zingale 1 , S. E.Subject headings: supernovae: general — white dwarfs —ame in Type Ia supernovae (SNe Ia) is well recognized (M¨

  20. Improving Type Ia Supernova Standard Candle Cosmology Measurements Using Observations of Early-Type Host Galaxies

    E-Print Network [OSTI]

    Meyers, Joshua Evan

    2012-01-01T23:59:59.000Z

    Host Galaxies of Type Ia Supernovae Introduction SN Ia Hosts109 C HAPTER 1 Cosmology, Type Ia Supernovae and HostGalaxies Observations of supernovae have played a role in

  1. UNU-IAS Policy Report Biofuels in Africa

    E-Print Network [OSTI]

    UNU-IAS Policy Report Biofuels in Africa Impacts on Ecosystem Services, Biodiversity and Human Well-being #12;#12;UNU-IAS Policy Report Biofuels in Africa Impacts on Ecosystem Services, Biodiversity and Human........................................................................................................... 9 1.2 Biofuel drivers, feedstocks and policies in Africa

  2. Nickel Bubble Expansion in Type Ia Supernovae: Adiabatic Solutions

    E-Print Network [OSTI]

    Chih-Yueh Wang

    2008-06-20T23:59:59.000Z

    This paper presents hydrodynamical and radiation-hydrodynamical simulations of the nickel bubble effect in Type Ia supernovae, comparison of results to self-similar solutions, and application to observations of Type Ia supernova remnants, with a particular emphasis on Tycho's SNR.

  3. Type Ia Supernova Remnants: Shaping by Iron Bullets

    E-Print Network [OSTI]

    Tsebrenko, Danny

    2015-01-01T23:59:59.000Z

    Using 2D numerical hydrodynamical simulations of type Ia supernova remnants (SNR Ia) we show that iron clumps few times denser than the rest of the SN ejecta might form protrusions in an otherwise spherical SNR. Such protrusions exist in some SNR Ia, e.g., SNR 1885 and Tycho. Iron clumps are expected to form in the deflagration to detonation explosion model. In SNR Ia where there are two opposite protrusions, termed ears, such as Kepler's SNR and SNR G1.9+0.3, our scenario implies that the dense clumps, or iron bullets, were formed along an axis. Such a preferred axis can result from a rotating white dwarf progenitor. If our claim holds, this offers an important clue to the SN Ia explosion scenario.

  4. Direct numerical simulations of type Ia supernovae flames I: The landau-darrieus instability

    E-Print Network [OSTI]

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2003-01-01T23:59:59.000Z

    Simulations of Type Ia Supernovae Flames I: The Landau-Subject headings: supernovae: general — white dwarfs —could occur in Type Ia supernovae (Niemeyer & Woosley 1997),

  5. Electrodeposition of high Mo content Ni-Mo alloys under forced convection

    SciTech Connect (OSTI)

    Podlaha, E.J.; Matlosz, M.; Landolt, D. (Ecole Polytechnique Federale de Lausanne, Lausanee (Switzerland). Dept. des materiaux)

    1993-10-01T23:59:59.000Z

    Bright, compact, adherent, metallic Ni-Mo alloys, containing over 48 wt % Mo have been electrodeposited from an aqueous solution. The Mo content, which is the highest achieved so far in induced codeposition of Ni-Mo, was determined by X-ray fluorescence spectroscopy. The absence of oxygen was verified by Auger electron spectroscopy. Electrodeposition experiments were performed on rotating cylinder electrodes and demonstrate that the Mo content of the alloy is strongly influenced by convective transport.

  6. Phases of a Type Ia supernova explosion

    E-Print Network [OSTI]

    J. C. Niemeyer

    1998-02-13T23:59:59.000Z

    In the framework of the Chandrasekhar mass white dwarf model for Type Ia supernovae, various stages of the explosion are described in terms of the burning regimes of the thermonuclear flame front. In the early flamelet regime following the ``smoldering'' phase prior to the explosion, the flame is sufficiently thin and fast to remain laminar on small scales. As the white dwarf density declines, the thermal flame structure becomes subject to penetration by turbulent eddies, and it enters the ``distributed burning'' regime. A specific control parameter for this transition is proposed. Furthermore, we outline an argument for the coincidence of the transition between burning regimes with the onset of a deflagration-detonation-transition (DDT) in the late phase of the explosion.

  7. K-corrections and spectral templates of Type Ia supernovae

    SciTech Connect (OSTI)

    Nugent, Peter E; Hsiao, E.Y.; Conley, A.; Howell, D.A.; Sullivan, M.; Pritchet, C.J.; Carlberg, R.G.; Nugent, P.E.; Phillips, M.M.

    2007-03-20T23:59:59.000Z

    With the advent of large dedicated Type Ia supernova (SN Ia) surveys, K-corrections of SNe Ia and their uncertainties have become especially important in the determination of cosmological parameters. While K-corrections are largely driven by SN Ia broadband colors, it is shown here that the diversity in spectral features of SNe Ia can also be important. For an individual observation, the statistical errors from the inhomogeneity in spectral features range from 0.01 (where the observed and rest-frame filters are aligned) to 0.04 (where the observed and rest-frame filters are misaligned). To minimize the systematic errors caused by an assumed SN Ia spectral energy distribution (SED), we outline a prescription for deriving a mean spectral template time series that incorporates a large and heterogeneous sample of observed spectra. We then remove the effects of broadband colors and measure the remaining uncertainties in the K-corrections associated with the diversity in spectral features. Finally, we present a template spectroscopic sequence near maximum light for further improvement on the K-correction estimate. A library of ~;;600 observed spectra of ~;;100 SNe Ia from heterogeneous sources is used for the analysis.

  8. Type Ia Supernova Progenitors, Environmental Effects, and Cosmic Supernova Rates

    E-Print Network [OSTI]

    Ken'ichi Nomoto; Hideyuki Umeda; Izumi Hachisu; Mariko Kato; Chiaki Kobayashi; Takuji Tsujimoto

    1999-07-27T23:59:59.000Z

    Relatively uniform light curves and spectral evolution of Type Ia supernovae (SNe Ia) have led to the use of SNe Ia as a ``standard candle'' to determine cosmological parameters, such as the Hubble constant, the density parameter, and the cosmological constant. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effects of cosmic and galactic evolutions. Here we first review the single degenerate scenario for the Chandrasekhar mass white dwarf (WD) models of SNe Ia. We identify the progenitor's evolution and population with two channels: (1) the WD+RG (red-giant) and (2) the WD+MS (near main-sequence He-rich star) channels. In these channels, the strong wind from accreting white dwarfs plays a key role, which yields important age and metallicity effects on the evolution. We then address the questions whether the nature of SNe Ia depends systematically on environmental properties such as metallicity and age of the progenitor system and whether significant evolutionary effects exist. We suggest that the variation of the carbon mass fraction $X$(C) in the C+O WD (or the variation of the initial WD mass) causes the diversity of the brightness of SNe Ia. This model can explain the observed dependence of SNe Ia brighness on the galaxy types. Finally, applying the metallicity effect on the evolution of SN Ia progenitors, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in different types of galaxies.

  9. Type Ia Supernovae: Progenitors and Evolution with Redshift

    E-Print Network [OSTI]

    Ken'ichi Nomoto; Hideyuki Umeda; Chiaki Kobayashi; Izumi Hachisu; Mariko Kato; Takuji Tsujimoto

    2000-03-09T23:59:59.000Z

    Relatively uniform light curves and spectral evolution of Type Ia supernovae (SNe Ia) have led to the use of SNe Ia as a ``standard candle'' to determine cosmological parameters. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effects of cosmic and galactic evolutions. Here we first review the single degenerate scenario for the Chandrasekhar mass white dwarf (WD) models of SNe Ia. We identify the progenitor's evolution and population with two channels: (1) the WD+RG (red-giant) and (2) the WD+MS (near main-sequence He-rich star) channels. In these channels, the strong wind from accreting WDs plays a key role, which yields important age and metallicity effects on the evolution. We then address the questions whether the nature of SNe Ia depends systematically on environmental properties such as metallicity and age of the progenitor system and whether significant evolutionary effects exist. We suggest that the variation of the carbon mass fraction $X$(C) in the C+O WD (or the variation of the initial WD mass) causes the diversity of the brightness of SNe Ia. This model can explain the observed dependences of SNe Ia brightness on the galaxy types and the distance from the galactic center. Finally, applying the metallicity effect on the evolution of SN Ia progenitors, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in different types of galaxies.

  10. Will Jets Identify the Progenitors of Type Ia Supernovae?

    E-Print Network [OSTI]

    Mario Livio; Adam Riess; William Sparks

    2002-04-26T23:59:59.000Z

    We use the fact that a Type Ia supernova has been serendipitously discovered near the jet of the active galaxy 3C 78 to examine the question of whether jets can enhance accretion onto white dwarfs. One interesting outcome of such a jet-induced accretion process is an enhanced rate of novae in the vicinity of jets. We present results of observations of the jet in M87 which appear to have indeed discovered 11 novae in close proximity to the jet. We show that a confirmation of the relation between jets and novae and Type Ia supernovae can finally identify the elusive progenitors of Type Ia supernovae.

  11. Single-Degenerate Type Ia Supernovae Are Preferentially Overluminous

    E-Print Network [OSTI]

    Fisher, Robert

    2015-01-01T23:59:59.000Z

    Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly-accreting Chandrasekhar mass white dwarfs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions. Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass white dwarfs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We thus infer that single-degenerate SNe Ia are gen...

  12. CIRCUMSTELLAR ABSORPTION IN DOUBLE DETONATION TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Shen, Ken J. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Guillochon, James [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Foley, Ryan J., E-mail: kenshen@astro.berkeley.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-06-20T23:59:59.000Z

    Upon formation, degenerate He core white dwarfs are surrounded by a radiative H-rich layer primarily supported by ideal gas pressure. In this Letter, we examine the effect of this H-rich layer on mass transfer in He+C/O double white dwarf binaries that will eventually merge and possibly yield a Type Ia supernova (SN Ia) in the double detonation scenario. Because its thermal profile and equation of state differ from the underlying He core, the H-rich layer is transferred stably onto the C/O white dwarf prior to the He core's tidal disruption. We find that this material is ejected from the binary system and sweeps up the surrounding interstellar medium hundreds to thousands of years before the SN Ia. The close match between the resulting circumstellar medium profiles and values inferred from recent observations of circumstellar absorption in SNe Ia gives further credence to the resurgent double detonation scenario.

  13. The Photometric Properties of Nearby Type Ia Supernovae

    E-Print Network [OSTI]

    Ganeshalingam, Mohan

    2012-01-01T23:59:59.000Z

    The Rise-Time Distribution of Nearby Type Ia Supernovae 3.1Highlight: The Physics of Supernovae, ed. W. Hillebrandt &1.1 Supernovae . . . . . . . . . . . . . . 1.1.1

  14. TYPE Ia SUPERNOVAE STRONGLY INTERACTING WITH THEIR CIRCUMSTELLAR MEDIUM

    SciTech Connect (OSTI)

    Silverman, Jeffrey M. [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States); Nugent, Peter E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gal-Yam, Avishay; Arcavi, Iair; Ben-Ami, Sagi [Benoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Howell, D. Andrew; Graham, Melissa L. [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Filippenko, Alexei V.; Bloom, Joshua S.; Cenko, S. Bradley; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cao, Yi; Horesh, Assaf; Kulkarni, Shrinivas R. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Chornock, Ryan; Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Coil, Alison L. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Griffith, Christopher V. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Kasliwal, Mansi M., E-mail: jsilverman@astro.as.utexas.edu [Observatories of the Carnegie Institution of Science, Pasadena, CA 91101 (United States); and others

    2013-07-01T23:59:59.000Z

    Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well studied previously, three were previously known but are analyzed in depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by H{alpha} emission (with widths of {approx}2000 km s{sup -1}) and exhibit large H{alpha}/H{beta} intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They also show possible evidence of dust formation through a decrease in the red wing of H{alpha} 75-100 days past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na I D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be -21.3 mag {<=} M{sub R} {<=} -19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population. This work represents the most detailed analysis of the SN Ia-CSM class to date.

  15. EARLY EMISSION FROM TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Rabinak, Itay; Waxman, Eli [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Livne, Eli, E-mail: itay.rabinak@weizmann.ac.il [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)

    2012-09-20T23:59:59.000Z

    A unique feature of deflagration-to-detonation (DDT) white dwarf explosion models of supernovae of type Ia is the presence of a strong shock wave propagating through the outer envelope. We consider the early emission expected in such models, which is produced by the expanding shock-heated outer part of the ejecta and precedes the emission driven by radioactive decay. We expand on earlier analyses by considering the modification of the pre-detonation density profile by the weak shocks generated during the deflagration phase, the time evolution of the opacity, and the deviation of the post-shock equation of state from that obtained for radiation pressure domination. A simple analytic model is presented and shown to provide an acceptable approximation to the results of one-dimensional numerical DDT simulations. Our analysis predicts a {approx}10{sup 3} s long UV/optical flash with a luminosity of {approx}1 to {approx}3 Multiplication-Sign 10{sup 39} erg s{sup -1}. Lower luminosity corresponds to faster (turbulent) deflagration velocity. The luminosity of the UV flash is predicted to be strongly suppressed at t > t{sub drop} {approx} 1 hr due to the deviation from pure radiation domination.

  16. US WNC MO Site Consumption

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro IndustriesTownDells,1Stocks Nov-14TotalThe Outlook269,023Year69,023USWNC MO Site

  17. alvos contendo mo: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CaMoO4 crystal scintillators. A high sensitivity experiment to search for neutrinoless double beta decay of 100-Mo by using CaMoO4 scintillators is discussed. Annenkov, A N;...

  18. Type Ia Supernova Explosion Models: Homogeneity versus Diversity

    E-Print Network [OSTI]

    W. Hillebrandt; J. C. Niemeyer; M. Reinecke

    2000-05-30T23:59:59.000Z

    Type Ia supernovae (SN Ia) are generally believed to be the result of the thermonuclear disruption of Chandrasekhar-mass carbon-oxygen white dwarfs, mainly because such thermonuclear explosions can account for the right amount of Ni-56, which is needed to explain the light curves and the late-time spectra, and the abundances of intermediate-mass nuclei which dominate the spectra near maximum light. Because of their enormous brightness and apparent homogeneity SN Ia have become an important tool to measure cosmological parameters. In this article the present understanding of the physics of thermonuclear explosions is reviewed. In particular, we focus our attention on subsonic (``deflagration'') fronts, i.e. we investigate fronts propagating by heat diffusion and convection rather than by compression. Models based upon this mode of nuclear burning have been applied very successfully to the SN Ia problem, and are able to reproduce many of their observed features remarkably well. However, the models also indicate that SN Ia may differ considerably from each other, which is of importance if they are to be used as standard candles.

  19. Simulations of Turbulent Thermonuclear Burning in Type Ia Supernovae

    E-Print Network [OSTI]

    W. Hillebrandt; M. Reinecke; W. Schmidt; F. K. Roepke; C. Travaglio; J. C. Niemeyer

    2004-05-11T23:59:59.000Z

    Type Ia supernovae have recently received considerable attention because it appears that they can be used as "standard candles" to measure cosmic distances out to billions of light years away from us. Observations of type Ia supernovae seem to indicate that we are living in a universe that started to accelerate its expansion when it was about half its present age. These conclusions rest primarily on phenomenological models which, however, lack proper theoretical understanding, mainly because the explosion process, initiated by thermonuclear fusion of carbon and oxygen into heavier elements, is difficult to simulate even on supercomputers. Here, we investigate a new way of modeling turbulent thermonuclear deflagration fronts in white dwarfs undergoing a type Ia supernova explosion. Our approach is based on a level set method which treats the front as a mathematical discontinuity and allows for full coupling between the front geometry and the flow field. New results of the method applied to the problem of type Ia supernovae are obtained. It is shown that in 2-D with high spatial resolution and a physically motivated subgrid scale model for the nuclear flames numerically "converged" results can be obtained, but for most initial conditions the stars do not explode. In contrast, simulations in 3-D, do give the desired explosions and many of their properties, such as the explosion energies, lightcurves and nucleosynthesis products, are in very good agreement with observed type Ia supernovae.

  20. K-corrections and extinction corrections for Type Ia supernovae

    SciTech Connect (OSTI)

    Nugent, Peter; Kim, Alex; Perlmutter, Saul

    2002-05-21T23:59:59.000Z

    The measurement of the cosmological parameters from Type Ia supernovae hinges on our ability to compare nearby and distant supernovae accurately. Here we present an advance on a method for performing generalized K-corrections for Type Ia supernovae which allows us to compare these objects from the UV to near-IR over the redshift range 0 < z < 2. We discuss the errors currently associated with this method and how future data can improve upon it significantly. We also examine the effects of reddening on the K-corrections and the light curves of Type Ia supernovae. Finally, we provide a few examples of how these techniques affect our current understanding of a sample of both nearby and distant supernovae.

  1. The ignition of thermonuclear flames in Type Ia supernovae

    E-Print Network [OSTI]

    L. Iapichino; M. Brüggen; W. Hillebrandt; J. C. Niemeyer

    2005-12-12T23:59:59.000Z

    In the framework of the Chandrasekhar-mass deflagration model for Type Ia supernovae (SNe Ia), a persisting free parameter is the initial morphology of the flame front, which is linked to the ignition process in the progenitor white dwarf. Previous analytical models indicate that the thermal runaway is driven by temperature perturbations (''bubbles'') that develop in the white dwarf's convective core. In order to probe the conditions at ignition (diameters, temperatures and evolutionary timescales), we have performed hydrodynamical 2D simulations of buoyant bubbles in white dwarf interiors. Our results show that fragmentation occurring during the bubble rise affects the outcome of the bubble evolution. Possible implications for the ignition process of SNe Ia are discussed.

  2. Refined numerical models for multidimensional Type Ia supernova simulations

    E-Print Network [OSTI]

    Reinecke, M; Niemeyer, J C

    2002-01-01T23:59:59.000Z

    Following up on earlier work on this topic (Reinecke et al. 1999, A&A 347, pp. 724 and 739), we present an improved set of numerical models for simulations of white dwarfs exploding as Type Ia supernovae (SNe Ia). Two-dimensional simulations were used to test the reliability and numerical robustness of these algorithms; the results indicate that integral quantities like the total energy release are insensitive to changes of the grid resolution (above a certain threshold), which was not the case for our former code. The models were further enhanced to allow fully three-dimensional simulations of SNe Ia. A direct comparison of a 2D and a 3D calculation with identical initial conditions shows that the explosion is considerably more energetic in three dimensions; this is most likely caused by the assumption of axisymmetry in 2D, which inhibits the growth of flame instabilities in the azimuthal direction and thereby decreases the flame surface.

  3. Refined numerical models for multidimensional Type Ia supernova simulations

    E-Print Network [OSTI]

    M. Reinecke; W. Hillebrandt; J. C. Niemeyer

    2001-11-26T23:59:59.000Z

    Following up on earlier work on this topic (Reinecke et al. 1999, A&A 347, pp. 724 and 739), we present an improved set of numerical models for simulations of white dwarfs exploding as Type Ia supernovae (SNe Ia). Two-dimensional simulations were used to test the reliability and numerical robustness of these algorithms; the results indicate that integral quantities like the total energy release are insensitive to changes of the grid resolution (above a certain threshold), which was not the case for our former code. The models were further enhanced to allow fully three-dimensional simulations of SNe Ia. A direct comparison of a 2D and a 3D calculation with identical initial conditions shows that the explosion is considerably more energetic in three dimensions; this is most likely caused by the assumption of axisymmetry in 2D, which inhibits the growth of flame instabilities in the azimuthal direction and thereby decreases the flame surface.

  4. The ignition of thermonuclear flames in Type Ia supernovae

    E-Print Network [OSTI]

    Iapichino, L; Hillebrandt, W; Niemeyer, J C

    2005-01-01T23:59:59.000Z

    In the framework of the Chandrasekhar-mass deflagration model for Type Ia supernovae (SNe Ia), a persisting free parameter is the initial morphology of the flame front, which is linked to the ignition process in the progenitor white dwarf. Previous analytical models indicate that the thermal runaway is driven by temperature perturbations (''bubbles'') that develop in the white dwarf's convective core. In order to probe the conditions at ignition (diameters, temperatures and evolutionary timescales), we have performed hydrodynamical 2D simulations of buoyant bubbles in white dwarf interiors. Our results show that fragmentation occurring during the bubble rise affects the outcome of the bubble evolution. Possible implications for the ignition process of SNe Ia are discussed.

  5. Strong Ultraviolet Pulse From a Newborn Type Ia Supernova

    E-Print Network [OSTI]

    Cao, Yi; Howell, D Andrew; Gal-Yam, Avishay; Kasliwal, Mansi M; Valenti, Stefano; Johansson, J; Amanullah, R; Goobar, A; Sollerman, J; Taddia, F; Horesh, Assaf; Sagiv, Ilan; Cenko, S Bradley; Nugent, Peter E; Arcavi, Iair; Surace, Jason; Wo?niak, P R; Moody, Daniela I; Rebbapragada, Umaa D; Bue, Brian D; Gehrels, Neil

    2015-01-01T23:59:59.000Z

    Type Ia supernovae are destructive explosions of carbon oxygen white dwarfs. Although they are used empirically to measure cosmological distances, the nature of their progenitors remains mysterious, One of the leading progenitor models, called the single degenerate channel, hypothesizes that a white dwarf accretes matter from a companion star and the resulting increase in its central pressure and temperature ignites thermonuclear explosion. Here we report observations of strong but declining ultraviolet emission from a Type Ia supernova within four days of its explosion. This emission is consistent with theoretical expectations of collision between material ejected by the supernova and a companion star, and therefore provides evidence that some Type Ia supernovae arise from the single degenerate channel.

  6. Diagnosing multiplicative error by lensing magnification of type Ia supernovae

    E-Print Network [OSTI]

    Zhang, Pengjie

    2015-01-01T23:59:59.000Z

    Weak lensing causes spatially coherent fluctuations in flux of type Ia supernovae (SNe Ia). This lensing magnification allows for weak lensing measurement independent of cosmic shear. It is free of shape measurement errors associated with cosmic shear and can therefore be used to diagnose and calibrate multiplicative error. Although this lensing magnification is difficult to measure accurately in auto correlation, its cross correlation with cosmic shear and galaxy distribution in overlapping area can be measured to significantly higher accuracy. Therefore these cross correlations can put useful constraint on multiplicative error, and the obtained constraint is free of cosmic variance in weak lensing field. We present two methods implementing this idea and estimate their performances. We find that, with $\\sim 1$ million SNe Ia that can be achieved by the proposed D2k survey with the LSST telescope (Zhan et al. 2008), multiplicative error of $\\sim 0.5\\%$ for source galaxies at $z_s\\sim 1$ can be detected and la...

  7. Type Ia supernovae from merging white dwarfs. I. Prompt detonations

    SciTech Connect (OSTI)

    Moll, R.; Woosley, S. E. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Raskin, C.; Kasen, D. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2014-04-20T23:59:59.000Z

    Merging white dwarfs are a possible progenitor of Type Ia supernovae (SNe Ia). Numerical models suggest that a detonation might be initiated before the stars have coalesced to form a single compact object. Here we study such prompt detonations by means of numerical simulations, modeling the disruption and nucleosynthesis of the stars until the ejecta reach the coasting phase, and generating synthetic light curves and spectra. Three models are considered with primary masses 0.96 M {sub ?}, 1.06 M {sub ?}, and 1.20 M {sub ?}. Of these, the 0.96 M {sub ?} dwarf merging with a 0.81 M {sub ?} companion, with an {sup 56}Ni yield of 0.58 M {sub ?}, is the most promising candidate for reproducing common SNe Ia. The more massive mergers produce unusually luminous SNe Ia with peak luminosities approaching those attributed to 'super-Chandrasekhar' mass SNe Ia. While the synthetic light curves and spectra of some of the models resemble observed SNe Ia, the significant asymmetry of the ejecta leads to large orientation effects. The peak bolometric luminosity varies by more than a factor of two with the viewing angle, and the velocities of the spectral absorption features are lower when observed from angles where the light curve is brightest. The largest orientation effects are seen in the ultraviolet, where the flux varies by more than an order of magnitude. The set of three models roughly obeys a width-luminosity relation, with the brighter light curves declining more slowly in the B band. Spectral features due to unburned carbon from the secondary star are also seen in some cases.

  8. SPECTROSCOPY OF TYPE Ia SUPERNOVAE BY THE CARNEGIE SUPERNOVA PROJECT

    SciTech Connect (OSTI)

    Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, 277-8583 Kashiwa (Japan); Morrell, Nidia; Phillips, Mark M.; Hsiao, Eric; Campillay, Abdo; Contreras, Carlos; Castellon, Sergio; Roth, Miguel [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Hamuy, Mario; Anderson, Joseph P. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Krzeminski, Wojtek [N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa (Poland); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Burns, Christopher R.; Freedman, Wendy L.; Madore, Barry F.; Murphy, David; Persson, S. E. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Prieto, Jose L. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Ln., Princeton, NJ 08544 (United States); Suntzeff, Nicholas B.; Krisciunas, Kevin, E-mail: gaston.folatelli@ipmu.jp [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); and others

    2013-08-10T23:59:59.000Z

    This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of Almost-Equal-To 0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a Almost-Equal-To 2{sigma}-3{sigma} correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.

  9. FIRST EVIDENCE OF GLOBULAR CLUSTER FORMATION FROM THE EJECTA OF PROMPT TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Tsujimoto, Takuji [National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan); Bekki, Kenji, E-mail: taku.tsujimoto@nao.ac.jp [ICRAR, M468, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)

    2012-06-01T23:59:59.000Z

    Recent spectroscopic observations of globular clusters (GCs) in the Large Magellanic Cloud (LMC) have discovered that one of the intermediate-age GCs, NGC 1718, with [Fe/H] = -0.7 has an extremely low [Mg/Fe] ratio of {approx}-0.9. We propose that NGC 1718 was formed from the ejecta of Type Ia supernovae mixed with very metal-poor ([Fe/H] <-1.3) gas about {approx}2 Gyr ago. The proposed scenario is shown to be consistent with the observed abundances of Fe-group elements such as Cr, Mn, and Ni. In addition, compelling evidence for asymptotic giant branch stars playing a role in chemical enrichment during this GC formation is found. We suggest that the origin of the metal-poor gas is closely associated with efficient gas transfer from the outer gas disk of the Small Magellanic Cloud to the LMC disk. We anticipate that the outer part of the LMC disk contains field stars exhibiting significantly low [Mg/Fe] ratios, formed through the same process as NGC 1718.

  10. Sampling the Probability Distribution of Type Ia Supernova Lightcurve Parameters in Cosmological Analysis

    E-Print Network [OSTI]

    Dai, Mi

    2015-01-01T23:59:59.000Z

    In order to obtain robust cosmological constraints from Type Ia supernova (SN Ia) data, we have applied Markov Chain Monte Carlo (MCMC) to SN Ia lightcurve fitting. We develop a method for sampling the resultant probability density distributions (pdf) of the SN Ia lightcuve parameters in the MCMC likelihood analysis to constrain cosmological parameters. Applying this method to the Joint Lightcurve Analysis (JLA) data set of SNe Ia, we find that sampling the SN Ia lightcurve parameter pdf's leads to cosmological parameters closer to that of a flat Universe with a cosmological constant, compared to the usual practice of using only the best fit values of the SN Ia lightcurve parameters. Our method will be useful in the use of SN Ia data for precision cosmology.

  11. Spectral Observations and Analyses of Low-Redshift Type Ia Supernovae

    E-Print Network [OSTI]

    Silverman, Jeffrey Michael

    2011-01-01T23:59:59.000Z

    1.3.2 Thermonuclear Supernovae . . . . . . . . 1.4 Why WriteIa are the result of thermonuclear explosions of C/O whiteIa are the result of thermonuclear explosions of C/O white

  12. CfA3: 185 TYPE Ia SUPERNOVA LIGHT CURVES FROM THE CfA

    E-Print Network [OSTI]

    Krauss, Miriam

    We present multiband photometry of 185 type-Ia supernovae (SNe Ia), with over 11,500 observations. These were acquired between 2001 and 2008 at the F. L. Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics ...

  13. Feasibility of Measuring the Cosmological Constant [LAMBDA] and Mass Density [Omega] using Type Ia Supernovae

    E-Print Network [OSTI]

    Goobar, A.

    2008-01-01T23:59:59.000Z

    at z = 1. uncertainty for supernovae at z = 1. mR Adding theMass Density .Q Using Type Ia Supernovae A. Goobar and S.Density Q Using Type Ia Supernovae Ariel Goobar l and Saul

  14. UV Spectroscopy of Type Ia Supernovae at Low- and High-Redshift

    E-Print Network [OSTI]

    Nugent, Peter

    2005-01-01T23:59:59.000Z

    Spectroscopy of Type Ia Supernovae at Low- and High-RedshiftUV properties of Type Ia Supernovae. The low-redshift studyULDA Access Guide No. 6: Supernovae, The Netherlands: ESA

  15. Nearby Supernova Factory Observations of SN 2006D: On Sporadic Carbon Signatures in Early Type Ia Supernova Spectra

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    with low volume-?lling factor. Subject headings: supernovae:general — supernovae: individual (SN 2006D)Introduction Type Ia supernovae (SNe Ia) make valuable

  16. Experto Universitario Java Enterprise 2012-2013 Depto. Ciencia de la Computacin e IA

    E-Print Network [OSTI]

    Escolano, Francisco

    Experto Universitario Java Enterprise © 2012-2013 Depto. Ciencia de la Computación e IA Lenguaje Lenguaje Java Avanzado © 2012-2013 Depto. Ciencia de la Computación e IA Lenguaje Java 2 Índice. Ciencia de la Computación e IA Lenguaje Java 3 Java · Java es un lenguaje OO creado por Sun Microsystems

  17. Experto Universitario Java Enterprise 2012-2013 Depto. Ciencia de la Computacin e IA

    E-Print Network [OSTI]

    Escolano, Francisco

    Experto Universitario Java Enterprise © 2012-2013 Depto. Ciencia de la Computación e IA Lenguaje Avanzado © 2012-2013 Depto. Ciencia de la Computación e IA Depuración y logs - 2 · El depurador de Eclipse Enterprise Lenguaje Java Avanzado © 2012-2013 Depto. Ciencia de la Computación e IA Depuración y logs - 3 El

  18. Innovation Academy Change of Major Form (Out of IA) College of Agricultural and Life Sciences

    E-Print Network [OSTI]

    Jawitz, James W.

    Innovation Academy Change of Major Form (Out of IA) College of Agricultural and Life Sciences Academy Change of Major Form (Out of IA) College of Agricultural and Life Sciences SECTION 3: TO BE COMPLETED BY THE INNOVATION ACADEMY ADVISER IA Adviser's Comments/Conditions (circle

  19. MoS2 Nanoribbons Thermoelectric Generators

    E-Print Network [OSTI]

    Arab, Abbas

    2015-01-01T23:59:59.000Z

    In this work, we have designed and simulated new thermoelectric generator based on monolayer and few-layer MoS2 nanoribbons. The proposed thermoelectric generator is composed of thermocouples made of both n-type and p-type MoS2 nanoribbon legs. Density Functional Tight-Binding Non-Equilibrium Green's Function (DFTB-NEGF) method has been used to calculate the transmission spectrum of MoS2 armchair and zigzag nanoribbons. Phonon transmission spectrum are calculated based on parameterization of Stillinger-Weber potential. Thermoelectric figure of merit, ZT, is calculated using these electronic and phonon transmission spectrum. Monolayer and bilayer MoS2 armchair nanoribbons are found to have the highest ZT value for p-type and n-type legs, repectively. Moreover, we have compared the thermoelectric current of doped monolayer MoS2 armchair nanoribbons and SZi thin films. Results indicate that thermoelectric current of MoS2 monolayer nanoribbons is several orders of magnitude higher than that of Si thin films.

  20. Type Ia supernovae from exploding oxygen-neon white dwarfs

    E-Print Network [OSTI]

    Marquardt, Kai S; Ruiter, Ashley J; Seitenzahl, Ivo R; Ohlmann, Sebastian T; Kromer, Markus; Pakmor, Ruediger; Roepke, Friedrich K

    2015-01-01T23:59:59.000Z

    The progenitor problem of Type Ia supernovae (SNe Ia) is still unsolved. Most of these events are thought to be explosions of carbon-oxygen (CO) white dwarfs (WDs), but for many of the explosion scenarios, particularly those involving the externally triggered detonation of a sub-Chandrasekhar mass WD (sub-M Ch WD), there is also a possibility of having an oxygen-neon (ONe) WD as progenitor. We simulate detonations of ONe WDs and calculate synthetic observables from these models. The results are compared with detonations in CO WDs of similar mass and observational data of SNe Ia. We perform hydrodynamic explosion simulations of detonations in initially hydrostatic ONe WDs for a range of masses below the Chandrasekhar mass (M Ch), followed by detailed nucleosynthetic postprocessing with a 384-isotope nuclear reaction network. The results are used to calculate synthetic spectra and light curves, which are then compared with observations of SNe Ia. We also perform binary evolution calculations to determine the nu...

  1. Cosmic Supernova Rate History and Type Ia Supernova Progenitors

    E-Print Network [OSTI]

    Chiaki Kobayashi; Ken'ichi Nomoto; Takuji Tsujimoto

    2001-02-14T23:59:59.000Z

    Adopting a single degenerate scenario for Type Ia supernova progenitors with the metallicity effect, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in spiral and elliptical galaxies, and compare with the recent observational data up to z ~ 0.55.

  2. Probing the Type Ia environment with Light Echoes

    E-Print Network [OSTI]

    F. Patat

    2004-11-19T23:59:59.000Z

    In general, Light Echoes (LE) are beautiful, rather academical and therefore unavoidably useless phenomena. In some cases, however, they can give interesting information about the environment surrounding the exploding star. After giving a brief introduction to the subject, I describe its application to the case of Type Ia Supernovae and discuss the implications for progenitors and their location within the host galaxies.

  3. Weld Surfacing Edited by Dr I.A. Bucklow

    E-Print Network [OSTI]

    Cambridge, University of

    becomesconfigurationally frozen at a temperature of about 1150°Cduring deposition by the manual-metal-arc welding techniqueV01.II Weld Surfacing Edited by Dr I.A. Bucklow ConferenceTechnicalDirector Organised by The Welding Institute in associationwith The Surface Engineering Society THE WELDING INSTITUTE #12;L

  4. Signatures of Explosion Models for SN ~Ia & Cosmology

    E-Print Network [OSTI]

    P. Hoeflich

    2004-09-07T23:59:59.000Z

    We give an overview of the current understanding of Type Ia supernovae relevant for their use as cosmological distance indicators. We present the physical basis to understand their homogeneity of the observed light curves and spectra and the observed correlations. SNe Ia have been well established as distance indicators on the 10 % level. However, the quest for the nature of the dark energy requires improvements in the accuracy to the 2 to 3 % level, we must understand the diversity within the SNe Ia population, and its evolution with redshift. Based on detailed models for the progenitors, explosions, light curves and spectra, we discuss signatures of thermonuclear explosions, and the implications for cosmology. We emphasize the relation between LC properties and spectra because, for local SNe~Ia, the diversity becomes apparent the combination of spectra and LCs whereas, by enlarge, we have to for high-z objects. At some examples, we show how we can actually probe the properties of the progenitor, its environment, and details of the explosion physics.

  5. Type Ia Supernova Cosmology in the Near-Infrared

    E-Print Network [OSTI]

    Stanishev, V; Amanullah, R; Bassett, B; Fantaye, Y T; Garnavich, P; Hlozek, R; Nordin, J; Okouma, P M; Ostman, L; Sako, M; Scalzo, R; Smith, M

    2015-01-01T23:59:59.000Z

    We main goal of this paper is to test whether the NIR peak magnitudes of SNe Ia could be accurately estimated with only a single observation obtained close to maximum light, provided the time of B band maximum and the optical stretch parameter are known. We obtained multi-epoch UBVRI and single-epoch J and H photometric observations of 16 SNe Ia in the redshift range z=0.037-0.183, doubling the leverage of the current SN Ia NIR Hubble diagram and the number of SNe beyond redshift 0.04. This sample was analyzed together with 102 NIR and 458 optical light curves (LCs) of normal SNe Ia from the literature. The analysis of 45 well-sampled NIR LCs shows that a single template accurately describes them if its time axis is stretched with the optical stretch parameter. This allows us to estimate the NIR peak magnitudes even with one observation obtained within 10 days from B-band maximum. We find that the NIR Hubble residuals show weak correlation with DM_15 and E(B-V), and for the first time we report a possible dep...

  6. On the Explosion Mechanism of SNe Type Ia

    E-Print Network [OSTI]

    M. Reinecke; J. C. Niemeyer; W. Hillebrandt

    2001-11-26T23:59:59.000Z

    In this article we discuss the first simulations of two- and three-dimensional Type Ia supernovae with an improved hydrodynamics code. After describing the various enhancements, the obtained results are compared to those of earlier code versions, observational data and the findings of other researchers in this field.

  7. Could there be a hole in type Ia supernovae?

    SciTech Connect (OSTI)

    Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

    2004-04-23T23:59:59.000Z

    In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity.

  8. Nucleosynthesis in type Ia supernovae driven by asymmetric thermonuclear ignition

    SciTech Connect (OSTI)

    Maeda, Keiichi [Institute for the Physics and Mathematics of the Universe (IPMU), Todai Institutes for Advanced Study (TODIAS), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)

    2012-11-12T23:59:59.000Z

    Type Ia Supernovae (SNe Ia) are believed to be thermonuclear explosions of a white dwarf. They can be used as mature cosmological standardized candles, leading to the discovery of the accelerating expansion of the Universe. However, the explosion mechanism has not yet been fully clarified. In this paper, we first present nucleosynthetic features of a leading explosion scenario, namely a delayed-detonation scenario. Based on this, we propose a new and strong observational constraint on the explosion mechanism through emission lines from neutron-rich Fe-peaks. Especially, we show that an asymmetry in the explosion is likely a generic feature. We further argue that the diversity arising from various viewing angles can be an origin of observational diversities of SNe Ia seen in their spectral features (suspected possible biases in cosmology) and colors (related to the extinction estimate in cosmology). Using these new insights could open up a possibility of using SNe Ia as more precise distance indicators than currently employed.

  9. Effect of nuclear structure on Type Ia supernova nucleosynthesis

    E-Print Network [OSTI]

    D. J. Dean

    2000-12-08T23:59:59.000Z

    The relationship among nuclear structure, the weak processes in nuclei, and astrophysics becomes quite apparent in supernova explosion and nucleosynthesis studies. In this brief article, I report on progress made in the last few years on calculating electron capture and beta-decay rates in iron-group nuclei. I also report on applications of these rates to Type-Ia nucleosynthesis studies.

  10. Thermonuclear supernova models, and observations of Type Ia supernovae

    E-Print Network [OSTI]

    E. Bravo; C. Badenes; D. Garcia-Senz

    2004-12-07T23:59:59.000Z

    In this paper, we review the present state of theoretical models of thermonuclear supernovae, and compare their predicitions with the constraints derived from observations of Type Ia supernovae. The diversity of explosion mechanisms usually found in one-dimensional simulations is a direct consequence of the impossibility to resolve the flame structure under the assumption of spherical symmetry. Spherically symmetric models have been successful in explaining many of the observational features of Type Ia supernovae, but they rely on two kinds of empirical models: one that describes the behaviour of the flame on the scales unresolved by the code, and another that takes account of the evolution of the flame shape. In contrast, three-dimensional simulations are able to compute the flame shape in a self-consistent way, but they still need a model for the propagation of the flame in the scales unresolved by the code. Furthermore, in three dimensions the number of degrees of freedom of the initial configuration of the white dwarf at runaway is much larger than in one dimension. Recent simulations have shown that the sensitivity of the explosion output to the initial conditions can be extremely large. New paradigms of thermonuclear supernovae have emerged from this situation, as the Pulsating Reverse Detonation. The resolution of all these issues must rely on the predictions of observational properties of the models, and their comparison with current Type Ia supernova data, including X-ray spectra of Type Ia supernova remnants.

  11. Highly Active Yeast MnSOD has a Novel Mechanism Involving Six-coordinate Mn(3+) Species

    E-Print Network [OSTI]

    Sheng, Yuewei

    2012-01-01T23:59:59.000Z

    2009) Functional roles of the tetramer organization of malicGrez, M. (2010) Dimer-tetramer transition controls RUNX1/ETOdimer, Å) Mn•••Mn (A/C, tetramer, Å) Mn•••Mn (A/D, tetramer,

  12. Structure and magnetic properties of rf thermally plasma synthesized Mn and MnZn ferrite nanoparticles

    E-Print Network [OSTI]

    McHenry, Michael E.

    Structure and magnetic properties of rf thermally plasma synthesized Mn and Mn­Zn ferrite has previously been shown to be a viable route to producing nanocrystalline magnetite and Ni ferrite nanoparticles. In this work nanocrystalline powders of Mn and Mn­Zn ferrites have been synthesized using a 50 k

  13. Prompt {gamma}-ray spectroscopy of the {sup 104}Mo and {sup 108}Mo fission fragments

    SciTech Connect (OSTI)

    Guessous, A.; Schulz, N.; Bentaleb, M.; Lubkiewicz, E. [Centre de Recherches Nucleaires, Institut National de Physique Nucleaire et de Physique des Particules, Centre National de la Recherche Scientifique, Universite Louis Pasteur, 67037 Strasbourg (France)] [Centre de Recherches Nucleaires, Institut National de Physique Nucleaire et de Physique des Particules, Centre National de la Recherche Scientifique, Universite Louis Pasteur, 67037 Strasbourg (France); Durell, J.L.; Pearson, C.J.; Phillips, W.R.; Shannon, J.A.; Urban, W.; Varley, B.J. [Department of Physics, University of Manchester, M13 9PL (United Kingdom)] [Department of Physics, University of Manchester, M13 9PL (United Kingdom); Ahmad, I.; Lister, C.J.; Morss, L.R.; Nash, K.L.; Williams, C.W. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Khazrouni, S. [Laboratoire de Physique Nucleaire Appliquee, Faculte des Sciences, Kenitra, Maroc (France)] [Laboratoire de Physique Nucleaire Appliquee, Faculte des Sciences, Kenitra, Maroc (France)

    1996-03-01T23:59:59.000Z

    The level structures of the neutron-rich {sup 104}Mo and {sup 108}Mo nuclei have been investigated by observing prompt {gamma} rays emitted in the spontaneous fission of {sup 248}Cm with the EUROGAM spectrometer. Levels with spins up to 12{h_bar} have been observed and {gamma} branching obtained. The data can be satisfactorily described when {sup 104,108}Mo are considered as axially symmetric nuclei: in {sup 104}Mo, rotational bands based on the ground state, the one-phonon and the two-phonon {gamma}-vibrational states and a quasiparticle state have been observed, whereas in {sup 108}Mo the information is limited to the yrast band and the one phonon {gamma} band. {copyright} {ital 1996 The American Physical Society.}

  14. Tunable MoS{sub 2} bandgap in MoS{sub 2}-graphene heterostructures

    SciTech Connect (OSTI)

    Ebnonnasir, Abbas [Department of Mechanical Engineering and Materials Science Program, Colorado School of Mines, Golden, Colorado 80401 (United States); Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, California 90095 (United States); Narayanan, Badri; Ciobanu, Cristian V., E-mail: cciobanu@mines.edu, E-mail: kodambaka@ucla.edu [Department of Mechanical Engineering and Materials Science Program, Colorado School of Mines, Golden, Colorado 80401 (United States); Kodambaka, Suneel, E-mail: cciobanu@mines.edu, E-mail: kodambaka@ucla.edu [Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, California 90095 (United States)

    2014-07-21T23:59:59.000Z

    Using density functional theory calculations with van der Waals corrections, we investigated how the interlayer orientation affects the structure and electronic properties of MoS{sub 2}-graphene bilayer heterostructures. Changing the orientation of graphene with respect to MoS{sub 2} strongly influences the type and the value of the electronic bandgap in MoS{sub 2}, while not significantly altering the binding energy between the layers or the interlayer spacing. We show that the physical origin of this tunable bandgap arises from variations in the S–S interplanar distance (MoS{sub 2} thickness) with the interlayer orientation, variations which are caused by electron transfer away from the Mo–S bonds.

  15. Low-Metallicity Inhibition of Type Ia Supernovae and Galactic and Cosmic Chemical Evolution

    E-Print Network [OSTI]

    Chiaki Kobayashi; Takuji Tsujimoto; Ken'ich Nomoto; Izumi Hachisu; Mariko Kato

    1998-06-25T23:59:59.000Z

    We introduce a metallicity dependence of Type Ia supernova (SN Ia) rate into the Galactic and cosmic chemical evolution models. In our SN Ia progenitor scenario, the accreting white dwarf (WD) blows a strong wind to reach the Chandrasekhar mass limit. If the iron abundance of the progenitors is as low as [Fe/H] 1-2, SNe Ia can be found only in the environments where the timescale of metal enrichment is sufficiently short as in starburst galaxies and ellipticals. The low-metallicity inhibition of SNe Ia can shed new light on the following issues: 1) The limited metallicity range of the SN Ia progenitors would imply that ``evolution effects'' are relatively small for the use of high redshift SNe Ia to determine the cosmological parameters. 2) WDs of halo populations are poor producers of SNe Ia, so that the WD contribution to the halo mass is not constrained from the iron abundance in the halo. 3) The abundance patterns of globular clusters and field stars in the Galactic halo lack of SN Ia signatures in spite of their age difference of several Gyrs, which can be explained by the low-metallicity inhibition of SNe Ia. 4) It could also explain why the SN Ia contamination is not seen in the damped Ly\\alpha systems for over a wide range of redshift.

  16. An Analysis of Department of Defense Instruction 8500.2 'Information Assurance (IA) Implementation.'

    SciTech Connect (OSTI)

    Campbell, Philip LaRoche

    2012-01-01T23:59:59.000Z

    The Department of Defense (DoD) provides its standard for information assurance in its Instruction 8500.2, dated February 6, 2003. This Instruction lists 157 'IA Controls' for nine 'baseline IA levels.' Aside from distinguishing IA Controls that call for elevated levels of 'robustness' and grouping the IA Controls into eight 'subject areas' 8500.2 does not examine the nature of this set of controls, determining, for example, which controls do not vary in robustness, how this set of controls compares with other such sets, or even which controls are required for all nine baseline IA levels. This report analyzes (1) the IA Controls, (2) the subject areas, and (3) the Baseline IA levels. For example, this report notes that there are only 109 core IA Controls (which this report refers to as 'ICGs'), that 43 of these core IA Controls apply without variation to all nine baseline IA levels and that an additional 31 apply with variations. This report maps the IA Controls of 8500.2 to the controls in NIST 800-53 and ITGI's CoBIT. The result of this analysis and mapping, as shown in this report, serves as a companion to 8500.2. (An electronic spreadsheet accompanies this report.)

  17. Comparative Study on the Corrosion Resistance of Fe-Based Amorphous Metal, Borated Stainless Steel and Ni-Cr-Mo-Gd Alloy

    SciTech Connect (OSTI)

    Lian, Tiangan; Day, Daniel; Hailey, Phillip; Choi, Jor-Shan; Farmer, Joseph [Lawrence Livermore National Laboratory, Livermore, CA, 94550 (United States)

    2007-07-01T23:59:59.000Z

    Iron-based amorphous alloy Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} was compared to borated stainless steel and Ni-Cr-Mo-Gd alloy on their corrosion resistance in various high-concentration chloride solutions. The melt-spun ribbon of this iron-based amorphous alloy have demonstrated a better corrosion resistance than the bulk borated stainless steel and the bulk Ni-Cr-Mo-Gd alloy, in high-concentration chloride brines at temperatures 90 deg. C or higher. (authors)

  18. Elevated Temperature Tensile Tests on DU–10Mo Rolled Foils

    SciTech Connect (OSTI)

    Jason Schulthess

    2014-09-01T23:59:59.000Z

    Tensile mechanical properties for uranium-10 wt.% molybdenum (U–10Mo) foils are required to support modeling and qualification of new monolithic fuel plate designs. It is expected that depleted uranium-10 wt% Mo (DU–10Mo) mechanical behavior is representative of the low enriched U–10Mo to be used in the actual fuel plates, therefore DU-10Mo was studied to simplify material processing, handling, and testing requirements. In this report, tensile testing of DU-10Mo fuel foils prepared using four different thermomechanical processing treatments were conducted to assess the impact of foil fabrication history on resultant tensile properties.

  19. Wetting of metals and glasses on Mo

    SciTech Connect (OSTI)

    Saiz, Eduardo; Tomsia, Antoni P.; Saiz, Eduardo; Lopez-Esteban, Sonia; Benhassine, Mehdi; de Coninck, Joel; Rauch, Nicole; Ruehle, Manfred

    2008-01-08T23:59:59.000Z

    The wetting of low melting point metals and Si-Ca-Al-Ti-O glasses on molybdenum has been investigated. The selected metals (Au, Cu, Ag) form a simple eutectic with Mo. Metal spreading occurs under nonreactive conditions without interdiffusion or ridge formation. The metals exhibit low (non-zero) contact angles on Mo but this requires temperatures higher than 1100 C in reducing atmospheres in order to eliminate a layer of adsorbed impurities on the molybdenum surface. By controlling the oxygen activity in the furnace, glass spreading can take place under reactive or nonreactive conditions. We have found that in the glass/Mo system the contact angle does not decrease under reactive conditions. In all cases, adsorption from the liquid seems to accelerate the diffusivity on the free molybdenum surface.

  20. Learning from the Scatter in Type Ia Supernovae

    E-Print Network [OSTI]

    Scott Dodelson; Alberto Vallinotto

    2005-11-02T23:59:59.000Z

    Type Ia Supernovae are standard candles so their mean apparent magnitude has been exploited to learn about the redshift-distance relationship. Besides intrinsic scatter in this standard candle, additional source of scatter is caused by gravitational magnification by large scale structure. Here we probe the dependence of this dispersion on cosmological parameters and show that information about the amplitude of clustering, \\sigma_8, is contained in the scatter. In principle, it will be possible to constrain \\sigma_8 to within 5% with observations of 2000 Type Ia Supernovae. However, extracting this information requires subtlety as the distribution of magnifications is far from Gaussian. If one incorrectly assumes a Gaussian distribution, the estimate of the clustering amplitude will be biased three-\\sigma away from the true value.

  1. Multi-spot ignition in type Ia supernova models

    E-Print Network [OSTI]

    Roepke, F K; Niemeyer, J C; Woosley, S E

    2005-01-01T23:59:59.000Z

    We present a systematic survey of the capabilities of type Ia supernova explosion models starting from a number of flame seeds distributed around the center of the white dwarf star. To this end we greatly improved the resolution of the numerical simulations in the initial stages. This novel numerical approach facilitates a detailed study of multi-spot ignition scenarios with up to hundreds of ignition sparks. Two-dimensional simulations are shown to be inappropriate to study the effects of initial flame configurations. Based on a set of three-dimensional models, we conclude that multi-spot ignition scenarios may improve type Ia supernova models towards better agreement with observations. The achievable effect reaches a maximum at a limited number of flame ignition kernels as shown by the numerical models and corroborated by a simple dimensional analysis.

  2. Multi-spot ignition in type Ia supernova models

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt; J. C. Niemeyer; S. E. Woosley

    2005-10-17T23:59:59.000Z

    We present a systematic survey of the capabilities of type Ia supernova explosion models starting from a number of flame seeds distributed around the center of the white dwarf star. To this end we greatly improved the resolution of the numerical simulations in the initial stages. This novel numerical approach facilitates a detailed study of multi-spot ignition scenarios with up to hundreds of ignition sparks. Two-dimensional simulations are shown to be inappropriate to study the effects of initial flame configurations. Based on a set of three-dimensional models, we conclude that multi-spot ignition scenarios may improve type Ia supernova models towards better agreement with observations. The achievable effect reaches a maximum at a limited number of flame ignition kernels as shown by the numerical models and corroborated by a simple dimensional analysis.

  3. Type Ia Supernova Spectral Line Ratios as LuminosityIndicators

    SciTech Connect (OSTI)

    Bongard, Sebastien; Baron, E.; Smadja, G.; Branch, David; Hauschildt, Peter H.

    2005-12-07T23:59:59.000Z

    Type Ia supernovae have played a crucial role in thediscovery of the dark energy, via the measurement of their light curvesand the determination of the peak brightness via fitting templates to theobserved lightcurve shape. Two spectroscopic indicators are also known tobe well correlated with peak luminosity. Since the spectroscopicluminosity indicators are obtained directly from observed spectra, theywill have different systematic errors than do measurements usingphotometry. Additionally, these spectroscopic indicators may be usefulfor studies of effects of evolution or age of the SNe~;Ia progenitorpopulation. We present several new variants of such spectroscopicindicators which are easy to automate and which minimize the effects ofnoise. We show that these spectroscopic indicators can be measured byproposed JDEM missions such as snap and JEDI.

  4. Investigating the Flame Microstructure in Type Ia Supernovae

    E-Print Network [OSTI]

    Roepke, F K; Niemeyer, J C

    2002-01-01T23:59:59.000Z

    We present a numerical model to study the behavior of thermonuclear flames in the discontinuity approximation. This model is applied to investigate the Landau-Darrieus instability under conditions found in Type Ia supernova explosions of Chandrasekhar mass white dwarfs. This is a first step to explore the flame microstructure in these events. The model reproduces Landau's linearized stability analysis in early stages of the flame evolution and the stabilization in a cellular flame structure in the nonlinear stage.

  5. Investigating the Flame Microstructure in Type Ia Supernovae

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt; J. C. Niemeyer

    2002-04-02T23:59:59.000Z

    We present a numerical model to study the behavior of thermonuclear flames in the discontinuity approximation. This model is applied to investigate the Landau-Darrieus instability under conditions found in Type Ia supernova explosions of Chandrasekhar mass white dwarfs. This is a first step to explore the flame microstructure in these events. The model reproduces Landau's linearized stability analysis in early stages of the flame evolution and the stabilization in a cellular flame structure in the nonlinear stage.

  6. Oxidation, Reduction, and Condensation of Alcohols over (MO3)3 (M=Mo, W) Nanoclusters

    SciTech Connect (OSTI)

    Fang, Zongtang; Li, Zhenjun; Kelley, Matthew S.; Kay, Bruce D.; Li, Shenggang; Hennigan, Jamie M.; Rousseau, Roger J.; Dohnalek, Zdenek; Dixon, David A.

    2014-10-02T23:59:59.000Z

    The reactions of deuterated methanol, ethanol, 1-propanol, 1-butanol, 2-propanol, 2-butanol and t-butanol over cyclic (MO3)3 (M = Mo, W) clusters were studied experimentally with temperature programmed desorption (TPD) and theoretically with coupled cluster CCSD(T) theory and density functional theory. The reactions of two alcohols per M3O9 cluster are required to provide agreement with experiment for D2O release, dehydrogenation and dehydration. The reaction begins with the elimination of water by proton transfers and forms an intermediate dialkoxy species which can undergo further reaction. Dehydration proceeds by a ? hydrogen transfer to a terminal M=O. Dehydrogenation takes place via an ? hydrogen transfer to an adjacent MoVI = O atom or a WVI metal center with redox involved for M = Mo and no redox for M = W. The two channels have comparable activation energies. H/D exchange to produce alcohols can take place after olefin is released or via the dialkoxy species depending on the alcohol and the cluster. The Lewis acidity of the metal center with WVI being larger than MoVI results in the increased reactivity of W3O9 over Mo3O9 for dehydrogenation and dehydration.

  7. Effect of Mn Concentration on the Structural, optical and Magnetic Properties of GaMnN

    SciTech Connect (OSTI)

    Thaler, G.; Frazier, R.; Gila, B.; Stapleton, J.; Davidson, M.; Abernathy, C.R.; Pearton, S.J.; Segre, C.U. (IIT); (Florida)

    2010-11-16T23:59:59.000Z

    The room temperature magnetization of GaMnN films grown by molecular beam epitaxy on (0001) sapphire substrates with Mn concentrations varying from 0 to 9 at. % was found to depend on Mn concentration, with a maximum magnetization found at -3 at. % Mn. High-resolution x-ray diffraction measurements show that the c-plane lattice constant initially decreases with increasing Mn concentration, then increases when the Mn content increases above -3 at. %. This increase is accompanied by a decrease in the full width at half maximum of the rocking curves. Extended x-ray absorption fine structure results indicate that the nonsubstitutional Mn is not present in the form of Ga{sub x}Mn{sub y} clusters and thus is most likely present in the form of an interstitial. Optical absorption measurements show only a slight increase in the band gap for material with 3 at. % Mn, relative to undoped GaN.

  8. X- and Gamma-Ray Flashes from Type Ia Supernovae?

    E-Print Network [OSTI]

    Hoflich, Peter

    2009-01-01T23:59:59.000Z

    We investigate two potential mechanisms that will produce X-ray and gamma-ray flashes from Type Ia supernovae (SN-Ia). The mechanisms are the breakout of the thermonuclear burning front as it reaches the surface of the white dwarf and the interaction of the rapidly expanding envelope with an accretion disk. Based on the delayed-detonation scenario and detailed radiation-hydro calculation which include nuclear networks, we find that both mechanisms produce ~1 second flashes of high energy radiation with peak luminosities of 10^48 to 10^50 erg/sec with fast rises and exponential declines. The X- and gamma-ray visibility of a SN-Ia will depend strongly on self absorption within the progenitor system, specifically on the properties of the accretion disk and its orientation towards the observer. Such X-ray and gamma-ray flashes could be detected as triggered events by Gamma-Ray Burst (GRB) detectors on satellites, with events in current GRB catalogs. We have searched through the GRB catalogs (for the BATSE, HETE, ...

  9. The type Ia supernovae and the Hubble's constant

    E-Print Network [OSTI]

    Ari Brynjolfsson

    2004-07-20T23:59:59.000Z

    The Hubble's constant is usually surmised to be a constant; but the experiments show a large spread and conflicting estimates. According to the plasma-redshift theory, the Hubble's constant varies with the plasma densities along the line of sight. It varies then slightly with the direction and the distance to a supernova and a galaxy. The relation between the magnitudes of type Ia supernovae and their observed redshifts results in an Hubble's constant with an average value in intergalactic space of 59.44 km per s per Mpc. The standard deviation from this average value is only 0.6 km per s per Mpc, but the standard deviation in a single measurement is about 8.2 km per s per Mpc. These deviations do not include possible absolute calibration errors. The experiments show that the Hubble's constant varies with the intrinsic redshifts of the Milky Way galaxy and the host galaxies for type Ia supernovae, and that it varies with the galactic latitude. These findings support the plasma-redshift theory and contradict the contemporary big-bang theory. Together with the previously reported absence of time dilation in type Ia supernovae measurements, these findings have profound consequences for the standard cosmological theory.

  10. Theoretical Clues to the Ultraviolet Diversity of Type Ia Supernovae

    E-Print Network [OSTI]

    Brown, Peter J; Milne, Peter; Roming, Peter W A; Wang, Lifan

    2015-01-01T23:59:59.000Z

    The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, ^56 Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of t...

  11. CARBON DEFLAGRATION IN TYPE Ia SUPERNOVA. I. CENTRALLY IGNITED MODELS

    SciTech Connect (OSTI)

    Ma, H.; Woosley, S. E.; Malone, C. M. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Almgren, A.; Bell, J. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Lab, Berkeley, CA 94720 (United States)

    2013-07-01T23:59:59.000Z

    A leading model for Type Ia supernovae (SNe Ia) begins with a white dwarf near the Chandrasekhar mass that ignites a degenerate thermonuclear runaway close to its center and explodes. In a series of papers, we shall explore the consequences of ignition at several locations within such dwarfs. Here we assume central ignition, which has been explored before, but is worth revisiting, if only to validate those previous studies and to further elucidate the relevant physics for future work. A perturbed sphere of hot iron ash with a radius of {approx}100 km is initialized at the middle of the star. The subsequent explosion is followed in several simulations using a thickened flame model in which the flame speed is either fixed-within the range expected from turbulent combustion-or based on the local turbulent intensity. Global results, including the explosion energy and bulk nucleosynthesis (e.g., {sup 56}Ni of 0.48-0.56 M{sub Sun }) turn out to be insensitive to this speed. In all completed runs, the energy released by the nuclear burning is adequate to unbind the star, but not enough to give the energy and brightness of typical SNe Ia. As found previously, the chemical stratification observed in typical events is not reproduced. These models produce a large amount of unburned carbon and oxygen in central low velocity regions, which is inconsistent with spectroscopic observations, and the intermediate mass elements and iron group elements are strongly mixed during the explosion.

  12. Mo Supply Chain for Nuclear Medicine Ladimer S. Nagurney

    E-Print Network [OSTI]

    Nagurney, Anna

    The 99 Mo Supply Chain for Nuclear Medicine Ladimer S. Nagurney Department of Electrical November 13, 2012 #12;Nuclear Medicine: Meeting Patient Needs with 99 Mo Ladimer S. Nagurney The 99 Mo Supply Chain #12;Background and Motivation Study of Nuclear Medicine Supply Chains is a combination

  13. Behavior of vortices near twin boundaries in underdoped Ba(Fe <mn>1mn> <mo>?> x Co x <mo stretchy="false">)mo> <mn>2mn> As <mn>2mn>

    SciTech Connect (OSTI)

    Kalisky, B.; Kirtley, J. R.; Analytis, J. G.; Chu, J.-H.; Fisher, I. R.; Moler, K. A.

    2011-02-01T23:59:59.000Z

    We use scanning superconducting quantum interference device (SQUID) microscopy to investigate the behavior of vortices in the presence of twin boundaries in the pnictide superconductor Ba(Fe1-xCox)?As?. We show that the vortices avoid pinning on twin boundaries. Individual vortices move in a preferential way when manipulated with the SQUID: They tend to not cross a twin boundary, but rather to move parallel to it. This behavior can be explained by the observation of enhanced superfluid density on twin boundaries in Ba(Fe1-xCox)?As?. The observed repulsion from twin boundaries may be a mechanism for enhanced critical currents observed in twinned samples in pnictides and other superconductors.

  14. Role of SrMoO{sub 4} in Sr{sub 2}MgMoO{sub 6} synthesis

    SciTech Connect (OSTI)

    Vasala, S.; Yamauchi, H. [Laboratory of Inorganic Chemistry, Department of Chemistry, School of Chemical Technology, Aalto University, P.O. Box 16100, FI-00076 Aalto (Finland); Karppinen, M., E-mail: maarit.karppinen@aalto.f [Laboratory of Inorganic Chemistry, Department of Chemistry, School of Chemical Technology, Aalto University, P.O. Box 16100, FI-00076 Aalto (Finland)

    2011-05-15T23:59:59.000Z

    Here we investigate the elemental and phase compositions during the solid-state synthesis of the promising SOFC-anode material, Sr{sub 2}MgMoO{sub 6}, and demonstrate that molybdenum does not notably evaporate under the normal synthesis conditions with temperatures up to 1200 {sup o}C due to the formation of SrMoO{sub 4} as an intermediate product at low temperatures, below 600 {sup o}C. However, partial decomposition of the Sr{sub 2}MgMoO{sub 6} phase becomes evident at the higher temperatures ({approx}1500 {sup o}C). The effect of SrMoO{sub 4} on the electrical conductivity of Sr{sub 2}MgMoO{sub 6} is evaluated by preparing a series of Sr{sub 2}MgMoO{sub 6} samples with different amounts of additional SrMoO{sub 4}. Under the reducing operation conditions of an SOFC anode the insulating SrMoO{sub 4} phase is apparently reduced to the highly conductive SrMoO{sub 3} phase. Percolation takes place with 20-30 wt% of SrMoO{sub 4} in a Sr{sub 2}MgMoO{sub 6} matrix, with a notable increase in electrical conductivity after reduction. Conductivity values of 14, 60 and 160 S/cm are determined at 800 {sup o}C in 5% H{sub 2}/Ar for the Sr{sub 2}MgMoO{sub 6} samples with 30, 40 and 50 wt% of added SrMoO{sub 4}, respectively. -- Graphical abstract: SrMoO{sub 4} is formed at low temperatures during the synthesis of Sr{sub 2}MgMoO{sub 6}, which prevents the volatilization of Mo from typical precursor mixtures of this promising SOFC anode material. SrMoO{sub 4} is insulating and it is often found as an impurity in Sr{sub 2}MgMoO{sub 6} samples. It is however readily reduced to highly conducting SrMoO{sub 3}. Composites of Sr{sub 2}MgMoO{sub 6} and SrMoO{sub 3} show increased electrical conductivities compared to pure Sr{sub 2}MgMoO{sub 6} under the reductive operation conditions of an SOFC anode. Display Omitted Highlights: {yields} Sr{sub 2}MgMoO{sub 6} is a promising SOFC anode material. {yields} During the Sr{sub 2}MgMoO{sub 6} synthesis SrMoO{sub 4} is formed at low temperatures. {yields} Formation of SrMoO{sub 4} effectively prevents volatilization of Mo at high temperatures. {yields} Insulating SrMoO{sub 4} reduces to highly conductive SrMoO{sub 3} under SOFC-anode conditions. {yields} Composites of Sr{sub 2}MgMoO{sub 6} and SrMoO{sub 3} show high electrical conductivities.

  15. Development of CaMoO4 crystal scintillators for double beta decay experiment with 100-Mo

    E-Print Network [OSTI]

    A. N. Annenkov; O. A. Buzanov; F. A. Danevich; A. Sh. Georgadze; S. K. Kim; H. J. Kim; Y. D. Kim; V. V. Kobychev; V. N. Kornoukhov; M. Korzhik; J. I. Lee; O. Missevitch; V. M. Mokina; S. S. Nagorny; A. S. Nikolaiko; D. V. Poda; R. B. Podviyanuk; D. J. Sedlak; O. G. Shkulkova; J. H. So; I. M. Solsky; V. I. Tretyak; S. S. Yurchenko

    2007-07-10T23:59:59.000Z

    Energy resolution, alpha/beta ratio, pulse-shape discrimination for gamma rays and alpha particles, temperature dependence of scintillation properties, and radioactive contamination were studied with CaMoO4 crystal scintillators. A high sensitivity experiment to search for neutrinoless double beta decay of 100-Mo by using CaMoO4 scintillators is discussed.

  16. THE IMPACT OF METALLICITY ON THE RATE OF TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Kistler, Matthew D. [California Institute of Technology, Mail Code 350-17, Pasadena, CA 91125 (United States); Stanek, K. Z.; Kochanek, Christopher S.; Thompson, Todd A. [Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Prieto, Jose L. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2013-06-20T23:59:59.000Z

    The metallicity of a star strongly affects both its evolution and the properties of the stellar remnant that results from its demise. It is generally accepted that stars with initial masses below {approx}8 M{sub Sun} leave behind white dwarfs and that some sub-population of these lead to Type Ia supernovae (SNe Ia). However, it is often tacitly assumed that metallicity has no effect on the rate of SNe Ia. We propose that a consequence of the effects of metallicity is to significantly increase the SN Ia rate in lower-metallicity galaxies, in contrast to previous expectations. This is because lower-metallicity stars leave behind higher-mass white dwarfs, which should be easier to bring to explosion. We first model SN Ia rates in relation to galaxy masses and ages alone, finding that the elevation in the rate of SNe Ia in lower-mass galaxies measured by Lick Observatory SN Search is readily explained. However, we then see that models incorporating this effect of metallicity agree just as well. Using the same parameters to estimate the cosmic SN Ia rate, we again find good agreement with data up to z Almost-Equal-To 2. We suggest that this degeneracy warrants more detailed examination of host galaxy metallicities. We discuss additional implications, including for hosts of high-z SNe Ia, the SN Ia delay time distribution, super-Chandrasekhar SNe, and cosmology.

  17. High-Redshift Type Ia Supernova Rates in Galaxy Cluster and Field Environments

    E-Print Network [OSTI]

    Barbary, Kyle Harris

    2011-01-01T23:59:59.000Z

    29 Candidates classified as supernovae . . . . . . . .1.1 Type Ia Supernovae as Standard Candles . . . . . . . .4.2.3 Supernovae . . . . . . . . . . . . . . . . 4.2.4

  18. Multi-layered Spectral Formation in SNe Ia Around Maximum Light

    E-Print Network [OSTI]

    Bongard, Sebastien

    2008-01-01T23:59:59.000Z

    stars: atmospheres — supernovae DISCLAIMER This document wasIntroduction Type Ia supernovæ have been used as “spanning the “normal” supernovæ blue magnitudes. Single Ion

  19. Timescale stretch parameterization of Type Ia supernova B-band light curves

    E-Print Network [OSTI]

    2001-01-01T23:59:59.000Z

    the light curve of Type Ia supernovae discovered by theof the high-redshift supernovae. This work was supported inobjects. Subject headings: supernovae: general – cosmology:

  20. HOST GALAXY PROPERTIES AND HUBBLE RESIDUALS OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

    SciTech Connect (OSTI)

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon (France); Universite de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucleaire de Lyon (France); and others

    2013-06-20T23:59:59.000Z

    We examine the relationship between Type Ia supernova (SN Ia) Hubble residuals and the properties of their host galaxies using a sample of 115 SNe Ia from the Nearby Supernova Factory. We use host galaxy stellar masses and specific star formation rates fitted from photometry for all hosts, as well as gas-phase metallicities for a subset of 69 star-forming (non-active galactic nucleus) hosts, to show that the SN Ia Hubble residuals correlate with each of these host properties. With these data we find new evidence for a correlation between SN Ia intrinsic color and host metallicity. When we combine our data with those of other published SN Ia surveys, we find the difference between mean SN Ia brightnesses in low- and high-mass hosts is 0.077 {+-} 0.014 mag. When viewed in narrow (0.2 dex) bins of host stellar mass, the data reveal apparent plateaus of Hubble residuals at high and low host masses with a rapid transition over a short mass range (9.8 {<=} log (M{sub *}/M{sub Sun }) {<=} 10.4). Although metallicity has been a favored interpretation for the origin of the Hubble residual trend with host mass, we illustrate how dust in star-forming galaxies and mean SN Ia progenitor age both evolve along the galaxy mass sequence, thereby presenting equally viable explanations for some or all of the observed SN Ia host bias.

  1. Direct numerical simulations of type Ia supernovae flames II: The rayleigh-taylor instability

    E-Print Network [OSTI]

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2004-01-01T23:59:59.000Z

    Weaver, T. A. 1994, in Supernovae, Les Houches, Session LIV,Simulations of Type Ia Supernovae Flames II: The Rayleigh-Subject headings: supernovae: general — white dwarfs —

  2. Structural And Physical Characterization of Tetranuclear [Mn**II(3)Mn**IV] And [Mn**II(2)Mn**III(2)] Valence-Isomer Manganese Complexes

    SciTech Connect (OSTI)

    Zaleski, C.M.; Weng, T.-C.; Dendrinou-Samara, C.; Alexiou, M.; Kanakaraki, P.; Hsieh, W.-Y.; Kampf, J.; Penner-Hahn, J.E.; Pecoraro, V.L.; Kessissoglou, D.P.

    2009-05-28T23:59:59.000Z

    Two tetranuclear Mn complexes with an average Mn oxidation state of +2.5 have been prepared. These valence isomers have been characterized by a combination of X-ray crystallography, X-ray absorption spectroscopy, and magnetic susceptibility. The Mn{sup II}{sub 3}Mn{sup IV} tetramer has the Mn ions arranged in a distorted tetrahedron, with an S = 6 ground spin state, dominated by ferromagnetic exchange among the manganese ions. The Mn{sup II}{sub 2}Mn{sup III}{sub 2} tetramer also has a distorted tetrahedral arrangement of Mn ions but shows magnetic behavior, suggesting that it is a single-molecule magnet. The X-ray absorption near-edge structure (XANES) spectra for the two complexes are similar, suggesting that, while Mn XANES has sufficient sensitivity to distinguish between trinuclear valence isomers (Alexiou et al. Inorg. Chem. 2003, 42, 2185), similar distinctions are difficult for tetranuclear complexes such as that found in the photosynthetic oxygen-evolving complex.

  3. Reflections on Reflexions: I. Light Echoes in Type Ia Supernovae

    E-Print Network [OSTI]

    F. Patat

    2004-09-28T23:59:59.000Z

    In the last ten years, observational evidences about a possible connection between Type Ia Supernovae (SNe) properties and the environment where they explode have been steadily growing. In this paper I discuss, from a theoretical point of view but with an observer's perspective, the usage of light echoes (LEs) to probe the CSM around SNe of Type Ia since, in principle, they give us a unique opportunity of getting a three-dimensional description of the SN environment. In turn, this can be used to check the often suggested association of some Ia's with dusty/star forming regions, which would point to a young population for the progenitors. After giving a brief introduction to the LE phenomenon in single scattering approximation, I derive analytical and numerical solutions for the optical light and colour curves for a few simple dust geometries. A fully 3D multiple scattering treatment has also been implemented in a Monte Carlo code, which I have used to investigate the effects of multiple scattering. In particular, I have explored in detail the LE colour dependency from time and dust distribution, since this is a promising tool to determine the dust density and derive the effective presence of multiple scattering from the observed properties. Finally, again by means of Monte Carlo simulations, I have studied the effects of multiple scattering on the LE linear polarization, analyzing the dependencies from the dust parameters and geometry. Both the analytical formalism and MC codes described in this paper can be used for any LE for which the light curve of the central source is known.

  4. The Carnegie Supernova Project: Intrinsic colors of type Ia supernovae

    SciTech Connect (OSTI)

    Burns, Christopher R.; Persson, S. E.; Freedman, Wendy L.; Madore, Barry F. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Stritzinger, Maximilian; Contreras, Carlos [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Phillips, M. M.; Hsiao, E. Y.; Boldt, Luis; Campillay, Abdo; Castellón, Sergio; Morrell, Nidia; Salgado, Francisco [Carnegie Institution of Washington, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, the University of Tokyo, 277-8583 Kashiwa (Japan); Suntzeff, Nicholas B. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, College Station, TX 77843 (United States)

    2014-07-01T23:59:59.000Z

    We present an updated analysis of the intrinsic colors of Type Ia supernova (SNe Ia) using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of 'normal' SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B – V light-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of R{sub V} , though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, R{sub V} , and the color excess, E(B – V), such that larger E(B – V) tends to favor lower R{sub V} . The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in R{sub V} or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.

  5. A Model for Multidimensional Delayed Detonations in SN Ia Explosions

    E-Print Network [OSTI]

    I. Golombek; J. C. Niemeyer

    2005-03-29T23:59:59.000Z

    We show that a flame tracking/capturing scheme originally developed for deflagration fronts can be used to model thermonuclear detonations in multidimensional explosion simulations of type Ia supernovae. After testing the accuracy of the front model, we present a set of two-dimensional simulations of delayed detonations with a physically motivated off-center deflagration-detonation-transition point. Furthermore, we demonstrate the ability of the front model to reproduce the full range of possible interactions of the detonation with clumps of burned material. This feature is crucial for assessing the viability of the delayed detonation scenario.

  6. Can Deflagration-Detonation-Transitions occur in Type Ia Supernovae?

    E-Print Network [OSTI]

    J. C. Niemeyer

    1999-07-19T23:59:59.000Z

    The mechanism for deflagration-detonation-transition (DDT) by turbulent preconditioning, suggested to explain the possible occurrence of delayed detonations in Type Ia supernova explosions, is argued to be conceptually inconsistent. It relies crucially on diffusive heat losses of the burned material on macroscopic scales. Regardless of the amplitude of turbulent velocity fluctuations, the typical gradient scale for temperature fluctuations is shown to be the laminar flame width or smaller, rather than the factor of thousand more required for a DDT. Furthermore, thermonuclear flames cannot be fully quenched in regions much larger than the laminar flame width as a consequence of their simple ``chemistry''. Possible alternative explosion scenarios are briefly discussed.

  7. Three-dimensional simulations of type Ia supernovae

    E-Print Network [OSTI]

    M. Reinecke; W. Hillebrandt; J. C. Niemeyer

    2002-06-26T23:59:59.000Z

    We present the results of three-dimensional hydrodynamical simulations of the subsonic thermonuclear burning phase in type Ia supernovae. The burning front model contains no adjustable parameters so that variations of the explosion outcome can be linked directly to changes in the initial conditions. In particular, we investigate the influence of the initial flame geometry on the explosion energy and find that it appears to be weaker than in 2D. Most importantly, our models predict global properties such as the produced nickel masses and ejecta velocities within their observed ranges without any fine tuning.

  8. Three-dimensional simulations of type Ia supernovae

    E-Print Network [OSTI]

    Reinecke, M; Niemeyer, J C

    2002-01-01T23:59:59.000Z

    We present the results of three-dimensional hydrodynamical simulations of the subsonic thermonuclear burning phase in type Ia supernovae. The burning front model contains no adjustable parameters so that variations of the explosion outcome can be linked directly to changes in the initial conditions. In particular, we investigate the influence of the initial flame geometry on the explosion energy and find that it appears to be weaker than in 2D. Most importantly, our models predict global properties such as the produced nickel masses and ejecta velocities within their observed ranges without any fine tuning.

  9. Marginal evidence for cosmic acceleration from Type Ia supernovae

    E-Print Network [OSTI]

    Nielsen, Jeppe Trøst; Sarkar, Subir

    2015-01-01T23:59:59.000Z

    The `standard' model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present --- as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these `standardisable candles' indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.

  10. Thermal Stability of MnBi Magnetic Materials. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    because Mn is easy to react with oxygen. MnO formation is irreversible and causes degradation to the magnetic properties. In this paper, we report our effort on developing MnBi...

  11. Re Effects on Phase Stability and Mechanical Properties of MoSS+Mo3Si+Mo5SiB2 alloys

    SciTech Connect (OSTI)

    Yang, Ying [ORNL; Bei, Hongbin [ORNL; George, Easo P [ORNL; Tiley, Jaimie [Air Force Research Laboratory, Wright-Patterson AFB, OH

    2013-01-01T23:59:59.000Z

    Because of their high melting points and good oxidation resistance Mo-Si-B alloys are of interest as potential ultrahigh-temperature structural materials. But their major drawbacks are poor ductility and fracture toughness at room temperature. Since alloying with Re has been suggested as a possible solution, we investigate here the effects of Re additions on the microstructure and mechanical properties of a ternary alloy with the composition Mo-12.5Si-8.5B (at.%). This alloy has a three-phase microstructure consisting of Mo solid-solution (MoSS), Mo3Si, and Mo5SiB2 and our results show that up to 8.4 at.% Re can be added to it without changing its microstructure or forming any brittle phase at 1600 C. Three-point bend tests using chevron-notched specimens showed that Re did not improve fracture toughness of the three-phase alloy. Nanoindentation performed on the MoSS phase in the three-phase alloy showed that Re increases Young s modulus, but does not lower hardness as in some Mo solid solution alloys. Based on our thermodynamic calculations and microstructural analyses, the lack of a Re softening effect is attributed to the increased Si levels in the Re-containing MoSS phase since Si is known to increase its hardness. This lack of softening is possibly why there is no Re-induced improvement in fracture toughness.

  12. Microstructural analysis of a single pass 2.25% Cr-1.0% Mo steel weld metal with different manganese contents

    SciTech Connect (OSTI)

    Guimares de Souza, Luis Felipe [Centro Federal de Educacao Tecnologica Celso Suckow da Fonseca (CEFET-RJ), Av. Maracana, 229, Rio de Janeiro, RJ, 20271-110 (Brazil); Souza Bott, Ivani de [Pontificia Universidade Catolica (PUC-RIO), R. Marques de SaoVicente, 225, Rio de Janeiro, RJ, 22453-900 (Brazil); Ferreira Jorge, Jorge Carlos [Centro Federal de Educacao Tecnologica Celso Suckow da Fonseca (CEFET-RJ), Av. Maracana, 229, Rio de Janeiro, RJ, 20271-110 (Brazil); Sauer Guimaraes, Ari [Universidade Federal do Rio de Janeiro (COPPE/UFRJ), Caixa Postal 68.505, Cidade Universitaria, Ilha do Fundao, RJ, 21945-970 (Brazil); Pinheiro Rocha Paranhos, Ronaldo [Universidade Estadual do Norte Fluminense (UENF), Av. Alberto Lamego, 2000, Campos, RJ, 28013-602 (Brazil)]. E-mail: paranhos@uenf.br

    2005-07-15T23:59:59.000Z

    Weld metals of the 2.25% Cr-1.0% Mo type with 0.84%, 1.21% and 2.3% Mn produced by submerged-arc welding were analyzed in the as-welded (AW), post weld heat treatment (PWHT) and PWHT followed by step-cooling (SC) heat treatment conditions. Fracture surface analysis revealed an evolution in the mode of fracture due to Mn content variations and heat treatment conditions, the occurrence of intergranular fracture being observed in welds with 2.30% Mn that were step-cooled. Transmission electron microscopy revealed that the microstructure was predominantly composed of bainite, although martensite was also observed for high Mn contents. A marked carbide precipitation was observed, preferentially at grain boundaries. This could be attributed to the SC heat treatment and associated with the embrittlement. However, the application of a de-embrittlement heat treatment to this step cooled weld metal has proved efficient, because the impact energy levels after this heat treatment surpassed those obtained in the stress relieved condition. This indicates that segregation of impurities to grain boundaries was responsible for the low impact energy levels observed after SC of weld metal containing > 0.84% Mn.

  13. Grouping normal type Ia supernovae by UV to optical color differences

    SciTech Connect (OSTI)

    Milne, Peter A. [University of Arizona, Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85719 (United States); Brown, Peter J. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Roming, Peter W. A. [Space Science and Engineering Division, Southwest Research Corporation, P.O. Drawer 28510, San Antonio, TX 78228-0510 (United States); Bufano, Filomena [Universidad Andres Bello, Departmento de Cincias Fisicas, Avda. Republica 220, Santiago (Chile); Gehrels, Neil, E-mail: pbrown@physics.tamu.edu [NASA-Goddard Space Flight Center, Astrophysics Science Division, Codes 660.1 and 662, Greenbelt, MD 20771 (United States)

    2013-12-10T23:59:59.000Z

    Observations of many Type Ia supernovae (SNe Ia) for multiple epochs per object with the Swift Ultraviolet Optical Telescope instrument have revealed that there exists order to the differences in the UV-optical colors of optically normal supernovae (SNe). We examine UV-optical color curves for 23 SNe Ia, dividing the SNe into four groups, and find that roughly one-third of 'NUV-blue' SNe Ia have bluer UV-optical colors than the larger 'NUV-red' group. Two minor groups are recognized, 'MUV-blue' and 'irregular' SNe Ia. While we conclude that the latter group is a subset of the NUV-red group, containing the SNe with the broadest optical peaks, we conclude that the 'MUV-blue' group is a distinct group. Separating into the groups and accounting for the time evolution of the UV-optical colors lowers the scatter in two NUV-optical colors (e.g., u – v and uvw1 – v) to the level of the scatter in b – v. This finding is promising for extending the cosmological utilization of SNe Ia into the NUV. We generate spectrophotometry of 33 SNe Ia and determine the correct grouping for each. We argue that there is a fundamental spectral difference in the 2900-3500 Å wavelength range, a region suggested to be dominated by absorption from iron-peak elements. The NUV-blue SNe Ia feature less absorption than the NUV-red SNe Ia. We show that all NUV-blue SNe Ia in this sample also show evidence of unburned carbon in optical spectra, whereas only one NUV-red SN Ia features that absorption line. Every NUV-blue event also exhibits a low gradient of the Si II ?6355 absorption feature. Many NUV-red events also exhibit a low gradient, perhaps suggestive that NUV-blue events are a subset of the larger low-velocity gradient group.

  14. Effect of Mn doping on the structural, morphological, optical...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Mn doping on the structural, morphological, optical and magnetic properties of indium tin oxide films. Effect of Mn doping on the structural, morphological, optical and magnetic...

  15. MULTIMEDIA INSTRUCTIONS IN IA-64 Ruby B. Lee, A. Murat Fiskiran and Abdulla Bubshait

    E-Print Network [OSTI]

    Lee, Ruby B.

    MULTIMEDIA INSTRUCTIONS IN IA-64 Ruby B. Lee, A. Murat Fiskiran and Abdulla Bubshait Department discuss the integer and floating-point multimedia instructions in the IA-64 instruction-set architecture (ISA). These multimedia instructions implement subword parallelism, also called packed parallelism

  16. Experto Universitario Java Enterprise 2012-2013 Depto. Ciencia de la Computacin e IA

    E-Print Network [OSTI]

    Escolano, Francisco

    Experto Universitario Java Enterprise © 2012-2013 Depto. Ciencia de la Computación e IA Lenguaje Java Avanzado Sesión 3: Tratamiento de errores #12;Lenguaje Java Avanzado © 2012-2013 Depto. Ciencia de · Tipos genéricos #12;Lenguaje Java Avanzado © 2012-2013 Depto. Ciencia de la Computación e IA Errores - 3

  17. 2010-2011 Depto. Ciencia de la Computacin e IA Especialista Universitario Java Enterprise

    E-Print Network [OSTI]

    Escolano, Francisco

    © 2010-2011 Depto. Ciencia de la Computación e IA Especialista Universitario Java Enterprise Struts Sesión 4: Introducción a Struts 2 #12;© 2010-2011 Depto. Ciencia de la Computación e IA Especialista · Taglibs · Internacionalización · Validación · Conceptos nuevos en Struts 2 #12;© 2010-2011 Depto. Ciencia

  18. Type Ia supernova rate studies from the SDSS-II Supernova Study

    SciTech Connect (OSTI)

    Dilday, Benjamin; /Chicago U.

    2008-08-01T23:59:59.000Z

    The author presents new measurements of the type Ia SN rate from the SDSS-II Supernova Survey. The SDSS-II Supernova Survey was carried out during the Fall months (Sept.-Nov.) of 2005-2007 and discovered {approx} 500 spectroscopically confirmed SNe Ia with densely sampled (once every {approx} 4 days), multi-color light curves. Additionally, the SDSS-II Supernova Survey has discovered several hundred SNe Ia candidates with well-measured light curves, but without spectroscopic confirmation of type. This total, achieved in 9 months of observing, represents {approx} 15-20% of the total SNe Ia discovered worldwide since 1885. The author describes some technical details of the SN Survey observations and SN search algorithms that contributed to the extremely high-yield of discovered SNe and that are important as context for the SDSS-II Supernova Survey SN Ia rate measurements.

  19. Measurement of Omega_m, Omega_Lambda from a blind analysis of Type Ia supernovae with CMAGIC: Using color information to verify the acceleration of the Universe

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    analysis of Type Ia supernovae with CMAGIC: Using colorof 21 high redshift supernovae using a new technique (lightcurves of Type Ia supernovae, ?rst introduced in Wang

  20. The Effect of Host Galaxies on Type Ia Supernovae in the SDSS-II Supernova Survey

    SciTech Connect (OSTI)

    Lampeitl, Hubert; /Portsmouth U., ICG; Smith, Mathew; /Cape Town U. /Portsmouth U., ICG; Nichol, Robert C.; /Portsmouth U., ICG; Bassett, Bruce; /South African Astron. Observ. /Cape Town U.; Cinabro, David; /Wayne State U.; Dilday, Benjamin; /Rutgers U., Piscataway; Foley, Ryan J.; /Harvard-Smithsonian Ctr. Astrophys.; Frieman, Joshua A.; /Chicago U. /Fermilab; Garnavich, Peter M.; /Notre Dame U.; Goobar, Ariel; /Stockholm U., OKC; Im, Myungshin; /Seoul Natl. U. /Rutgers U., Piscataway

    2010-05-01T23:59:59.000Z

    We present an analysis of the host galaxy dependencies of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We re-discover, to high significance, the strong correlation between host galaxy type and the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2 to 3{sigma}) that SNe Ia are {approx_equal} 0.1 magnitudes brighter in passive host galaxies, than in star-forming hosts, after the SN Ia light curves have been standardized using the light curve shape and color variations: This difference in brightness is present in both the SALT2 and MCLS2k2 light curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R{sub V} {approx_equal} 1, while SNe Ia in star-forming hosts require R{sub V} {approx} 2. The significance of these trends depends on the range of SN colors considered. We demonstrate that these effects can be parameterized using the stellar mass of the host galaxy (with a confidence of > 4{sigma}) and including this extra parameter provides a better statistical fit to our data. Our results suggest that future cosmological analyses of SN Ia samples should include host galaxy information.

  1. Supernova progenitor constraints from circumstellar interaction: Type Ia

    E-Print Network [OSTI]

    Peter Lundqvist; Robert J. Cumming

    1996-10-03T23:59:59.000Z

    Searching for the presence of a circumstellar medium is a direct observational way to discriminate between different types of progenitor systems for Type Ia supernovae. We have modeled whether such gas may give rise to detectable emission, especially in H-alpha, and compare the models with observations of SN 1994D. We obtain a mass loss rate less than about 2.5 10^{-5} solar masses per year for a wind speed of 10 km/s. We find that X-ray observations in the range 5-10 keV, e.g., with AXAF, provide the most useful limits on the mass loss, while high-resolution optical spectroscopy offers the only direct way of identifying circumstellar hydrogen.

  2. Polarisation spectral synthesis for Type Ia supernova explosion models

    E-Print Network [OSTI]

    Bulla, M; Kromer, M

    2015-01-01T23:59:59.000Z

    We present a Monte Carlo radiative transfer technique for calculating synthetic spectropolarimetry for multi-dimensional supernova explosion models. The approach utilises "virtual-packets" that are generated during the propagation of the Monte Carlo quanta and used to compute synthetic observables for specific observer orientations. Compared to extracting synthetic observables by direct binning of emergent Monte Carlo quanta, this virtual-packet approach leads to a substantial reduction in the Monte Carlo noise. This is vital for calculating synthetic spectropolarimetry (since the degree of polarisation is typically very small) but also useful for calculations of light curves and spectra. We first validate our approach via application of an idealised test code to simple geometries. We then describe its implementation in the Monte Carlo radiative transfer code ARTIS and present test calculations for simple models for Type Ia supernovae. Specifically, we use the well-known one-dimensional W7 model to verify tha...

  3. Type Ia supernova Hubble residuals and host-galaxy properties

    SciTech Connect (OSTI)

    Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Fleury, M.; Guy, J. [Laboratoire de Physique Nucléaire et des Hautes Énergies, Université Pierre et Marie Curie Paris 6, Université Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Feindt, U.; Greskovic, P.; Kowalski, M. [Physikalisches Institut, Universität Bonn, Nußallee 12, D-53115 Bonn (Germany); Childress, M. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Chotard, N.; Copin, Y.; Gangler, E. [Université de Lyon, F-69622 Lyon (France); Université de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucléaire de Lyon (France); and others

    2014-03-20T23:59:59.000Z

    Kim et al. introduced a new methodology for determining peak-brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spectrophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ± 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at <<1?, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the host mass is 0.045 ± 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch parameters: steps at >2? significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light-curve width and color around peak (similar to the ?m {sub 15} and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.

  4. On silicon group elements ejected by supernovae type IA

    SciTech Connect (OSTI)

    De, Soma; Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Brown, Edward F. [Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN 46556 (United States); Calder, Alan C. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY (United States); Townsley, Dean M. [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL (United States); Athanassiadou, Themis [Swiss National Supercomputing Centre, Via Trevano 131, 6900 Lugano (Switzerland); Chamulak, David A. [Physics Division, Argonne National Laboratory, Argonne, IL (United States); Hawley, Wendy [Laboratoire d'Astrophysique de Marseille, Marseille cedex 13 F-13388 (France); Jack, Dennis, E-mail: somad@asu.edu [Departamento de Astronomía, Universidad de Guanajuato, Apartado Postal 144, 36000 Guanajuato (Mexico)

    2014-06-01T23:59:59.000Z

    There is evidence that the peak brightness of a Type Ia supernova is affected by the electron fraction Y {sub e} at the time of the explosion. The electron fraction is set by the aboriginal composition of the white dwarf and the reactions that occur during the pre-explosive convective burning. To date, determining the makeup of the white dwarf progenitor has relied on indirect proxies, such as the average metallicity of the host stellar population. In this paper, we present analytical calculations supporting the idea that the electron fraction of the progenitor systematically influences the nucleosynthesis of silicon group ejecta in Type Ia supernovae. In particular, we suggest the abundances generated in quasi-nuclear statistical equilibrium are preserved during the subsequent freeze-out. This allows potential recovery of Y {sub e} at explosion from the abundances recovered from an observed spectra. We show that measurement of {sup 28}Si, {sup 32}S, {sup 40}Ca, and {sup 54}Fe abundances can be used to construct Y {sub e} in the silicon-rich regions of the supernovae. If these four abundances are determined exactly, they are sufficient to recover Y {sub e} to 6%. This is because these isotopes dominate the composition of silicon-rich material and iron-rich material in quasi-nuclear statistical equilibrium. Analytical analysis shows the {sup 28}Si abundance is insensitive to Y {sub e}, the {sup 32}S abundance has a nearly linear trend with Y {sub e}, and the {sup 40}Ca abundance has a nearly quadratic trend with Y {sub e}. We verify these trends with post-processing of one-dimensional models and show that these trends are reflected in the model's synthetic spectra.

  5. Upcoming Management and Operating (M&O) Contract Competition...

    National Nuclear Security Administration (NNSA)

    Upcoming Management and Operating (M&O) Contract Competition | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile...

  6. MoRu/Be multilayers for extreme ultraviolet applications

    DOE Patents [OSTI]

    Bajt, Sasa C. (Livermore, CA); Wall, Mark A. (Stockton, CA)

    2001-01-01T23:59:59.000Z

    High reflectance, low intrinsic roughness and low stress multilayer systems for extreme ultraviolet (EUV) lithography comprise amorphous layers MoRu and crystalline Be layers. Reflectance greater than 70% has been demonstrated for MoRu/Be multilayers with 50 bilayer pairs. Optical throughput of MoRu/Be multilayers can be 30-40% higher than that of Mo/Be multilayer coatings. The throughput can be improved using a diffusion barrier to make sharper interfaces. A capping layer on the top surface of the multilayer improves the long-term reflectance and EUV radiation stability of the multilayer by forming a very thin native oxide that is water resistant.

  7. Interdiffusion between Zr Diffusion Barrier and U-Mo Alloy

    SciTech Connect (OSTI)

    K. Huang; Y. Park; Y. H. Sohn

    2012-12-01T23:59:59.000Z

    U-Mo alloys are being developed as low enrichment uranium fuels under the Reduced Enrichment for Research and Test Reactor (RERTR) program. Significant reactions have been observed between U-Mo fuels and Al or Al alloy matrix. Refractory metal Zr has been proposed as barrier material to reduce the interactions. In order to investigate the compatibility and barrier effects between U-Mo alloy and Zr, solid-to-solid U-10wt.%Mo vs. Zr diffusion couples were assembled and annealed at 600, 700, 800, 900 and 1000 °C for various times. The microstructures and concentration profiles due to interdiffusion and reactions were examined via scanning electron microscopy and electron probe microanalysis, respectively. Intermetallic phase Mo2Zr was found at the interface and its population increased when annealing temperature decreased. Diffusion paths were also plotted on the U-Mo-Zr ternary phase diagrams with good consistency. The growth rate of interdiffusion zone between U-10wt.%Mo and Zr was also calculated under the assumption of parabolic diffusion, and was determined to be about 103 times lower than the growth rate of diffusional interaction layer found in diffusion couples U-10wt.%Mo vs. Al or Al-Si alloy. Other desirable physical properties of Zr as barrier material, such as neutron adsorption rate, melting point and thermal conductivity are presented as supplementary information to demonstrate the great potential of Zr as the diffusion barrier for U-Mo fuel systems in RERTR.

  8. Mo Year Report Period: EIA ID NUMBER:

    U.S. Energy Information Administration (EIA) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro IndustriesTownDells, Wisconsin:DeploymentSite Name:24,High824 2.839 2.8352.747 2.759 2.699Mo

  9. Catalytic Properties of Supported MoO3 Catalysts for Oxidative Dehydrogenation of Propane

    E-Print Network [OSTI]

    Iglesia, Enrique

    Catalytic Properties of Supported MoO3 Catalysts for Oxidative Dehydrogenation of Propane Kaidong The effects of MoOx structure on propane oxidative dehydrogenation (ODH) rates and selectivity were examined with those obtained on MoOx/ZrO2. On MoOx/Al2O3 catalysts, propane turnover rate increased with increasing Mo

  10. Type Ia Supernovae Rates and Galaxy Clustering from the CFHT Supernova Legacy Survey

    E-Print Network [OSTI]

    M. L. Graham; C. J. Pritchet; M. Sullivan; S. D. J. Gwyn; J. D. Neill; E. Y. Hsiao; P. Astier; D. Balam; C. Balland; S. Basa; R. G. Carlberg; A. Conley; D. Fouchez; J. Guy; D. Hardin; I. M. Hook; D. A. Howell; R. Pain; K. Perrett; N. Regnault; S. Baumont; J. Le Du; C. Lidman; S. Perlmutter; P. Ripoche; N. Suzuki; E. S. Walker; T. Zhang

    2008-01-31T23:59:59.000Z

    The Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS) has created a large homogeneous database of intermediate redshift (0.2 rates, properties, and host galaxy star formation rates. The SNLS SN Ia database has now been combined with a photometric redshift galaxy catalog and an optical galaxy cluster catalog to investigate the possible influence of galaxy clustering on the SN Ia rate, over and above the expected effect due to the dependence of SFR on clustering through the morphology-density relation. We identify three cluster SNe Ia, plus three additional possible cluster SNe Ia, and find the SN Ia rate per unit mass in clusters at intermediate redshifts is consistent with the rate per unit mass in field early-type galaxies and the SN Ia cluster rate from low redshift cluster targeted surveys. We also find the number of SNe Ia in cluster environments to be within a factor of two of expectations from the two component SNIa rate model.

  11. Stellar Populations and the White Dwarf Mass Function: Connections To Supernova Ia Luminosities

    E-Print Network [OSTI]

    Ted von Hippel; G. D. Bothun; R. A. Schommer

    1997-06-11T23:59:59.000Z

    We discuss the luminosity function of SNe Ia under the assumption that recent evidence for dispersion in this standard candle is related to variations in the white dwarf mass function (WDMF) in the host galaxies. We develop a simple parameterization of the WDMF as a function of age of a stellar population and apply this to galaxies of different morphological types. We show that this simplified model is consistent with the observed WDMF of Bergeron et al. (1992) for the solar neighborhood. Our simple models predict that WDMF variations can produce a range of more than 1.8 mag in M$_B$(SN Ia), which is comparable to the observed value using the data of Phillips (1993) and van den Bergh (1996). We also predict a galaxy type dependence of M$_B$(SN Ia) under standard assumptions of the star formation history in these galaxies and show that M$_B$(SN Ia) can evolve with redshift. In principle both evolutionary and galaxy type corrections should be applied to recover the intrinsic range of M$_B$(SN Ia) from the observed values. Our current inadequate knowledge of the star formation history of galaxies coupled with poor physical understanding of the SN Ia mechanism makes the reliable estimation of these corrections both difficult and controversial. The predictions of our models combined with the observed galaxy and redshift correlations may have the power to discriminate between the Chandrasekhar and the sub-Chandrasekhar progenitor scenarios for SNe Ia.

  12. A systematic study of carbon-oxygen white dwarf mergers: mass combinations for Type Ia supernovae

    E-Print Network [OSTI]

    Sato, Yushi; Tanikawa, Ataru; Nomoto, Ken'ichi; Maeda, Keiichi; Hachisu, Izumi

    2015-01-01T23:59:59.000Z

    Mergers of two carbon-oxygen (CO) white dwarfs (WDs) have been considered as progenitors of Type Ia supernovae (SNe Ia). Based on smoothed particle hydrodynamics (SPH) simulations, previous studies claimed that mergers of CO WDs lead to an SN Ia explosion either in the dynamical merger phase or stationary rotating merger remnant phase. However, the mass range of CO WDs that lead to an SN Ia has not been clearly identified yet. In the present work, we perform systematic SPH merger simulations for the WD masses ranging from $0.5~M_{\\odot}$ to $1.1~M_{\\odot}$ with higher resolutions than the previous systematic surveys and examine whether or not carbon burning occurs dynamically or quiescently in each phase. We further study the possibility of SN Ia explosion and estimate the mass range of CO WDs that lead to an SN Ia. We found that when the both WDs are massive, i.e., in the mass range of $0.9~M_{\\odot} {\\le} M_{1,2} {\\le} 1.1~M_{\\odot}$, they can explode as an SN Ia in the merger phase. On the other hand, when...

  13. The Hubble Constant from Type Ia Supernovae in Early-Type Galaxies

    E-Print Network [OSTI]

    Tom Richtler; Georg Drenkhahn

    1999-09-07T23:59:59.000Z

    Type Ia supernovae (SNe) are the best standard candles available today in spite of an appreciable intrinsic variation of their luminosities at maximum phase, and of probably non-uniform progenitors. For an unbiased use of type Ia SNe as distance indicators it is important to know accurately how the decline rate and colour at maximum phase correlate with the peak brightness. In order to calibrate the Hubble diagram of type Ia SNe, i.e. to derive the Hubble constant, one needs to determine the absolute brightness of nearby type Ia SNe. Globular cluster systems of early type Ia host galaxies provide suitable distance indicators. We discuss how Ia SNe can be calibrated and explain the method of Globular Cluster Luminosity Functions (GCLFs). At present, the distance to the Fornax galaxy cluster is most important for deriving the Hubble constant. Our present data indicate a Hubble constant of H_0=72+-4 km/s/Mpc. As an appendix, we summarise what is known about absolute magnitudes of Ia's in late-type galaxies.

  14. HOST GALAXIES OF TYPE Ia SUPERNOVAE FROM THE NEARBY SUPERNOVA FACTORY

    SciTech Connect (OSTI)

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon (France); Universite de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucleaire de Lyon (France); and others

    2013-06-20T23:59:59.000Z

    We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and H{alpha}-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M{sub *}/M{sub Sun }) > 8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.

  15. IMPROVEMENT OF CdMnTe DETECTOR PERFORMANCE BY MnTe PURIFICATION

    SciTech Connect (OSTI)

    Kim, K.H.; Bolotnikov, A.E.; Camarda, G.S.; Tappero, R.; Hossain, A.; Cui, Y.; Yang, G.; Gul, R.; and James, R.B.

    2011-04-25T23:59:59.000Z

    Residual impurities in manganese (Mn) are a big obstacle to obtaining high-performance CdMnTe (CMT) X-ray and gamma-ray detectors. Generally, the zone-refining method is an effective way to improve the material's purity. In this work, we purified the MnTe compounds combining the zone-refining method with molten Te, which has a very high solubility for most impurities. We confirmed the improved purity of the material by glow-discharge mass spectrometry (GDMS). We also found that CMT crystals from a multiply-refined MnTe source, grown by the vertical Bridgman method, yielded better performing detectors.

  16. Co layer thickness dependence of exchange biasing for IrMnCo and FeMnCo

    E-Print Network [OSTI]

    Reilly, Anne

    Co layer thickness dependence of exchange biasing for IrMnÕCo and FeMnÕCo K. A. Seua) and H. Huang) in IrMn/Co and FeMn/Co bilayers using the magneto-optical Kerr effect. Samples are sputtered wedges on silicon with Co thicknesses ranging from 1 to 17 nm. The IrMn/Co with exchange bias interface energy of 0

  17. Neutron Hole States of Mo-93,95

    E-Print Network [OSTI]

    Bindal, P. K.; Youngblood, David H.; Kozub, R. L.

    1977-01-01T23:59:59.000Z

    - topes but less than half is observed for '"Mo. The hole strength distributions for l =1 and 4 are displayed in Fig. 10 for all the Mo isotopes. It is apparent from this figure that the states corres- ponding to lgg/2 2Py/2 and 2P, /, orbitals, which...

  18. Neutrino scattering off the stable even-even Mo isotopes

    SciTech Connect (OSTI)

    Balasi, K. G.; Kosmas, T. S.; Divari, P. C. [Theoretical Physics Section, University of Ioannina, GR 45110 Ioannina (Greece)

    2009-11-09T23:59:59.000Z

    Inelastic neutrino-nucleus reaction cross sections are studied focusing on the neutral current processes. Particularly, we investigate the angular and initial neutrino-energy dependence of the differential and integrated cross sections for low and intermediate energies of the incoming neutrino. The nuclear wave functions for the initial and final nuclear states are constructed in the context of the quasi-particle random phase approximation (QRPA) tested on the reproducibility of the low-lying energy spectrum. The results presented here refer to the isotopes Mo{sup 92}, Mo{sup 94}, Mo{sup 96}, Mo{sup 98} and Mo{sup 100}. These isotopes could play a significant role in supernova neutrino detection in addition to their use in double-beta and neutrinoless double-beta decay experiments (e.g. MOON, NEMO III)

  19. University Engagement and Outreach Committee Chair: PVC (IA), Prof. M Cardew-Hall

    E-Print Network [OSTI]

    Botea, Adi

    University Engagement and Outreach Committee Chair: PVC (IA), Prof. M Cardew-Hall Alternate Chair: PVC (IO), Dr. Erik Lithander Secretary: Ms. Jan O'Connor (Jan.OConnor@anu.edu.au) / Ms. Joanne Gash

  20. Structural studies of allosteric regulation in the class Ia Ribonucleotide reductase from Escherichia coli

    E-Print Network [OSTI]

    Zimanyi, Christina Marie

    2013-01-01T23:59:59.000Z

    Ribonucleotide reductase (RNR) converts ribonucleotides to deoxyribonucleotides, the building blocks for DNA replication and repair. The E. coli class Ia enzyme requires two subunits to catalyze the radical-based reduction ...

  1. Type Ia supernova rate at a redshift of ~ 0.1

    E-Print Network [OSTI]

    Blanc, G; Alard, C; Albert, J N; Aldering, G; Amadon, A; Andersen, J; Ansari, R; Aubourg, E; Balland, C; Bareyre, P; Beaulieu, J P; Charlot, X; Conley, A; Coutures, C; Dahlen, T; Derue, F; Fan, X; Ferlet, R; Folatelli, G; Fouqué, P; Garavini, G; Glicenstein, J F; Goldman, B; Goobar, A; Gould, A; Graff, D; Gros, M; Haïssinski, J; Hamadache, C; Hardin, D; Hook, I M; De Kat, J; Kent, S; Kim, A; Lasserre, T; Le Guillou, Laurent; Lesquoy, E; Loup, C; Magneville, C; Marquette, J B; Maurice, E; Maury, A; Milsztajn, A; Moniez, M; Mouchet, M; Newberg, H; Nobili, S; Palanque-Delabrouille, Nathalie; Perdereau, O; Prévôt, L; Rahal, Y R; Regnault, N; Rich, J; Ruiz-Lapuente, P; Spiro, M; Tisserand, P; Vidal-Madjar, A; Vigroux, L; Walton, N A; Zylberajch, S

    2004-01-01T23:59:59.000Z

    We present the type Ia rate measurement based on two EROS supernova search campaigns (in 1999 and 2000). Sixteen supernovae identified as type Ia were discovered. The measurement of the detection efficiency, using a Monte Carlo simulation, provides the type Ia supernova explosion rate at a redshift ~ 0.13. The result is $0.125^{+0.044+0.028}_{-0.034-0.028} h_{70}^2$ SNu where 1 SNu = 1 SN / $10^{10} L_{sun}^B$ / century. This value is compatible with the previous EROS measurement (Hardin et al. 2000), done with a much smaller sample, at a similar redshift. Comparison with other values at different redshifts suggests an evolution of the type Ia supernova rate.

  2. Type Ia supernova rate at a redshift of ~ 0.1

    E-Print Network [OSTI]

    G. Blanc; C. Afonso; C. Alard; J. N. Albert; G. Aldering; A. Amadon; J. Andersen; R. Ansari; E. Aubourg; C. Balland; P. Bareyre; J. P. Beaulieu; X. Charlot; A. Conley; C. Coutures; T. Dahlen; F. Derue; X. Fan; R. Ferlet; G. Folatelli; P. Fouque; G. Garavini; J. F. Glicenstein; B. Goldman; A. Goobar; A. Gould; D. Graff; M. Gros; J. Haissinski; C. Hamadache; D. Hardin; I. M. Hook; J. deKat; S. Kent; A. Kim; T. Lasserre; L. LeGuillou; E. Lesquoy; C. Loup; C. Magneville; J. B. Marquette; E. Maurice; A. Maury; A. Milsztajn; M. Moniez; M. Mouchet; H. Newberg; S. Nobili; N. Palanque-Delabrouille; O. Perdereau; L. Prevot; Y. R. Rahal; N. Regnault; J. Rich; P. Ruiz-Lapuente; M. Spiro; P. Tisserand; A. Vidal-Madjar; L. Vigroux; N. A. Walton; S. Zylberajch

    2004-05-11T23:59:59.000Z

    We present the type Ia rate measurement based on two EROS supernova search campaigns (in 1999 and 2000). Sixteen supernovae identified as type Ia were discovered. The measurement of the detection efficiency, using a Monte Carlo simulation, provides the type Ia supernova explosion rate at a redshift ~ 0.13. The result is $0.125^{+0.044+0.028}_{-0.034-0.028} h_{70}^2$ SNu where 1 SNu = 1 SN / $10^{10} L_{sun}^B$ / century. This value is compatible with the previous EROS measurement (Hardin et al. 2000), done with a much smaller sample, at a similar redshift. Comparison with other values at different redshifts suggests an evolution of the type Ia supernova rate.

  3. Hipparcos calibration of the peak brightness of four SNe Ia and the value of Ho

    E-Print Network [OSTI]

    P. Lanoix

    1997-12-10T23:59:59.000Z

    Hipparcos geometrical parallaxes allowed us to calibrate the Cepheid Period-Luminosity relation and to compute the true distance moduli of 17 galaxies. Among these 17 galaxies, we selected those which generated type Ia Supernovae (SNe Ia). We found NGC 5253, parent galaxy of 1895B and 1972E, IC 4182 and NGC 4536 parents of 1937C and 1981B, respectively. We used the available B-band photometry to determine the peak brightness of these four SNe Ia. We obtained = -19.65 \\pm 0.09. Then, we built a sample of 57 SNe Ia in order to plot the Hubble diagram and determine its zero-point. Our result (ZP_{B} = -3.16 \\pm 0.10) is in agreement with other determinations and allows us to derive the following Hubble constant : Ho = 50 \\pm 3 (internal) km.s^-1.Mpc^-1.

  4. , SEYMOUR AND MacGREGOR COGNlTlYb NEUROPSYCHOLOGY. IdyslexIa. Brain. 102. 4363.

    E-Print Network [OSTI]

    Mehler, Jacques

    .T. (1980) Word-form dyslexIa. Brain. 102. 4363. REFERENCENOTES On Reducing Language to Biology I. Holmes. J. M. (1973) Dyslexia: a lIeurolinguistic study 0/ traumatic and developmental disorders 0/ reading

  5. Imprint of modified Einstein's gravity on white dwarfs: Unifying type Ia supernovae

    E-Print Network [OSTI]

    Das, Upasana

    2015-01-01T23:59:59.000Z

    We establish the importance of modified Einstein's gravity (MG) in white dwarfs (WDs) for the first time in the literature. We show that MG leads to significantly sub- and super-Chandrasekhar limiting mass WDs, depending on a single model parameter. However, conventional WDs on approaching Chandrasekhar's limit are expected to trigger type Ia supernovae (SNeIa), a key to unravel the evolutionary history of the universe. Nevertheless, observations of several peculiar, under- and over-luminous SNeIa argue for the limiting mass widely different from Chandrasekhar's limit. Explosions of MG induced sub- and super-Chandrasekhar limiting mass WDs explain under- and over-luminous SNeIa respectively, thus unifying these two apparently disjoint sub-classes. Our discovery questions both the global validity of Einstein's gravity and the uniqueness of Chandrasekhar's limit.

  6. EVIDENCE FOR TYPE Ia SUPERNOVA DIVERSITY FROM ULTRAVIOLET OBSERVATIONS WITH THE HUBBLE SPACE TELESCOPE

    E-Print Network [OSTI]

    Lewin, Walter H. G.

    We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This ...

  7. Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

    E-Print Network [OSTI]

    Garavini, G.; Supernova Cosmology Project

    2008-01-01T23:59:59.000Z

    Highlight - The Physics of Supernovae, ESO/MPA/MPE Workshop,Evolution in high-redshift supernovae Fig. 8 “Ca ii H&K”SN 1991T/SN 1999aa-like supernovae. 1. Introduction Type Ia

  8. Constructing a cosmological model-independent Hubble diagram of type Ia supernovae with cosmic chronometers

    E-Print Network [OSTI]

    Li, Zhengxiang; Yu, Hongwei; Zhu, Zong-Hong; Alcaniz, J S

    2015-01-01T23:59:59.000Z

    We apply two methods to reconstruct the Hubble parameter $H(z)$ as a function of redshift from 15 measurements of the expansion rate obtained from age estimates of passively evolving galaxies. These reconstructions enable us to derive the luminosity distance to a certain redshift $z$, calibrate the light-curve fitting parameters accounting for the (unknown) intrinsic magnitude of type Ia supernova (SNe Ia) and construct cosmological model-independent Hubble diagrams of SNe Ia. In order to test the compatibility between the reconstructed functions of $H(z)$, we perform a statistical analysis considering the latest SNe Ia sample, the so-called JLA compilation. We find that, while one of the reconstructed functions leads to a value of the local Hubble parameter $H_0$ in excellent agreement with the one reported by the Planck collaboration, the other requires a higher value of $H_0$, which is consistent with recent measurements of this quantity from Cepheids and other local distance indicators.

  9. Demonstration of resonant photopumping of Mo VII by Mo XII for a VUV laser near 600 {Angstrom}

    SciTech Connect (OSTI)

    Ilcisin, K.J.; Aumayr, F.; Schwob, J.L.; Suckewer, S.

    1993-09-01T23:59:59.000Z

    We present data of experiments on the resonant photopumping of Mo VII by Mo XII as a method of generating a coherent VUV source near 600 {angstrom}. The experiment is based on a scheme proposed by Feldman and Reader in which the 4p{sup 6} -- 4p{sup 5}6s transition in Mo VII in resonantly photopumped by the 5s {sup 2}S{sub 1/2} -- 4p {sup 2}P{sub 1/2} transition in Mo XII. Results of the laser produced plasma experiments show the successful enhancement of the population of the Mo VII 4p{sup 5}6s upper lasing level when pumped by an adjacent Mo VII plasma. No enhancement was seen in a control experiment where the Mo VII plasma was pumped by a Zr X plasma. Improvements of the intensity of the Mo XII pump source, achieved using an additional pump laser, lead to the generation of a population inversion for the VUV transition.

  10. Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra

    E-Print Network [OSTI]

    Childress, Michael J; Seitenzahl, Ivo; Sullivan, Mark; Maguire, Kate; Taubenberger, Stefan; Scalzo, Richard; Ruiter, Ashley; Blagorodnova, Nadejda; Camacho, Yssavo; Castillo, Jayden; Elias-Rosa, Nancy; Fraser, Morgan; Gal-Yam, Avishay; Graham, Melissa; Howell, D Andrew; Inserra, Cosimo; Jha, Saurabh W; Kumar, Sahana; Mazzali, Paolo A; McCully, Curtis; Morales-Garoffolo, Antonia; Pandya, Viraj; Polshaw, Joe; Schmidt, Brian; Smartt, Stephen; Smith, Ken W; Sollerman, Jesper; Spyromilio, Jason; Tucker, Brad; Valenti, Stefano; Walton, Nicholas; Wolf, Christian; Yaron, Ofer; Young, D R; Yuan, Fang; Zhang, Bonnie

    2015-01-01T23:59:59.000Z

    The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of $^{56}$Ni to $^{56}$Co at early times, and the decay of $^{56}$Co to $^{56}$Fe from ~60 days after explosion. We examine the evolution of the [Co III] 5892 A emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of $^{56}$Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in $^{56}$Co decay, and long-term stability of the ionization state of the nebula. We compile 77 nebular spectra of 25 SN Ia from the literature and present 17 new nebular spectra of 7 SNe Ia, including SN2014J. From these we measure the flux in the [Co III] 5892 A line and remove its well-behaved time dependence to infer the initial mass of $^{56}$Ni ($M_{Ni}$) produced in the explosion. We then examine $^{56}$Ni yields for different SN Ia ejected masses ($M_{ej}$ - calculated using the relation between light...

  11. Tycho Brahe's 1572 supernova as a standard type Ia explosion revealed from its light echo spectrum

    E-Print Network [OSTI]

    Oliver Krause; Masaomi Tanaka; Tomonori Usuda; Takashi Hattori; Miwa Goto; Stephan Birkmann; Ken'ichi Nomoto

    2008-10-28T23:59:59.000Z

    Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions are how the explosion actually proceeds and whether accretion occurs from a companion or via the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a SN Ia in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the yet unknown exact spectroscopic type of SN 1572 is crucial to relate these results to the diverse population of SNe Ia. Here we report an optical spectrum of Tycho Brahe's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light of the explosion swept past Earth. We find that SN 1572 belongs to the majority class of normal SNe Ia. The presence of a strong Ca II IR feature at velocities exceeding 20,000 km/s, which is similar to the previously observed polarized features in other SNe Ia, suggests asphericity in SN 1572.

  12. THE ABSENCE OF EX-COMPANIONS IN TYPE Ia SUPERNOVA REMNANTS

    SciTech Connect (OSTI)

    Di Stefano, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kilic, Mukremin, E-mail: rd@cfa.harvard.edu, E-mail: kilic@ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks Street, Norman, OK 73019 (United States)

    2012-11-01T23:59:59.000Z

    Type Ia supernovae (SNe Ia) play important roles in our study of the expansion and acceleration of the universe, but because we do not know the exact nature or natures of the progenitors, there is a systematic uncertainty that must be resolved if SNe Ia are to become more precise cosmic probes. No progenitor system has ever been identified either in the pre- or post-explosion images of a Ia event. There have been recent claims for and against the detection of ex-companion stars in several SNe Ia remnants. These studies, however, usually ignore the angular momentum gain of the progenitor white dwarf (WD), which leads to a spin-up phase and a subsequent spin-down phase before explosion. For spin-down timescales greater than 10{sup 5} years, the donor star could be too dim to detect by the time of explosion. Here we revisit the current limits on ex-companion stars to SNR 0509-67.5, a 400-year-old remnant in the Large Magellanic Cloud. If the effects of possible angular momentum gain on the WD are included, a wide range of single-degenerate progenitor models are allowed for this remnant. We demonstrate that the current absence of evidence for ex-companion stars in this remnant, as well as other SNe Ia remnants, does not necessarily provide the evidence of absence for ex-companions. We discuss potential ways to identify such ex-companion stars through deep imaging observations.

  13. THE DISCOVERY OF THE MOST DISTANT KNOWN TYPE Ia SUPERNOVA AT REDSHIFT 1.914

    SciTech Connect (OSTI)

    Jones, David O.; Rodney, Steven A.; Riess, Adam G. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Dahlen, Tomas; Casertano, Stefano; Koekemoer, Anton [Space Telescope Science Institute, Baltimore, MD 21218 (United States); McCully, Curtis; Keeton, Charles R.; Patel, Brandon [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); Frederiksen, Teddy F.; Hjorth, Jens [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Strolger, Louis-Gregory [Department of Physics, Western Kentucky University, Bowling Green, KY 42101 (United States); Wiklind, Tommy G. [Joint ALMA Observatory, ESO, Santiago (Chile); Challis, Peter [Harvard/Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Graur, Or [School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Hayden, Brian; Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Weiner, Benjamin J. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); and others

    2013-05-10T23:59:59.000Z

    We present the discovery of a Type Ia supernova (SN) at redshift z = 1.914 from the CANDELS multi-cycle treasury program on the Hubble Space Telescope (HST). This SN was discovered in the infrared using the Wide-Field Camera 3, and it is the highest-redshift Type Ia SN yet observed. We classify this object as a SN Ia by comparing its light curve and spectrum with those of a large sample of Type Ia and core-collapse SNe. Its apparent magnitude is consistent with that expected from the {Lambda}CDM concordance cosmology. We discuss the use of spectral evidence for classification of z > 1.5 SNe Ia using HST grism simulations, finding that spectral data alone can frequently rule out SNe II, but distinguishing between SNe Ia and SNe Ib/c can require prohibitively long exposures. In such cases, a quantitative analysis of the light curve may be necessary for classification. Our photometric and spectroscopic classification methods can aid the determination of SN rates and cosmological parameters from the full high-redshift CANDELS SN sample.

  14. A novel three dimensional semimetallic MoS{sub 2}

    SciTech Connect (OSTI)

    Tang, Zhen-Kun [Beijing Computational Science Research Center, Beijing 100084 (China); Departments of Physics and Electronics, Hengyang Normal University, Hengyang 421008 (China); Zhang, Hui; Liu, Li-Min, E-mail: limin.liu@csrc.ac.cn [Beijing Computational Science Research Center, Beijing 100084 (China); Liu, Hao [Chengdu Green Energy and Green Manufacturing Technology R and D Center, Chengdu, Sichuan 610207 (China); Lau, Woon-Ming [Beijing Computational Science Research Center, Beijing 100084 (China); Chengdu Green Energy and Green Manufacturing Technology R and D Center, Chengdu, Sichuan 610207 (China)

    2014-05-28T23:59:59.000Z

    Transition metal dichalcogenides (TMDs) have many potential applications, while the performances of TMDs are generally limited by the less surface active sites and the poor electron transport efficiency. Here, a novel three-dimensional (3D) structure of molybdenum disulfide (MoS{sub 2}) with larger surface area was proposed based on first-principle calculations. 3D layered MoS{sub 2} structure contains the basal surface and joint zone between the different nanoribbons, which is thermodynamically stable at room temperature, as confirmed by first principles molecular dynamics calculations. Compared the two-dimensional layered structures, the 3D MoS{sub 2} not only owns the large surface areas but also can effectively avoid the aggregation. Interestingly, although the basal surface remains the property of the intrinsic semiconductor as the bulk MoS{sub 2}, the joint zone of 3D MoS{sub 2} exhibits semimetallic, which is derived from degenerate 3d orbitals of the Mo atoms. The high stability, large surface area, and high conductivity make 3D MoS{sub 2} have great potentials as high performance catalyst.

  15. Diffusion Barrier Selection from Refractory Metals (Zr, Mo and Nb) via Interdiffusion Investigation for U-Mo RERTR Fuel Alloy

    SciTech Connect (OSTI)

    K. Huang; C. Kammerer; D. D. Keiser, Jr.; Y. H. Sohn

    2014-04-01T23:59:59.000Z

    U-Mo alloys are being developed as low enrichment monolithic fuel under the Reduced Enrichment for Research and Test Reactor (RERTR) Program. Diffusional interactions between the U-Mo fuel alloy and Al-alloy cladding within the monolithic fuel plate construct necessitate incorporation of a barrier layer. Fundamentally, a diffusion barrier candidate must have good thermal conductivity, high melting point, minimal metallurgical interaction, and good irradiation performance. Refractory metals, Zr, Mo, and Nb are considered based on their physical properties, and the diffusion behavior must be carefully examined first with U-Mo fuel alloy. Solid-to-solid U-10wt.%Mo vs. Mo, Zr, or Nb diffusion couples were assembled and annealed at 600, 700, 800, 900 and 1000 degrees C for various times. The interdiffusion microstructures and chemical composition were examined via scanning electron microscopy and electron probe microanalysis, respectively. For all three systems, the growth rate of interdiffusion zone were calculated at 1000, 900 and 800 degrees C under the assumption of parabolic growth, and calculated for lower temperature of 700, 600 and 500 degrees C according to Arrhenius relationship. The growth rate was determined to be about 10 3 times slower for Zr, 10 5 times slower for Mo and 10 6 times slower for Nb, than the growth rates reported for the interaction between the U-Mo fuel alloy and pure Al or Al-Si cladding alloys. Zr, however was selected as the barrier metal due to a concern for thermo- mechanical behavior of UMo/Nb interface observed from diffusion couples, and for ductile-to-brittle transition of Mo near room temperature.

  16. Effect of Mo Dispersion Size and Water Vapor on Oxidation of Two-Phase Directionally Solidified NiAl-9Mo In-Situ Composites

    SciTech Connect (OSTI)

    Brady, Michael P [ORNL] [ORNL; Bei, Hongbin [ORNL] [ORNL; Meisner, Roberta Ann [ORNL] [ORNL; Lance, Michael J [ORNL] [ORNL; Tortorelli, Peter F [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    Oxidation of two-phase NiAl-9Mo eutectics with 3 different growth rates/2nd phase Mo dispersion sizes were investigated at 900 C in air and air with 10% water vapor. Good oxidation resistance via alumina formation was observed in dry air, with Mo volatilization loss minimized by fine submicron Mo dispersions. However, extensive Mo volatilization and in-place internal oxidation of prior Mo phase regions was observed in wet air oxidation. Ramifications of this phenomenon for the development of multi-phase high-temperature alloys are discussed

  17. Energy absorption in Ni-Mn-Ga/ polymer composites

    E-Print Network [OSTI]

    Feuchtwanger, Jorge

    2006-01-01T23:59:59.000Z

    In recent years Ni-Mn-Ga has attracted considerable attention as a new kind of actuator material. Off-stoichiometric single crystals of Ni2MnGa can regularly exhibit 6% strain in tetragonal martensites and orthorhombic ...

  18. Fracture and fatigue resistance of MoSiB alloys for ultrahigh-temperature structural applications

    E-Print Network [OSTI]

    Ritchie, Robert

    Fracture and fatigue resistance of Mo­Si­B alloys for ultrahigh-temperature structural applications­Mo3Si­Mo5SiB2 alloys, which utilize a continuous a-Mo matrix to achieve unprecedented room. Introduction For applications such as aerospace engines and power generation, future advancements are limited

  19. Oxidation, Reduction, and Condensation of Alcohols over (MO3...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Alcohols over (MO3)3 (MMo, W) Nanoclusters . Abstract: The reactions of deuterated methanol, ethanol, 1-propanol, 1-butanol, 2-propanol, 2-butanol and t-butanol over cyclic...

  20. Co-Mo Electric Cooperative- Residential Energy Efficiency Rebate Program

    Broader source: Energy.gov [DOE]

    Co-Mo Electric Cooperative provides rebates to residential and commercial members who install air source, dual fuel, and/or geothermal heat pumps, and certain energy efficient appliances. The...

  1. 9 Cr-- 1 Mo steel material for high temperature application

    DOE Patents [OSTI]

    Jablonski, Paul D; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-11-27T23:59:59.000Z

    One or more embodiments relates to a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The 9 Cr-1 Mo steel has a tempered martensite microstructure and is comprised of both large (0.5-3 .mu.m) primary titanium carbides and small (5-50 nm) secondary titanium carbides in a ratio of. from about 1:1.5 to about 1.5:1. The 9 Cr-1 Mo steel may be fabricated using exemplary austenizing, rapid cooling, and tempering steps without subsequent hot working requirements. The 9 Cr-1 Mo steel exhibits improvements in total mass gain, yield strength, and time-to-rupture over ASTM P91 and ASTM P92 at the temperature and time conditions examined.

  2. Q value of the 100Mo Double-Beta Decay

    E-Print Network [OSTI]

    S. Rahaman; V. -V. Elomaa; T. Eronen; J. Hakala; A. Jokinen; J. Julin; A. Kankainen; A. Saastamoinen; J. Suhonen; C. Weber; J. Äystö

    2007-12-20T23:59:59.000Z

    Penning trap measurements using mixed beams of 100Mo - 100Ru and 76Ge - 76Se have been utilized to determine the double-beta decay Q-values of 100Mo and 76Ge with uncertainties less than 200 eV. The value for 76Ge, 2039.04(16) keV is in agreement with the published SMILETRAP value. The new value for 100Mo, 3034.40(17) keV is 30 times more precise than the previous literature value, sufficient for the ongoing neutrinoless double-beta decay searches in 100Mo. Moreover, the precise Q-value is used to calculate the phase-space integrals and the experimental nuclear matrix element of double-beta decay.

  3. General Doppler Shift Equation and the Possibility of Systematic Error in Calculation of Z for High Redshift Type Ia Supernovae

    E-Print Network [OSTI]

    Steven M Taylor

    2007-04-10T23:59:59.000Z

    Systematic error in calculation of z for high redshift type Ia supernovae could help explain unexpected luminosity values that indicate an accelerating rate of expansion of the universe.

  4. A New Determination of the High Redshift Type Ia Supernova Rates with the Hubble Space Telescope Advanced Camera for Surveys

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    Schmidt, B. P. , 2003, in Supernovae and Gamma Ray Bursts,for identifying Type Ia supernovae (although spectroscopicfor future high-statistics supernovae searches in which

  5. The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    magnitudes of Type IA supernovae. Astrophys. J. Lett. 413,from 42 High-Redshift Supernovae. Astrophys. J. 517, 565–Observational Evidence from Supernovae for an Accelerating

  6. Ethanol Conversion on Cyclic (MO3)3 (M = Mo, W) Clusters

    SciTech Connect (OSTI)

    Li, Zhenjun; Fang, Zongtang; Kelley, Matthew S.; Kay, Bruce D.; Rousseau, Roger J.; Dohnalek, Zdenek; Dixon, David A.

    2014-03-06T23:59:59.000Z

    Oxides of molybdenum and tungsten are an important class of catalytic materials with applications ranging from isomerization of alkanes and alkenes, partial oxidation of alcohols, selective reduction of nitric oxide and metathesis of alkeness.[1-10] While many studies have focused on the structure - function relationships, the nature of high catalytic activity is still being extensively investigated. There is a general agreement that the activity of supported MOx (M = W, Mo) catalysts is correlated with the presence of acidic sites, where the catalytic activity is strongly affected by the type of oxide support, delocalization of electron density, structures of tungsten oxide domains and presence of protons

  7. Theory of weak localization in ferromagnetic (Ga,Mn)As

    E-Print Network [OSTI]

    Garate, Ion; Sinova, Jairo; Jungwirth, T.; MacDonald, A. H.

    2009-01-01T23:59:59.000Z

    We study quantum interference corrections to the conductivity in (Ga,Mn)As ferromagnetic semiconductors using a model with disordered valence-band holes coupled to localized Mn moments through a p-d kinetic-exchange interaction. We find that at Mn...

  8. Strong near-infrared carbon in the Type Ia supernova iPTF13ebh

    E-Print Network [OSTI]

    Hsiao, E Y; Contreras, C; Höflich, P; Sand, D; Marion, G H; Phillips, M M; Stritzinger, M; González-Gaitán, S; Mason, R E; Folatelli, G; Parent, E; Gall, C; Amanullah, R; Anupama, G C; Arcavi, I; Banerjee, D P K; Beletsky, Y; Blanc, G A; Bloom, J S; Brown, P J; Campillay, A; Cao, Y; De Cia, A; Diamond, T; Freedman, W L; Gonzalez, C; Goobar, A; Holmbo, S; Howell, D A; Johansson, J; Kasliwal, M M; Kirshner, R P; Krisciunas, K; Kulkarni, S R; Maguire, K; Milne, P A; Morrell, N; Nugent, P E; Ofek, E O; Osip, D; Palunas, P; Perley, D A; Persson, S E; Piro, A L; Rabus, M; Roth, M; Schiefelbein, J M; Srivastav, S; Sullivan, M; Suntzeff, N B; Surace, J; Wo?nia, P R; Yaron, O

    2015-01-01T23:59:59.000Z

    We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2.3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR C I lines, and the C I {\\lambda}1.0693 {\\mu}m line is the strongest ever observed in a SN Ia. Interestingly, no strong optical C II counterparts were found, even though the optical spectroscopic time series began early and is densely-cadenced. Except at the very early epochs, within a few days from the time of explosion, we show that the strong NIR C I compared to the weaker optical C II appears to be general in SNe Ia. iPTF13ebh is a fast decliner with {\\Delta}m15(B) = 1.79 $\\pm$ 0.01, and its absolute magnitude obeys the linear part of the width-luminosity relation. It is therefore categ...

  9. A Precise Distance Indicator: Type Ia Supernova Multicolor Light Curve Shapes

    E-Print Network [OSTI]

    Adam Riess; William Press; Robert Kirshner

    1996-04-24T23:59:59.000Z

    We present an empirical method that uses multicolor light curve shapes (MLCS) to estimate the luminosity, distance, and total line-of-sight extinction of Type Ia supernovae (SN Ia). The empirical correlation between the MLCS and the luminosity is derived from a ``training set'' of nine SN Ia light curves with independent distance and reddening estimates. We find that intrinsically dim SN Ia are redder and have faster light curves than the bright ones which are slow and blue. By thirty-five days after maximum the intrinsic color variations become negligable. A formal treatment of extinction employing Bayes' theorem is used to estimate the best value and its uncertainty. Applying MLCS to both light curves and to color curves provides enough information to determine which supernovae are dim because they are distant, which are intrinsically dim, and which are dim because of extinction by dust. The precision of the MLCS distances is examined by constructing a Hubble diagram with an independent set of twenty SN Ia's. The dispersion of 0.12 mag indicates a typical distance accuracy of 5 % for a single object, and the intercept yields a Hubble constant on the Cepheid distance scale (Sandage et al 1994, 1996) of H_0=65 \\pm 3 (statistical) km/s/Mpc ( \\pm 6 total error). The slope of 0.2010 pm 0.0035 mag over the distance interval 32.2 < mu < 38.3 yields the most precise confirmation of the linearity of the Hubble law.

  10. Wind-driven evolution of white dwarf binaries to type Ia supernovae

    SciTech Connect (OSTI)

    Ablimit, Iminhaji; Xu, Xiao-jie; Li, X.-D. [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2014-01-01T23:59:59.000Z

    In the single-degenerate scenario for the progenitors of Type Ia supernovae (SNe Ia), a white dwarf rapidly accretes hydrogen- or helium-rich material from its companion star and appears as a supersoft X-ray source. This picture has been challenged by the properties of the supersoft X-ray sources with very low mass companions and the observations of several nearby SNe Ia. It has been pointed out that the X-ray radiation or the wind from the accreting white dwarf can excite winds or strip mass from the companion star, thus significantly influencing the mass transfer processes. In this paper, we perform detailed calculations of the wind-driven evolution of white dwarf binaries. We present the parameter space for the possible SN Ia progenitors and for the surviving companions after the SNe. The results show that the ex-companion stars of SNe Ia have characteristics more compatible with the observations, compared with those in the traditional single-degenerate scenario.

  11. Type Ia supernovae from merging white dwarfs. II. Post-merger detonations

    SciTech Connect (OSTI)

    Raskin, Cody; Kasen, Daniel [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Moll, Rainer; Woosley, Stan [Department of Physics and Department of Astronomy, University of California, Santa Cruz, CA (United States); Schwab, Josiah [Department of Physics and Department of Astronomy, University of California, Berkeley, CA (United States)

    2014-06-10T23:59:59.000Z

    Merging carbon-oxygen (CO) white dwarfs are a promising progenitor system for Type Ia supernovae (SNe Ia), but the underlying physics and timing of the detonation are still debated. If an explosion occurs after the secondary star is fully disrupted, the exploding primary will expand into a dense CO medium that may still have a disk-like structure. This interaction will decelerate and distort the ejecta. Here we carry out multidimensional simulations of 'tamped' SN Ia models, using both particle and grid-based codes to study the merger and explosion dynamics and a radiative transfer code to calculate synthetic spectra and light curves. We find that post-merger explosions exhibit an hourglass-shaped asymmetry, leading to strong variations in the light curves with viewing angle. The two most important factors affecting the outcome are the scale height of the disk, which depends sensitively on the binary mass ratio, and the total {sup 56}Ni yield, which is governed by the central density of the remnant core. The synthetic broadband light curves rise and decline very slowly, and the spectra generally look peculiar, with weak features from intermediate mass elements but relatively strong carbon absorption. We also consider the effects of the viscous evolution of the remnant and show that a longer time delay between merger and explosion probably leads to larger {sup 56}Ni yields and more symmetrical remnants. We discuss the relevance of this class of aspherical 'tamped' SN Ia for explaining the class of 'super-Chandrasekhar' SN Ia.

  12. SALT: a Spectral Adaptive Light curve Template for Type Ia Supernovae

    E-Print Network [OSTI]

    J. Guy; P. Astier; S. Nobili; N. Regnault; R. Pain

    2005-07-01T23:59:59.000Z

    We present a new method to parameterize Type Ia Supernovae (SN Ia) multi-color light curves. The method was developed in order to analyze the large number of SN Ia multi-color light curves measured in current high-redshift projects. The technique is based on empirically modeling SN Ia luminosity variations as a function of phase, wavelength, a shape parameter, and a color parameter. The model is trained with a sample of well measured nearby SN Ia and then tested with an independent set of supernovae by building an optimal luminosity distance estimator combining the supernova rest-frame luminosity, shape parameter and color reconstructed with the model. The distances we measure using B- and V-band data show a dispersion around the Hubble line comparable or lower than obtained with other methods. With this model, we are able to measure distances using U- and B-band data with a dispersion around the Hubble line of 0.16 +- 0.05.

  13. Confirmation of Hostless Type Ia Supernovae Using Hubble Space Telescope Imaging

    E-Print Network [OSTI]

    Graham, Melissa L; Zaritsky, Dennis; Pritchet, Chris J

    2015-01-01T23:59:59.000Z

    We present deep Hubble Space Telescope imaging at the locations of four, potentially hostless, long-faded Type Ia supernovae (SNe Ia) in low-redshift, rich galaxy clusters that were identified in the Multi-Epoch Nearby Cluster Survey. Assuming a steep faint-end slope for the galaxy cluster luminosity function ($\\alpha_d=-1.5$), our data includes all but $\\lesssim0.2\\%$ percent of the stellar mass in cluster galaxies ($\\lesssim0.005\\%$ with $\\alpha_d=-1.0$), a factor of 10 better than our ground-based imaging. Two of the four SNe Ia still have no possible host galaxy associated with them ($M_R>-9.2$), confirming that their progenitors belong to the intracluster stellar population. The third SNe Ia appears near a faint disk galaxy ($M_V=-12.2$) which has a relatively high probability of being a chance alignment. A faint, red, point source coincident with the fourth SN Ia's explosion position ($M_V=-8.4$) may be either a globular cluster (GC) or faint dwarf galaxy. We estimate the local surface densities of GCs ...

  14. COMPARING THE LIGHT CURVES OF SIMULATED TYPE Ia SUPERNOVAE WITH OBSERVATIONS USING DATA-DRIVEN MODELS

    SciTech Connect (OSTI)

    Diemer, Benedikt; Kessler, Richard; Graziani, Carlo; Jordan, George C. IV; Lamb, Donald Q.; Long, Min; Van Rossum, Daniel R., E-mail: bdiemer@oddjob.uchicago.edu [Flash Center for Computational Science, University of Chicago, Chicago, IL 60637 (United States)

    2013-08-20T23:59:59.000Z

    We propose a robust, quantitative method to compare the synthetic light curves of a Type Ia supernova (SN Ia) explosion model with a large set of observed SNe Ia, and derive a figure of merit for the explosion model's agreement with observations. The synthetic light curves are fit with the data-driven model SALT2 which returns values for stretch, color, and magnitude at peak brightness, as well as a goodness-of-fit parameter. Each fit is performed multiple times with different choices of filter bands and epoch range in order to quantify the systematic uncertainty on the fitted parameters. We use a parametric population model for the distribution of observed SN Ia parameters from large surveys, and extend it to represent red, dim, and bright outliers found in a low-redshift SN Ia data set. We discuss the potential uncertainties of this population model and find it to be reliable given the current uncertainties on cosmological parameters. Using our population model, we assign each set of fitted parameters a likelihood of being observed in nature, and a figure of merit based on this likelihood. We define a second figure of merit based on the quality of the light curve fit, and combine the two measures into an overall figure of merit for each explosion model. We compute figures of merit for a variety of one-, two-, and three-dimensional explosion models and show that our evaluation method allows meaningful inferences across a wide range of light curve quality and fitted parameters.

  15. Mn/DOT's Project Peer Review

    E-Print Network [OSTI]

    Minnesota, University of

    and sustain this culture #12;Project Management #12;Recent National Work in Transportation Project ManagementMn/DOT's Project Management Peer Review Creating a Project Management Culture 2010 CTS Research a Peer Review? Why Project Management? ·Improve project delivery performance ­ on time, on budget (an

  16. MN4602 Crouch 2004 REASSESSING WEAPON SYSTEM

    E-Print Network [OSTI]

    MN4602 Crouch 2004 REASSESSING WEAPON SYSTEM OPERATIONAL TEST & EVALUATION METHODOLOGIES LTC Thom support assessing a weapon systems true cost and performance characteristics? S1: Can/should cost, operational effectiveness and suitability be assessed independent of one another? S2: Do current test

  17. Materials Data on Mn3Mo2H34C22N16O5 (SG:15) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Influence of interstitial Mn on magnetism in room-temperature ferromagnet Mn(1+delta)Sb

    SciTech Connect (OSTI)

    Taylor, Alice E [ORNL; Berlijn, Tom [ORNL; Hahn, Steven E [ORNL; May, Andrew F [ORNL; Williams, Travis J [ORNL; Poudel, Lekhanath N [ORNL; Calder, Stuart A [ORNL; Fishman, Randy Scott [ORNL; Stone, Matthew B [ORNL; Aczel, Adam A [ORNL; Cao, Huibo [ORNL; Lumsden, Mark D [ORNL; Christianson, Andrew D [ORNL

    2015-01-01T23:59:59.000Z

    We report elastic and inelastic neutron scattering measurements of the high-TC ferromagnet Mn(1+delta)Sb. Measurements were performed on a large, TC = 434 K, single crystal with interstitial Mn content of delta=0.13. The neutron diffraction results reveal that the interstitial Mn has a magnetic moment, and that it is aligned antiparallel to the main Mn moment. We perform density functional theory calculations including the interstitial Mn, and find the interstitial to be magnetic in agreement with the diffraction data. The inelastic neutron scattering measurements reveal two features in the magnetic dynamics: i) a spin-wave-like dispersion emanating from ferromagnetic Bragg positions (H K 2n), and ii) a broad, non-dispersive signal centered at forbidden Bragg positions (H K 2n+1). The inelastic spectrum cannot be modeled by simple linear spin-wave theory calculations, and appears to be significantly altered by the presence of the interstitial Mn ions. The results show that the influence of the int

  19. Evidence of N substitution by Mn in GaN

    E-Print Network [OSTI]

    Pereira, LMC; Decoster, S; Correia, JG; da Silva, MR; Vantomme, A; Araújo, JP

    2012-01-01T23:59:59.000Z

    We report on the lattice location of Mn in wurtzite GaN using beta? emission channeling. In addition to the majority substituting for Ga, we locate up to 20% of the Mn atoms in N sites. We propose that the incorporation of Mn in N sites is enabled under sufficiently high concentrations of N vacancies, and stabilized by a highly charged state of the Mn cations. Since N substitution by Mn impurities in wurtzite GaN has never been observed experimentally or even considered theoretically before, it challenges the current paradigm of transition metal incorporation in wide-gap dilute magnetic semiconductors.

  20. Spectral Modeling of SNe Ia Near Maximum Light: Probing the Characteristics of Hydro Models

    E-Print Network [OSTI]

    E. Baron; S. Bongard; David Branch; Peter H. Hauschildt

    2006-03-03T23:59:59.000Z

    We have performed detailed NLTE spectral synthesis modeling of 2 types of 1-D hydro models: the very highly parameterized deflagration model W7, and two delayed detonation models. We find that overall both models do about equally well at fitting well observed SNe Ia near to maximum light. However, the Si II 6150 feature of W7 is systematically too fast, whereas for the delayed detonation models it is also somewhat too fast, but significantly better than that of W7. We find that a parameterized mixed model does the best job of reproducing the Si II 6150 line near maximum light and we study the differences in the models that lead to better fits to normal SNe Ia. We discuss what is required of a hydro model to fit the spectra of observed SNe Ia near maximum light.

  1. The Late-Time Rebrightening of Type Ia SN 2005gj in the Mid-Infrared

    E-Print Network [OSTI]

    Fox, Ori D

    2013-01-01T23:59:59.000Z

    A growing number of observations reveal a subset of Type Ia supernovae undergoing circumstellar interaction (SNe Ia-CSM). We present unpublished archival Spitzer Space Telescope data on SNe Ia-CSM 2002ic and 2005gj obtained > 1300 and 500 days post-discovery, respectively. Both SNe show evidence for late-time mid-infrared (mid-IR) emission from warm dust. The dust parameters are most consistent with a pre-existing dust shell that lies beyond the forward-shock radius, most likely radiatively heated by optical and X-ray emission continuously generated by late-time CSM interaction. In the case of SN 2005gj, the mid-IR luminosity more than doubles after 1 year post-discovery. While we are not aware of any late-time optical-wavelength observations at these epochs, we attribute this rebrightening to renewed shock interaction with a dense circumstellar shell.

  2. [O I] ??6300, 6364 IN THE NEBULAR SPECTRUM OF A SUBLUMINOUS TYPE Ia SUPERNOVA

    SciTech Connect (OSTI)

    Taubenberger, S.; Kromer, M.; Hillebrandt, W. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany)] [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Pakmor, R. [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany)] [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Pignata, G. [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile)] [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); Maeda, K. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)] [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Hachinger, S. [Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 31, D-97074 Würzburg (Germany)] [Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 31, D-97074 Würzburg (Germany); Leibundgut, B. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)] [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)

    2013-10-01T23:59:59.000Z

    In this Letter, a late-phase spectrum of SN 2010lp, a subluminous Type Ia supernova (SN Ia), is presented and analyzed. As in 1991bg-like SNe Ia at comparable epochs, the spectrum is characterized by relatively broad [Fe II] and [Ca II] emission lines. However, instead of narrow [Fe III] and [Co III] lines that dominate the emission from the innermost regions of 1991bg-like supernovae (SNe), SN 2010lp shows [O I] ??6300, 6364 emission, usually associated with core-collapse SNe and never previously observed in a subluminous thermonuclear explosion. The [O I] feature has a complex profile with two strong, narrow emission peaks. This suggests that oxygen is distributed in a non-spherical region close to the center of the ejecta, severely challenging most thermonuclear explosion models discussed in the literature. We conclude that, given these constraints, violent mergers are presently the most promising scenario to explain SN 2010lp.

  3. THE LATE-TIME REBRIGHTENING OF TYPE Ia SN 2005gj IN THE MID-INFRARED

    SciTech Connect (OSTI)

    Fox, Ori D.; Filippenko, Alexei V., E-mail: ofox@berkeley.edu [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

    2013-07-20T23:59:59.000Z

    A growing number of observations reveal a subset of Type Ia supernovae undergoing circumstellar interaction (SNe Ia-CSM). We present unpublished archival Spitzer Space Telescope data on SNe Ia-CSM 2002ic and 2005gj obtained >1300 and 500 days post-discovery, respectively. Both SNe show evidence for late-time mid-infrared (mid-IR) emission from warm dust. The dust parameters are most consistent with a preexisting dust shell that lies beyond the forward-shock radius, most likely radiatively heated by optical and X-ray emission continuously generated by late-time CSM interaction. In the case of SN 2005gj, the mid-IR luminosity more than doubles after 1 yr post-discovery. While we are not aware of any late-time optical-wavelength observations at these epochs, we attribute this rebrightening to renewed shock interaction with a dense circumstellar shell.

  4. SALT2: using distant supernovae to improve the use of Type Ia supernovae as distance indicators

    E-Print Network [OSTI]

    J. Guy; P. Astier; S. Baumont; D. Hardin; R. Pain; N. Regnault; S. Basa; R. G. Carlberg; A. Conley; S. Fabbro; D. Fouchez; I. M. Hook; D. A. Howell; K. Perrett; C. J. Pritchet; J. Rich; M. Sullivan; P. Antilogus; E. Aubourg; G. Bazin; J. Bronder; M. Filiol; N. Palanque-Delabrouille; P. Ripoche; V. Ruhlmann-Kleider

    2007-01-29T23:59:59.000Z

    We present an empirical model of Type Ia supernovae spectro-photometric evolution with time. The model is built using a large data set including light-curves and spectra of both nearby and distant supernovae, the latter being observed by the SNLS collaboration. We derive the average spectral sequence of Type Ia supernovae and their main variability components including a color variation law. The model allows us to measure distance moduli in the spectral range 2500-8000 A with calculable uncertainties, including those arising from variability of spectral features. Thanks to the use of high-redshift SNe to model the rest-frame UV spectral energy distribution, we are able to derive improved distance estimates for SNe Ia in the redshift range 0.8supernovae.

  5. MoSe2 thin films synthesized by solid state reactions between Mo and Se J. Pouzet (1) and J. C. Bernede (2)

    E-Print Network [OSTI]

    Boyer, Edmond

    807 MoSe2 thin films synthesized by solid state reactions between Mo and Se thin films J. Pouzet (1 reaction, induced by annealing, between the Mo and Se constituents in thin films form. The films have been thin films annealed under selenium pressure at only 770 K are well crystallized. The electrical

  6. EARLY PHASE OBSERVATIONS OF EXTREMELY LUMINOUS TYPE Ia SUPERNOVA 2009dc

    SciTech Connect (OSTI)

    Yamanaka, M.; Arai, A.; Chiyonobu, S.; Fukazawa, Y.; Ikejiri, Y.; Itoh, R.; Komatsu, T.; Miyamoto, H. [Department of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526 (Japan); Kawabata, K. S. [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Kinugasa, K.; Hashimoto, O.; Honda, S. [Gunma Astronomical Observatory, Takayama, Gunma 377-0702 (Japan); Tanaka, M. [Department of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Imada, A.; Kuroda, D. [Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Kamogata, Asakuchi-shi, Okayama 719-0232 (Japan); Maeda, K.; Nomoto, K. [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa (Japan); Kamata, Y. [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); Kawai, N. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Konishi, K., E-mail: myamanaka@hiroshima-u.ac.j [Institute for Cosmic Ray Research, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba, 277-8582 (Japan)

    2009-12-20T23:59:59.000Z

    We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of the light curve is DELTAm{sub 15}(B) = 0.65 +- 0.03, which is one of the slowest among SNe Ia. The peak V-band absolute magnitude is estimated to be M{sub V} = -19.90 +- 0.15 mag if no host extinction is assumed. It reaches M{sub V} = -20.19 +- 0.19 mag if we assume the host extinction of A{sub V} = 0.29 mag. SN 2009dc belongs to the most luminous class of SNe Ia, like SNe 2003fg and 2006gz. Our JHK{sub s} -band photometry shows that this SN is also one of the most luminous SNe Ia in near-infrared wavelengths. We estimate the ejected {sup 56}Ni mass of 1.2 +- 0.3 M{sub sun} for the no host extinction case (and of 1.6 +- 0.4 M{sub sun} for the host extinction of A{sub V} = 0.29 mag). The C II lambda6580 absorption line remains visible until a week after the maximum brightness, in contrast to its early disappearance in SN 2006gz. The line velocity of Si II lambda6355 is about 8000 km s{sup -1} around the maximum, being considerably slower than that of SN 2006gz. The velocity of the C II line is similar to or slightly less than that of the Si II line around the maximum. The presence of the carbon line suggests that the thick unburned C+O layer remains after the explosion. Spectropolarimetric observations by Tanaka et al. indicate that the explosion is nearly spherical. These observational facts suggest that SN 2009dc is a super-Chandrasekhar mass SN Ia.

  7. OPTICAL CROSS-CORRELATION FILTERS: AN ECONOMICAL APPROACH FOR IDENTIFYING SNe Ia AND ESTIMATING THEIR REDSHIFTS

    SciTech Connect (OSTI)

    Scolnic, Daniel M.; Riess, Adam G.; Huber, Mark E. [Department of Physics and Astronomy, Johns Hopkins University, MD 21218 (United States); Rest, Armin; Stubbs, Christoper W. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Tonry, John L. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

    2009-11-20T23:59:59.000Z

    Large photometric surveys of transient phenomena, such as Panoramic Survey Telescope and Rapid Response System and Large Synoptic Survey Telescope, will locate thousands to millions of Type Ia supernova (SN Ia) candidates per year, a rate prohibitive for acquiring spectroscopy to determine each candidate's type and redshift. In response, we have developed an economical approach to identifying SNe Ia and their redshifts using an uncommon type of optical filter which has multiple, discontinuous passbands on a single substrate. Observation of a supernova through a specially designed pair of these 'cross-correlation filters' measures the approximate amplitude and phase of the cross-correlation between the spectrum and a SN Ia template, a quantity typically used to determine the redshift and type of a high-redshift SN Ia. Simulating the use of these filters, we obtain a sample of SNe Ia which is approx98% pure with individual redshifts measured to sigma{sub z} = 0.01 precision. The advantages of this approach over standard broadband photometric methods are that it is insensitive to reddening, independent of the color data used for subsequent distance determinations which reduce selection or interpretation bias, and because it makes use of the spectral features its reliability is greater. A great advantage over long-slit spectroscopy comes from increased throughput, enhanced multiplexing, and reduced setup time resulting in a net gain in speed of up to approx30 times. This approach is also insensitive to host galaxy contamination. Prototype filters were built and successfully used on Magellan with LDSS-3 to characterize three SuperNova Legacy Survey candidates. We discuss how these filters can provide critical information for the upcoming photometric supernova surveys.

  8. Ultraviolet observations of Super-Chandrasekhar mass type Ia supernova candidates with swift UVOT

    SciTech Connect (OSTI)

    Brown, Peter J.; Smitka, Michael T.; Krisciunas, Kevin; Wang, Lifan [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Kuin, Paul; De Pasquale, Massimiliano [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking Surrey, RH5 6NT (United Kingdom); Scalzo, Richard [Research School of Astronomy and Astrophysics, The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT 2611 (Australia); Holland, Stephen [Space Telescope Science Center 3700 San Martin Drive, Baltimore, MD 21218 (United States); Milne, Peter, E-mail: pbrown@physics.tamu.edu [Steward Observatory, University of Arizona, Tucson, AZ 85719 (United States)

    2014-05-20T23:59:59.000Z

    Among Type Ia supernovae (SNe Ia), a class of overluminous objects exist whose ejecta mass is inferred to be larger than the canonical Chandrasekhar mass. We present and discuss the UV/optical photometric light curves, colors, absolute magnitudes, and spectra of three candidate Super-Chandrasekhar mass SNe—2009dc, 2011aa, and 2012dn—observed with the Swift Ultraviolet/Optical Telescope. The light curves are at the broad end for SNe Ia, with the light curves of SN 2011aa being among the broadest ever observed. We find all three to have very blue colors which may provide a means of excluding these overluminous SNe from cosmological analysis, though there is some overlap with the bluest of 'normal' SNe Ia. All three are overluminous in their UV absolute magnitudes compared to normal and broad SNe Ia, but SNe 2011aa and 2012dn are not optically overluminous compared to normal SNe Ia. The integrated luminosity curves of SNe 2011aa and 2012dn in the UVOT range (1600-6000 Å) are only half as bright as SN 2009dc, implying a smaller {sup 56}Ni yield. While it is not enough to strongly affect the bolometric flux, the early time mid-UV flux makes a significant contribution at early times. The strong spectral features in the mid-UV spectra of SNe 2009dc and 2012dn suggest a higher temperature and lower opacity to be the cause of the UV excess rather than a hot, smooth blackbody from shock interaction. Further work is needed to determine the ejecta and {sup 56}Ni masses of SNe 2011aa and 2012dn and to fully explain their high UV luminosities.

  9. Coated U(Mo) Fuel: As-Fabricated Microstructures

    SciTech Connect (OSTI)

    Emmanuel Perez; Dennis D. Keiser, Jr.; Ann Leenaers; Sven Van den Berghe; Tom Wiencek

    2014-04-01T23:59:59.000Z

    As part of the development of low-enriched uranium fuels, fuel plates have recently been tested in the BR-2 reactor as part of the SELENIUM experiment. These fuel plates contained fuel particles with either Si or ZrN thin film coating (up to 1 µm thickness) around the U-7Mo fuel particles. In order to best understand irradiation performance, it is important to determine the starting microstructure that can be observed in as-fabricated fuel plates. To this end, detailed microstructural characterization was performed on ZrN and Si-coated U-7Mo powder in samples taken from AA6061-clad fuel plates fabricated at 500°C. Of interest was the condition of the thin film coatings after fabrication at a relatively high temperature. Both scanning electron microscopy and transmission electron microscopy were employed. The ZrN thin film coating was observed to consist of columns comprised of very fine ZrN grains. Relatively large amounts of porosity could be found in some areas of the thin film, along with an enrichment of oxygen around each of the the ZrN columns. In the case of the pure Si thin film coating sample, a (U,Mo,Al,Si) interaction layer was observed around the U-7Mo particles. Apparently, the Si reacted with the U-7Mo and Al matrix during fuel plate fabrication at 500°C to form this layer. The microstructure of the formed layer is very similar to those that form in U-7Mo versus Al-Si alloy diffusion couples annealed at higher temperatures and as-fabricated U-7Mo dispersion fuel plates with Al-Si alloy matrix fabricated at 500°C.

  10. Constraining the Lattice Fluid Dark Energy from SNe Ia, BAO and OHD

    E-Print Network [OSTI]

    Duan, Xiaoxian; Gao, Changjun

    2011-01-01T23:59:59.000Z

    Sanchez and Lacombe have ever developed a lattice fluid theory based on a well-defined statistical mechanical model. Taking the lattice fluid as a candidate of dark energy, we investigate the cosmic evolution of this fluid. Using the combined observational data of Type Ia Supernova (SNe Ia), Baryon Acoustic Oscillations (BAO) and Observational Hubble Data (OHD), we find the best fit value of the parameter in the model, $A = -0.3_{-0.1}^{+0.1}$. Then the cosmological implications of the model are presented.

  11. Constraining the Lattice Fluid Dark Energy from SNe Ia, BAO and OHD

    E-Print Network [OSTI]

    Xiaoxian Duan; Yichao Li; Changjun Gao

    2011-11-15T23:59:59.000Z

    Sanchez and Lacombe have ever developed a lattice fluid theory based on a well-defined statistical mechanical model. Taking the lattice fluid as a candidate of dark energy, we investigate the cosmic evolution of this fluid. Using the combined observational data of Type Ia Supernova (SNe Ia), Baryon Acoustic Oscillations (BAO) and Observational Hubble Data (OHD), we find the best fit value of the parameter in the model, $A = -0.3_{-0.1}^{+0.1}$. Then the cosmological implications of the model are presented.

  12. Experto Universitario Java Enterprise Componentes de presentacin 2012-2013 Depto. Ciencia de la Computacin e IA Sesin 1

    E-Print Network [OSTI]

    Escolano, Francisco

    Experto Universitario Java Enterprise Componentes de presentación © 2012-2013 Depto. Ciencia de la Universitario Java Enterprise Componentes de presentación © 2012-2013 Depto. Ciencia de la Computación e IA Componentes de presentación © 2012-2013 Depto. Ciencia de la Computación e IA Sesión 1 Experto Universitario

  13. Especialista Universitario Java Enterprise Componentes de presentacin 2012-2013 Depto. Ciencia de la Computacin e IA Sesin 4

    E-Print Network [OSTI]

    Escolano, Francisco

    Especialista Universitario Java Enterprise Componentes de presentación © 2012-2013 Depto. Ciencia presentación © 2012-2013 Depto. Ciencia de la Computación e IA Sesión 4 Experto Universitario Java Enterprise Componentes de presentación © 2012-2013 Depto. Ciencia de la Computación e IA Sesión 4 Experto Universitario

  14. A TYPE Ia SUPERNOVA AT REDSHIFT 1.55 IN HUBBLE SPACE TELESCOPE INFRARED OBSERVATIONS FROM CANDELS

    SciTech Connect (OSTI)

    Rodney, Steven A.; Riess, Adam G.; Jones, David O. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Dahlen, Tomas; Ferguson, Henry C.; Casertano, Stefano; Grogin, Norman A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Strolger, Louis-Gregory [Department of Physics, Western Kentucky University, Bowling Green, KY 42101 (United States); Hjorth, Jens; Frederiksen, Teddy F. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Weiner, Benjamin J. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Challis, Peter; Kirshner, Robert P. [Harvard/Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Faber, S. M. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 92064 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Garnavich, Peter; Hayden, Brian [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Graur, Or [Department of Astrophysics, Tel Aviv University, 69978 Tel Aviv (Israel); Jha, Saurabh W. [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); and others

    2012-02-10T23:59:59.000Z

    We report the discovery of a Type Ia supernova (SN Ia) at redshift z = 1.55 with the infrared detector of the Wide Field Camera 3 (WFC3-IR) on the Hubble Space Telescope (HST). This object was discovered in CANDELS imaging data of the Hubble Ultra Deep Field and followed as part of the CANDELS+CLASH Supernova project, comprising the SN search components from those two HST multi-cycle treasury programs. This is the highest redshift SN Ia with direct spectroscopic evidence for classification. It is also the first SN Ia at z > 1 found and followed in the infrared, providing a full light curve in rest-frame optical bands. The classification and redshift are securely defined from a combination of multi-band and multi-epoch photometry of the SN, ground-based spectroscopy of the host galaxy, and WFC3-IR grism spectroscopy of both the SN and host. This object is the first of a projected sample at z > 1.5 that will be discovered by the CANDELS and CLASH programs. The full CANDELS+CLASH SN Ia sample will enable unique tests for evolutionary effects that could arise due to differences in SN Ia progenitor systems as a function of redshift. This high-z sample will also allow measurement of the SN Ia rate out to z Almost-Equal-To 2, providing a complementary constraint on SN Ia progenitor models.

  15. Unexpected crystal and magnetic structures in MnCu4In and MnCu4Sn

    SciTech Connect (OSTI)

    Provino, A.; Paudyal, D.; Fornasini, ML; Dhiman, I.; Dhar, SK.; Das, A.; Mudryk, Y.; Manfrinetti, P.; Pecharsky, VK

    2013-01-29T23:59:59.000Z

    We discovered a new compound MnCu4In with its own hexagonal structure type (hP12-P63mc, ternary ordered derivative of the hexagonal MgZn2-type) that becomes ferromagnetic at TC = 540 K. This transition temperature is higher than that found in the MnCu2In and MnCu2Sn alloys. In contrast, the homologous compound MnCu4Sn, which crystallizes in the cubic MgCu4Sn-type, orders antiferromagnetically with TN = 110 K. The neutron diffraction studies show ferromagnetic spin orientation in the {1 0 1} plane in MnCu4In with a magnetic moment of 4.5 ?B/Mn at 22 K, and a corresponding value of 4.7 ?B/Mn in the antiferromagnetic MnCu4Sn with propagation vector View the MathML source. The first-principles electronic structure calculations show that the unexpected difference in both magnetic and crystal structures of MnCu4In and MnCu4Sn is due to the difference in the Mn-3d bands and exchange interactions relating to different crystal anisotropy, coordination numbers, and interatomic distances.

  16. Effect of Mn doping on structural and magnetic susceptibility of C-type rare earth nano oxides Er{sub 2?x}Mn{sub x}O{sub 3}

    SciTech Connect (OSTI)

    Heiba, Zein K. [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt) [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Taif University, Faculty of Science, Physics Department (Saudi Arabia); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Fuess, H. [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)] [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)

    2012-12-15T23:59:59.000Z

    Graphical abstract: Display Omitted Highlights: ? Er{sub 2?x}Mn{sub x}·O{sub 3} (0.0 ? x ? 0.20) prepared by sol–gel method. ? The change in lattice parameter is not linear with x due to the change in crystallite size with doping. ? Anomalous concentration dependence is found in magnetic susceptibility. ? The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x. ? Superexchange interactions between Er ions depending on the amount of Mn or Er in different sites. -- Abstract: The manganese doped rare earth oxides Er{sub 2?x}Mn{sub x} O{sub 3} (0.0 ? x ? 0.20) were synthesized by a sol–gel process and analyzed by X-ray diffraction using Rietveld refinement methods. A single phase solid solution is formed up to x = 0.15 while for x ? 0.2 a manganese oxide phase appears in the diffraction pattern. Preferential cationic distribution between the non-equivalent sites 8b and 24d of space group Ia3{sup ¯} is found for all samples but to a different extent. The octahedral volume and average bond length of Er{sub 1}-O for 8b site decrease while both octahedral volume and bond length of Er{sub 2}-O for 24d site increase. Magnetization measurements were done in the temperature range 5–300 K. The effective magnetic moment ?{sub eff} is found to decrease with composition parameter x, except for sample x = 0.05 where the magnetization is enhanced. The Curie-Weiss paramagnetic temperatures indicate antiferromagnetic interaction.

  17. Multi-color light curves of type Ia supernovae on the color-magnitude diagram: A novel step toward more precise distance and extinction estimates

    E-Print Network [OSTI]

    Wang, Lifan; Goldhaber, Gerson; Aldering, Greg; Perlmutter, Saul

    2003-01-01T23:59:59.000Z

    Date is earlier than for supernovae with smaller ?m 15 . SeeLight Curves of Type Ia Supernovae on the Color-Magnituderelation of Type Ia supernovae after optical maximum can

  18. Predicting the amount of hydrogen stripped by the SN explosion for SN 2002cx-like SNe Ia

    SciTech Connect (OSTI)

    Liu, Zheng-Wei; Chen, X. F.; Wang, B.; Han, Z. W. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Kromer, M. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Fink, M.; Röpke, F. K. [Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Pakmor, R., E-mail: zwliu@ynao.ac.cn [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany)

    2013-12-01T23:59:59.000Z

    The most favored progenitor scenarios for Type Ia supernovae (SNe Ia) involve the single-degenerate (SD) scenario and the double-degenerate scenario. The absence of stripped hydrogen (H) in the nebular spectra of SNe Ia challenges the SD progenitor models. Recently, it was shown that pure deflagration explosion models of Chandrasekhar-mass white dwarfs, ignited off-center, reproduce the characteristic observational features of 2002cx-like SNe Ia very well. In this work we predict, for the first time, the amount of stripped H for the off-center, pure deflagration explosions. We find that their low kinetic energies lead to inefficient H mass stripping (? 0.01 M {sub ?}), indicating that the stripped H may be hidden in (observed) late-time spectra of SN 2002cx-like SNe Ia.

  19. Type-Ia supernova rates to redshift 2.4 from clash: The cluster lensing and supernova survey with Hubble

    SciTech Connect (OSTI)

    Graur, O.; Rodney, S. A.; Riess, A. G.; Medezinski, E. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Maoz, D. [School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Jha, S. W.; Holoien, T. W.-S.; McCully, C.; Patel, B. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Postman, M.; Dahlen, T.; Strolger, L.-G.; Coe, D.; Bradley, L.; Koekemoer, A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Benítez, N.; Molino, A. [Instituto de Astrofísica de Andalucía (CSIC), E-18080 Granada (Spain); Jouvel, S. [Institut de Ciencies de l'Espai, (IEEC-CSIC), E-08193 Bellaterra (Barcelona) (Spain); Nonino, M.; Balestra, I., E-mail: orgraur@jhu.edu [INAF-Osservatorio Astronomico di Trieste, I-34143 Trieste (Italy); and others

    2014-03-01T23:59:59.000Z

    We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, ?13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z > 1.2. We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit on the SN Ia rate in the range 1.8 < z < 2.4. The results are consistent with the rates measured by the HST/GOODS and Subaru Deep Field SN surveys. We model these results together with previous measurements at z < 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of ?1.00{sub ?0.06(0.10)}{sup +0.06(0.09)} (statistical){sub ?0.08}{sup +0.12} (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at >99% significance level.

  20. Multiphonon resonant Raman scattering in MoS{sub 2}

    SciTech Connect (OSTI)

    Go?asa, K., E-mail: Katarzyna.Golasa@fuw.edu.pl; Grzeszczyk, M.; Wysmo?ek, A.; Babi?ski, A. [Faculty of Physics, University of Warsaw, ul. Ho?a 69, 00-681 Warszawa (Poland); Leszczy?ski, P.; Faugeras, C.; Nicolet, A. A. L.; Potemski, M. [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble (France)

    2014-03-03T23:59:59.000Z

    Optical emission spectrum of a resonantly (??=?632.8?nm) excited molybdenum disulfide (MoS{sub 2}) is studied at liquid helium temperature. More than 20 peaks in the energy range spanning up to 1400?cm{sup ?1} from the laser line, which are related to multiphonon resonant Raman scattering processes, are observed. The attribution of the observed lines involving basic lattice vibrational modes of MoS{sub 2} and both the longitudinal (LA(M)) and the transverse (TA(M) and/or ZA(M)) acoustic phonons from the vicinity of the high-symmetry M point of the MoS{sub 2} Brillouin zone is proposed.

  1. Identification of phases in the interaction layer between U-Mo-Zr/Al and U-Mo-Zr/Al-Si

    SciTech Connect (OSTI)

    Varela, C.L. Komar; Arico, S.F.; Mirandou, M.; Balart, S.N. [Departamento Materiales, GIDAT, GAEN, CNEA, Avda. Gral Paz 1499, B1650KNA, San Martin (Argentina); Gribaudo, L.M. [Departamento Materiales, GIDAT, GAEN, CNEA, Avda. Gral Paz 1499, B1650KNA, San Martin (Argentina); CONICET, Avda. Rivadavia 1917, C1033AAJ, Buenos Aires (Argentina)

    2008-07-15T23:59:59.000Z

    Out-of-pile diffusion experiments were performed between U-7wt.% Mo-1wt.% Zr and Al or Al A356 (7,1wt.% Si) at 550 deg. C. In this work morphological characterization and phase identification on both interaction layer are presented. They were carried out by the use of different techniques: optical and scanning electron microscopy, X-Ray diffraction and WDS microanalysis. In the interaction layer U-7wt.% Mo-1wt.% Zr/Al, the phases UAl{sub 3}, UAl{sub 4}, Al{sub 20}Mo{sub 2}U and Al{sub 43}Mo{sub 4}U{sub 6} were identified. In the interaction layer U-7wt.% Mo-1wt.% Zr/Al A356, the phases U(Al, Si) with 25at.% Si and Si{sub 5}U{sub 3} were identified. This last phase, with a higher Si concentration, was identified with XRD Synchrotron radiation performed at the National Synchrotron Light Laboratory (LNLS), Campinas, Brasil. (author)

  2. Hydrotreatment of Athabasca bitumen derived gas oil over Ni-Mo, Ni-W, and Co-Mo catalysts

    SciTech Connect (OSTI)

    Diaz-Real, R.A.; Mann, R.S.; Sambi, I.S. (Univ. of Ottawa, Ontario (Canada). Dept. of Chemical Engineering)

    1993-07-01T23:59:59.000Z

    The hydrotreatment of Athabasca bitumen derived heavy gas oil containing 4.08% S and 0.49% N was carried out in a trickle bed reactor over Ni-W, Ni-Mo, and Co-Mo catalysts supported on zeolite-alumina-silica at 623-698 K, LHSV of 1-4, gas flow rate 890 m[sup 3][sub H2]/m[sup 3][sub oil] (5,000 sef/bbl), and pressure of 6.89 MPa. Analyses for viscosity, density, aniline point, ASTM mid boiling point distillation, C/H ratio, and percentage of N and S in the final product were carried out to characterize the product oil. The amounts of N and S removed indicated the hydrodenitrogenation and hydrodesulfurization activity of the catalysts. Results of zeolite-alumina-silica-supported catalysts are compared to those obtained with commercially available Ni-Mo, Ni-W, and Co-Mo on [gamma]-alumina. Ni-Mo supported on zeolite-alumina-silica was most active and could remove as much as 99 % S and 89% N present in the oil at 698 K. The data for HDN and HDS fitted the pseudo first order model. The kinetic model is described in detail.

  3. BIBLIOGRAPHY Abramowitz, M. and Stegun, I.A., Handbook of Mathematical Functions, 10th ed,

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    352 BIBLIOGRAPHY · Abramowitz, M. and Stegun, I.A., Handbook of Mathematical Functions, 10th ed, New York:Dover, 1972. · Akivis, M.A., Goldberg, V.V., An Introduction to Linear Algebra and Tensors. · Goodbody, A.M., Cartesian Tensors, Chichester, England:Ellis Horwood Ltd, 1982. · Hay, G.E., Vector

  4. BIBLIOGRAPHY . Abramowitz, M. and Stegun, I.A., Handbook of Mathematical Functions, 10th ed,

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    352 BIBLIOGRAPHY . Abramowitz, M. and Stegun, I.A., Handbook of Mathematical Functions, 10th ed, New York:Dover, 1972. . Akivis, M.A., Goldberg, V.V., An Introduction to Linear Algebra and Tensors, A.M., Cartesian Tensors, Chichester, England:Ellis Horwood Ltd, 1982. . Hay, G.E., Vector and Tensor

  5. AN EXPLORATORY STUDY OF THE EXPOSURE DRAFT OF IAS 19 DUE

    E-Print Network [OSTI]

    Boyer, Edmond

    a strategic issue for both private and public entities. In response to the ED published in April 2010 of three questions, asked respondents to approve a common discount rate to be applied to both the defined be of interest to the accounting profession and the public at large. Key words: IAS 19, Due process, net interest

  6. IAS 3353 001 Modern Brazil Instructor: Dr. Erika Robb-Larkins

    E-Print Network [OSTI]

    Oklahoma, University of

    IAS 3353 001 Modern Brazil Instructor: Dr. Erika Robb-Larkins MW 3:00-4:15 p.m. Hester Hall, room an anthropological perspective. Beginning with a broad overview of Brazil's colonial history and emergence the course with an appreciation of the complexities of Brazil today.... and with a desire to hop on the next

  7. X-ray amplification from a Raman Free Electron Laser I.A. Andriyash,

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    X-ray amplification from a Raman Free Electron Laser I.A. Andriyash, E. d'Humi`eres, V 5107, F33400 Talence, France We demonstrate that a mm-scale free electron laser can operate in the X and health applications. Large scale X-ray free electron laser (XFEL) projects have been launched, and start

  8. Especialista Universitario Java Enterprise 2010-2011 Depto. Ciencia de la Computacin e IA

    E-Print Network [OSTI]

    Escolano, Francisco

    Especialista Universitario Java Enterprise © 2010-2011 Depto. Ciencia de la Computación e IA Sesión 1: Introducción a JMS #12;Servicios de Mensajes con JMS © 2010-2011 Depto. Ciencia de la Computación · Una Aplicación JMS · PTP · Pub/Sub #12;Servicios de Mensajes con JMS © 2010-2011 Depto. Ciencia de la

  9. Tycho Brahe's 1572 supernova as a standard type Ia explosion revealed from its light echo spectrum

    E-Print Network [OSTI]

    Krause, Oliver; Usuda, Tomonori; Hattori, Takashi; Goto, Miwa; Birkmann, Stephan; Nomoto, Ken'ichi

    2008-01-01T23:59:59.000Z

    Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions are how the explosion actually proceeds and whether accretion occurs from a companion or via the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a SN Ia in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the yet unknown exact spectroscopic type of SN 1572 is crucial to relate these results to the diverse population of SNe Ia. Here we report an optical spectrum of Tycho Brahe's supernova near maximum brightness, obtained from a scatter...

  10. On the thermonuclear runaway in Type Ia supernovae: How to run away

    E-Print Network [OSTI]

    P. Höflich; J. Stein

    2002-01-01T23:59:59.000Z

    Type Ia Supernovae are thought to be thermonuclear explosions of massive white dwarfs (WD). We present the first study of multi-dimensional effects during the final hours prior to the thermonuclear runaway which leads to the explosion. The calculations utilize an implicit, 2-D hydrodynamical code

  11. Turbulent Oxygen Flames in Type Ia Supernovae A. J. Aspden1

    E-Print Network [OSTI]

    Turbulent Oxygen Flames in Type Ia Supernovae A. J. Aspden1 , J. B. Bell1 , and S. E. Woosley2 oxygen flames. The two aims of the paper are to examine the response of the inductive oxygen flame to intense levels of turbulence, and to explore the possibility of transition to detonation in the oxygen

  12. Revealing progenitors of type Ia supernovae from their light curves and spectra

    E-Print Network [OSTI]

    Kutsuna, Masamichi

    2015-01-01T23:59:59.000Z

    In the single degenerate (SD) scenario of type Ia supernovae (SNe Ia), the collision of the ejecta with its companion results in stripping hydrogen rich matter from the companion star. This hydrogen rich matter might leave its trace in the light curves and/or spectra. In this paper, we perform radiation hydrodynamical simulations of this collision for three binary systems. As a result, we find that the emission from the shock-heated region is not as strong as in the previous study. This weak emission, however, may be a result of our underestimate of the coupling between the gas and radiation in the shock interaction. Therefore, though our results suggest that the observed early light curves of SNe Ia can not rule out binary systems with a short separation as the progenitor system, more elaborate numerical studies will be needed to reach a fair conclusion. Alternatively, our results indicate that the feature observed in the early phase of a recent type Ia SN 2014J might result from interaction of the ejecta wi...

  13. METALLICITY DIFFERENCES IN TYPE Ia SUPERNOVA PROGENITORS INFERRED FROM ULTRAVIOLET SPECTRA

    SciTech Connect (OSTI)

    Foley, Ryan J.; Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-05-20T23:59:59.000Z

    Two ''twin'' Type Ia supernovae (SNe Ia), SNe 2011by and 2011fe, have extremely similar optical light-curve shapes, colors, and spectra, yet have different ultraviolet (UV) continua as measured in Hubble Space Telescope spectra and measurably different peak luminosities. We attribute the difference in the UV continua to significantly different progenitor metallicities. This is the first robust detection of different metallicities for SN Ia progenitors. Theoretical reasoning suggests that differences in metallicity also lead to differences in luminosity. SNe Ia with higher progenitor metallicities have lower {sup 56}Ni yields and lower luminosities for the same light-curve shape. SNe 2011by and 2011fe have different peak luminosities ({Delta}M{sub V} Almost-Equal-To 0.6 mag), which correspond to different {sup 56}Ni yields: M{sub 11fe}({sup 56}Ni) / M{sub 11by}({sup 56}Ni) = 1.7{sup +0.7}{sub -0.5}. From theoretical models that account for different neutron-to-proton ratios in progenitors, the differences in {sup 56}Ni yields for SNe 2011by and 2011fe imply that their progenitor stars were above and below solar metallicity, respectively. Although we can distinguish progenitor metallicities in a qualitative way from UV data, the quantitative interpretation in terms of abundances is limited by the present state of theoretical models.

  14. ON THE LIRA LAW AND THE NATURE OF EXTINCTION TOWARD TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Foerster, Francisco; Gonzalez-Gaitan, Santiago [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study (TODIAS), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Morrell, Nidia [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile)

    2013-07-20T23:59:59.000Z

    We have studied the relation between the color evolution of Type Ia supernovae (SNe Ia) from maximum light to the Lira law regime and the presence of narrow absorption features. Based on a nearby sample of 89 SNe Ia, we have found that the rate of change of B - V colors at late phases (between 35 and 80 days after maximum) varies significantly among different SNe Ia. At maximum light, faster Lira law B - V decliners have significantly higher equivalent widths of blended Na I D1 and D2 narrow absorption lines, redder colors, and lower R{sub V} reddening laws. We do not find faster Lira law B - V decliners to have a strong preference for younger galaxy environments, where higher interstellar material (ISM) column densities would be expected. We interpret these results as evidence for the presence of circumstellar material. The differences in colors and reddening laws found at maximum light are also present 55 days afterward, but unlike the colors at maximum they show a significant variation among different host galaxy morphological types. This suggests that the effect of ISM on the colors is more apparent at late times. Finally, we discuss how the transversal expansion of the ejecta in an inhomogeneous ISM could mimic some of these findings.

  15. High-Velocity Features of Calcium and Silicon in the Spectra of Type Ia Supernovae

    E-Print Network [OSTI]

    Silverman, Jeffrey M; Marion, G H; Wheeler, J Craig; Barna, Barnabas; Szalai, Tamas; Mulligan, Brian; Filippenko, Alexei V

    2015-01-01T23:59:59.000Z

    "High-velocity features" (HVFs) are spectral features in Type Ia supernovae (SNe Ia) that have minima indicating significantly higher (by greater than about 6000 km/s) velocities than typical "photospheric-velocity features" (PVFs). The PVFs are absorption features with minima indicating typical photospheric (i.e., bulk ejecta) velocities (usually ~9000-15,000 km/s near B-band maximum brightness). In this work we undertake the most in-depth study of HVFs ever performed. The dataset used herein consists of 445 low-resolution optical and near-infrared (NIR) spectra (at epochs up to 5 d past maximum brightness) of 210 low-redshift SNe Ia that follow the "Phillips relation." A series of Gaussian functions is fit to the data in order to characterise possible HVFs of Ca II H&K, Si II {\\lambda}6355, and the Ca II NIR triplet. The temporal evolution of the velocities and strengths of the PVFs and HVFs of these three spectral features is investigated, as are possible correlations with other SN Ia observables. We f...

  16. California ISO Glossary CAL I F O R N IA I S O

    E-Print Network [OSTI]

    California ISO Glossary CAL I F O R N IA I S O A watt is a measure of electricity. If you have 10 under less pressure for delivery through the straws. The ISO's job is to make sure that in the high; the ISO refers to utilities like PG&E as "load-serving entities" because that's what they do, they serve

  17. A Test for the Nature of the Type Ia Supernova Explosion Mechanism

    E-Print Network [OSTI]

    Philip A. Pinto; Ronald G. Eastman; Tamara Rogers

    2000-08-21T23:59:59.000Z

    Currently popular models for Type Ia supernovae (SNe Ia) fall into two general classes. The first comprises explosions of nearly pure carbon/oxygen (C/O) white dwarfs at the Chandrasekhar limit which ignite near their centers. The second consists of lower-mass C/O cores which are ignited by the detonation of an accreted surface helium layer. Explosions of the latter type produce copious Fe, Co and Ni K-alpha emission from 56Ni and 56Co decay in the detonated surface layers, emission which is much weaker from Chandrasekhar-mass models. The presence of this emission provides a simple and unambiguous discriminant between these two models for SNe Ia. Both mechanisms may produce 0.1-0.6 solar masses of 56Ni, making them bright gamma-ray line emitters. The time to maximum brightness of 56Ni decay lines is distinctly shorter in the sub-Chandrasekhar mass class of model (approximately 15 days) than in the Chandrasekhar mass model (approximately 30 days), making gamma-ray line evolution another direct test of the explosion mechanism. It should just be possible to detect K-shell emission from a sub-Chandrasekhar explosion from SNe Ia as far away as the Virgo cluster with the XMM Observatory. A 1 to 2 square meter X-ray telescope such as the proposed Con-X Observatory could observe K-alpha emission from sub-Chandrasekhar mass SNe Ia in the Virgo cluster, providing not just a detection, but high-accuracy flux and kinematic information.

  18. HIGH-VELOCITY LINE FORMING REGIONS IN THE TYPE Ia SUPERNOVA 2009ig

    SciTech Connect (OSTI)

    Marion, G. H.; Foley, Ryan J.; Challis, Peter; Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Vinko, Jozsef; Wheeler, J. Craig; Silverman, Jeffrey M. [University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Hsiao, Eric Y. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Brown, Peter J. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, 4242 AMU, College Station, TX 77843 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Garnavich, Peter [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Landsman, Wayne B. [Adnet Systems, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Parrent, Jerod T. [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Pritchard, Tyler A.; Roming, Peter W. A. [Department of Astronomy and Astrophysics, Penn State University, 525 Davey Lab, University Park, PA 16802 (United States); Wang, Xiaofeng, E-mail: gmarion@cfa.harvard.edu [Physics Department and Tsinghua Center for Astrophysics (THCA), Tsinghua University, Beijing 1,00084 (China)

    2013-11-01T23:59:59.000Z

    We report measurements and analysis of high-velocity (HVF) (>20,000 km s{sup –1}) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between –14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (M{sub B} = –19.46 mag and ?m{sub 15}(B) = 0.90 mag). Similarly, the Si II ?6355 velocity at the time of B-max is greater than 'normal' for an SN Ia, but it is not extreme (v{sub Si} = 13,400 km s{sup –1}). The –14 days and –13 days spectra clearly resolve HVF from Si II ?6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From –12 days to –6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s{sup –1}. After –6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before –10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II ?6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF.

  19. Regional Report Issue Paper

    E-Print Network [OSTI]

    Garfunkel, Eric

    South Atlantic Delaware, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia [The District of Columbia is part of this division but is not included in the analysis Nebraska SD South Dakota KS Kansas MN Minnesota IA Iowa MO Missouri WI Wisconsin IL Illinois IN Indiana OH

  20. Synthesis and characterization of a novel tube-in-tube nanostructured PPy/MnO{sub 2}/CNTs composite for supercapacitor

    SciTech Connect (OSTI)

    Li, Juan, E-mail: lj-panpan@163.com [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China) [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Que, Tingli [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China)] [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Huang, Jianbin, E-mail: JBhuang@pku.edu.cn [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China) [College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046 (China); Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2013-02-15T23:59:59.000Z

    Graphical abstract: A novel tube-in-tube nanostructured PPy/MnO{sub 2}/CNTs composite have been successfully fabricated. Its inner tubules are CNTs and the outer tubules are template-synthesized PPy. Most MnO{sub 2} nanoparticles are sandwiched between the inner and outer wall, some relatively large particles are also latched onto the outside wall of the PPy tube. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test and galvanostatic charge–discharge experiments at different current densities. Display Omitted Highlights: ? We fabricate a ternary organic–inorganic complex of PPy/MnO{sub 2}/CNTs composite. ? We characterize its morphological structures and properties by several techniques. ? The composite possesses the typical tube-in-tube nanostructures. ? Most MnO{sub 2} nanoparticles are sandwiched between the inner CNTs and outer PPy wall. ? The composite has good electrochemical reversibility for supercapacitor. -- Abstract: Ternary organic–inorganic complex of polypyrrole/manganese dioxide/carbon nanotubes (PPy/MnO{sub 2}/CNTs) composite was prepared by in situ chemical oxidation polymerization of pyrrole in the host of inorganic matrix of MnO{sub 2} and CNTs, using complex of methyl orange (MO)/FeCl{sub 3} was used as a reactive self-degraded soft-template. The morphological structures of the composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopic (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), respectively. All the results indicate that the PPy/MnO{sub 2}/CNTs composite possesses the typical tube-in-tube nanostructures: the inner tubules are CNTs and the outer tubules are template-synthesized PPy. MnO{sub 2} nanoparticles may either sandwich the space between the inner and outer tubules or directly latch onto the wall of the PPy tubes. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test in the potential range of ?0.6 to 0.4 V and its specific capacitance was up to 402.7 F g{sup ?1} at a current density of 1 A g{sup ?1} in galvanostatic charge–discharge experiment.

  1. Structure And Radiation Damage Behavior Of Epitaxial CrxMo1-x...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    And Radiation Damage Behavior Of Epitaxial CrxMo1-x Alloy Thin Films On MgO. Structure And Radiation Damage Behavior Of Epitaxial CrxMo1-x Alloy Thin Films On MgO. Abstract:...

  2. Adsorption of Potassium on the MoS2(100) Surface: A First-Principles...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Potassium on the MoS2(100) Surface: A First-Principles Investigation. Adsorption of Potassium on the MoS2(100) Surface: A First-Principles Investigation. Abstract: Periodic density...

  3. High Capacity MoO3 Nanoparticle Li-Ion Battery Anode

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    energy functional were employed.) 10 AccomplishmentStatus Theoretical changes in Li-ion intercalated -MoO 3 Mo Li O * Four Li inserted in a theoretical nanoparticle. * 9 ps...

  4. Domestic production of medical isotope Mo-99 moves a step closer

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Domestic production of medical isotope Mo-99 Domestic production of medical isotope Mo-99 moves a step closer Irradiated uranium fuel has been recycled and reused for molybdenum-99...

  5. ,"International Falls, MN Natural Gas Pipeline Imports From Canada...

    U.S. Energy Information Administration (EIA) Indexed Site

    International Falls, MN Natural Gas Pipeline Imports From Canada (MMcf)" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description"," Of...

  6. ,"Noyes, MN Natural Gas Pipeline Imports From Canada (MMcf)"

    U.S. Energy Information Administration (EIA) Indexed Site

    Imports From Canada (MMcf)" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description"," Of Series","Frequency","Latest Data for" ,"Data 1","Noyes, MN...

  7. ,"Warroad, MN Natural Gas Pipeline Imports From Canada (MMcf...

    U.S. Energy Information Administration (EIA) Indexed Site

    Imports From Canada (MMcf)" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description"," Of Series","Frequency","Latest Data for" ,"Data 1","Warroad, MN...

  8. Type Ia supernova rate measurements to redshift 2.5 from CANDELS: Searching for prompt explosions in the early universe

    SciTech Connect (OSTI)

    Rodney, Steven A.; Riess, Adam G.; Graur, Or; Jones, David O. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Strolger, Louis-Gregory; Dahlen, Tomas; Casertano, Stefano; Ferguson, Henry C.; Koekemoer, Anton M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Dickinson, Mark E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Hayden, Brian [E.O. Lawrence Berkeley National Lab, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Jha, Saurabh W.; McCully, Curtis; Patel, Brandon [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Weiner, Benjamin J. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); and others

    2014-07-01T23:59:59.000Z

    The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ?0.25 deg{sup 2} with ?900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z ? 2.5. We classify ?24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only ?3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (<500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction is f{sub P} = 0.53{sub stat0.10}{sup ±0.09}{sub sys0.26}{sup ±0.10}, consistent with a delay time distribution that follows a simple t {sup –1} power law for all times t > 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions—though further analysis and larger samples will be needed to examine that suggestion.

  9. Corrosion report for the U-Mo fuel concept

    SciTech Connect (OSTI)

    Henager, Jr., Charles H. [Pacific Northwest National Laboratory (PNNL), Richland, WA (US); Bennett, Wendy D. [Pacific Northwest National Laboratory (PNNL), Richland, WA (US); Doherty, Ann L. [Pacific Northwest National Laboratory (PNNL), Richland, WA (US); Fuller, E. S. [Pacific Northwest National Laboratory (PNNL), Richland, WA (US); Hardy, John S. [Pacific Northwest National Laboratory (PNNL), Richland, WA (US); Omberg, Ronald P. [Pacific Northwest National Laboratory (PNNL), Richland, WA (US)

    2014-08-28T23:59:59.000Z

    The Fuel Cycle Research and Development (FCRD) program of the Office of Nuclear Energy (NE) has implemented a program to develop a Uranium-Molybdenum (U-Mo) metal fuel for Light Water Reactors (LWR)s. Uranium-Molybdenum fuel has the potential to provide superior performance based on its thermo-physical properties, which includes high thermal conductivity for less stored heat energy. With sufficient development, it may be able to provide the Light Water industry with a melt-resistant accident tolerant fuel with improved safety response. However, the corrosion of this fuel in reactor water environments needs to be further explored and optimized by additional alloying. The Pacific Northwest National Laboratory has been tasked with performing ex-reactor corrosion testing to characterize the performance of U-Mo fuel. This report documents the results of the effort to characterize and develop the U-Mo metal fuel concept for LWRs with regard to corrosion testing. The results of a simple screening test in buffered water at 30°C using surface alloyed U-10Mo is documented and discussed. The screening test was used to guide the selection of several potential alloy improvements that were found and are recommended for further testing in autoclaves to simulate PWR water conditions more closely.

  10. MO"BIUS-INVARIANT KNOT ENERGIES R.B. KUSNER

    E-Print Network [OSTI]

    Sullivan, John M.

    for divergence-free vector fields which arise in modeling incompressible fluid flow.6,7These new knot energies MO"BIUS-INVARIANT KNOT ENERGIES R.B. KUSNER, Urbana, IL, USA 61801-2975 There has been recent interest in knot energies among mathematicians

  11. MO"BIUS-INVARIANT KNOT ENERGIES R.B. KUSNER

    E-Print Network [OSTI]

    for divergence-free vector fields which arise in modeling incompressible fluid flow.? These new knot energies may MO"BIUS-INVARIANT KNOT ENERGIES R.B. KUSNER, Urbana, IL, USA 61801-2975 There has been recent interest in knot energies among mathematicians

  12. Introduction THE YERINGTON DISTRICT, Nevada, contains porphyry Cu(Mo),

    E-Print Network [OSTI]

    Barton, Mark D.

    55 Introduction THE YERINGTON DISTRICT, Nevada, contains porphyry Cu(Mo), Cu skarn, Fe oxide with the Jurassic Yerington batholith, which serves as either host rock or as source for heat and ma- terials of the Yerington Porphyry Copper District: Magmatic to Nonmagmatic Sources of Hydrothermal Fluids, Their Flow Paths

  13. Sweetspot: Near-infrared observations of 13 type Ia supernovae from a new NOAO survey probing the nearby smooth Hubble flow

    SciTech Connect (OSTI)

    Weyant, Anja; Wood-Vasey, W. Michael [Pittsburgh Particle physics, Astrophysics, and Cosmology Center (PITT PACC), Physics and Astronomy Department, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Allen, Lori; Joyce, Richard; Matheson, Thomas [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Garnavich, Peter M. [Department of Physics, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Jha, Saurabh W., E-mail: anw19@pitt.edu [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)

    2014-04-01T23:59:59.000Z

    We present 13 Type Ia supernovae (SNe Ia) observed in the rest-frame near-infrared (NIR) from 0.02 < z < 0.09 with the WIYN High-resolution Infrared Camera on the WIYN 3.5 m telescope. With only one to three points per light curve and a prior on the time of maximum from the spectrum used to type the object, we measure an H-band dispersion of spectroscopically normal SNe Ia of 0.164 mag. These observations continue to demonstrate the improved standard brightness of SNe Ia in an H band, even with limited data. Our sample includes two SNe Ia at z ? 0.09, which represent the most distant rest-frame NIR H-band observations published to date. This modest sample of 13 NIR SNe Ia represent the pilot sample for {sup S}weetSpot{sup —}a 3 yr NOAO Survey program that will observe 144 SNe Ia in the smooth Hubble flow. By the end of the survey we will have measured the relative distance to a redshift of z ? 0.05%-1%. Nearby Type Ia supernova (SN Ia) observations such as these will test the standard nature of SNe Ia in the rest-frame NIR, allow insight into the nature of dust, and provide a critical anchor for future cosmological SN Ia surveys at higher redshift.

  14. Polarized x-ray spectroscopy of quaternary ferromagnetic semiconductor (Ga,Mn)(As,P)

    E-Print Network [OSTI]

    Wadley, P.

    2011-01-01T23:59:59.000Z

    quaternary diluted magnetic semiconductor (Ga,Mn)(As,P) as aIn diluted magnetic semiconductors such as (Ga,Mn)As, whichquaternary diluted magnetic semiconductors such as (Ga,Mn)(

  15. Alignment of micro-crystals of Mn12-acetate and direct observation of single molecules thereof

    E-Print Network [OSTI]

    Seo, Dongmin

    2009-05-15T23:59:59.000Z

    This dissertation focuses on three separate studies. First, magnetization of the Mn12- acetate was studied by low temperature hysteresis loops and DC magnetization data on magnetically aligned Mn12-acetate micro-crystals. Secondly, Mn12-acetate thin...

  16. Experimental and first-principles study of ferromagnetism in Mn-doped zinc stannate nanowires

    SciTech Connect (OSTI)

    Deng Rui; Zhou Hang; Qin Jieming; Wan Yuchun; Jiang Dayong; Liang Qingcheng [School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Li Yongfeng [Key Laboratory of Physics and Technology for Advanced Batteries, College of Physics, Jilin University, Changchun 130012 (China); Wu, Tom [Physical Sciences and Engineering Division, Solar and Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Yao Bin [State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China); Liu Lei [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, No.3888 Dongnanhu Road, Changchun 130033 (China)

    2013-07-21T23:59:59.000Z

    Room temperature ferromagnetism was observed in Mn-doped zinc stannate (ZTO:Mn) nanowires, which were prepared by chemical vapor transport. Structural and magnetic properties and Mn chemical states of ZTO:Mn nanowires were investigated by X-ray diffraction, superconducting quantum interference device (SQUID) magnetometry and X-ray photoelectron spectroscopy. Manganese predominantly existed as Mn{sup 2+} and substituted for Zn (Mn{sub Zn}) in ZTO:Mn. This conclusion was supported by first-principles calculations. Mn{sub Zn} in ZTO:Mn had a lower formation energy than that of Mn substituted for Sn (Mn{sub Sn}). The nearest neighbor Mn{sub Zn} in ZTO stabilized ferromagnetic coupling. This observation supported the experimental results.

  17. COSMOLOGY WITH PHOTOMETRICALLY CLASSIFIED TYPE Ia SUPERNOVAE FROM THE SDSS-II SUPERNOVA SURVEY

    SciTech Connect (OSTI)

    Campbell, Heather; D'Andrea, Chris B; Nichol, Robert C.; Smith, Mathew; Lampeitl, Hubert [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)] [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Sako, Masao [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States)] [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Olmstead, Matthew D.; Brown, Peter; Dawson, Kyle S. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East 201, Salt Lake City, UT 84112 (United States)] [Department of Physics and Astronomy, University of Utah, 115 South 1400 East 201, Salt Lake City, UT 84112 (United States); Bassett, Bruce [Mathematics Department, University of Cape Town, Rondebosch, Cape Town (South Africa)] [Mathematics Department, University of Cape Town, Rondebosch, Cape Town (South Africa); Biswas, Rahul; Kuhlmann, Steve [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)] [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States); Cinabro, David [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48126 (United States)] [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48126 (United States); Dilday, Ben [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States)] [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr., Suite 102, Goleta, CA 93117 (United States); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Frieman, Joshua A. [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)] [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Hlozek, Renee [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)] [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Jha, Saurabh W. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)] [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Kunz, Martin, E-mail: Heather.Campbell@port.ac.uk [African Institute for Mathematical Sciences, Muizenberg, 7945, Cape Town (South Africa)] [African Institute for Mathematical Sciences, Muizenberg, 7945, Cape Town (South Africa); and others

    2013-02-15T23:59:59.000Z

    We present the cosmological analysis of 752 photometrically classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey. Our photometric-classification method is based on the SN classification technique of Sako et al., aided by host-galaxy redshifts (0.05 < z < 0.55). SuperNova ANAlysis simulations of our methodology estimate that we have an SN Ia classification efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia) SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints. We quantify and correct for our selection effects (e.g., Malmquist bias) using simulations. When fitting to a flat {Lambda}CDM cosmological model, we find that our photometric sample alone gives {Omega} {sub m} = 0.24{sup +0.07} {sub -0.05} (statistical errors only). If we relax the constraint on flatness, then our sample provides competitive joint statistical constraints on {Omega} {sub m} and {Omega}{sub {Lambda}}, comparable to those derived from the spectroscopically confirmed Three-year Supernova Legacy Survey (SNLS3). Using only our data, the statistics-only result favors an accelerating universe at 99.96% confidence. Assuming a constant wCDM cosmological model, and combining with H {sub 0}, cosmic microwave background, and luminous red galaxy data, we obtain w = -0.96{sup +0.10} {sub -0.10}, {Omega} {sub m} = 0.29{sup +0.02} {sub -0.02}, and {Omega} {sub k} = 0.00{sup +0.03} {sub -0.02} (statistical errors only), which is competitive with similar spectroscopically confirmed SNe Ia analyses. Overall this comparison is reassuring, considering the lower redshift leverage of the SDSS-II SN sample (z < 0.55) and the lack of spectroscopic confirmation used herein. These results demonstrate the potential of photometrically classified SN Ia samples in improving cosmological constraints.

  18. Minnesota Guidestar www.dot.state.mn.us/guidestar

    E-Print Network [OSTI]

    Minnesota, University of

    .dot.state.mn.us/guidestar What is ITS? · Application of technology to improve the safety and efficiency of the transportation system. #12;Minnesota Guidestar www.dot.state.mn.us/guidestar What is ITS? · Traffic Management ­ Signal Systems ­ Ramp Meters · Emergency Response ­ Mobile Data Terminals ­ 911 Dispatch ­ RF Data Networks

  19. Function of the Diiron Cluster of Escherichia coli Class Ia Ribonucleotide Reductase in Proton-Coupled Electron Transfer

    E-Print Network [OSTI]

    Wörsdörfer, Bigna

    The class Ia ribonucleotide reductase (RNR) from Escherichia coli employs a free-radical mechanism, which involves bidirectional translocation of a radical equivalent or “hole” over a distance of ~35 Å from the stable ...

  20. Experto Universitario Java Enterprise Validacin e internacionalizacin 2012-2013 Depto. Ciencia de la Computacin e IA Spring

    E-Print Network [OSTI]

    Escolano, Francisco

    Experto Universitario Java Enterprise Validación e internacionalización © 2012-2013 Depto. Ciencia #12;Experto Universitario Java Enterprise Validación e internacionalización © 2012-2013 Depto. Ciencia Java Enterprise Validación e internacionalización © 2012-2013 Depto. Ciencia de la Computación e IA

  1. In vivo cofactor biosynthesis and maintenance in the class Ia ribonucleotide reductase small subunit of Escherichia coli

    E-Print Network [OSTI]

    Wu, Chia-Hung, Ph. D. Massachusetts Institute of Technology

    2009-01-01T23:59:59.000Z

    The small subunit ([beta]2) of Escherichia coli class Ia ribonucleotide reductases (RNRs) contains a diferric tyrosyl radical (Y*) cofactor essential for the conversion of nucleotides to deoxynucleotides that are needed ...

  2. Restframe I-band Hubble diagram for type Ia supernovae up to redshift z ~; 0.5

    E-Print Network [OSTI]

    2005-01-01T23:59:59.000Z

    in STScI Symposium Ser. 13, Supernovae and gamma-ray bursts:Highlight: The Physics of Supernovae, ed. W. Hillebrandt &diagram for type Ia supernovae up to redshift z ? 0.5 ? S.

  3. Mechanistic studies of proton-coupled electron transfer in aminotyrosine- and fluorotyrosine- substituted class Ia Ribonucleotide reductase

    E-Print Network [OSTI]

    Minnihan, Ellen Catherine

    2012-01-01T23:59:59.000Z

    Ribonucleotide reductase (RNR) catalyzes the conversion of nucleotides to 2'- deoxynucleotides in all organisms. The class Ia RNR from Escherichia coli is active as an a2p2 complex and utilizes an unprecedented mechanism ...

  4. The growth and characterization of LiGd?(Mo0?)? single crystals

    E-Print Network [OSTI]

    Reimund, James Allyn

    1981-01-01T23:59:59.000Z

    ' C/second 37 Pyroelectric Current vs. Temperature dT/dt = 30' C/second 180' Domains (Gd (MoO ) ) 37 39 INTRODUCTION This thesis discusses the growth and some single crystalline properties of lithium-gadolinium-molybdate of the type LiGd (Mo...O ) 3 45' This compound is one of the three thus far discovered compounds of the lithium ? gadolinium-molybdate (LGMO) system. In general, this system can be expressed as Li2Mo04. XGd2(Mo04)3, where LiGd3(MoO, )5 4 5 single crystals synthesize when X...

  5. On the small-scale stability of thermonuclear flames in Type Ia supernovae

    E-Print Network [OSTI]

    F. K. Roepke; J. C. Niemeyer; W. Hillebrandt

    2003-05-02T23:59:59.000Z

    We present a numerical model which allows us to investigate thermonuclear flames in Type Ia supernova explosions. The model is based on a finite-volume explicit hydrodynamics solver employing PPM. Using the level-set technique combined with in-cell reconstruction and flux-splitting schemes we are able to describe the flame in the discontinuity approximation. We apply our implementation to flame propagation in Chandrasekhar-mass Type Ia supernova models. In particular we concentrate on intermediate scales between the flame width and the Gibson-scale, where the burning front is subject to the Landau-Darrieus instability. We are able to reproduce the theoretical prediction on the growth rates of perturbations in the linear regime and observe the stabilization of the flame in a cellular shape. The increase of the mean burning velocity due to the enlarged flame surface is measured. Results of our simulation are in agreement with semianalytical studies.

  6. The ignition process in type Ia supernovae: numerical simulations of core temperature perturbations

    E-Print Network [OSTI]

    L. Iapichino; M. Brüggen; W. Hillebrandt; J. C. Niemeyer

    2007-11-13T23:59:59.000Z

    The onset of the thermonuclear runaway in a Chandrasekhar-mass white dwarf, leading to the explosion as a type Ia supernova, is studied with hydrodynamical simulations. We investigate the evolution of temperature fluctuations (``bubbles'') in the WD's convective core by means of 2D numerical simulations. We show how the occurrence of the thermonuclear runaway depends on various bubble parameters. The relevance of the progenitor's composition for the ignition process is also discussed.

  7. The ignition process in type Ia supernovae: numerical simulations of core temperature perturbations

    E-Print Network [OSTI]

    Iapichino, L; Hillebrandt, W; Niemeyer, J C

    2007-01-01T23:59:59.000Z

    The onset of the thermonuclear runaway in a Chandrasekhar-mass white dwarf, leading to the explosion as a type Ia supernova, is studied with hydrodynamical simulations. We investigate the evolution of temperature fluctuations (``bubbles'') in the WD's convective core by means of 2D numerical simulations. We show how the occurrence of the thermonuclear runaway depends on various bubble parameters. The relevance of the progenitor's composition for the ignition process is also discussed.

  8. TIDAL TAIL EJECTION AS A SIGNATURE OF TYPE Ia SUPERNOVAE FROM WHITE DWARF MERGERS

    SciTech Connect (OSTI)

    Raskin, Cody; Kasen, Daniel [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2013-07-20T23:59:59.000Z

    The merger of two white dwarfs may be preceded by the ejection of some mass in ''tidal tails,'' creating a circumstellar medium around the system. We consider the variety of observational signatures from this material, which depend on the lag time between the start of the merger and the ultimate explosion (assuming one occurs) of the system in a Type Ia supernova (SN Ia). If the time lag is fairly short, then the interaction of the supernova ejecta with the tails could lead to detectable shock emission at radio, optical, and/or X-ray wavelengths. At somewhat later times, the tails produce relatively broad NaID absorption lines with velocity widths of the order of the white dwarf escape speed ({approx}1000 km s{sup -1}). That none of these signatures have been detected in normal SNe Ia constrains the lag time to be either very short ({approx}< 100 s) or fairly long ({approx}> 100 yr). If the tails have expanded and cooled over timescales {approx}10{sup 4} yr, then they could be observable through narrow NaID and Ca II H and K absorption lines in the spectra, which are seen in some fraction of SNe Ia. Using a combination of three-dimensional and one-dimensional hydrodynamical codes, we model the mass loss from tidal interactions in binary systems, and the subsequent interactions with the interstellar medium, which produce a slow-moving, dense shell of gas. We synthesize NaID line profiles by ray casting through this shell, and show that in some circumstances tidal tails could be responsible for narrow absorptions similar to those observed.

  9. Magnetic Moment Enhancement for Mn7 Cluster on Graphene

    SciTech Connect (OSTI)

    Liu, Xiaojie [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Lin, Hai-Qing [Beijing Computational Science Research Center; Ho, Kai-Ming [Ames Laboratory

    2014-08-21T23:59:59.000Z

    Mn7 cluster on graphene with different structural motifs and magnetic orders are investigated systematically by first-principles calculations. The calculations show that Mn7 on graphene prefers a two-layer motif and exhibits a ferrimagnetic coupling. The magnetic moment of the Mn7 cluster increases from 5.0 ?B at its free-standing state to about 6.0 ?B upon adsorption on graphene. Mn7 cluster also induces about 0.3 ?B of magnetic moment in the graphene layer, leading to an overall enhancement of 1.3 ?B magnetic moment for Mn7 on graphene. Detail electron transfer and bonding analysis have been carried out to investigate the origin of the magnetic enhancement.

  10. Spectroscopy of Mn atoms isolated in solid {sup 4}He

    SciTech Connect (OSTI)

    Moroshkin, P., E-mail: petr.moroshkin@riken.jp; Lebedev, V.; Weis, A. [Department of Physics, University of Fribourg, Chemin du Musée 3, 1700 Fribourg (Switzerland)

    2014-06-07T23:59:59.000Z

    We present an experimental study of the laser-induced luminescence spectra of Mn atoms in solid helium matrices. We observe transitions of the valence electron and of inner-shell electrons. We find that the Mn-He interaction perturbs the inner-shell transitions to a lesser extent than the valence-electron transitions. The observed lineshapes of the inner-shell transitions of Mn are similar to those of an inner-shell transition in Ba studied earlier. At the same time, they are more strongly perturbed than the corresponding transitions in Au and Cu under the same conditions. We suggest a qualitative explanation of these observations based on the atomic bubble model. Our results also suggest that the inner-shell transitions of Mn in solid He are more strongly perturbed than the same lines of Mn isolated in solid Ar or Kr matrices.

  11. Precipitation sensitivity to alloy composition in Fe-Cr-Mn austenitic steels developed for reduced activation for fusion application

    SciTech Connect (OSTI)

    Maziasz, P.J.; Klueh, R.L.

    1988-01-01T23:59:59.000Z

    Special austenitic steels are being designed in which alloying elements like Mo, Nb, and Ni are replaced with Mn, W, V, Ti, and/or Ta to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400--600/degree/C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements W, Ti, V, P, and B for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti+V+P+B produced fine MC precipitation along network dislocations and recovery/recrystallization resistance in 20% cold worked material aged at 800/degree/C for 166h, whereas W, Ti, W+Ti, or Ti+P+B additions did not. Addition of W+Ti+V+P+B also produced fine MC, but caused some sigma phase formation and more recrystallization as well. 29 refs., 14 figs., 9 tabs.

  12. Observational constraints from SNe Ia and Gamma-Ray Bursts on a clumpy universe

    E-Print Network [OSTI]

    Nora Bretón; Ariadna Montiel

    2013-03-06T23:59:59.000Z

    The luminosity distance describing the effect of local inhomogeneities in the propagation of light proposed by Zeldovich-Kantowski-Dyer-Roeder (ZKDR) is tested with two probes for two distinct ranges of redshifts: supernovae Ia (SNe Ia) in 0.015 gamma-ray bursts (GRBs) in 1.547 < z < 3.57. Our analysis is performed by a Markov Chain Monte Carlo (MCMC) code that allows us to constrain the matter density parameter \\Omega_m as well as the smoothness parameter $\\alpha$ that measures the inhomogeneous-homogeneous rate of the cosmic fluid in a flat \\LambdaCDM model. The obtained best fits are (\\Omega_m=0.285^{+0.019}_{-0.018}, \\alpha= 0.856^{+0.106}_{-0.176}) from SNe Ia and (\\Omega_m=0.259^{+0.028}_{-0.028}, \\alpha=0.587^{+0.201}_{-0.202}) from GRBs, while from the joint analysis the best fits are (\\Omega_m=0.284^{+0.021}_{-0.020}, \\alpha= 0.685^{+0.164}_{-0.171}) with a \\chi^2_{\\rm red}=0.975. The value of the smoothness parameter $\\alpha$ indicates a clumped universe however it does not have an impact on the amount of dark energy (cosmological constant) needed to fit observations. This result may be an indication that the Dyer-Roeder approximation does not describe in a precise form the effects of clumpiness in the expansion of the universe.

  13. Observations of Type Ia Supernova 2014J with FLITECAM/SOFIA

    E-Print Network [OSTI]

    Vacca, William D; Savage, Maureen; Shenoy, Sachindev; Becklin, E E; McLean, Ian S; Logsdon, Sarah E; Gehrz, R D; Spyromilio, J; Garnavich, P; Marion, G H; Fox, O D

    2015-01-01T23:59:59.000Z

    We present medium resolution near-infrared (NIR) spectra, covering 1.1 to 3.4 microns, of the normal Type Ia supernova (SN Ia) SN 2014J in M82 obtained with the FLITECAM instrument aboard SOFIA approximately 17-25 days after maximum B light. Our 2.8-3.4 micron spectra may be the first ~3 micron spectra of a SN Ia ever published. The spectra spanning the 1.5-2.7 micron range are characterized by a strong emission feature at ~1.77 microns with a full width at half maximum of ~11,000-13,000 km/s. We compare the observed FLITECAM spectra to the recent non-LTE delayed detonation models of Dessart et al. (2014) and find that the models agree with the spectra remarkably well in the 1.5-2.7 micron wavelength range. Based on this comparison we identify the ~1.77 micron emission peak as a blend of permitted lines of Co II. Other features seen in the 2.0 - 2.5 micron spectra are also identified as emission from permitted transitions of Co II. However, the models are not as successful at reproducing the spectra in the 1....

  14. The Cellular Burning Regime in Type Ia Supernova Explosions - I. Flame Propagation into Quiescent Fuel

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt; J. C. Niemeyer

    2003-12-03T23:59:59.000Z

    We present a numerical investigation of the cellular burning regime in Type Ia supernova explosions. This regime holds at small scales (i.e. below the Gibson scale), which are unresolved in large-scale Type Ia supernova simulations. The fundamental effects that dominate the flame evolution here are the Landau-Darrieus instability and its nonlinear stabilization, leading to a stabilization of the flame in a cellular shape. The flame propagation into quiescent fuel is investigated addressing the dependence of the simulation results on the specific parameters of the numerical setup. Furthermore, we investigate the flame stability at a range of fuel densities. This is directly connected to the questions of active turbulent combustion (a mechanism of flame destabilization and subsequent self-turbulization) and a deflagration-to-detonation transition of the flame. In our simulations we find no substantial destabilization of the flame when propagating into quiescent fuels of densities down to ~10^7 g/cm^3, corroborating fundamental assumptions of large-scale SN Ia explosion models. For these models, however, we suggest an increased lower cutoff for the flame propagation velocity to take the cellular burning regime into account.

  15. Is the X-ray pulsating companion of HD 49798 a possible type Ia supernova progenitor?

    E-Print Network [OSTI]

    Liu, Dong-Dong; Wu, Cheng-Yuan; Wang, Bo

    2015-01-01T23:59:59.000Z

    HD 49798 (a hydrogen depleted subdwarf O6 star) with its massive white dwarf (WD) companion has been suggested to be a progenitor candidate of type Ia supernovae (SNe Ia). However, it is still uncertain whether the companion of HD 49798 is a carbon-oxygen (CO) WD or an oxygen-neon (ONe) WD. A CO WD will explode as an SN Ia when its mass grows approach to Chandrasekhar mass, while the outcome of an accreting ONe WD is likely to be a neutron star. We followed a series of Monte Carlo binary population synthesis approach to simulate the formation of ONe WD + He star systems. We found that there is almost no orbital period as large as HD 49798 with its WD companion in these ONe WD + He star systems based on our simulations, which means that the companion of HD 49798 might not be an ONe WD. We suggest that the companion of HD 49798 is most likely a CO WD, which can be expected to increase its mass to the Chandrasekhar mass limit by accreting He-rich material from HD 49798. Thus, HD 49798 with its companion may prod...

  16. Searching for light echoes due to CSM in SN Ia spectra

    E-Print Network [OSTI]

    Marino, Sebastián; Förster, Francisco; Folatelli, Gastón; Hamuy, Mario; Hsiao, Eric

    2015-01-01T23:59:59.000Z

    We present an analytical model for light echoes (LEs) coming from circumstellar material (CSM) around Type Ia Supernovae (SNe Ia). Using this model we find two spectral signatures at 4100 {\\AA} and 6200 {\\AA} that are useful to identify LEs during the Lira law phase (between 35 and 80 days after maximum light) coming from nearby CSM at distances of 0.01-0.25 pc. We analyze a sample of 89 SNe Ia divided in two groups according to their B-V decline rate during the Lira law phase, and search for LEs from CSM interaction in the group of SNe with steeper slopes by comparing their spectra with our LE model. We find that a model with LEs + pure extinction from interstellar material (ISM) fits better the observed spectra than a pure ISM extinction model that is constant in time, but we find that a decreasing extinction alone explains better the observations without the need of LEs, possibly implying dust sublimation due to the radiation from the SN.

  17. Optical and ultraviolet observations of the narrow-lined type Ia SN 2012fr in NGC 1365

    SciTech Connect (OSTI)

    Zhang, Ju-Jia; Bai, Jin-Ming; Wang, Bo; Liu, Zheng-Wei [Yunnan Observatories (YNAO), Chinese Academy of Sciences, Kunming 650011 (China); Wang, Xiao-Feng; Zhao, Xu-Lin; Chen, Jun-Cheng [Physics Department and Tsinghua Center for Astrophysics (THCA), Tsinghua University, Beijing 100084 (China); Zhang, Tian-Meng, E-mail: jujia@ynao.ac.cn, E-mail: baijinming@ynao.ac.cn, E-mail: wang_xf@mail.tsinghua.edu.cn [National Astronomical Observatories of China (NAOC), Chinese Academy of Sciences, Beijing 100012 (China)

    2014-07-01T23:59:59.000Z

    Extensive optical and ultraviolet (UV) observations of the type Ia supernova (SN Ia) 2012fr are presented in this paper. It has a relatively high luminosity, with an absolute B-band peak magnitude of about –19.5 mag and a smaller post-maximum decline rate than normal SNe Ia (e.g., ?m {sub 15}(B) =0.85 ± 0.05 mag). Based on the UV and optical light curves, we derived that a {sup 56}Ni mass of about 0.88 M {sub ?} was synthesized in the explosion. The earlier spectra are characterized by noticeable high-velocity features of Si II ?6355 and Ca II with velocities in the range of ?22, 000-25, 000 km s{sup –1}. At around the maximum light, these spectral features are dominated by the photospheric components which are noticeably narrower than normal SNe Ia. The post-maximum velocity of the photosphere remains almost constant at ?12,000 km s{sup –1} for about one month, reminiscent of the behavior of some luminous SNe Ia like SN 1991T. We propose that SN 2012fr may represent a subset of the SN 1991T-like SNe Ia viewed in a direction with a clumpy or shell-like structure of ejecta, in terms of a significant level of polarization reported in Maund et al. in 2013.

  18. Constraining the Amount of Circumstellar Matter and Dust around Type Ia Supernovae through Near-Infrared Echo

    E-Print Network [OSTI]

    Maeda, Keiichi; Motohara, Kentaro

    2014-01-01T23:59:59.000Z

    Circumstellar (CS) environment is a key in understanding progenitors of type Ia supernovae (SNe Ia) as well as an origin of peculiar extinction property toward SNe Ia for cosmological application. It has been suggested that multiple em scatterings of SN photons on CS dust might explain a non-standard reddening law. In this paper, we investigate an effect of re-emissions of SN photons by CS dust in the Infrared (IR) wavelengths. We show that this effect allows observed IR light curves to be used to place a constraint on position/size and the amount of CSM dust. We apply the method to observed NIR SN Ia samples, showing that meaningful upper limits, even under conservative assumptions, on the CS dust mass can be derived. We thereby clarify a difficulty of the CS dust scattering model to be a general explanation for the peculiar reddening law, while it may still apply to a sub-sample of highly-reddened SNe Ia. For SNe Ia in general, environment at the interstellar scale should be responsible for the non-standard...

  19. Chemical and structural investigation of the role of both Mn and Mn oxide in the formation of manganese silicate barrier layers on SiO{sub 2}

    SciTech Connect (OSTI)

    Casey, P.; Bogan, J.; Hughes, G. [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); Lozano, J. G.; Nellist, P. D. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2011-09-01T23:59:59.000Z

    In this study, Mn silicate (MnSiO{sub 3}) barrier layers were formed on thermally grown SiO{sub 2} using both metallic Mn and oxidized Mn films, in order to investigate the role of oxygen in determining the extent of the interaction between the deposited Mn and the SiO{sub 2} substrate. Using x-ray photoelectron spectroscopy, it has been shown that a metallic Mn film with an approximate thickness of 1 nm cannot be fully converted to Mn silicate following vacuum annealing to 500 deg. C. Transmission electron microscopy (TEM) analysis suggests the maximum MnSiO{sub 3} layer thickness obtainable using metallic Mn is {approx}1.7 nm. In contrast, a {approx}1 nm partially oxidized Mn film can be fully converted to Mn silicate following thermal annealing to 400 deg. C, forming a MnSiO{sub 3} layer with a measured thickness of 2.6 nm. TEM analysis also clearly shows that MnSiO{sub 3} growth results in a corresponding reduction in the SiO{sub 2} layer thickness. It has also been shown that a fully oxidized Mn oxide thin film can be converted to Mn silicate, in the absence of metallic Mn. Based on these results it is suggested that the presence of Mn oxide species at the Mn/SiO{sub 2} interface facilitates the conversion of SiO{sub 2} to MnSiO{sub 3}, in agreement with previously published studies.

  20. Magnetic coupling in neutral and charged Cr{sub 2}, Mn{sub 2}, and CrMn dimers

    SciTech Connect (OSTI)

    Desmarais, N. [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland)] [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland); Reuse, F. A. [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland)] [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland); Khanna, S. N. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    2000-04-01T23:59:59.000Z

    Theoretical ab initio studies of neutral, cationic and anionic Cr{sub 2}, Mn{sub 2}, and CrMn dimers have been carried out to explore the progression of magnetic coupling with the number of electrons. It is shown that while Cr{sub 2} and Cr{sub 2}{sup -} have antiferromagnetically coupled atomic spins, Cr{sub 2}{sup +} has a ferromagnetic ground state closely followed by an antiferromagnetic state. On the other hand, all Mn{sub 2} dimers are ferromagnetic, irrespective of the charge. The neutral CrMn is ferrimagnetic while the charged CrMn are antiferromagnetic. In all cases, the charged dimers are found to be more stable than the neutral ones. The results are compared with available calculations and experiments and the difficulties associated with theoretical description and the experimental interpretations are discussed. (c) 2000 American Institute of Physics.

  1. NEGLIGIBLE CREEP CONDITIONS FOR MOD 9 CR 1 MO STEEL

    SciTech Connect (OSTI)

    Ren, Weiju [ORNL; Riou, Bernard [AREVA Group; Escaravage, Claude [AREVA Group; Swindeman, Robert W [ORNL; Cabrillat, Marie-Th?r?se [CEA Cadarache, St. Paul lex Durance, France; Allais, Lucien [CEA, Saclay, France

    2006-01-01T23:59:59.000Z

    Mod 9 Cr 1 Mo Steel (grade 91) is one of the materials envisaged for the Reactor Pressure Vessel of Very High Temperature Reactors. To avoid the implementation of a surveillance program covering the monitoring of the creep damage throughout the whole life of the reactor, it is recommended to operate the Reactor Pressure Vessel in the negligible creep regime. In this paper, the background of negligible creep criteria available in nuclear Codes is first recalled and their limitations were analyzed. Then, guidance for deriving criteria more appropriate for mod 9 Cr 1 Mo steel is provided. Finally, R&D actions in the U. S. and France to support the new approaches are discussed and recommended.

  2. Dislocations With Edge Components in Nanocrystalline bcc Mo

    SciTech Connect (OSTI)

    G. M. Cheng; W. Z. Xu; W. W. Jian; H. Yuan; M. H. Tsai; Y. T. Zhu; Y. F. Zhang; Paul C. Millett

    2013-07-01T23:59:59.000Z

    We report high-resolution transmission electron microscopy (HRTEM) observation of a high density of dislocations with edge components (approximately 1016 m-2) in nanocrystalline (NC) body-centered cubic (bcc) Mo prepared by high-pressure torsion. We also observed for the first time of the 1/2 <111> and <001> pure edge dislocations in NC Mo. Crystallographic analysis and image simulations reveal that the best way using HRTEM to study dislocations with edge components in bcc systems is to take images along <110> zone axis, from which it is possible to identify 1/2 <111> pure edge dislocations, and edge components of 1/2 <111> and <001> mixed dislocations. The <001> pure edge dislocations can only be identified from <100> zone axis. The high density of dislocations with edge components is believed to play a major role in the reduction of strain rate sensitivity in NC bcc metals and alloys.

  3. NO. REV. MO. _ ALSEP/LCRU EMC Test Results

    E-Print Network [OSTI]

    Rathbun, Julie A.

    NO. REV. MO. ATM 1050 _ ALSEP/LCRU EMC Test Results PAGE 1 OF 10 DATE 19 August 1971 The results of the ALSEP/LCRU EMC test are reported in this ATM. C~.·--~ s--·~e'Jn~,__')!).Prepared by:__~~~"f--.;;.~-------- Approved by: ~JM.MD. ithian #12;NO. RIV. NO. ATM 1050 ALSEP/LCRU EMC Test Results 2 10PAGE OF Aall

  4. Long-term corrosion of Cr-Mo steels in superheated steam at 482 and 538/sup 0/C. [21/4 Cr-1 Mo; 9 Cr-1 Mo; Sumitomo 9 Cr-2 Mo; Sandvik HT-9

    SciTech Connect (OSTI)

    Griess, J.C.; DeVan, J.H.; Maxwell, W.A.

    1980-01-01T23:59:59.000Z

    The corrosion of several Cr-Mo ferritic steels was investigated in superheated steam at an operating power plant. Tests were conducted at 482 and 538/sup 0/C (900 and 1000/sup 0/F) in a once-through loop for times up to 28,000 h. Chromium concentrations ranged from 2.0 to 11.3%, and the effect of surface preparation on corrosion was investigated. Only one of many specimens showed evidence of exfoliation at 482/sup 0/C, but at 538/sup 0/C exfoliation occurred on at least some of the specimens of most materials; the exceptions were the alloy with the highest chromium content (Sandvik HT-9), one heat of 9 Cr-1 Mo steel with the highest silicon content, and Sumitomo 9 Cr-2 Mo steel, which was in test for only 19,000 h. Parabolic oxidation kinetics adequately described the corrosion process for about the first year, after which corrosion rates were constant and lower than predicted from extrapolation of the initial part of the penetration versus time curves. With chromium concentrations between 2 and 9%, corrosion behavior was independent of chromium content, and corrosion was only slightly less with Sandvik HT-9. Corrosion was nearly independent of surface preparation, but in two cases the presence of mill scale on the surface prior to steam exposure seemed to retard oxidation in steam. 11 figures, 5 tables.

  5. IRRADIATION PERFORMANCE OF U-Mo MONOLITHIC FUEL

    SciTech Connect (OSTI)

    M.K. Meyer; J. Gan; J.-F. Jue; D.D. Keiser; E. Perez; A. Robinson; D.M. Wachs; N. Woolstenhulme; G.L. Hofman; Y.-S. Kim

    2014-04-01T23:59:59.000Z

    High-performance research reactors require fuel that operates at high specific power to high fission density, but at relatively low temperatures. Research reactor fuels are designed for efficient heat rejection, and are composed of assemblies of thin-plates clad in aluminum alloy. The development of low-enriched fuels to replace high-enriched fuels for these reactors requires a substantially increased uranium density in the fuel to offset the decrease in enrichment. Very few fuel phases have been identified that have the required combination of very-high uranium density and stable fuel behavior at high burnup. UMo alloys represent the best known tradeoff in these properties. Testing of aluminum matrix U-Mo aluminum matrix dispersion fuel revealed a pattern of breakaway swelling behavior at intermediate burnup, related to the formation of a molybdenum stabilized high aluminum intermetallic phase that forms during irradiation. In the case of monolithic fuel, this issue was addressed by eliminating, as much as possible, the interfacial area between U-Mo and aluminum. Based on scoping irradiation test data, a fuel plate system composed of solid U-10Mo fuel meat, a zirconium diffusion barrier, and Al6061 cladding was selected for development. Developmental testing of this fuel system indicates that it meets core criteria for fuel qualification, including stable and predictable swelling behavior, mechanical integrity to high burnup, and geometric stability. In addition, the fuel exhibits robust behavior during power-cooling mismatch events under irradiation at high power.

  6. Single Phase Melt Processed Powellite (Ba,Ca) MoO{sub 4} For The Immobilization Of Mo-Rich Nuclear Waste

    SciTech Connect (OSTI)

    Brinkman, Kyle [Savannah River Site (SRS), Aiken, SC (United States); Marra, James [Savannah River Site (SRS), Aiken, SC (United States); Fox, Kevin [Savannah River Site (SRS), Aiken, SC (United States); Reppert, Jason [Savannah River Site (SRS), Aiken, SC (United States); Crum, Jarrod [Paci fic Northwest National Laboratory , Richland, WA (United States); Tang, Ming [Los Alamos National Laboratory , Los Alamos, NM (United States)

    2012-09-17T23:59:59.000Z

    Crystalline and glass composite materials are currently being investigated for the immobilization of combined High Level Waste (HLW) streams resulting from potential commercial fuel reprocessing scenarios. Several of these potential waste streams contain elevated levels of transition metal elements such as molybdenum (Mo). Molybdenum has limited solubility in typical silicate glasses used for nuclear waste immobilization. Under certain chemical and controlled cooling conditions, a powellite (Ba,Ca)MoO{sub 4} crystalline structure can be formed by reaction with alkaline earth elements. In this study, single phase BaMoO{sub 4} and CaMoO{sub 4} were formed from carbonate and oxide precursors demonstrating the viability of Mo incorporation into glass, crystalline or glass composite materials by a melt and crystallization process. X-ray diffraction, photoluminescence, and Raman spectroscopy indicated a long range ordered crystalline structure. In-situ electron irradiation studies indicated that both CaMoO{sub 4} and BaMoO{sub 4} powellite phases exhibit radiation stability up to 1000 years at anticipated doses with a crystalline to amorphous transition observed after 1 X 10{sup 13} Gy. Aqueous durability determined from product consistency tests (PCT) showed low normalized release rates for Ba, Ca, and Mo (<0.05 g/m{sup 2}).

  7. Structural and magnetic properties of Sm{sub 2?x}Mn{sub x}O{sub 3} nanoparticles

    SciTech Connect (OSTI)

    Heiba, Zein K. [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Taif University, Faculty of Science, Physics Department (Saudi Arabia); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [Ain Shams University, Faculty of Science, Physics Department, Cairo (Egypt); Fuess, H. [Materials Science, Darmstadt University of Technology, D-64289 Darmstadt (Germany)

    2013-10-15T23:59:59.000Z

    Graphical abstract: - Highlights: • C-type Sm{sub 2?x}Mn{sub x}O{sub 3} (0.0 ? x ?0.20) is prepared by sol–gel method. • A maximum solubility of x = 0.15 is confirmed by X-ray diffraction, Raman and infrared techniques. • Samples with x > 0.05 exhibit weak ferromagnetic properties; for x ? 0.05 antiferromagnetic behaviors is obtained. • Correlation between magnetic behaviors and structural and microstructural parameters is discussed. - Abstract: Mixed oxide Sm{sub 2?x}Mn{sub x}O{sub 3} (SMO), x = 0.0, 0.05, 0.10, 0.15 and 0.20 were synthesized by a sol–gel process. A single phase solid solution is formed up to x = 0.15 which confirmed by using X-ray diffraction, Raman spectroscopy and infrared techniques. Crystal structure and microstructure analyses were performed by Rietveld refinement. Preferential cationic distribution, over the two crystallographic sites 8b and 24d of space group Ia3{sup ¯}, is found for doped samples but with different extent. The r.m.s. microstrain ??{sub L}{sup 2}?{sup 1/2} depends on composition x in a systematic way emphasizing the preferential distribution. Magnetization measurements show that samples with x ? 0.05 have antiferromagnetic behavior, while samples with x > 0.05 exhibit a weak ferromagnetic behavior with magnetic phase transformation at 15 and 16 K for x = 0.1 and x = 0.15, respectively.

  8. High-performance MoS{sub 2} transistors with low-resistance molybdenum contacts

    SciTech Connect (OSTI)

    Kang, Jiahao; Liu, Wei; Banerjee, Kaustav, E-mail: kaustav@ece.ucsb.edu [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

    2014-03-03T23:59:59.000Z

    In this Letter, molybdenum (Mo) is introduced and evaluated as an alternative contact metal to atomically-thin molybdenum disulphide (MoS{sub 2}), and high-performance field-effect transistors are experimentally demonstrated. In order to understand the physical nature of the interface and highlight the role of the various factors contributing to the Mo-MoS{sub 2} contacts, density functional theory (DFT) simulations are employed, which reveal that Mo can form high quality contact interface with monolayer MoS{sub 2} with zero tunnel barrier and zero Schottky barrier under source/drain contact, as well as an ultra-low Schottky barrier (0.1?eV) at source/drain-channel junction due to strong Fermi level pinning. In agreement with the DFT simulations, high mobility, high ON-current, and low contact resistance are experimentally demonstrated on both monolayer and multilayer MoS{sub 2} transistors using Mo contacts. The results obtained not only reveal the advantages of using Mo as a contact metal for MoS{sub 2} but also highlight the fact that the properties of contacts with 2-dimensional materials cannot be intuitively predicted by solely considering work function values and Schottky theory.

  9. Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge

    E-Print Network [OSTI]

    Zeng, Li

    2010-01-01T23:59:59.000Z

    Mn-Si (red squares) and Mn-Ge distances (blue circles) d asof the number of Si or Ge nearest neighbours N c ; (c) localthree Mn atoms with different N c in a-Mn 0.094 Ge 0.906 .

  10. Cumulative Effects Guidance 2007 MnDOT Environmental

    E-Print Network [OSTI]

    Minnesota, University of

    relevant for actions requiring an environmental impact statement § Analysis for projects processed as EACumulative Effects Guidance 2007 MnDOT Environmental Stewardship & Streamlining Workshop Presented by Dave Gamble Federal Highway Administration Resource Center Environmental Technical Service Team #12

  11. Transverse acoustic actuation of Ni-Mn-Ga single crystals

    E-Print Network [OSTI]

    Simon, Jesse Matthew

    2007-01-01T23:59:59.000Z

    Two methods for the transverse acoustic actuation of {110}-cut Ni-Mn-Ga single crystals are discussed. In this actuation mode, crystals are used that have the {110}- type twinning planes parallel to the base of the crystal. ...

  12. PRECIPITATION-STRENGTHENED AUSTENITIC FE-MN-TI ALLOYS

    E-Print Network [OSTI]

    Chiang, K.-M.

    2010-01-01T23:59:59.000Z

    energy spectrums showing that precipitates are rich in titanium, andtitanium additions can reduce the austenitic stacking fault energyfault energy of the Fe-Mn austenite is lowered by titanium

  13. Hubble Residuals of Nearby SN Ia Are Correlated with Host Galaxy Masses

    SciTech Connect (OSTI)

    Kelly, Patrick L.; /KIPAC, Menlo Park /SLAC; Hicken, Malcolm; /Harvard-Smithsonian Ctr. Astrophys.; Burke, David L.; /KIPAC, Menlo Park /SLAC; Mandel, Kaisey S.; Kirshner, Robert P.; /Harvard-Smithsonian Ctr. Astrophys.

    2010-05-03T23:59:59.000Z

    From Sloan Digital Sky Survey u{prime} g{prime} r{prime} i{prime} z{prime} imaging, we estimate the stellar masses of the host galaxies of 70 low redshift SN Ia (0.015 < z < 0.08) from the hosts absolute luminosities and mass-to-light ratios. These nearby SN were discovered largely by searches targeting luminous galaxies, and we find that their host galaxies are substantially more massive than the hosts of SN discovered by the flux-limited Supernova Legacy Survey. Testing four separate light curve fitters, we detect {approx}2.5{sigma} correlations of Hubble residuals with both host galaxy size and stellar mass, such that SN Ia occurring in physically larger, more massive hosts are {approx}10% brighter after light curve correction. The Hubble residual is the deviation of the inferred distance modulus to the SN, calculated from its apparent luminosity and light curve properties, away from the expected value at the SN redshift. Marginalizing over linear trends in Hubble residuals with light curve parameters shows that the correlations cannot be attributed to a light curve-dependent calibration error. Combining 180 higher-redshift ESSENCE, SNLS, and HigherZ SN with 30 nearby SN whose host masses are less than 10{sup 10.8} M{circle_dot} n a cosmology fit yields 1 + w = 0.22{sub -0.108}{sup +0.152}, while a combination where the 30 nearby SN instead have host masses greater than 10{sup 10.8} M{circle_dot} yields 1 + w = ?0.03{sub -0.143}{sup +0.217}. Progenitor metallicity, stellar population age, and dust extinction correlate with galaxy mass and may be responsible for these systematic effects. Host galaxy measurements will yield improved distances to SN Ia.

  14. Constraints on shallow {sup 56}Ni from the early light curves of type Ia supernovae

    SciTech Connect (OSTI)

    Piro, Anthony L. [Theoretical Astrophysics, California Institute of Technology, 1200 E California Boulevard, M/C 350-17, Pasadena, CA 91125 (United States); Nakar, Ehud, E-mail: piro@caltech.edu [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

    2014-03-20T23:59:59.000Z

    Ongoing transient surveys are presenting an unprecedented account of the rising light curves of Type Ia supernovae (SNe Ia). This early emission probes the shallowest layers of the exploding white dwarf (WD), which can provide constraints on the progenitor star and the properties of the explosive burning. We use semianalytic models of radioactively powered rising light curves to analyze these observations. As we have summarized in previous work, the main limiting factor in determining the surface distribution of {sup 56}Ni is the lack of an unambiguously identified time of explosion, as would be provided by detection of shock breakout or shock-heated cooling. Without this the SN may in principle exhibit a 'dark phase' for a few hours to days, where the only emission is from shock-heated cooling that is too dim to be detected. We show that by assuming a theoretically motivated time-dependent velocity evolution, the explosion time can be better constrained, albeit with potential systematic uncertainties. This technique is used to infer the surface {sup 56}Ni distributions of three recent SNe Ia that were caught especially early in their rise. In all three we find fairly similar {sup 56}Ni distributions. Observations of SN 2011fe and SN 2012cg probe shallower depths than SN 2009ig, and in these two cases {sup 56}Ni is present merely ?10{sup –2} M {sub ?} from the WDs' surfaces. The uncertainty in this result is up to an order of magnitude given the difficulty of precisely constraining the explosion time. We also use our conclusions about the explosion times to reassess radius constraints for the progenitor of SN 2011fe, as well as discuss the roughly t {sup 2} power law that is inferred for many observed rising light curves.

  15. IS WX CEN A POSSIBLE TYPE Ia SUPERNOVA PROGENITOR WITH WIND-DRIVEN MASS TRANSFER?

    SciTech Connect (OSTI)

    Qian, S.-B.; Shi, G.; Zhu, L.-Y.; Liu, L.; Zhao, E.-G.; Li, L.-J. [Yunnan Observatories, Chinese Academy of Sciences (CAS), P.O. Box 110, 650011 Kunming (China); Fernandez Lajus, E.; Di Sisto, R. P., E-mail: qsb@ynao.ac.cn [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires (Argentina)

    2013-08-01T23:59:59.000Z

    WX Cen is one of a few compact binary supersoft X-ray sources (CBSS) in the Galaxy that is a possible Type Ia supernova (SN Ia) progenitor. The supersoft X-ray radiation is explained as hydrostatic nuclear burning on the surface of the white dwarf component that is accreting hydrogen from a stellar companion at a high rate. If the mass donor in this system has a low mass, as has been suggested in the literature, one would expect a high wind-driven mass transfer rate. In that case, the orbital period of the system should increase. To test this theoretical prediction, we have monitored the system photometrically since 2010. By using four newly determined eclipse timings together with those collected from the literature, we discovered that the orbital period is decreasing at a rate of dP/dt = -5.15 Multiplication-Sign 10{sup -7} days yr{sup -1}. The long-term decrease in the orbital period is contrary to the prediction that the system is powered by wind-driven accretion. It therefore seems plausible that the mass donor could be more massive than the white dwarf, and that the mass transfer is driven by the thermal instability of the donor star. This finding suggests that WX Cen is a key object to check the physical mechanisms of mass accretion in CBSS. The corresponding timescale of the period change is about P/P-dot {approx} 0.81 x 10{sup 6} yr, indicating that WX Cen may evolve into an SNe Ia within one million years in the Galaxy.

  16. On the Thermonuclear Runaway in Type Ia Supernovae: How to run away?

    E-Print Network [OSTI]

    P. Hoeflich; J. Stein

    2001-12-07T23:59:59.000Z

    Type Ia Supernovae are thought to be thermonuclear explosions of massive white dwarfs (WD). We present the first study of multi-dimensional effects during the final hours prior to the thermonuclear runaway which leads to the explosion. The calculations utilize an implicit, 2-D hydro code.Mixing and the ignition process are studied in detail. We find that the initial chemical structure of the WD is changed but the material is not fully homogenized. The exploding WD sustains a central region with a low C/O ratio. This implies that the explosive nuclear burning will begin in a partially C-depleted environment. The thermonuclear runaway happens in a well defined region close to the center. It is induced by compressional heat when matter is brought inwards by convective flows. We find no evidence for multiple spot or strong off-center ignition. Convective velocities are of the order of 100 km/sec which is well above the effective burning speeds in SNe Ia previously expected right after the runaway. For about 0.5 to 1 sec, the speed of the burning front will neither be determined by the laminar speed nor the Rayleigh-Taylor instabilities but by convective flows produced prior to the runaway. The consequences are discussed for our under- standing of the detailed physics of the flame propagation, the deflagration detonation transition, and the nucleosynthesis in the central layers. Our results strongly suggest the pre-conditioning of the progenitor as a key-factor for our understanding of the diversity in SNeIa.

  17. The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-masswhite dwarf star

    SciTech Connect (OSTI)

    Howell, D.Andrew; Sullivan, Mark; Nugent, Peter E.; Ellis,Richard S.; Conley, Alexander J.; Le Borgne, Damien; Carlberg, RaymondG.; Guy, Julien; Balam, David; Basa, Stephane; Fouchez, Dominique; Hook,Isobel M.; Hsiao, Eric Y.; Neill, James D.; Pain, Reynald; Perrett,Kathryn M.; Pritchet, Christopher J.

    2006-02-01T23:59:59.000Z

    The acceleration of the expansion of the universe, and theneed for Dark Energy, were inferred from the observations of Type Iasupernovae (SNe Ia) 1;2. There is consensus that SNeIa are thermonuclearexplosions that destroy carbon-oxygen white dwarf stars that accretematter from a companion star3, although the nature of this companionremains uncertain. SNe Ia are thought to be reliable distance indicatorsbecause they have a standard amount of fuel and a uniform trigger theyare predicted to explode when the mass of the white dwarf nears theChandrasekhar mass 4 - 1.4 solar masses. Here we show that the highredshift supernova SNLS-03D3bb has an exceptionally high luminosity andlow kinetic energy that both imply a super-Chandrasekhar mass progenitor.Super-Chandrasekhar mass SNeIa shouldpreferentially occur in a youngstellar population, so this may provide an explanation for the observedtrend that overluminous SNe Ia only occur in young environments5;6. Sincethis supernova does not obey the relations that allow them to becalibrated as standard candles, and since no counterparts have been foundat low redshift, future cosmology studies will have to considercontamination from such events.

  18. A super-Eddington wind scenario for the progenitors of type Ia supernovae: binary population synthesis calculations

    E-Print Network [OSTI]

    Wang, Bo; Liu, Dongdong; Liu, Zhengwei; Wu, Chengyuan; Zhang, Jujia; Han, Zhanwen

    2015-01-01T23:59:59.000Z

    The super-Eddington wind scenario has been proposed as an alternative way for producing type Ia supernovae (SNe Ia). The super-Eddington wind can naturally prevent the carbon--oxygen white dwarfs (CO WDs) with high mass-accretion rates from becoming red-giant-like stars. Furthermore, it works in low-metallicity environments, which may explain SNe Ia observed at high redshifts. In this article, we systematically investigated the most prominent single-degenerate WD+MS channel based on the super-Eddington wind scenario. We combined the Eggleton stellar evolution code with a rapid binary population synthesis (BPS) approach to predict SN Ia birthrates for the WD+MS channel by adopting the super-Eddington wind scenario and detailed mass-accumulation efficiencies of H-shell flashes on the WDs. Our BPS calculations found that the estimated SN Ia birthrates for the WD+MS channel are ~0.009-0.315*10^{-3}{yr}^{-1} if we adopt the Eddington accretion rate as the critical accretion rate, which are much lower than that of ...

  19. Simple Molybdenum(IV) Olefin Complexes of the Type Mo(NR)(X)(Y)(olefin)

    E-Print Network [OSTI]

    Marinescu, Smaranda C.

    Exposure of heptane solutions of Mo(NAr)(CHCMe2Ph)(Me2Pyr)(OAr) (1a; Ar = 2,6-diisopropylphenyl), Mo(NAr)(CHCMe3)(Me2Pyr)[OCMe(CF3)2] (1b), and Mo(NAr)(CHCMe2Ph)(Me2Pyr)(OSiPh3) (1c) to one atmosphere of ethylene for 12 h ...

  20. Gamma-Rays as Probes for the Multi-Dimensionality of Type Ia Supernovae

    E-Print Network [OSTI]

    P. Hoeflich

    2001-10-03T23:59:59.000Z

    We present $\\gamma $-ray spectra for a set of Type Ia supernovae models. Our study is based on a detailed Monte Carlo transport scheme for both spherical and full 3-D geometries. Classical and new challenges of the $\\gamma $ ray astronomy are addressed. We find that $\\gamma $-rays are very suitable to reveal the structure of the envelope and, thus, they allow to probe properties of the nuclear burning front and the progenitor, namely its central density and global asphericities. The potential problems are discussed for the quantitative comparison between theoretical and observed line fluxes during the first few months after the explosion.

  1. Testing the isotropy of the Universe by using the JLA compilation of type-Ia supernovae

    E-Print Network [OSTI]

    Lin, Hai-Nan; Chang, Zhe; Li, Xin

    2015-01-01T23:59:59.000Z

    We probe the possible anisotropy in the accelerated expanding Universe by using the JLA compilation of type-Ia supernovae. We constrain the amplitude and direction of anisotropy in the anisotropic cosmological models. For the dipole-modulated $\\Lambda$CDM model, the anisotropic amplitude has an upper bound $D<1.04\\times10^{-3}$ at the $68\\%$ confidence level. Similar results are found in the dipole-modulated $w$CDM and CPL models. Our studies show that there are no significant evidence for the anisotropic expansion of the Universe. Thus the Universe is still well compatible with the isotropy.

  2. On the Stability of Thermonuclear Burning Fronts in Type Ia Supernovae

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt

    2004-04-26T23:59:59.000Z

    The propagation of cellularly stabilized thermonuclear flames is investigated by means of numerical simulations. In Type Ia supernova explosions the corresponding burning regime establishes at scales below the Gibson length. The cellular flame stabilization - which is a result of an interplay between the Landau-Darrieus instability and a nonlinear stabilization mechanism - is studied for the case of propagation into quiescent fuel as well as interaction with vortical fuel flows. Our simulations indicate that in thermonuclear supernova explosions stable cellular flames develop around the Gibson scale and that deflagration-to-detonation transition is unlikely to be triggered from flame evolution effects here.

  3. Experimental activities supporting commercial U.S. accelerator production of 99-Mo

    SciTech Connect (OSTI)

    Dale, Gregory E [Los Alamos National Laboratory; Chemerisov, Sergey D [ANL; Vandegrift, George F [ANL

    2010-01-01T23:59:59.000Z

    {sup 99m}Tc, the daughter product of {sup 99}Mo, is the most commonly used radioisotope for nuclear medicine in the U.S. Experiments are being performed at Los Alamos National Laboratory and Argonne National Laboratory to demonstrate production of {sup 99}Mo using accelerators. The {sup 100}Mo({gamma},n){sup 99}Mo reaction in an enriched {sup 100}Mo target is currently under investigation. Three scaled low-power production experiments using a 20-MeV electron linac at Argonne have been performed to date. Two of these experiments used natural Mo targets and produced a total of 613 {mu}C of {sup 99}Mo. The third experiment used an enriched {sup 100}Mo target and produced 10.5 mCi of {sup 99}Mo. Following irradiation the targets were dissolved and the low specific activity solution was processed through an ARSII generator from NorthStar Medical Radioisotopes. Yields of {sup 99m}Tc >95% have been observed.

  4. Conceptual design of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production

    SciTech Connect (OSTI)

    Liem, Peng Hong [Nippon Advanced Information Service (NAIS Co., Inc.) Scientific Computational Division, 416 Muramatsu, Tokaimura, Ibaraki (Japan); Tran, Hoai Nam [Chalmers University of Technology, Dept. of Applied Physics, Div. of Nuclear Engineering, SE-412 96 Gothenburg (Sweden); Sembiring, Tagor Malem [National Nuclear Energy Agency (BATAN), Center for Reactor Technology and Nuclear Safety, Kawasan Puspiptek, Serpong, Tangerang Selatan, Banten (Indonesia); Arbie, Bakri [PT MOTAB Technology, Kedoya Elok Plaza Blok DA 12, Jl. Panjang, Kebun Jeruk, Jakarta Barat (Indonesia)

    2014-09-30T23:59:59.000Z

    To partly solve the global and regional shortages of Mo-99 supply, a conceptual design of a nitrate-fuel-solution based homogeneous reactor dedicated for Mo-99/Tc-99m medical radioisotope production is proposed. The modified LEU Cintichem process for Mo-99 extraction which has been licensed and demonstrated commercially for decades by BATAN is taken into account as a key design consideration. The design characteristics and main parameters are identified and the advantageous aspects are shown by comparing with the BATAN's existing Mo-99 supply chain which uses a heterogeneous reactor (RSG GAS multipurpose reactor)

  5. Ambi-site substitution of Mn in lanthanum germanate apatites

    SciTech Connect (OSTI)

    Kendrick, E. [Chemical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Knight, K.S. [ISIS Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX (United Kingdom); Slater, P.R., E-mail: p.r.slater@bham.ac.uk [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2009-08-05T23:59:59.000Z

    A neutron diffraction study at 4 K of the Mn doped lanthanum germanate apatite-type oxide ion conductor of nominal starting composition 'La{sub 9.5}Mn{sub 0.5}(GeO{sub 4}){sub 6}O{sub 2.75}' is reported. The structure was refined in space group P6{sub 3}/m, although high thermal displacement parameters were observed for the oxide ion sites (particularly O3, and O4). Reduced thermal displacement parameters were obtained by splitting the O3 site, and allowing the O4 oxygen to move off site, which may indicate local regions of lower symmetry within the structure. In addition, the data suggested ambi-site substitution of Mn, with it being present on both the Ge site and the La site. Assuming no change in La:Mn:Ge ratio, a composition of La{sub 9.18}Mn{sub 0.28}(GeO{sub 4}){sub 5.8}(MnO{sub 4}){sub 0.2}O{sub 2} was determined. As such there are nominally no interstitial oxide ions, but rather cation vacancies on the La site. Therefore, the high conductivity for this sample is most likely related to the introduction of Frenkel-type defects at higher temperature, as previously proposed for other apatite-type systems containing vacancies on the La site.

  6. Greenfield Alternative Study LEU-Mo Fuel Fabrication Facility

    SciTech Connect (OSTI)

    Washington Division of URS

    2008-07-01T23:59:59.000Z

    This report provides the initial “first look” of the design of the Greenfield Alternative of the Fuel Fabrication Capability (FFC); a facility to be built at a Greenfield DOE National Laboratory site. The FFC is designed to fabricate LEU-Mo monolithic fuel for the 5 US High Performance Research Reactors (HPRRs). This report provides a pre-conceptual design of the site, facility, process and equipment systems of the FFC; along with a preliminary hazards evaluation, risk assessment as well as the ROM cost and schedule estimate.

  7. Phase transitions in the adsorption system Li/Mo(112)

    E-Print Network [OSTI]

    Fedorus, A.; Kolthoff, D.; Koval, V.; Lyuksyutov, Igor F.; Naumovets, AG; Pfnur, H.

    2000-01-01T23:59:59.000Z

    limit can be quasi-one-dimensional. Such model systems are formed upon submonolayer adsorption on surfaces with strongly an- PRB 620163-1829/2000/62~4!/2852~10!/$15.00 n system Li?Mo?112? ,1,3 A. G. Naumovets,1 and H. Pfnu?r2,* , Prospect Nauki 46... W/Re thermocouple and was con- trolled by a computerized feedback circuit with a resolution of 0.01 K. The source of lithium was constructed and outgassed as PRB 62 PHASE TRANSITIONS IN TH described in Ref. 6. The LEED patterns have been taken...

  8. Recovery of Mo/Si multilayer coated optical substrates

    DOE Patents [OSTI]

    Baker, Sherry L. (Pleasanton, CA); Vernon, Stephen P. (Pleasanton, CA); Stearns, Daniel G. (Los Altos, CA)

    1997-12-16T23:59:59.000Z

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO.sub.2 overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates.

  9. Recovery of Mo/Si multilayer coated optical substrates

    DOE Patents [OSTI]

    Baker, S.L.; Vernon, S.P.; Stearns, D.G.

    1997-12-16T23:59:59.000Z

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO{sub 2} overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates. 5 figs.

  10. DOE - Office of Legacy Management -- Petrolite Corp - MO 08

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling Corp - CTOregonPetrolite Corp - MO 08 FUSRAP

  11. Application of Mn/DOT Utility Coordination Process to Local Agencies Based on national best practices, the Minnesota Department of Transportation (Mn/DOT) Utility

    E-Print Network [OSTI]

    Minnesota, University of

    Application of Mn/DOT Utility Coordination Process to Local Agencies Based on national best practices, the Minnesota Department of Transportation (Mn/DOT) Utility Coordination Process incorporates Processes There are projects where the full process is not necessary. The Mn/DOT Utilities Manual provides

  12. Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)

    E-Print Network [OSTI]

    Zeng, Li

    2007-01-01T23:59:59.000Z

    Magnetization data for a-Mn 0.15 Ge 0.85 ?lms mea- suredSi 1?x and a-Mn x Ge 1?x samples. . . . . . . . . . . . . .both a-Mn x Si 1?x and a-Mn x Ge 1?x as a func- tion of Mn

  13. Constraining the Type Ia Supernova Progenitor: The Search for Hydrogen in Nebular Spectra

    E-Print Network [OSTI]

    Douglas C. Leonard

    2007-10-16T23:59:59.000Z

    Despite intense scrutiny, the progenitor system(s) that gives rise to Type Ia supernovae remains unknown. The favored theory invokes a carbon-oxygen white dwarf accreting hydrogen-rich material from a close companion until a thermonuclear runaway ensues that incinerates the white dwarf. However, simulations resulting from this single-degenerate, binary channel demand the presence of low-velocity H-alpha emission in spectra taken during the late nebular phase, since a portion of the companion's envelope becomes entrained in the ejecta. This hydrogen has never been detected, but has only rarely been sought. Here we present results from a campaign to obtain deep, nebular-phase spectroscopy of nearby Type Ia supernovae, and include multi-epoch observations of two events: SN 2005am (slightly subluminous) and SN 2005cf (normally bright). No H-alpha emission is detected in the spectra of either object. An upper limit of 0.01 M_Sun of solar abundance material in the ejecta is established from the models of Mattila et al. which, when coupled with the mass-stripping simulations of Marietta et al. and Meng et al. effectively rules out progenitor systems for these supernovae with secondaries close enough to the white dwarf to be experiencing Roche lobe overflow at the time of explosion. Alternative explanations for the absence of H-alpha emission, along with suggestions for future investigations necessary to confidently exclude them as possibilities, are critically evaluated.

  14. Inference for the dark energy equation of state using Type IA supernova data

    E-Print Network [OSTI]

    Christopher Genovese; Peter Freeman; Larry Wasserman; Robert Nichol; Christopher Miller

    2009-05-18T23:59:59.000Z

    The surprising discovery of an accelerating universe led cosmologists to posit the existence of "dark energy"--a mysterious energy field that permeates the universe. Understanding dark energy has become the central problem of modern cosmology. After describing the scientific background in depth, we formulate the task as a nonlinear inverse problem that expresses the comoving distance function in terms of the dark-energy equation of state. We present two classes of methods for making sharp statistical inferences about the equation of state from observations of Type Ia Supernovae (SNe). First, we derive a technique for testing hypotheses about the equation of state that requires no assumptions about its form and can distinguish among competing theories. Second, we present a framework for computing parametric and nonparametric estimators of the equation of state, with an associated assessment of uncertainty. Using our approach, we evaluate the strength of statistical evidence for various competing models of dark energy. Consistent with current studies, we find that with the available Type Ia SNe data, it is not possible to distinguish statistically among popular dark-energy models, and that, in particular, there is no support in the data for rejecting a cosmological constant. With much more supernova data likely to be available in coming years (e.g., from the DOE/NASA Joint Dark Energy Mission), we address the more interesting question of whether future data sets will have sufficient resolution to distinguish among competing theories.

  15. Spectroscopic Determination of the Low Redshift Type Ia Supernova Rate from the Sloan Digital Sky Survey

    SciTech Connect (OSTI)

    Krughoff, K. S. [Univ. of Washington, Seattle, WA (United States); Connolly, Andrew J. [Univ. of Washington, Seattle, WA (United States); Frieman, Joshua [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); SubbaRao, Mark [Univ. of Chicago, Chicago, IL (United States); Kilper, Gary [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Schneider, Donald P. [Davey Laboratory, PA (United States)

    2011-04-10T23:59:59.000Z

    Supernova rates are directly coupled to high mass stellar birth and evolution. As such, they are one of the few direct measures of the history of cosmic stellar evolution. In this paper we describe an probabilistic technique for identifying supernovae within spectroscopic samples of galaxies. We present a study of 52 type Ia supernovae ranging in age from -14 days to +40 days extracted from a parent sample of \\simeq 50,000 spectra from the SDSS DR5. We find a Supernova Rate (SNR) of 0.472^{+0.048}_{-0.039}(Systematic)^{+0.081}_{-0.071}(Statistical)SNu at a redshift of = 0.1. This value is higher than other values at low redshift at the 1{\\sigma}, but is consistent at the 3{\\sigma} level. The 52 supernova candidates used in this study comprise the third largest sample of supernovae used in a type Ia rate determination to date. In this paper we demonstrate the potential for the described approach for detecting supernovae in future spectroscopic surveys.

  16. Smoothed Particle Hydrodynamics simulations of the core-degenerate scenario for Type Ia supernovae

    E-Print Network [OSTI]

    Aznar-Siguán, G; Lorén-Aguilar, P; Soker, N; Kashi, A

    2015-01-01T23:59:59.000Z

    The core-degenerate (CD) scenario for type Ia supernovae (SN Ia) involves the merger of the hot core of an asymptotic giant branch (AGB) star and a white dwarf, and might contribute a non-negligible fraction of all thermonuclear supernovae. Despite its potential interest, very few studies, and based on only crude simplifications, have been devoted to investigate this possible scenario, compared with the large efforts invested to study some other scenarios. Here we perform the first three-dimensional simulations of the merger phase, and find that this process can lead to the formation of a massive white dwarf, as required by this scenario. We consider two situations, according to the mass of the circumbinary disk formed around the system during the final stages of the common envelope phase. If the disk is massive enough, the stars merge on a highly eccentric orbit. Otherwise, the merger occurs after the circumbinary disk has been ejected and gravitational wave radiation has brought the stars close to the Roche...

  17. Consistent use of type Ia supernovae highly magnified by galaxy clusters to constrain the cosmological parameters

    SciTech Connect (OSTI)

    Zitrin, Adi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Redlich, Matthias [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Philosophenweg 12, D-69120 Heidelberg (Germany); Broadhurst, Tom, E-mail: adizitrin@gmail.com [Department of Theoretical Physics, University of Basque Country UPV/EHU, Bilbao (Spain)

    2014-07-01T23:59:59.000Z

    We discuss how Type Ia supernovae (SNe) strongly magnified by foreground galaxy clusters should be self-consistently treated when used in samples fitted for the cosmological parameters. While the cluster lens magnification of a SN can be well constrained from sets of multiple images of various background galaxies with measured redshifts, its value is typically dependent on the fiducial set of cosmological parameters used to construct the mass model. In such cases, one should not naively demagnify the observed SN luminosity by the model magnification into the expected Hubble diagram, which would create a bias, but instead take into account the cosmological parameters a priori chosen to construct the mass model. We quantify the effect and find that a systematic error of typically a few percent, up to a few dozen percent per magnified SN may be propagated onto a cosmological parameter fit unless the cosmology assumed for the mass model is taken into account (the bias can be even larger if the SN is lying very near the critical curves). We also simulate how such a bias propagates onto the cosmological parameter fit using the Union2.1 sample supplemented with strongly magnified SNe. The resulting bias on the deduced cosmological parameters is generally at the few percent level, if only few biased SNe are included, and increases with the number of lensed SNe and their redshift. Samples containing magnified Type Ia SNe, e.g., from ongoing cluster surveys, should readily account for this possible bias.

  18. The Cellular Burning Regime in Type Ia Supernova Explosions - II. Flame Propagation into Vortical Fuel

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt; J. C. Niemeyer

    2003-12-08T23:59:59.000Z

    We investigate the interaction of thermonuclear flames in Type Ia supernova explosions with vortical flows by means of numerical simulations. In our study, we focus on small scales, where the flame propagation is no longer dominated by the turbulent cascade originating from large-scale effects. Here, the flame propagation proceeds in the cellular burning regime, resulting from a balance between the Landau-Darrieus instability and its nonlinear stabilization. The interaction of a cellularly stabilized flame front with a vortical fuel flow is explored applying a variety of fuel densities and strengths of the velocity fluctuations. We find that the vortical flow can break up the cellular flame structure if it is sufficiently strong. In this case the flame structure adapts to the imprinted flow field. The transition from the cellularly stabilized front to the flame structure dominated by vortices of the flow proceeds in a smooth way. The implications of the results of our simulations for Type Ia Supernova explosion models are discussed.

  19. Delayed detonations in full-star models of Type Ia supernova explosions

    E-Print Network [OSTI]

    F. K. Roepke; J. C. Niemeyer

    2007-03-14T23:59:59.000Z

    Aims: We present the first full-star three-dimensional explosion simulations of thermonuclear supernovae including parameterized deflagration-to-detonation transitions that occur once the flame enters the distributed burning regime. Methods: Treating the propagation of both the deflagration and the detonation waves in a common front-tracking approach, the detonation is prevented from crossing ash regions. Results: Our criterion triggers the detonation wave at the outer edge of the deflagration flame and consequently it has to sweep around the complex structure and to compete with expansion. Despite the impeded detonation propagation, the obtained explosions show reasonable agreement with global quantities of observed type Ia supernovae. By igniting the flame in different numbers of kernels around the center of the exploding white dwarf, we set up three different models shifting the emphasis from the deflagration phase to the detonation phase. The resulting explosion energies and iron group element productions cover a large part of the diversity of type Ia supernovae. Conclusions: Flame-driven deflagration-to-detonation transitions, if hypothetical, remain a possibility deserving further investigation.

  20. Spectroscopic Observations and Analysis of the Unusual Type Ia SN1999ac

    SciTech Connect (OSTI)

    Garavini, G.; Aldering, G.; Amadon, A.; Amanullah, R.; Astier,P.; Balland, C.; Blanc, G.; Conley, A.; Dahlen, T.; Deustua, S.E.; Ellis,R.; Fabbro, S.; Fadeyev, V.; Fan, X.; Folatelli, G.; Frye, B.; Gates,E.L.; Gibbons, R.; Goldhaber, G.; Goldman, B.; Goobar, A.; Groom, D.E.; Haissinski, J.; Hardin, D.; Hook, I.; Howell, D.A.; Kent, S.; Kim, A.G.; Knop, R.A.; Kowalski, M.; Kuznetsova, N.; Lee, B.C.; Lidman, C.; Mendez,J.; Miller, G.J.; Moniez, M.; Mouchet, M.; Mourao, A.; Newberg, H.; Nobili, S.; Nugent, P.E.; Pain, R.; Perdereau, O.; Perlmutter, S.; Quimby, R.; Regnault, N.; Rich, J.; Richards, G.T.; Ruiz-Lapuente, P.; Schaefer, B.E.; Schahmaneche, K.; Smith, E.; Spadafora, A.L.; Stanishev,V.; Thomas, R.C.; Walton, N.A.; Wang, L.; Wood-Vasey, W.M.

    2005-07-12T23:59:59.000Z

    The authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from Si II are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v{sub 10}(Si II), R(Si II), v, and {Delta}m{sub 15} further underlines the unique characteristics of SN 1999ac. They find convincing evidence of C II {lambda}6580 in the day -15 spectrum with ejection velocity v > 16,000 km s{sup -1}, but this signature disappears by day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.

  1. TYCHO SN 1572: A NAKED Ia SUPERNOVA REMNANT WITHOUT AN ASSOCIATED AMBIENT MOLECULAR CLOUD

    SciTech Connect (OSTI)

    Tian, W. W. [National Astronomical Observatories, CAS, Beijing 100012 (China); Leahy, D. A., E-mail: tww@bao.ac.cn [Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4 (Canada)

    2011-03-10T23:59:59.000Z

    The historical supernova remnant (SNR) Tycho SN 1572 originates from the explosion of a normal Type Ia supernova that is believed to have originated from a carbon-oxygen white dwarf in a binary system. We analyze the 21 cm continuum, H I, and {sup 12}CO-line data from the Canadian Galactic Plane Survey in the direction of SN 1572 and the surrounding region. We construct H I absorption spectra to SN 1572 and three nearby compact sources. We conclude that SN 1572 has no molecular cloud interaction, which argues against previous claims that a molecular cloud is interacting with the SNR. This new result does not support a recent claim that dust, newly detected by AKARI, originates from such an SNR-cloud interaction. We suggest that the SNR has a kinematic distance of 2.5-3.0 kpc based on a nonlinear rotational curve model. Very high energy {gamma}-ray emission from the remnant has been detected by the VERITAS telescope, so our result shows that its origin should not be an SNR-cloud interaction. Both radio and X-ray observations support that SN 1572 is an isolated Type Ia SNR.

  2. Variable Selection for Modeling the Absolute Magnitude at Maximum of Type Ia Supernovae

    E-Print Network [OSTI]

    Uemura, Makoto; Kawabata, S; Ikeda, Shiro; Maeda, Keiichi

    2015-01-01T23:59:59.000Z

    We discuss what is an appropriate set of explanatory variables in order to predict the absolute magnitude at the maximum of Type Ia supernovae. In order to have a good prediction, the error for future data, which is called the "generalization error," should be small. We use cross-validation in order to control the generalization error and LASSO-type estimator in order to choose the set of variables. This approach can be used even in the case that the number of samples is smaller than the number of candidate variables. We studied the Berkeley supernova database with our approach. Candidates of the explanatory variables include normalized spectral data, variables about lines, and previously proposed flux-ratios, as well as the color and light-curve widths. As a result, we confirmed the past understanding about Type Ia supernova: i) The absolute magnitude at maximum depends on the color and light-curve width. ii) The light-curve width depends on the strength of Si II. Recent studies have suggested to add more va...

  3. Identification of single nucleotides in MoS2 nanopores

    E-Print Network [OSTI]

    Jiandong Feng; Ke Liu; Roman D. Bulushev; Sergey Khlybov; Dumitru Dumcenco; Andras Kis; Aleksandra Radenovic

    2015-05-07T23:59:59.000Z

    Ultrathin membranes have drawn much attention due to their unprecedented spatial resolution for DNA nanopore sequencing. However, the high translocation velocity (3000-50000 nt/ms) of DNA molecules moving across such membranes limits their usability. To this end, we have introduced a viscosity gradient system based on room-temperature ionic liquids (RTILs) to control the dynamics of DNA translocation through a nanometer-size pore fabricated in an atomically thin MoS2 membrane. This allows us for the first time to statistically identify all four types of nucleotides with solid state nanopores. Nucleotides are identified according to the current signatures recorded during their transient residence in the narrow orifice of the atomically thin MoS2 nanopore. In this novel architecture that exploits high viscosity of RTIL, we demonstrate single-nucleotide translocation velocity that is an optimal speed (1-50 nt/ms) for DNA sequencing, while keeping the signal to noise ratio (SNR) higher than 10. Our findings pave the way for future low-cost and rapid DNA sequencing using solid-state nanopores.

  4. Characterization of U-Mo Foils for AFIP-7

    SciTech Connect (OSTI)

    Edwards, Danny J.; Ermi, Ruby M.; Schemer-Kohrn, Alan L.; Overman, Nicole R.; Henager, Charles H.; Burkes, Douglas; Senor, David J.

    2012-11-07T23:59:59.000Z

    Twelve AFIP in-process foil samples, fabricated by either Y-12 or LANL, were shipped from LANL to PNNL for potential characterization using optical and scanning electron microscopy techniques. Of these twelve, nine different conditions were examined to one degree or another using both techniques. For this report a complete description of the results are provided for one archive foil from each source of material, and one unirradiated piece of a foil of each source that was irradiated in the Advanced Test Reactor. Additional data from two other LANL conditions are summarized in very brief form in an appendix. The characterization revealed that all four characterized conditions contained a cold worked microstructure to different degrees. The Y-12 foils exhibited a higher degree of cold working compared to the LANL foils, as evidenced by the highly elongated and obscure U-Mo grain structure present in each foil. The longitudinal orientations for both of the Y-12 foils possesses a highly laminar appearance with such a distorted grain structure that it was very difficult to even offer a range of grain sizes. The U-Mo grain structure of the LANL foils, by comparison, consisted of a more easily discernible grain structure with a mix of equiaxed and elongated grains. Both materials have an inhomogenous grain structure in that all of the characterized foils possess abnormally coarse grains.

  5. A Generalized {ital K} Correction for Type Ia Supernovae: Comparing {ital R}-band Photometry Beyond {ital z=9.2} with B,V, and {ital R}-band Nearby Photometry

    E-Print Network [OSTI]

    Goodbar, Ariel

    2008-01-01T23:59:59.000Z

    spectroscopically peculiar supernovae, and to search for anyK Correction for Type Ia Supernovae: Comparing R-bandK Correction for Type Ia Supernovae: Comparing R-band

  6. Hydrothermal synthesis and catalytic properties of {alpha}- and {beta}-MnO{sub 2} nanorods

    SciTech Connect (OSTI)

    Cao, Guangsheng, E-mail: daqingcgs@163.com [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China)] [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China); Su, Ling; Zhang, Xiaojuan; Li, Hui [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China)] [Key Laboratory of Enhanced Oil and Gas Recovery of Ministry of Education, Daqing Petroleum Institute, Daqing 163318 (China)

    2010-04-15T23:59:59.000Z

    One-dimensional {alpha}-MnO{sub 2} and {beta}-MnO{sub 2} single-crystalline nanostructures were prepared by hydrothermal process. The products were characterized in detail by multiform techniques: X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Experimental results indicate that the temperature plays important roles in determining produce {alpha}-MnO{sub 2} and {beta}-MnO{sub 2} nanorods. In addition, the as-prepared {alpha}-MnO{sub 2} and {beta}-MnO{sub 2} nanorods showed excellent catalytic performance in the Fenton-like reaction.

  7. Fe3O4-LiMo3Se3 Nanoparticle Clusters as Superparamagnetic Nanocompasses

    E-Print Network [OSTI]

    Osterloh, Frank

    -iodopropionic acid treated LiMo3Se3 nanowire bundles with oleic acid-stabilized Fe3O4 nanoparticles of 2.8, 5Fe3O4-LiMo3Se3 Nanoparticle Clusters as Superparamagnetic Nanocompasses Frank E. Osterloh,*, Hiroki A scaleable chemical approach to functional nanoscale analogues of the magnetic compasses in magnetotactic

  8. Hole Selective MoOx Contact for Silicon Solar Cells Corsin Battaglia,,,

    E-Print Network [OSTI]

    Javey, Ali

    Hole Selective MoOx Contact for Silicon Solar Cells Corsin Battaglia,,, Xingtian Yin,,,§, Maxwell Laboratory, Xi'an Jiaotong University, Xi'an, 710049 Shaanxi, People's Republic of China Joint Center/silicon solar cell with a power conversion efficiency of 14.3%. While MoOx is commonly considered

  9. MoIAC Pre-Audit Form Ways to submit this form

    E-Print Network [OSTI]

    Noble, James S.

    information: #12;MoIAC Pre-Audit Form Major Energy Consuming Equipment: Please provide informationMoIAC Pre-Audit Form Ways to submit this form: 1. Fill up the form and fax it to 573-882-2693 Attn: Dr. Bin Wu 2. Print and return this form by mail to: Dr. Bin Wu University of Missouri

  10. Adsorption studies of Mo and V onto ferrihydrite *, L. G. BENNING

    E-Print Network [OSTI]

    Benning, Liane G.

    Adsorption studies of Mo and V onto ferrihydrite L. BRINZA 1, *, L. G. BENNING 1 AND P. J. STATHAM-sorbate experiments, 100% adsorption was observed at pH values below 6 and 8, respectively. Above the point of zero charge (PZC = 7.97) of FHY, the adsorption efficiency for Mo dropped dramatically (20% at pH 8) while V

  11. Stability of Graphene doping with MoO_3 and I_2

    E-Print Network [OSTI]

    D’Arsié, Lorenzo; Esconjauregui, Santiago; Weatherup, Robert; Guo, Yuzheng; Bhardwaj, Sunil; Centeno, Alba; Zurutuza, Amaia; Cepek, Cinzia; Robertson, John

    2014-09-08T23:59:59.000Z

    We dope graphene by evaporation of MoO_3 or by solution-deposition of I_2 and assess the doping stability for its use as transparent electrodes. Electrical measurements show that both dopants increase the graphene sheet conductivity and find that Mo...

  12. Student Financial Aid 11 Jesse Hall University of Missouri Columbia Columbia, MO 65211-1600

    E-Print Network [OSTI]

    Taylor, Jerry

    Student Financial Aid 11 Jesse Hall University of Missouri ­ Columbia Columbia, MO 65211-1600 PHONE;Student Financial Aid 11 Jesse Hall University of Missouri ­ Columbia Columbia, MO 65211-1600 PHONE (573 ________________________________________________________________________________________________________________________ Name of Host Institution (College or University you will be attending or taking additional classes

  13. Ligand Conjugation of Chemically Exfoliated MoS2 Stanley S. Chou,+

    E-Print Network [OSTI]

    Huang, Jiaxing

    Ligand Conjugation of Chemically Exfoliated MoS2 Stanley S. Chou,+ Mrinmoy De,+ Jaemyung Kim,+ Segi and chemical properties. Here, we demonstrate ligand conjugation of chemically exfoliated MoS2 using thiol-nitrilotriacetic acid chelation.13 However, colloidal sur- face modification of water dispersible, chemically exfoliated

  14. Characterization of Single-Walled Carbon Nanotubes (SWNTs) Produced by CO Disproportionation on Co-Mo

    E-Print Network [OSTI]

    Resasco, Daniel

    Characterization of Single-Walled Carbon Nanotubes (SWNTs) Produced by CO Disproportionation on Co Received November 15, 2001. Revised Manuscript Received February 6, 2002 The disproportionation of CO over Co-Mo/SiO2 catalysts with low Co/Mo ratios results in a high selectivity to single-walled carbon

  15. Corrosion Behavior of Solution-Annealed CoCrMo Medical Implant

    E-Print Network [OSTI]

    Shull, Kenneth R.

    ! ! ! Corrosion Behavior of Solution- Annealed CoCrMo Medical Implant Alloys Pooja Panigrahi University June 6, 2011 #12;! ! ""! Corrosion Behavior of Solution-Annealed CoCrMo Medical Implant Alloys and Applied Sciences Northwestern University June 6, 2011 Abstract Corrosion behavior of solution annealed

  16. Double beta decays and solar neutrinos with 100 MOON(Mo Observatory Of Neutrinos)

    E-Print Network [OSTI]

    Washington at Seattle, University of

    nuclear laboratory for spectroscopic studies of neutrinos Neutrinos are key particles for new frontiers) are sensitive and realistic experiments for studying the Majorana nature of the neutrino and the absolute massDouble beta decays and solar neutrinos with 100 Mo ­MOON(Mo Observatory Of Neutrinos)­ May 24, 2005

  17. Posting type Advisory Subject Shifts in Mo-anode XRF element calibration factors

    E-Print Network [OSTI]

    Fischer, Emily V.

    Posting type Advisory Subject Shifts in Mo-anode XRF element calibration factors Module/Species A@crocker.ucdavis.edu Supporting information A molybdenum-anode XRF instrument is used to analyze the heavier elements (Ni, Cu, Zn with lighter deposits were acquired and used in the Mo-anode XRF system. The new calibration foils resulted

  18. A comparative study of magnetic behaviors in TbNi{sub 2}, TbMn{sub 2} and TbNi{sub 2}Mn

    SciTech Connect (OSTI)

    Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Md Din, M. F.; Hong, F.; Cheng, Z. X.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Kennedy, S. J.; Studer, A. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

    2014-05-07T23:59:59.000Z

    All TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn compounds exhibit the cubic Laves phase with AB{sub 2}-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi{sub 2}Mn is 1:3. Rietveld refinement indicates that in TbNi{sub 2}Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a?=?14.348?Å (space group F-43?m), 7.618?Å, and 7.158?Å (space group Fd-3?m) for TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn, respectively. The magnetic transition temperatures T{sub C} were found to be T{sub C}?=?38?K and T{sub C}?=?148?K for TbNi{sub 2} and TbNi{sub 2}Mn, respectively, while two magnetic phase transitions are detected for TbMn{sub 2} at T{sub 1}?=?20?K and T{sub 2}?=?49?K. Clear magnetic history effects in a low magnetic field are observed in TbMn{sub 2} and TbNi{sub 2}Mn. The magnetic entropy changes have been obtained.

  19. Spin dependent transport properties of Mn-Ga/MgO/Mn-Ga magnetic tunnel junctions with metal(Mg, Co, Cr) insertion layer

    SciTech Connect (OSTI)

    Liang, S. H.; Tao, L. L.; Liu, D. P., E-mail: dpliu@iphy.ac.cn; Han, X. F., E-mail: xfhan@iphy.ac.cn [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Y. [Institut Jean Lamour, UMR 7198, CNRS-Nancy Université, BP 239, 54506 Vandoeuvre (France)

    2014-04-07T23:59:59.000Z

    We report a first principles theoretical investigation of spin polarized quantum transport in Mn{sub 2}Ga/MgO/Mn{sub 2}Ga and Mn{sub 3}Ga/MgO/Mn{sub 3}Ga magnetic tunneling junctions (MTJs) with the consideration of metal(Mg, Co, Cr) insertion layer effect. By changing the concentration of Mn, our calculation shows a considerable disparity in transport properties: A tunneling magnetoresistance (TMR) ratio of 852% was obtained for Mn{sub 2}Ga-based MTJs, however, only a 5% TMR ratio for Mn{sub 3}Ga-based MTJs. In addition, the influence of insertion layer has been considered in our calculation. We found the Co insertion layer can increase the TMR of Mn{sub 2}Ga-based MTJ to 904%; however, the Cr insertion layer can decrease the TMR by 668%; A negative TMR ratio can be obtained with Mg insertion layer. Our work gives a comprehensive understanding of the influence of different insertion layer in Mn-Ga based MTJs. It is proved that, due to the transmission can be modulated by the interfacial electronic structure of insertion, the magnetoresistance ratio of Mn{sub 2}Ga/MgO/Mn{sub 2}Ga MTJ can be improved by inserting Co layer.

  20. Photo-oxidation method using MoS2 nanocluster materials

    DOE Patents [OSTI]

    Wilcoxon, Jess P. (Albuquerque, NM)

    2001-01-01T23:59:59.000Z

    A method of photo-oxidizing a hydrocarbon compound is provided by dispersing MoS.sub.2 nanoclusters in a solvent containing a hydrocarbon compound contaminant to form a stable solution mixture and irradiating the mixture to photo-oxide the hydrocarbon compound. Hydrocarbon compounds of interest include aromatic hydrocarbon and chlorinated hydrocarbons. MoS.sub.2 nanoclusters with an average diameter less than approximately 10 nanometers are shown to be effective in decomposing potentially toxic aromatic and chlorinated hydrocarbons, such as phenol, pentachlorophenol, chlorinated biphenols, and chloroform, into relatively non-toxic compounds. The irradiation can occur by exposing the MoS.sub.2 nanoclusters and hydrocarbon compound mixture with visible light. The MoS.sub.2 nanoclusters can be introduced to the toxic hydrocarbons as either a MoS.sub.2 solution or deposited on a support material.

  1. LATE-TIME SPECTRAL OBSERVATIONS OF THE STRONGLY INTERACTING TYPE Ia SUPERNOVA PTF11kx

    SciTech Connect (OSTI)

    Silverman, Jeffrey M. [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States); Nugent, Peter E.; Filippenko, Alexei V.; Cenko, S. Bradley [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gal-Yam, Avishay [Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Howell, D. Andrew [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Pan, Yen-Chen; Hook, Isobel M., E-mail: jsilverman@astro.as.utexas.edu [Department of Physics (Astrophysics), University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)

    2013-08-01T23:59:59.000Z

    PTF11kx was a Type Ia supernova (SN Ia) that showed time-variable absorption features, including saturated Ca II H and K lines that weakened and eventually went into emission. The strength of the emission component of H{alpha} gradually increased, implying that the SN was undergoing significant interaction with its circumstellar medium (CSM). These features, and many others, were blueshifted slightly and showed a P-Cygni profile, likely indicating that the CSM was directly related to, and probably previously ejected by, the progenitor system itself. These and other observations led Dilday et al. to conclude that PTF11kx came from a symbiotic nova progenitor like RS Oph. In this work we extend the spectral coverage of PTF11kx to 124-680 rest-frame days past maximum brightness. The late-time spectra of PTF11kx are dominated by H{alpha} emission (with widths of full width at half-maximum intensity Almost-Equal-To 2000 km s{sup -1}), strong Ca II emission features ({approx}10,000 km s{sup -1} wide), and a blue 'quasi-continuum' due to many overlapping narrow lines of Fe II. Emission from oxygen, He I, and Balmer lines higher than H{alpha} is weak or completely absent at all epochs, leading to large observed H{alpha}/H{beta} intensity ratios. The H{alpha} emission appears to increase in strength with time for {approx}1 yr, but it subsequently decreases significantly along with the Ca II emission. Our latest spectrum also indicates the possibility of newly formed dust in the system as evidenced by a slight decrease in the red wing of H{alpha}. During the same epochs, multiple narrow emission features from the CSM temporally vary in strength. The weakening of the H{alpha} and Ca II emission at late times is possible evidence that the SN ejecta have overtaken the majority of the CSM and agrees with models of other strongly interacting SNe Ia. The varying narrow emission features, on the other hand, may indicate that the CSM is clumpy or consists of multiple thin shells.

  2. Unique light-induced degradation in yellow-emitting K?SiF?:Mn²? phosphor

    SciTech Connect (OSTI)

    Oyama, Takuya; Adachi, Sadao, E-mail: adachi@el.gunma-u.ac.jp [Division of Electronics and Informatics, Faculty of Science and Technology, Gunma University, Kiryu-shi, Gunma 376-8515 (Japan)

    2014-10-07T23:59:59.000Z

    Photo-induced luminescence intensity degradation in yellow-emitting K?SiF?:Mn²? phosphor is studied using x-ray diffraction measurement, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, PL decay analysis, and electron spin resonance (ESR) measurement. The yellow-emitting K?SiF?:Mn²? phosphor exhibits remarkable degradation in the PL intensity under Xe lamp exposure. Coherent laser irradiation also induces degradation and its degree is in the order of He–Cd (? = 325 nm) > Ar? (488 nm) > He–Ne laser (632.8 nm). The degradation mechanism is proposed to be due to change in the valence state of manganese ions from Mn²? to Mn³? by the photooxidation (Mn²? ? Mn³?) or disproportionation reaction (2Mn²? ? Mn? + Mn³?). The ESR measurement confirms the decreased Mn²? spin density in the sample exposed with Xe lamp. The PLE spectrum suggests that the excitation of Mn³? ions occurs through energy transfer upon absorption of exciting radiation by the Mn²? ions. Thermal annealing of the degraded samples at ?200 °C causes a blueshift in the PL emission band with an appearance of the Mn??-related sharp red emission lines.

  3. Phase transformation of ZnMoO{sub 4} by localized thermal spike

    SciTech Connect (OSTI)

    Agarwal, D. C.; Avasthi, D. K.; Kabiraj, D. [Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067 (India); Varma, S. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Kremer, Felipe; Ridgway, M. C. [Australian National University, Canberra ACT 0200 (Australia)

    2014-04-28T23:59:59.000Z

    We show that ZnMoO{sub 4} remains in stable phase under thermal annealing up to 1000?°C, whereas it decomposes to ZnO and MoO{sub 3} under transient thermal spike induced by 100?MeV Ag irradiation. The transformation is evidenced by X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Thin films of ZnMoO{sub 4} were synthesized by thermal evaporation and subsequent annealing in oxygen ambient at 600?°C for 4?h. XRD results show that as the irradiation fluence increases, the peak related to ZnMoO{sub 4} decreases gradually and eventually disappear, whereas peaks related to ZnO grow steadily up to fluence of 3?×?10{sup 12} ions/cm{sup 2} and thereafter remain stable till highest fluence. This indicates that polycrystalline ZnMoO{sub 4} film has transformed to polycrystalline ZnO thin film. The Raman lines related to ZnMoO{sub 4} are observed to have disappeared with increasing irradiation fluence. XPS results show modification in bonding and depletion of Mo from near surface region after the ion irradiation. Cross-sectional transmission electron microscopy result shows the formation of ion track of diameter 12–16?nm. These results demonstrate that ion beam methods provide the means to control phase splitting of ZnMoO{sub 4} to ZnO and MoO{sub 3} within nanometric dimension along the ion track. The observation of phase splitting and Mo loss are explained in the framework of ion beam induced thermal spike formalism.

  4. Late-Time Photometry of Type Ia Supernova SN2012cg Reveals the Radioactive Decay of $^{57}$Co

    E-Print Network [OSTI]

    Graur, Or; Shara, Michael M; Riess, Adam G

    2015-01-01T23:59:59.000Z

    Seitenzahl et al. (2009) have predicted that $\\sim 3$ years after its explosion, the light we receive from a Type Ia supernova will come mostly from reprocessing of electrons and X-rays emitted by the radioactive decay chain $^{57}{\\rm Co}~\\to~^{57}{\\rm Fe}$, instead of positrons from the decay chain $^{56}{\\rm Co}~\\to~^{56}{\\rm Fe}$ that dominates the supernova light at earlier times. Using the Hubble Space Telescope, we followed the light curve of the Type Ia supernova SN2012cg out to $1055$ days after maximum light. Our measurements are consistent with the light curves predicted by the contribution of energy from the reprocessing of electrons and X-rays emitted by the decay of $^{57}$Co. This provides conclusive evidence that $^{57}$Co is produced in Type Ia supernova explosions. The ratio of luminosities produced by the decays of $^{57}$Co and $^{56}$Co, a strong constraint on any Type Ia supernova explosion model, is in the range $(0.4$ - $8.5)\\times10^{-3}$.

  5. Utilizing the Updated Gamma-Ray Bursts and Type Ia Supernovae to Constrain the Cardassian Expansion Model and Dark Energy

    E-Print Network [OSTI]

    Wei, Jun-Jie; Wu, Xue-Feng

    2015-01-01T23:59:59.000Z

    We update gamma-ray burst (GRB) luminosity relations among certain spectral and light-curve features with 139 GRBs. The distance modulus of 82 GRBs at $z>1.4$ can be calibrated with the sample at $z\\leq1.4$ by using the cubic spline interpolation method from the Union2.1 Type Ia supernovae (SNe Ia) set. We investigate the joint constraints on the Cardassian expansion model and dark energy with 580 Union2.1 SNe Ia sample ($z<1.4$) and 82 calibrated GRBs data ($1.4Ia significantly improves the constrain on $\\Omega_{m}-\\Omega_{\\Lambda}$ plane. In the Cardassian expansion model, the best fit is $\\Omega_{m}= 0.24_{-0.15}^{+0.15}$ and $n=0.16_{-0.52}^{+0.30}$ $(1\\sigma)$, which is consistent with the $\\Lambda$CDM cosmology $(n=0)$ in the $1\\sigma$ confidence region. We also discuss two dark energy models in which the equation of state $w(z)$ is parametrized as $w(z)=w_{0}$ and $w(z)=w_{0}+w_{1}z/(1+z)$, respectively. Based on o...

  6. RESULTS OF THE LICK OBSERVATORY SUPERNOVA SEARCH FOLLOW-UP PHOTOMETRY PROGRAM: BVRI LIGHT CURVES OF 165 TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Ganeshalingam, Mohan; Li Weidong; Filippenko, Alexei V.; Anderson, Carmen; Foster, Griffin; Griffith, Christopher V.; Joubert, Niels; Leja, Joel; Macomber, Brent; Pritchard, Tyler; Thrasher, Patrick; Winslow, Dustin [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L.; Grigsby, Bryant J.; Lowe, Thomas B. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States)

    2010-10-15T23:59:59.000Z

    We present BVRI light curves of 165 Type Ia supernovae (SNe Ia) from the Lick Observatory Supernova Search follow-up photometry program from 1998 through 2008. Our light curves are typically well sampled (cadence of 3-4 days) with an average of 21 photometry epochs. We describe our monitoring campaign and the photometry reduction pipeline that we have developed. Comparing our data set to that of Hicken et al., with which we have 69 overlapping supernovae (SNe), we find that as an ensemble the photometry is consistent, with only small overall systematic differences, although individual SNe may differ by as much as 0.1 mag, and occasionally even more. Such disagreement in specific cases can have significant implications for combining future large data sets. We present an analysis of our light curves which includes template fits of light-curve shape parameters useful for calibrating SNe Ia as distance indicators. Assuming the B - V color of SNe Ia at 35 days past maximum light can be presented as the convolution of an intrinsic Gaussian component and a decaying exponential attributed to host-galaxy reddening, we derive an intrinsic scatter of {sigma} = 0.076 {+-} 0.019 mag, consistent with the Lira-Phillips law. This is the first of two papers, the second of which will present a cosmological analysis of the data presented herein.

  7. CS3600 Lab Manual CyberCIEGE is an information assurance (IA) training tool that illustrates computer and

    E-Print Network [OSTI]

    CS3600 Lab Manual Lab SSL CyberCIEGE is an information assurance (IA) training tool. The CyberCIEGE SSL scenario illustrates the use of SSL to authenticate the identity of web servers. This scenario explores the following concepts: · SSL is a means of authenticating a server (e.g., a web server

  8. Restframe I-band Hubble diagram for type Ia supernovae up to redshift z ~; 0.5

    E-Print Network [OSTI]

    2005-01-01T23:59:59.000Z

    up to redshift z ? 0.5 ? S. Nobili 1,2 , R. Amanullah 2 , G.up to redshift z ? 0.5 Filippenko, A.V. , Richmond, M.W. ,Ia supernovae up to redshift z ? 0.5 ported by cross-cutting

  9. Mn-Fe base and Mn-Cr-Fe base austenitic alloys

    DOE Patents [OSTI]

    Brager, Howard R. (Richland, WA); Garner, Francis A. (Richland, WA)

    1987-01-01T23:59:59.000Z

    Manganese-iron base and manganese-chromium-iron base austenitic alloys designed to have resistance to neutron irradiation induced swelling and low activation have the following compositions (in weight percent): 20 to 40 Mn; up to about 15 Cr; about 0.4 to about 3.0 Si; an austenite stabilizing element selected from C and N, alone or in combination with each other, and in an amount effective to substantially stabilize the austenite phase, but less than about 0.7 C, and less than about 0.3 N; up to about 2.5 V; up to about 0.1 P; up to about 0.01 B; up to about 3.0 Al; up to about 0.5 Ni; up to about 2.0 W; up to about 1.0 Ti; up to about 1.0 Ta; and with the remainder of the alloy being essentially iron.

  10. HgMn Stars as apparent X-ray emitters

    E-Print Network [OSTI]

    Hubrig, S; Mathys, G

    1998-01-01T23:59:59.000Z

    In the ROSAT all-sky survey 11 HgMn stars were detected as soft X-ray emitters (Berghoefer, Schmitt & Cassinelli 1996). Prior to ROSAT, X-ray observations with the Einstein Observatory had suggested that stars in the spectral range B5-A7 are devoid of X-ray emission. Since there is no X-ray emitting mechanism available for these stars (also not for HgMn stars), the usual argument in the case of an X-ray detected star of this spectral type is the existence of an unseen low-mass companion which is responsible for the X-ray emission. The purpose of the present work is to use all available data for our sample of X-ray detected HgMn stars and conclude on the nature of possible companions.

  11. Resonant spin tunneling in randomly oriented nanospheres of Mn?? acetate

    SciTech Connect (OSTI)

    Lendinez, S. [Univ. de Barcelona, Barcelona, Spain (Europe); Billinge, S. J. L. [Columbia Univ., New York, NY (United States); Zarzuela, R. [Univ. de Barcelona, Barcelona, Spain (Europe); Tejada, J. [Univ. de Barcelona, Barcelona, Spain (Europe); Terban, M. W. [Columbia Univ., New York, NY (United States); Espin, J. [Univ. Autonoma Barcelona, Barcelona, Spain (Europe); Imaz, I. [Univ. Autonoma Barcelona, Barcelona, Spain (Europe); Maspoch, D. [Univ. Autonoma Barcelona, Barcelona, Spain (Europe); Chudnovsky, E. M. [City Univ. of New York, Bronx, NY (United States)

    2015-01-01T23:59:59.000Z

    We report measurements and theoretical analysis of resonant spin tunneling in randomly oriented nanospheres of a molecular magnet. Amorphous nanospheres of Mn?? acetate have been fabricated and characterized by chemical, infrared, TEM, X-ray, and magnetic methods. Magnetic measurements have revealed sharp tunneling peaks in the field derivative of the magnetization that occur at the typical resonant field values for the Mn?? acetate crystal in the field parallel to the easy axis.Theoretical analysis is provided that explains these observations. We argue that resonant spin tunneling in a molecular magnet can be established in a powder sample, without the need for a single crystal and without aligning the easy magnetization axes of the molecules. This is confirmed by re-analyzing the old data on a powdered sample of non-oriented micron-size crystals of Mn?? acetate. Our findings can greatly simplify the selection of candidates for quantum spin tunneling among newly synthesized molecular magnets.

  12. Water and Methanol Adsorption on MgO(100)/Mo(100) Studied by Electron Spectroscopies and Thermal Programmed Desorption

    E-Print Network [OSTI]

    Goodman, Wayne

    Water and Methanol Adsorption on MgO(100)/Mo(100) Studied by Electron Spectroscopies and Thermal, 2000 The adsorption of methanol (CH3OH) and water (D2O) on the MgO(100)/Mo(100) surface at 100 K has covered MgO(100)/Mo(100) surface. On the other hand, the formation of a methanol multilayer desorption

  13. Influence of Co/Mo Ratio on Synthesis of Single-Walled Carbon Nanotubes from Carbon Monoxide

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Influence of Co/Mo Ratio on Synthesis of Single-Walled Carbon Nanotubes from Carbon Monoxide, Bunkyo-ku, Tokyo 113-8656 Co and Mo are often used as catalysts for the catalytic chemical vapor in synthesizing random, vertical and parallel aligned SWNTs on Co and Mo dip-coated quartz substrates from carbon

  14. Small-scale Interaction of Turbulence with Thermonuclear Flames in Type Ia Supernovae

    E-Print Network [OSTI]

    J. C. Niemeyer; W. K. Bushe; G. R. Ruetsch

    1999-05-07T23:59:59.000Z

    Microscopic turbulence-flame interactions of thermonuclear fusion flames occuring in Type Ia Supernovae were studied by means of incompressible direct numerical simulations with a highly simplified flame description. The flame is treated as a single diffusive scalar field with a nonlinear source term. It is characterized by its Prandtl number, Pr << 1, and laminar flame speed, S_L. We find that if S_L ~ u', where u' is the rms amplitude of turbulent velocity fluctuations, the local flame propagation speed does not significantly deviate from S_L even in the presence of velocity fluctuations on scales below the laminar flame thickness. This result is interpreted in the context of subgrid-scale modeling of supernova explosions and the mechanism for deflagration-detonation-transitions.

  15. Do Type-Ia Supernovae Constrain the Total Equation of State?

    E-Print Network [OSTI]

    William Komp

    2007-02-01T23:59:59.000Z

    In this paper, we consider a couple of alternative dark energy models using the total equation of state of the cosmological fluid, $\\wt$. These models are fit to the recent type-Ia supernovae data and are compared to previously considered models. The first model is based on the hyperbolic tangent and provides a good estimate of the rate of the transition to dark energy domination. The second model is a cubic spline model. This model demonstrates and quantifies the non-monotonicity in the total equation of state coming from the supernovae observations. At present, the supernovae observations indicate significance to non-monotonically decreasing dark energy. We derive constraints on the spline paramters and compare and constrast the results to the Cosmological Constant dark energy model. Both the hyperbolic and splines models indicate that a precise physical notion of dark enegy is a potentially ever more mysterious quantity?

  16. Type Ia Supernova Intrinsic Magnitude Dispersion and the Fitting of Cosmological Parameters

    SciTech Connect (OSTI)

    Kim, Alex G

    2010-12-10T23:59:59.000Z

    I present an analysis for fitting cosmological parameters from a Hubble Diagram of a standard candle with unknown intrinsic magnitude dispersion. The dispersion is determined from the data themselves, simultaneously with the cosmological parameters. This contrasts with the strategies used to date. The advantages of the presented analysis are that it is done in a single fit (it is not iterative), it provides a statistically founded and unbiased estimate of the intrinsic dispersion, and its cosmological-parameter uncertainties account for the intrinsic dispersion uncertainty. Applied to Type Ia supernovae, my strategy provides a statistical measure to test for sub-types and assess the significance of any magnitude corrections applied to the calibrated candle. Parameter bias and differences between likelihood distributions produced by the presented and currently-used fitters are negligibly small for existing and projected supernova data sets.

  17. Turbulence in a three-dimensional deflagration model for Type Ia supernovae: I. Scaling properties

    E-Print Network [OSTI]

    Ciaraldi-Schoolmann, F; Niemeyer, J C; Roepke, F K; Hillebrandt, W

    2009-01-01T23:59:59.000Z

    We analyze the statistical properties of the turbulent velocity field in the deflagration model for Type Ia supernovae. In particular, we consider the question of whether turbulence is isotropic and consistent with the Kolmogorov theory at small length scales. Using numerical data from a high-resolution simulation of a thermonuclear supernova explosion, spectra of the turbulence energy and velocity structure functions are computed. We show that the turbulent velocity field is isotropic at small length scales and follows a scaling law that is consistent with the Kolmogorov theory until most of the nuclear fuel is burned. At length scales greater than a certain characteristic scale, turbulence becomes anisotropic. Here, the radial velocity fluctuations follow the scaling law of the Rayleigh-Taylor instability, whereas the angular component still obeys Kolmogorov scaling. In the late phase of the explosion, this characteristic scale drops below the numerical resolution of the simulation. The analysis confirms th...

  18. Measurements of the Rate of Type Ia Supernovae at Redshift z < ~0.3 from the SDSS-II Supernova Survey

    SciTech Connect (OSTI)

    Dilday, Benjamin; /Rutgers U., Piscataway /Chicago U. /KICP, Chicago; Smith, Mathew; /Cape Town U., Dept. Math. /Portsmouth U.; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Becker, Andrew; /Washington U., Seattle, Astron. Dept.; Bender, Ralf; /Munich, Tech. U. /Munich U. Observ.; Castander, Francisco; /Barcelona, IEEC; Cinabro, David; /Wayne State U.; Filippenko, Alexei V.; /UC, Berkeley; Frieman, Joshua A.; /Chicago U. /Fermilab; Galbany, Lluis; /Barcelona, IFAE; Garnavich, Peter M.; /Notre Dame U. /Stockholm U., OKC /Stockholm U.

    2010-01-01T23:59:59.000Z

    We present a measurement of the volumetric Type Ia supernova (SN Ia) rate based on data from the Sloan Digital Sky Survey II (SDSS-II) Supernova Survey. The adopted sample of supernovae (SNe) includes 516 SNe Ia at redshift z {approx}< 0.3, of which 270 (52%) are spectroscopically identified as SNe Ia. The remaining 246 SNe Ia were identified through their light curves; 113 of these objects have spectroscopic redshifts from spectra of their host galaxy, and 133 have photometric redshifts estimated from the SN light curves. Based on consideration of 87 spectroscopically confirmed non-Ia SNe discovered by the SDSS-II SN Survey, we estimate that 2.04{sub -0.95}{sup +1.61}% of the photometric SNe Ia may be misidentified. The sample of SNe Ia used in this measurement represents an order of magnitude increase in the statistics for SN Ia rate measurements in the redshift range covered by the SDSS-II Supernova Survey. If we assume a SN Ia rate that is constant at low redshift (z < 0.15), then the SN observations can be used to infer a value of the SN rate of r{sub V} = (2.69{sub -0.30-0.01}{sup +0.34+0.21}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} at a mean redshift of {approx} 0.12, based on 79 SNe Ia of which 72 are spectroscopically confirmed. However, the large sample of SNe Ia included in this study allows us to place constraints on the redshift dependence of the SN Ia rate based on the SDSS-II Supernova Survey data alone. Fitting a power-law model of the SN rate evolution, r{sub V} (z) = A{sub p} x ((1+z)/(1+z{sub 0})){sup {nu}}, over the redshift range 0.0 < z < 0.3 with z{sub 0} = 0.21, results in A{sub p} = (3.43{sub -0.15}{sup +0.15}) x 10{sup -5} SNe yr{sup -1} Mpc{sup -3} (H{sub 0}/(70 km s{sup -1} Mpc{sup -1})){sup 3} and {nu} = 2.04{sub -0.89}{sup +0.90}.

  19. Assessment of the Diffusive Gradients in Thin-films (DGT) technique to assess the plant availability of Mn in soils.

    E-Print Network [OSTI]

    Mundus, Simon; Husted, Søren; Lombi, Enzo

    2009-01-01T23:59:59.000Z

    predicts copper availability to plants. EnvironmentalAttempts to assess Mn availability have been impeded due towill influence the Mn availability. Often flooding of soils

  20. The Use of Silica Coated MnO Nanoparticles to Control MRI Relaxivity in Response to Specific Physiological Changes

    E-Print Network [OSTI]

    Krishnan, Kannan M.

    -tracing could be observed due to the released Mn2þ . Intravenous infusion of MnO@SiO2 particles showed little

  1. DUST IN A TYPE Ia SUPERNOVA PROGENITOR: SPITZER SPECTROSCOPY OF KEPLER'S SUPERNOVA REMNANT

    SciTech Connect (OSTI)

    Williams, Brian J.; Borkowski, Kazimierz J.; Reynolds, Stephen P. [Physics Department, North Carolina State University, Raleigh, NC 27695-8202 (United States); Ghavamian, Parviz [Department of Physics, Astronomy, and Geosciences, Towson University, Towson, MD 21252 (United States); Blair, William P. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Long, Knox S. [STScI, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Sankrit, Ravi, E-mail: brian.j.williams@nasa.gov [SOFIA/USRA, NASA Ames Research Center, M/S N211-3, Moffett Field, CA 94035 (United States)

    2012-08-10T23:59:59.000Z

    Characterization of the relatively poorly understood progenitor systems of Type Ia supernovae is of great importance in astrophysics, particularly given the important cosmological role that these supernovae play. Kepler's supernova remnant, the result of a Type Ia supernova, shows evidence for an interaction with a dense circumstellar medium (CSM), suggesting a single-degenerate progenitor system. We present 7.5-38 {mu}m infrared (IR) spectra of the remnant, obtained with the Spitzer Space Telescope, dominated by emission from warm dust. Broad spectral features at 10 and 18 {mu}m, consistent with various silicate particles, are seen throughout. These silicates were likely formed in the stellar outflow from the progenitor system during the asymptotic giant branch stage of evolution, and imply an oxygen-rich chemistry. In addition to silicate dust, a second component, possibly carbonaceous dust, is necessary to account for the short-wavelength Infrared Spectrograph and Infrared Array Camera data. This could imply a mixed chemistry in the atmosphere of the progenitor system. However, non-spherical metallic iron inclusions within silicate grains provide an alternative solution. Models of collisionally heated dust emission from fast shocks (>1000 km s{sup -1}) propagating into the CSM can reproduce the majority of the emission associated with non-radiative filaments, where dust temperatures are {approx}80-100 K, but fail to account for the highest temperatures detected, in excess of 150 K. We find that slower shocks (a few hundred km s{sup -1}) into moderate density material (n{sub 0} {approx} 50-250 cm{sup -3}) are the only viable source of heating for this hottest dust. We confirm the finding of an overall density gradient, with densities in the north being an order of magnitude greater than those in the south.

  2. Initiation of the detonation in the gravitationally confined detonation model of type Ia supernovae.

    SciTech Connect (OSTI)

    Seitenzahl, I. R.; Meakin, C. A.; Lamb, D. Q.; Truran, J. W. (Physics); (Univ. of Chicago); (Max-Planck-Inst. for Astrophysics); (Univ. of Arizona)

    2009-07-20T23:59:59.000Z

    We study the initiation of the detonation in the gravitationally confined detonation (GCD) model of Type Ia supernovae (SNe Ia). In this model, ignition occurs at one or several off-center points, resulting in a burning bubble of hot ash that rises rapidly, breaks through the surface of the star, and collides at a point on the stellar surface opposite the breakout, producing a high-velocity inwardly directed flow. Initiation of the detonation occurs spontaneously in a region where the length scale of the temperature gradient extending from the flow (in which carbon burning is already occurring) into unburned fuel is commensurate to the range of critical length scales which have been derived from one-dimensional simulations that resolve the initiation of a detonation. By increasing the maximum resolution in a truncated cone that encompasses this region, beginning somewhat before initiation of the detonation occurs, we successfully simulate in situ the first gradient-initiated detonation in a whole-star simulation. The detonation emerges when a compression wave overruns a pocket of fuel situated in a Kelvin-Helmholtz cusp at the leading edge of the inwardly directed jet of burning carbon. The compression wave preconditions the temperature in the fuel in such a way that the Zel'dovich gradient mechanism can operate and a detonation ensues. We explore the dependence of the length scale of the temperature gradient on spatial resolution and discuss the implications for the robustness of this detonation mechanism. We find that the time and the location at which initiation of the detonation occurs varies with resolution. In particular, initiation of a detonation had not yet occurred in our highest resolution simulation by the time we ended the simulation because of the computational demand it required. However, it may detonate later. We suggest that the turbulent shear layer surrounding the inwardly directed jet provides the most favorable physical conditions, and therefore the most likely location, for initiation of a detonation in the GCD model.

  3. INITIATION OF THE DETONATION IN THE GRAVITATIONALLY CONFINED DETONATION MODEL OF TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Seitenzahl, Ivo R. [Department of Physics, University of Chicago, Chicago, IL 60637 (United States); Meakin, Casey A.; Truran, James W. [Joint Institute for Nuclear Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Lamb, Don Q. [Center for Astrophysical Thermonuclear Flashes, University of Chicago, Chicago, IL 60637 (United States)

    2009-07-20T23:59:59.000Z

    We study the initiation of the detonation in the gravitationally confined detonation (GCD) model of Type Ia supernovae (SNe Ia). In this model, ignition occurs at one or several off-center points, resulting in a burning bubble of hot ash that rises rapidly, breaks through the surface of the star, and collides at a point on the stellar surface opposite the breakout, producing a high-velocity inwardly directed flow. Initiation of the detonation occurs spontaneously in a region where the length scale of the temperature gradient extending from the flow (in which carbon burning is already occurring) into unburned fuel is commensurate to the range of critical length scales which have been derived from one-dimensional simulations that resolve the initiation of a detonation. By increasing the maximum resolution in a truncated cone that encompasses this region, beginning somewhat before initiation of the detonation occurs, we successfully simulate in situ the first gradient-initiated detonation in a whole-star simulation. The detonation emerges when a compression wave overruns a pocket of fuel situated in a Kelvin-Helmholtz cusp at the leading edge of the inwardly directed jet of burning carbon. The compression wave preconditions the temperature in the fuel in such a way that the Zel'dovich gradient mechanism can operate and a detonation ensues. We explore the dependence of the length scale of the temperature gradient on spatial resolution and discuss the implications for the robustness of this detonation mechanism. We find that the time and the location at which initiation of the detonation occurs varies with resolution. In particular, initiation of a detonation had not yet occurred in our highest resolution simulation by the time we ended the simulation because of the computational demand it required. However, it may detonate later. We suggest that the turbulent shear layer surrounding the inwardly directed jet provides the most favorable physical conditions, and therefore the most likely location, for initiation of a detonation in the GCD model.

  4. Study of the detonation phase in the gravitationally confined detonation model of type Ia supernovae.

    SciTech Connect (OSTI)

    Meakin, C. A.; Seitenzahl, I.; Jordan, G. C.; Truran,, J.; Lamb, D.; Physics; Univ. of Chicago; Univ. of Arizona

    2009-07-20T23:59:59.000Z

    We study the initiation of the detonation in the gravitationally confined detonation (GCD) model of Type Ia supernovae (SNe Ia). In this model, ignition occurs at one or several off-center points, resulting in a burning bubble of hot ash that rises rapidly, breaks through the surface of the star, and collides at a point on the stellar surface opposite the breakout, producing a high-velocity inwardly directed flow. Initiation of the detonation occurs spontaneously in a region where the length scale of the temperature gradient extending from the flow (in which carbon burning is already occurring) into unburned fuel is commensurate to the range of critical length scales which have been derived from one-dimensional simulations that resolve the initiation of a detonation. By increasing the maximum resolution in a truncated cone that encompasses this region, beginning somewhat before initiation of the detonation occurs, we successfully simulate in situ the first gradient-initiated detonation in a whole-star simulation. The detonation emerges when a compression wave overruns a pocket of fuel situated in a Kelvin-Helmholtz cusp at the leading edge of the inwardly directed jet of burning carbon. The compression wave preconditions the temperature in the fuel in such a way that the Zeldovich gradient mechanism can operate and a detonation ensues. We explore the dependence of the length scale of the temperature gradient on spatial resolution and discuss the implications for the robustness of this detonation mechanism. We find that the time and the location at which initiation of the detonation occurs varies with resolution. In particular, initiation of a detonation had not yet occurred in our highest resolution simulation by the time we ended the simulation because of the computational demand it required. However, it may detonate later. We suggest that the turbulent shear layer surrounding the inwardly directed jet provides the most favorable physical conditions, and therefore the most likely location, for initiation of a detonation in the GCD model.

  5. Incompatibility of a comoving Ly-alpha forest with supernova-Ia luminosity distances

    E-Print Network [OSTI]

    Jens Thomas; Hartmut Schulz

    2001-03-18T23:59:59.000Z

    Recently Perlmutter et al. suggested a positive value of Einstein's cosmological constant Lambda on the basis of luminosity distances from type-Ia supernovae. However, Lambda world models had earlier been proposed by Hoell & Priester and Liebscher et al. on the basis of quasar absorption-line data. Employing more general repulsive fluids ("dark energy") encompassing the Lambda component we quantitatively compare both approaches with each other. Fitting the SN-data by a minimum-component model consisting of dark energy + dust yields a closed universe with a large amount of dust exceeding the baryonic content constrained by big-bang nucleosynthesis. The nature of the dark energy is hardly constrained. Only when enforcing a flat universe there is a clear tendency to a dark-energy Lambda fluid and the `canonical' value Omega_M = 0.3 for dust. Conversely, fitting the quasar-data by a minimum-component model yields a sharply defined, slightly closed model with a low dust density ruling out significant pressureless dark matter. The dark-energy component obtains an equation-of-state P = -0.96 epsilon close to that of a Lambda-fluid. Omega_M = 0.3 or a precisely flat spatial geometry are inconsistent with minimum-component models. It is found that quasar and supernova data sets cannot be reconciled with each other via (repulsive ideal fluid+dust+radiation)-world models. Compatibility could be reached by drastic expansion of the parameter space with at least two exotic fluids added to dust and radiation as world constituents. If considering such solutions as far-fetched one has to conclude that the quasar absorption line and the SN-Ia constraints are incompatible.

  6. Sensitivity study of explosive nucleosynthesis in Type Ia supernovae: I. Modification of individual thermonuclear reaction rates

    E-Print Network [OSTI]

    Eduardo Bravo; Gabriel Martínez-Pinedo

    2012-04-09T23:59:59.000Z

    We explore the sensitivity of the nucleosynthesis due to type Ia supernovae with respect to uncertainties in nuclear reaction rates. We have adopted a standard one-dimensional delayed detonation model of the explosion of a Chandrasekhar-mass white dwarf, and have post-processed the thermodynamic trajectories of every mass-shell with a nucleosynthetic code, with increases (decreases) by a factor of ten on the rates of 1196 nuclear reactions. We have computed as well hydrodynamic models for different rates of the fusion reactions of 12C and of 16O. For selected reactions, we have recomputed the nucleosynthesis with alternative prescriptions for their rates taken from the JINA REACLIB database, and have analyzed the temperature ranges where modifications of their rates have the strongest effect on nucleosynthesis. The nucleosynthesis resulting from the Type Ia supernova models is quite robust with respect to variations of nuclear reaction rates, with the exception of the reaction of fusion of 12C nuclei. The energy of the explosion changes by less than \\sim4%. The changes in the nucleosynthesis due to the modification of the rates of fusion reactions are as well quite modest, for instance no species with a mass fraction larger than 0.02 experiences a variation of its yield larger than a factor of two. We provide the sensitivity of the yields of the most abundant species with respect to the rates of the most intense reactions with protons, neutrons, and alphas. In general, the yields of Fe-group nuclei are more robust than the yields of intermediate-mass elements. Among the charged particle reactions, the most influential on supernova nucleosynthesis are 30Si + p \\rightleftarrows 31P + {\\gamma}, 20Ne + {\\alpha} \\rightleftarrows 24Mg + {\\gamma}, and 24Mg + {\\alpha} \\rightleftarrows 27Al + p. The temperatures at which a modification of their rate has a larger impact are in the range 2 < T < 4 GK. (abridged)

  7. Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses

    E-Print Network [OSTI]

    Chen, Jiajun

    2010-01-01T23:59:59.000Z

    of nanosized LiMnPO 4 by combustion synthesis Figure 2. X-a) nanometric LiMnPO 4 made by combustion synthesis and b)typically formed by combustion synthesis. The average

  8. Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses

    E-Print Network [OSTI]

    Chen, Jiajun

    2008-01-01T23:59:59.000Z

    of nanosized LiMnPO 4 by combustion synthesis Figure 2. X-a) nanometric LiMnPO 4 made by combustion synthesis and b)typically formed by combustion synthesis. The average

  9. Electrodeposited Al-Mn Alloys with Microcrystalline, Nanocrystalline, Amorphous and Nano-quasicrystalline Structures

    E-Print Network [OSTI]

    Ruan, Shiyun

    Al–Mn alloys with Mn content ranging from 0 to 15.8 at.% are prepared by electrodeposition from an ionic liquid at room temperature, and exhibit a remarkably broad range of structures. The alloys are characterized through ...

  10. Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)

    E-Print Network [OSTI]

    Guchhait, S.

    2011-01-01T23:59:59.000Z

    segregation in Mn-doped Ge”, Journal of Applied Physics 101,Room-temperature ferromagnetism in Ge 1-x Mn x nanowires”,BC high-?/metal gate Ge/C alloy pMOSFETs fabricated directly

  11. Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge

    E-Print Network [OSTI]

    Zeng, Li

    2010-01-01T23:59:59.000Z

    Mn)As: A new diluted magnetic semiconductor based on GaAs.Mn x Ge 1-x diluted magnetic semiconductor: experiment andx Si 1-x amorphous magnetic semiconductor. Phys. Rev. B 67 ,

  12. Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)

    E-Print Network [OSTI]

    Guchhait, S.

    2011-01-01T23:59:59.000Z

    group-IV-based dilute magnetic semiconductors by electronicMn x Ge 1-x dilute magnetic semiconductor”, Applied Physicsamorphous Ge 1-x Mn x magnetic semiconductor films”, Journal

  13. Mn12-acetate thin film patterns and their interaction with superconductors

    E-Print Network [OSTI]

    Kim, Kyongwan

    2009-05-15T23:59:59.000Z

    Mn12-acetate single-molecule magnets (SMMs) are nano-scale magnets showing a strong magnetic anisotropy, slow relaxation and stepwise magnetic hysteresis curves. Possible applications of Mn12-acetate, e.g. for ultra high density magnetic information...

  14. Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge

    E-Print Network [OSTI]

    Zeng, Li

    2010-01-01T23:59:59.000Z

    Li, A. P. et al. Magnetism in Mn x Ge 1-x semiconductorsElectronic Structure and Magnetism for Mn in Amorphous Sistructure that determines magnetism. Figure 3 shows XAS data

  15. On deformation twinning in a 17.5%Mn-TWIP steel: A physically...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    On deformation twinning in a 17.5%Mn-TWIP steel: A physically-based phenomenological model. On deformation twinning in a 17.5%Mn-TWIP steel: A physically-based phenomenological...

  16. Ba and Ni speciation in a nodule of binary Mn oxide phase composition from Lake Baikal

    E-Print Network [OSTI]

    , and absorption spectroscopy. Fe is speciated as goethite, and Mn as romanechite (psilomelane) and 10 A is separated from the other type by goethite. The binary Mn oxide banding pattern is interpreted by a two

  17. EVOLUTION OF POST-IMPACT REMNANT HELIUM STARS IN TYPE Ia SUPERNOVA REMNANTS WITHIN THE SINGLE-DEGENERATE SCENARIO

    SciTech Connect (OSTI)

    Pan, Kuo-Chuan; Ricker, Paul M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Taam, Ronald E., E-mail: kpan2@illinois.edu, E-mail: pmricker@illinois.edu, E-mail: r-taam@northwestern.edu [Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2013-08-10T23:59:59.000Z

    The progenitor systems of Type Ia supernovae (SNe Ia) are still under debate. Based on recent hydrodynamics simulations, non-degenerate companions in the single-degenerate scenario (SDS) should survive the supernova (SN) impact. One way to distinguish between the SDS and the double-degenerate scenario is to search for the post-impact remnant stars (PIRSs) in SN Ia remnants. Using a technique that combines multi-dimensional hydrodynamics simulations with one-dimensional stellar evolution simulations, we have examined the post-impact evolution of helium-rich binary companions in the SDS. It is found that these helium-rich PIRSs (He PIRSs) dramatically expand and evolve to a luminous phase (L {approx} 10{sup 4} L{sub Sun }) about 10 yr after an SN explosion. Subsequently, they contract and evolve to become hot blue-subdwarf-like (sdO-like) stars by releasing gravitational energy, persisting as sdO-like stars for several million years before evolving to the helium red-giant phase. We therefore predict that a luminous OB-like star should be detectable within {approx}30 yr after the SN explosion. Thereafter, it will shrink and become an sdO-like star in the central regions of SN Ia remnants within star-forming regions for SN Ia progenitors evolved via the helium-star channel in the SDS. These He PIRSs are predicted to be rapidly rotating (v{sub rot} {approx}> 50 km s{sup -1}) and to have high spatial velocities (v{sub linear} {approx}> 500 km s{sup -1}). Furthermore, if SN remnants have diffused away and are not recognizable at a later stage, He PIRSs could be an additional source of single sdO stars and/or hypervelocity stars.

  18. HELIUM-IGNITED VIOLENT MERGERS AS A UNIFIED MODEL FOR NORMAL AND RAPIDLY DECLINING TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Pakmor, R.; Springel, V. [Heidelberger Institut fuer Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Kromer, M. [Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Taubenberger, S. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany)

    2013-06-10T23:59:59.000Z

    The progenitors of Type Ia supernovae (SNe Ia) are still unknown, despite significant progress during the past several years in theory and observations. Violent mergers of two carbon-oxygen (CO) white dwarfs (WDs) are a candidate scenario suggested to be responsible for at least a significant fraction of normal SNe Ia. Here, we simulate the merger of two CO WDs using a moving-mesh code that allows for the inclusion of thin helium (He) shells (0.01 M{sub Sun }) on top of the WDs at an unprecedented numerical resolution. The accretion of He onto the primary WD leads to the formation of a detonation in its He shell. This detonation propagates around the CO WD and sends a converging shock wave into its core, known to robustly trigger a second detonation, as in the well-known double-detonation scenario for He-accreting CO WDs. However, in contrast to that scenario where a massive He shell is required to form a detonation through thermal instability, here the He detonation is ignited dynamically. Accordingly the required He-shell mass is significantly smaller, and hence its burning products are unlikely to affect the optical display of the explosion. We show that this scenario, which works for CO primary WDs with CO- as well as He-WD companions, has the potential to explain the different brightness distributions, delay times, and relative rates of normal and fast declining SNe Ia. Finally, we discuss extensions to our unified merger model needed to obtain a comprehensive picture of the full observed diversity of SNe Ia.

  19. Low-temperature magnetization of (Ga,Mn) As semiconductors

    E-Print Network [OSTI]

    Jungwirth, T.; Masek, J.; Wang, KY; Edmonds, KW; Sawicki, M.; Polini, M.; Sinova, Jairo; MacDonald, AH; Campion, RP; Zhao, LX; Farley, NRS; Johal, TK; van der Laan, G.; Foxon, CT; Gallagher, BL.

    2006-01-01T23:59:59.000Z

    temperature magnetometry and XMCD experiments. A series of #1;Ga,Mn#2;As films with Mn content varying between 1.7?6.7 % in the SQUID experiments and between 2.2 and 8.4 % in the XMCD experiments were grown by low-temperature molecular beam epitaxy #1;MBE.... Magnetometry The magnetic moment of the samples is measured in a SQUID magnetometer, at 5 K and under a 0.3 T external magnetic field. The external field is necessary to overcome in-plane anisotropy fields, so that the magnetization is aligned...

  20. Electron Band Structure of MnGaN Dimiter Alexandrov1

    E-Print Network [OSTI]

    Dietz, Nikolaus

    to this orbital to be occupied. LCAO electron band structure of wurtzite MnxGa1-xN for points c1 and v15 ( = 1 of the wurtzite MnxGa1-xN are determined as well. INTRODUCTION The MnxGa1-xN semiconductor alloy is important model the MnGaN alloy on Mn content. Segregated Mn species in wurtzite GaN containing Mn

  1. Heat treatment effects on microstructure and magnetic properties of MnZn ferrite powders

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Heat treatment effects on microstructure and magnetic properties of Mn­Zn ferrite powders Ping Hu Available online 6 September 2009 Keywords: Mn­Zn ferrite Heat treatment Microstructure Magnetic property a b s t r a c t Mn­Zn ferrite powders (Mn0.5Zn0.5Fe2O4) were prepared by the nitrate­citrate auto

  2. Disentangling the Mn moments on different sublattices in the half-metallic ferrimagnet Mn3?xCoxGa

    SciTech Connect (OSTI)

    Klaer, P.; Jenkins, C.A.; Alijani, V.; Winterlik, J.; Balke, B.; Felser, C.; Elmers, H.J.

    2011-05-03T23:59:59.000Z

    Ferrimagnetic Mn{sub 3-x}Co{sub x}Ga compounds have been investigated by magnetic circular dichroism in x-ray absorption (XMCD). Compounds with x > 0.5 crystallize in the CuHg{sub 2}Ti structure. A tetragonal distortion of the cubic structure occurs for x {le} 0.5. For the cubic phase, magnetometry reveals a linearly increasing magnetization of 2x Bohr magnetons per formula unit obeying the generalized Slater-Pauling rule. XMCD confirms the ferrimagnetic character with Mn atoms occupying two different sublattices with antiparallel spin orientation and different degrees of spin localization and identifies the region 0.6 < x {le} 0.8 as most promising for a high spin polarization at the Fermi level. Individual Mn moments on inequivalent sites are compared to theoretical predictions.

  3. Exchange interaction in hexagonal MnRhP from first-principles studies

    SciTech Connect (OSTI)

    Liu, X. B., E-mail: liuxubo@uta.edu; Zhang, Qiming; Ping Liu, J., E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yue, M. [College of Material Science and Engineering, Beijing University of Technology, 100022 Beijing (China); Altounian, Z. [Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada)

    2014-05-07T23:59:59.000Z

    Electronic structure and magnetic properties for MnRhP have been studied from a first-principles density functional calculation. The calculated lattice constants, a?=?6.228 Å and c?=?3.571?Å, are in good agreement with the experimental values of a?=?6.223 Å and c?=?3.585?Å. The calculated moment of Mn is 3.1 ?{sub B}/atom, resulting in a total moment of 3.0 ?{sub B}/atom due to small moments induced at Rh and P sites. The magnetic moment of Mn decreases with unit cell size. The exchange interactions are dominated by positive Mn-Mn exchange coupling (J{sub Mn?Mn}), implying a stable ferromagnetic ordering in Mn sublattice. In particular, J{sub Mn?Mn} shows a maximum value (1.5 mRy) at the the optimized unit cell size. The structural distortion or unit cell size change will affect J{sub Mn?Mn}, which is intimately related to the magneto-elastic and magneto-caloric effect.

  4. On the role of Mn(IV) vacancies in the photoreductive dissolution of hexagonal birnessite

    SciTech Connect (OSTI)

    Kwon, K.D.; Refson, K.; Sposito, G.

    2009-06-01T23:59:59.000Z

    Photoreductive dissolution of layer type Mn(IV) oxides (birnessite) under sunlight illumination to form soluble Mn(II) has been observed in both field and laboratory settings, leading to a consensus that this process is a key driver of the biogeochemical cycling of Mn in the euphotic zones of marine and freshwater ecosystems. However, the underlying mechanisms for the process remain unknown, although they have been linked to the semiconducting characteristics of hexagonal birnessite, the ubiquitous Mn(IV) oxide produced mainly by bacterial oxidation of soluble Mn(II). One of the universal properties of this biogenic mineral is the presence of Mn(IV) vacancies, long-identified as strong adsorption sites for metal cations. In this paper, the possible role of Mn vacancies in photoreductive dissolution is investigated theoretically using quantum mechanical calculations based on spin-polarized density functional theory (DFT). Our DFT study demonstrates unequivocally that Mn vacancies significantly reduce the band-gap energy for hexagonal birnessite relative to a hypothetical vacancy-free MnO{sub 2} and thus would increase the concentration of photo-induced electrons available for Mn(IV) reduction upon illumination of the mineral by sunlight. Calculations of the charge distribution in the presence of vacancies, although not fully conclusive, show a clear separation of photo-induced electrons and holes, implying a slow recombination of these charge-carriers that facilitates the two-electron reduction of Mn(IV) to Mn(II).

  5. NICKEL-FREE Fe-12Mn-0.2Ti ALLOY STEEL FOR CRYOGENIC APPLICATIONS

    E-Print Network [OSTI]

    Hwang, S.

    2010-01-01T23:59:59.000Z

    3, 1976 LBL-5401 l NICKEL-FREE Fe-12Mn-O. 2Ti ALLOY STEELowned rights. I v LBL-540l NICKEL-FREE Fe-12Mn-0.2Ti ALLOY94720 USA ABSTRACT A nickel-free Fe-12Mn-0.2Ti alloy steel

  6. Spark plasma sintering of Mn-Al-C hard magnets , E Fazakas2

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Spark plasma sintering of Mn-Al-C hard magnets A Pasko1 , M LoBue1 , E Fazakas2 , L K Varga2 and F characterization of isotropic Mn-Al-C bulk samples obtained by spark plasma sintering (SPS) is reported by spark plasma sintering (SPS). This technique, to our knowledge, has not been used for preparation of Mn

  7. Investigation of the optical properties of MoS{sub 2} thin films using spectroscopic ellipsometry

    SciTech Connect (OSTI)

    Yim, Chanyoung; O'Brien, Maria; Winters, Sinéad [School of Chemistry, Trinity College Dublin, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); McEvoy, Niall [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Mirza, Inam; Lunney, James G. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Duesberg, Georg S., E-mail: duesberg@tcd.ie [School of Chemistry, Trinity College Dublin, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Advanced Materials and BioEngineering Research (AMBER) Centre, Trinity College Dublin, Dublin 2 (Ireland)

    2014-03-10T23:59:59.000Z

    Spectroscopic ellipsometry (SE) characterization of layered transition metal dichalcogenide (TMD) thin films grown by vapor phase sulfurization is reported. By developing an optical dispersion model, the extinction coefficient and refractive index, as well as the thickness of molybdenum disulfide (MoS{sub 2}) films, were extracted. In addition, the optical band gap was obtained from SE and showed a clear dependence on the MoS{sub 2} film thickness, with thinner films having a larger band gap energy. These results are consistent with theory and observations made on MoS{sub 2} flakes prepared by exfoliation, showing the viability of vapor phase derived TMDs for optical applications.

  8. Masters of Nursing (MN) Degree Clinical Nurse Leader (CNL)

    E-Print Network [OSTI]

    Maxwell, Bruce D.

    Masters of Nursing (MN) Degree Clinical Nurse Leader (CNL) 4 Semester Program of Study Fall Design of Healthcare Delivery Systems ­ Lab (required) 1 (1 clinical lab) 611 Program Planning and Eval, Outcomes, & QI (required) 3 (3 lec) 510 Program Planning and Eval, Outcomes, & QI - Lab (required) 1 (1

  9. Masters of Nursing (MN) Degree Clinical Nurse Leader (CNL)

    E-Print Network [OSTI]

    Maxwell, Bruce D.

    , & QI (required) 3 (3 lec) 510 Program Planning and Eval, Outcomes, & QI - Lab (required) 1 (1 clinicalMasters of Nursing (MN) Degree Clinical Nurse Leader (CNL) 6 Semester Program of Study Fall Systems - Lab (required) 1 (1 clinical lab) 613 Finance and Budget (required) 2 6 (required) 612 Ethics

  10. Growing the renewable chemicals and advanced biofuels cluster in MN

    E-Print Network [OSTI]

    Levinson, David M.

    Growing the renewable chemicals and advanced biofuels cluster in MN #12;Renewable Chemical Value% Reduction 60% Reduction 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Gasoline Corn Ethanol Advanced Biofuel Cellulosic Biofuel Corn Ethanol 20% GHG Reduction Compared to gasoline: Advanced Biofuel 50% GHG Reduction e

  11. 1 Copyright 2006 by ASME Proceedings of MN2006

    E-Print Network [OSTI]

    Kostic, Milivoje M.

    1 Copyright © 2006 by ASME Proceedings of MN2006 Multifunctional Nanocomposites 2006 September 20 of nanoparticles (including nanofibers and functional nanocomposites) in common fluids, have a potential to meet-physical characteristics. Development of new-hybrid, drag-reducing nanofluids may lead to enhanced flow and heat transfer

  12. Mn/DOT's Ombudsman Program Collaboration and Process

    E-Print Network [OSTI]

    Minnesota, University of

    Mn/DOT's Ombudsman Program Collaboration and Process #12;Overview Ombudsman exists to rebuild trust on the environmental and municipal consent processes can be critical #12;A Large Organization #12;Tragedy;Ombudsman Does Not... ·! Advocate for one party or point of view ·! Own any formal process or policy

  13. High damage-resistant Mo mirror for high-power TEA CO/sub 2/ laser systems

    SciTech Connect (OSTI)

    Ichikawa, Y.; Yoshida, K.; Tsunawaki, Y.; Yamanaka, M.; Yamanaka, T.; Yamanaka, C.; Okamoto, H.; Matsusue, N.; Kitajima, K.

    1987-09-01T23:59:59.000Z

    A high-purity molybdenum (Mo) mirror was developed by an electron-beam melting method (e.b.m. Mo mirror). For high-power TEA CO/sub 2/ laser, the e.b.m. Mo mirror has two to four times higher surface damage threshold than that of an Au-coated glass mirror and three times longer lifetime than that of a powder metallurgy Mo mirror (p.m. Mo mirror) when laser energy density lower than 60 J/cm/sup 2/ was irradiated with a 0.5-pps repetition rate. It was found that the difference between the e.b.m. Mo mirror and the p.m. Mo mirror at the laser-damage threshold was due to the five surface without voids and the small amount of impurities.

  14. 0 1 2 3 4 5 Fig. S1. Core photograph combined with Ca, Mn, Fe counts and Mn/Fe ratio determined by XRF core

    E-Print Network [OSTI]

    Gilli, Adrian

    1. Core photograph combined with Ca, Mn, Fe counts and Mn/Fe ratio determined by XRF core scanning determined by XRF core scanning on core ZH10-19 from Lake Zurich recovered in 135 m water depth (2 m above counts and Mn/Fe ratio determined by XRF core scanning on core ZH10-21 from Lake Zurich recovered in 123

  15. EVALUATING SYSTEMATIC DEPENDENCIES OF TYPE Ia SUPERNOVAE: THE INFLUENCE OF PROGENITOR {sup 22}Ne CONTENT ON DYNAMICS

    SciTech Connect (OSTI)

    Townsley, Dean M. [Department of Astronomy/Steward Observatory, University of Arizona, Tucson, AZ (United States); Jackson, Aaron P.; Calder, Alan C. [Department of Physics and Astronomy, State University of New York - Stony Brook, Stony Brook, NY (United States); Chamulak, David A.; Brown, Edward F. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI (United States); Timmes, F. X. [Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States)], E-mail: townsley@as.arizona.edu

    2009-08-20T23:59:59.000Z

    We present a theoretical framework for formal study of systematic effects in supernovae Type Ia (SNe Ia) that utilizes two-dimensional simulations to implement a form of the deflagration-detonation transition (DDT) explosion scenario. The framework is developed from a randomized initial condition that leads to a sample of simulated SNe Ia whose {sup 56}Ni masses have a similar average and range to those observed, and have many other modestly realistic features such as the velocity extent of intermediate-mass elements. The intended purpose is to enable statistically well defined studies of both physical and theoretical parameters of the SNe Ia explosion simulation. We present here a thorough description of the outcome of the SNe Ia explosions produced by our current simulations. A first application of this framework is utilized to study the dependence of the SNe Ia on the {sup 22}Ne content, which is known to be directly influenced by the progenitor stellar population's metallicity. Our study is very specifically tailored to measure how the {sup 22}Ne content influences the competition between the rise of plumes of burned material and the expansion of the star before these plumes reach DDT conditions. This influence arises from the dependence of the energy release, progenitor structure, and laminar flame speed on {sup 22}Ne content. For this study, we explore these three effects for a fixed carbon content and DDT density. By setting the density at which nucleosynthesis takes place during the detonation phase of the explosion, the competition between plume rise and stellar expansion controls the amount of material in nuclear statistical equilibrium (NSE) and therefore {sup 56}Ni produced. Of particular interest is how this influence of {sup 22}Ne content compares to the direct modification of the {sup 56}Ni mass via the inherent neutron excess as discussed by Timmes et al. Although the outcome following from any particular ignition condition can change dramatically with {sup 22}Ne content, with a sample of 20 ignition conditions we find that the systematic change in the expansion of the star prior to detonation is not large enough to compete with the dependence discussed by Timmes et al. In fact, our results show no statistically significant dependence of the predetonation expansion on {sup 22}Ne content, pointing to the morphology of the ignition condition as being the dominant dynamical driver of the {sup 56}Ni yield of the explosion. However, variations in the DDT density, which were specifically excluded here, are also expected to be important and to depend systematically on {sup 22}Ne content.

  16. Aboveground test of an advanced Li$_2$MoO$_4$ scintillating bolometer to search for neutrinoless double beta decay of $^{100}$Mo

    E-Print Network [OSTI]

    T. B. Bekker; N. Coron; F. A. Danevich; V. Ya. Degoda; A. Giuliani; V. D. Grigorieva; N. V. Ivannikova; M. Mancuso; P. de Marcillac; I. M. Moroz; C. Nones; E. Olivieri; G. Pessina; D. V. Poda; V. N. Shlegel; V. I. Tretyak; M. Velazquez

    2014-12-17T23:59:59.000Z

    Large lithium molybdate (Li$_2$MoO$_4$) crystal boules were produced by using the low thermal gradient Czochralski growth technique from deeply purified molybdenum. A small sample from one of the boules was preliminary characterized in terms of X-ray-induced and thermally-excited luminescence. A large cylindrical crystalline element (with a size of $\\oslash 40\\times40$ mm) was used to fabricate a scintillating bolometer, which was operated aboveground at $\\sim 15$ mK by using a pulse-tube cryostat housing a high-power dilution refrigerator. The excellent detector performance in terms of energy resolution and $\\alpha$ background suppression along with preliminary positive indications on the radiopurity of this material show the potentiality of Li$_2$MoO$_4$ scintillating bolometers for low-counting experiment to search for neutrinoless double beta decay of $^{100}$Mo.

  17. Aboveground test of an advanced Li$_2$MoO$_4$ scintillating bolometer to search for neutrinoless double beta decay of $^{100}$Mo

    E-Print Network [OSTI]

    Bekker, T B; Danevich, F A; Degoda, V Ya; Giuliani, A; Grigorieva, V D; Ivannikova, N V; Mancuso, M; de Marcillac, P; Moroz, I M; Nones, C; Olivieri, E; Pessina, G; Poda, D V; Shlegel, V N; Tretyak, V I; Velazquez, M

    2014-01-01T23:59:59.000Z

    Large lithium molybdate (Li$_2$MoO$_4$) crystal boules were produced by using the low thermal gradient Czochralski growth technique from deeply purified molybdenum. A small sample from one of the boules was preliminary characterized in terms of X-ray-induced and thermally-excited luminescence. A large cylindrical crystalline element (with a size of $\\oslash 40\\times40$ mm) was used to fabricate a scintillating bolometer, which was operated aboveground at $\\sim 15$ mK by using a pulse-tube cryostat housing a high-power dilution refrigerator. The excellent detector performance in terms of energy resolution and $\\alpha$ background suppression along with preliminary positive indications on the radiopurity of this material show the potentiality of Li$_2$MoO$_4$ scintillating bolometers for low-counting experiment to search for neutrinoless double beta decay of $^{100}$Mo.

  18. Temperature dependence of the on-resonance portion Mn-NMR spectrum of a Mn(IV,IV) dimer

    E-Print Network [OSTI]

    --the tightly coupled techniques of cutting-edge cryogenic NMR experiments and highly electron correlated of leading-edge cryogenic nuclear magnetic resonance (NMR) measurements and advanced electronic structure with experimentally measureable parameters such as electric field gradient (EFG) tensor, electron's g-factor, 55 Mn

  19. The Mn effect on magnetic structure of FeMn-B amorphous metals , D.M.C. Nicholson2

    E-Print Network [OSTI]

    Widom, Michael

    magnetization and high permeability, which make them a good candidate for magnetic core materials in transformers and electrical motors. Lately, high Mn content, Fe-based bulk amorphous metals have been movement during the quenching process is determined by molecular dynamics simulation using the Vienna Ab

  20. Atomistic simulation of the electronic states of adatoms in monolayer MoS{sub 2}

    SciTech Connect (OSTI)

    Chang, Jiwon; Larentis, Stefano; Tutuc, Emanuel; Register, Leonard F.; Banerjee, Sanjay K. [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)

    2014-04-07T23:59:59.000Z

    Using an ab initio density functional theory based electronic structure method, we study the effects of adatoms on the electronic properties of monolayer transition metal dichalcogenide Molybdenum-disulfide (MoS{sub 2}). We consider the 1st (Li, Na, K) and 7th (F, Cl, Br) column atoms and metals (Sc, Ti, Ta, Mo, Pd, Pt, Ag, Au). Three high symmetry sites for the adatom on the surface of monolayer MoS{sub 2} are examined as starting points to search for the most energetically stable configuration for each adatom-monolayer MoS{sub 2} system, as well as the type of associated bonding. For the most stable adatom positions, we characterize the emergence of adatom-induced electronic states including any dopant states.

  1. Monolayers of MoS{sub 2} as an oxidation protective nanocoating material

    SciTech Connect (OSTI)

    Sen, H. Sener [UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Sahin, H.; Peeters, F. M. [Department of Physics, University of Antwerp, 2610 Antwerp (Belgium); Durgun, E., E-mail: durgun@unam.bilkent.edu.tr [UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey)

    2014-08-28T23:59:59.000Z

    First-principle calculations are employed to investigate the interaction of oxygen with ideal and defective MoS{sub 2} monolayers. Our calculations show that while oxygen atoms are strongly bound on top of sulfur atoms, the oxygen molecule only weakly interacts with the surface. The penetration of oxygen atoms and molecules through a defect-free MoS{sub 2} monolayer is prevented by a very high diffusion barrier indicating that MoS{sub 2} can serve as a protective layer for oxidation. The analysis is extended to WS{sub 2} and similar coating characteristics are obtained. Our calculations indicate that ideal and continuous MoS{sub 2} and WS{sub 2} monolayers can improve the oxidation and corrosion-resistance of the covered surface and can be considered as an efficient nanocoating material.

  2. Substrate interactions with suspended and supported monolayer MoS?: Angle-resolved photoemission spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jin, Wencan; Sadowski, Jerzy T.; Yeh, Po-Chun; Zaki, Nader; Zhang, Datong; Liou, Jonathan T.; Dadap, Jerry I.; Herman, Irving P.; Osgood, Jr., Richard M.; Sutter, Peter; et al

    2015-03-01T23:59:59.000Z

    We report the directly measured electronic structure of exfoliated monolayer molybdenum disulfide (MoS?) using micrometer-scale angle-resolved photoemission spectroscopy. Measurements of both suspended and supported monolayer MoS? elucidate the effects of interaction with a substrate. A suggested relaxation of the in-plane lattice constant is found for both suspended and supported monolayer MoS? crystals. For suspended MoS?, a careful investigation of the measured uppermost valence band gives an effective mass at ? and ? of 2.00m? and 0.43m?, respectively. We also measure an increase in the band linewidth from the midpoint of ?? to the vicinity of ? and briefly discuss itsmore »possible origin.« less

  3. Substrate interactions with suspended and supported monolayer MoS?: Angle-resolved photoemission spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jin, Wencan [Columbia Univ., New York, NY (United States); Sadowski, Jerzy T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Yeh, Po-Chun [Columbia Univ., New York, NY (United States); Zaki, Nader [Columbia Univ., New York, NY (United States); Zhang, Datong [Columbia Univ., New York, NY (United States); Liou, Jonathan T. [Columbia Univ., New York, NY (United States); Dadap, Jerry I. [Columbia Univ., New York, NY (United States); Herman, Irving P. [Columbia Univ., New York, NY (United States); Osgood, Jr., Richard M. [Columbia Univ., New York, NY (United States); Sutter, Peter [Brookhaven National Lab. (BNL), Upton, NY (United States); Barinov, Alexey [Elettra Sincrotrone Trieste, Basovizza, Trieste (Italy); Yablonskikh, Mikhail [Elettra Sincrotrone Trieste, Basovizza, Trieste (Italy)

    2015-03-01T23:59:59.000Z

    We report the directly measured electronic structure of exfoliated monolayer molybdenum disulfide (MoS?) using micrometer-scale angle-resolved photoemission spectroscopy. Measurements of both suspended and supported monolayer MoS? elucidate the effects of interaction with a substrate. A suggested relaxation of the in-plane lattice constant is found for both suspended and supported monolayer MoS? crystals. For suspended MoS?, a careful investigation of the measured uppermost valence band gives an effective mass at ? and ? of 2.00m? and 0.43m?, respectively. We also measure an increase in the band linewidth from the midpoint of ?? to the vicinity of ? and briefly discuss its possible origin.

  4. Intrinsic Electronic Transport Properties of High-Quality Monolayer and Bilayer MoS[subscript 2

    E-Print Network [OSTI]

    Baugher, Britton W. H.

    We report electronic transport measurements of devices based on monolayers and bilayers of the transition-metal dichalcogenide MoS[subscript 2]. Through a combination of in situ vacuum annealing and electrostatic gating ...

  5. MO"BIUS ENERGIES FOR KNOTS AND LINKS, SURFACES AND SUBMANIFOLDS

    E-Print Network [OSTI]

    Kusner, Robert B.

    MO"BIUS ENERGIES FOR KNOTS AND LINKS, SURFACES AND SUBMANIFOLDS energies, especially those which are invariant under M"obius transforma- tions of space. We describe computer experiments with such energies, and discuss ways of extending these to energies

  6. Isothermal activation of Mo2O5 ZSM-5 precursors during

    E-Print Network [OSTI]

    Iglesia, Enrique

    Isothermal activation of Mo2O5 21 ­ZSM-5 precursors during methane reactions: effects of reaction to petrochemicals and liquid fuels and chemicals remains a formidable technological challenge.1 Exchanged cations

  7. AB INITIO Modeling of Thermomechanical Properties of Mo-Based Alloys for Fossil Energy Conversion

    SciTech Connect (OSTI)

    Ching, Wai-Yim

    2013-12-31T23:59:59.000Z

    In this final scientific/technical report covering the period of 3.5 years started on July 1, 2011, we report the accomplishments on the study of thermo-mechanical properties of Mo-based intermetallic compounds under NETL support. These include computational method development, physical properties investigation of Mo-based compounds and alloys. The main focus is on the mechanical and thermo mechanical properties at high temperature since these are the most crucial properties for their potential applications. In particular, recent development of applying ab initio molecular dynamic (AIMD) simulations to the T1 (Mo{sub 5}Si{sub 3}) and T2 (Mo{sub 5}SiB{sub 2}) phases are highlighted for alloy design in further improving their properties.

  8. Electronic structure and conductivity of nanocomposite metal (Au,Ag,Cu,Mo)-containing amorphous carbon films

    E-Print Network [OSTI]

    Endrino, Jose L.

    2010-01-01T23:59:59.000Z

    dual-cathode arc deposition (PDC-FCVA) source containingand metal cathodes [2]. The PDC-FCVA system in combinationCu,Mo) incorporation in a-C by PDC-FCVA. The modification of

  9. Enhanced absorption of monolayer MoS{sub 2} with resonant back reflector

    SciTech Connect (OSTI)

    Liu, Jiang-Tao, E-mail: jtliu@semi.ac.cn; Liu, Nian-Hua [Nanoscale Science and Technology Laboratory, Institute for Advanced Study, Nanchang University, Nanchang 330031 (China); Department of Physics, Nanchang University, Nanchang 330031 (China); Wang, Tong-Biao [Department of Physics, Nanchang University, Nanchang 330031 (China); Li, Xiao-Jing [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China)

    2014-05-21T23:59:59.000Z

    The optical absorption of monolayer MoS{sub 2} on top of one-dimensional photonic crystal (1DPC) or metal films with spacer layers is theoretically investigated by extracting the permittivity of monolayer MoS{sub 2} from existing experimental results [K. F. Mak et al., Phys. Rev. Lett. 105, 136805 (2010)]. The absorption of graphene with 1DPC across a broad spectral range is substantially enhanced because of the photonic localization at the optical micro-cavity on top of the 1DPC or metal films. The absorption of monolayer MoS{sub 2} can be tuned by varying either the distance between the monolayer MoS{sub 2} and the back reflector or the thickness of the cover layers.

  10. Electronic structure and magnetism of Mn{sub 12}O{sub 12} clusters

    SciTech Connect (OSTI)

    Pederson, M.R. [Complex Systems Theory Branch-6692, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)] [Complex Systems Theory Branch-6692, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States); Khanna, S.N. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    1999-01-01T23:59:59.000Z

    To address the ferrimagnetic state of the Mn{sub 12} acetate matrix [Mn{sub 12}O{sub 12}(CH{sub 3}COO){sub 16}(H{sub 2}O){sub 4}] we have performed all-electron gradient-corrected density-functional calculations on (MnO){sub n} with n=1, 2, 4, and 12. In contrast to bulk MnO which is antiferromagnetic, the small (MnO){sub n} (n=1, 2, and 4) clusters are ferromagnetic with Mn moments of 5.0{mu}{sub B} but the ground state of Mn{sub 12}O{sub 12} is ferrimagnetic with a total magnetic moment of 20.0{mu}{sub B} as observed experimentally. The inner Mn sites in Mn{sub 12}O{sub 12} are found to have localized moments of 4.1{mu}{sub B} which are antiferromagnetically coupled to two types of outer Mn with moments of 4.2{mu}{sub B}. The cluster is shown to be marked by ionic as well as covalent bonds between Mn d and O p electrons and a strong intracluster magnetic coupling. {copyright} {ital 1999} {ital The American Physical Society}

  11. Distribution of water extractable heavy metals (Cd, Co, Mn and Mo) in the topsoil of Osijek-Baranja County (Eastern Croatia)

    E-Print Network [OSTI]

    Ivezic, Vladimir; Almås, Åsgeir R.; Loncaric, Zdenko; Singh, Bal Ram

    2009-01-01T23:59:59.000Z

    and Calcareous Soils in Croatia. VII. Alps- Adria Scientificagricultural region of Croatia and therefore food qualityHungary, Serbia and Croatia. Based on the pedological map 74

  12. Physical mechanisms of thermal-diffusivity depth-profile generation in a hardened low-alloy Mn, Si, Cr, Mo steel reconstructed

    E-Print Network [OSTI]

    Mandelis, Andreas

    hardening, and coating deposition.1 For determining the metallurgical properties of case-treated materials ability to produce high-core strength and toughness and is widely used in such applications as gears

  13. Giant Magnetic Moments and Magnetic Bistability of Stoichiomatric MnO Clusters

    SciTech Connect (OSTI)

    Nayak, S.K.; Jena, P. [Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    1998-10-01T23:59:59.000Z

    {ital Abthinspthinspinitio} calculations based on density functional theory and generalized gradient approximation reveal many unusual features of stoichiometric (MnO){sub x} (x{le}9) clusters that contrast with their bulk behavior. The clusters are ferromagnetic and carry atomiclike magnetic moments ranging from 4{mu}{sub B} to 5{mu}{sub B} per MnO unit, and the moments are localized at the Mn sites. The (MnO){sub 8} cluster, in particular, exhibits nearly degenerate ferromagnetic and atypical antiferromagnetic solutions with the ferromagnetic structure carrying a moment of 40{mu}{sub B} . The structures of (MnO){sub x} clusters are also unique with cubic and hexagonal forms competing for stability. (MnO){sub 2} and (MnO){sub 3} are unusually stable and form the foundation for further growth. {copyright} {ital 1998} {ital The American Physical Society}

  14. Bending properties of epoxy resin matrix composites filled with NiMnGa ferromagnetic shape memory alloy powders

    E-Print Network [OSTI]

    Zheng, Yufeng

    Bending properties of epoxy resin matrix composites filled with Ni­Mn­Ga ferromagnetic shape memory­Mn­Ga Composite materials Mechanical properties Microstructure Two types of epoxy resin matrix composites filled­Mn­Ga epoxy resin composites were reported, yet the bending property of Ni­Mn­Ga-polymer smart composites has

  15. Atomic-resolution study of Mn tetramer clusters using scanning tunneling Rong Yang, Haiqiang Yang, and Arthur R. Smitha

    E-Print Network [OSTI]

    Atomic-resolution study of Mn tetramer clusters using scanning tunneling microscopy Rong Yang clusters is investigated. The clusters are composed of a quadrant array of Mn atoms forming a tetramer of manganese nitride, on which are stabilized peri- odic, self-organized array of MnN-bonded Mn tetramer clus

  16. Diffusional Interactions between U-Mo and Zr at 650°C as a Function of Time

    SciTech Connect (OSTI)

    Y. Park; Y. H. Sohn; D. D. Keiser, Jr.

    2015-01-01T23:59:59.000Z

    Development of monolithic U-Mo alloy fuel (typically U-10wt.%Mo) for the Reduced Enrichment for Research and Test Reactors (RERTR) program requires a use of Zr diffusion barrier to eliminate the diffusional interaction between the fuel alloy and Al-alloy cladding. The application of Zr barrier to the U-Mo fuel requires co-rolling process that utilizes a soaking temperature of 650°C, which represents the highest temperature the fuel system is exposed to during both fuel manufacturing and reactor application. Therefore, in this study, development of phase constituents, microstructure and diffusion kinetics of U-10wt.%Mo and Zr was examined using solid-to-solid diffusion couples annealed at 650°C for 240, 480 and 720 hours. Diffusional interactions were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Within the diffusion zone, a single-phase layer of ß-Zr was observed along with a discontinuous layer of Mo2Zr at the interface between the terminal ?-U(Mo) alloy and ß-Zr. In the vicinity of Mo2Zr phase, islands of ß-U and a-Zr phases were also found. In addition, accicular a-Zr phases were observed within the ?-U(Mo). Growth rate of this diffuaional interaction layer was determined to be 8.76 x 10-15 m2/sec, however with an assumption of certain incubation period. Consistency in these observation along with concentration profiles and diffusion paths are presented and discussed with respect to the diffusion couple that was furnace-cooled, annealed at 700°C in our previous study, and isothermal ternary phase diagram at 700°C.

  17. The Sloan Digital Sky Survey-II: Photometry and Supernova Ia Light Curves from the 2005 Data

    SciTech Connect (OSTI)

    Holtzman, Jon A.; /New Mexico State U.; Marriner, John; /Fermilab; Kessler, Richard; /KICP, Chicago /Chicago U., EFI; Sako, Masao; /KIPAC, Menlo Park /Pennsylvania U.; Dilday, Ben; /KICP, Chicago /Chicago U.; Frieman, Joshua A.; /Fermilab /KICP, Chicago /Chicago U., Astron. Astrophys. Ctr.; Schneider, Donald P.; /Penn State U., Astron. Astrophys.; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Becker, Andrew; /Washington U., Seattle, Astron. Dept.; Cinabro, David; /Wayne State U.; DeJongh, Fritz; /KICP, Chicago; Depoy, Darren L.; /Ohio State U., Dept. Astron.; Doi, Mamoru; /Tokyo U., Inst. Astron.; Garnavich, Peter M.; /Notre Dame U.; Hogan, Craig J.; /Washington U., Seattle, Astron. Dept.; Jha, Saurabh; /KIPAC, Menlo Park /Rutgers U., Piscataway; Konishi, Kohki; /Tokyo U., ICRR; Lampeitl, Hubert; /Baltimore, Space Telescope Sci. /Portsmouth U., ICG; Marshall, Jennifer L.; /Ohio State U., Dept. Astron.; McGinnis, David; Miknaitis, Gajus; /KICP, Chicago /Portsmouth U., ICG /Ohio State U., Dept. Astron. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Rochester Inst. Tech. /KIPAC, Menlo Park /Portsmouth U., ICG /Tokyo U., Inst. Astron. /South African Astron. Observ. /Cape Town U. /Tokyo U., ICRR /KIPAC, Menlo Park

    2010-08-26T23:59:59.000Z

    We present ugriz light curves for 146 spectroscopically confirmed or spectroscopically probable Type Ia supernovae from the 2005 season of the SDSS-II Supernova survey. The light curves have been constructed using a photometric technique that we call scene modeling, which is described in detail here; the major feature is that supernova brightnesses are extracted from a stack of images without spatial resampling or convolution of the image data. This procedure produces accurate photometry along with accurate estimates of the statistical uncertainty, and can be used to derive photometry taken with multiple telescopes. We discuss various tests of this technique that demonstrate its capabilities. We also describe the methodology used for the calibration of the photometry, and present calibrated magnitudes and fluxes for all of the spectroscopic SNe Ia from the 2005 season.

  18. Is the central binary system of the planetary nebula Henize 2-428 a Type Ia supernova progenitor?

    E-Print Network [OSTI]

    Garcia-Berro, Enrique; Althaus, Leandro G

    2015-01-01T23:59:59.000Z

    We account for recent observations of the binary system at the center of the bipolar planetary nebula Henize 2-428 by the presence of one degenerate core with a low-mass main sequence companion, rather than by two degenerate objects. We argue that the variability of the He II 5412A spectral line can be accounted for by a time-varying broad absorption line from the central star on top of which there is a time-varying narrow emission line from the compact nebula. The two (almost) symmetric broad minima in the light curve are attributed to tidal distortion caused by a companion. We find problems in the recently proposed and competing explanation of two equal-mass degenerate objects that supposedly will eventually merge, possibly leading to a SN Ia. We conclude that Henize 2-428 cannot be claimed yet to support the double-degenerate scenario for Type Ia supernovae.

  19. MoS{sub 2} nanotube exfoliation as new synthesis pathway to molybdenum blue

    SciTech Connect (OSTI)

    Visic, B., E-mail: bojana.visic@ijs.si [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Gunde, M. Klanjsek [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia)] [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Kovac, J.; Iskra, I. [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia)] [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Jelenc, J.; Remskar, M. [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia) [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Centre of Excellence Namaste, Jamova cesta 39, SI-1000 Ljubljana (Slovenia)

    2013-02-15T23:59:59.000Z

    Graphical abstract: . Display Omitted Highlights: ? New synthesis approach to obtaining molybdenum blue via exfoliated MoS{sub 2} nanotubes. ? Material is prone to self assembly and is stable in high vacuum. ? Molecules are as small as 2 nm and their clusters are up to tens of nanometers. ? Change in absorption and oxidation states from the precursor MoS{sub 2}. -- Abstract: Molybdenum blue-type materials are usually obtained by partially reducing Mo{sup VI+} in acidic solutions, while in the presented method it is formed in ethanol solution of exfoliated MoS{sub 2} nanotubes, where the MoS{sub 2} flakes are the preferential location for their growth. Material was investigated by means of scanning electron and atomic force microscopy, showing the structure and self assembly, while also confirming that it is stable in high vacuum with molecules as small as 1.6 nm and the agglomerates of few tens of nanometres. The ultraviolet–visible and photoelectron spectrometry show the change in absorption properties and oxidation states from MoS{sub 2} structure to molybdenum blue, while the presence of sulphur suggests that this is a new type of molybdenum blue material.

  20. High reflectance and low stress Mo2C/Be multilayers

    DOE Patents [OSTI]

    Bajt, Sasa (Livermore, CA); Barbee, Jr., Troy W. (Palo Alto, CA)

    2001-01-01T23:59:59.000Z

    A material for extreme ultraviolet (EUV) multilayers that will reflect at about 11.3 nm, have a high reflectance, low stress, and high thermal and radiation stability. The material consists of alternating layers of Mo.sub.2 C and Be deposited by DC magnetron sputtering on a substrate, such as silicon. In one example a Mo.sub.2 C/Be multilayer gave 65.2% reflectance at 11.25 nm measured at 5 degrees off normal incidence angle, and consisted of 70 bilayers with a deposition period of 5.78 nm, and was deposited at 0.83 mTorr argon (Ar) sputtering pressure, with the first and last layers being Be. The stress of the multilayer is tensile and only +88 MPa, compared to +330 MPa of a Mo/Be multilayers of the same thickness. The Mo.sub.2 C/Be multilayer was capped with carbon which produced an increase in reflectivity of about 7% over a similar multilayer with no carbon capping material, thus raising the reflectivity from 58.3% to over 65%. The multilayers were formed using either Mo.sub.2 C or Be as the first and last layers, and initial testing has shown the formation of beryllium carbide at the interfaces between the layers which both stabilizes and has a smoothing effect, and appear to be smoother than the interfaces in Mo/Be multilayers.

  1. Effects of thermal treatment on the co-rolled U-Mo fuel foils

    SciTech Connect (OSTI)

    Dennis D. Keiser, Jr.; Tammy L. Trowbridge; Cynthia R. Breckenridge; Brady L. Mackowiak; Glenn A. Moore; Barry H. Rabin; Mitchell K. Meyer

    2014-11-01T23:59:59.000Z

    A monolithic fuel type is being developed to convert US high performance research and test reactors such as Advanced Test Reactor (ATR) at Idaho National Laboratory from highly enriched uranium (HEU) to low-enriched uranium (LEU). The interaction between the cladding and the U-Mo fuel meat during fuel fabrication and irradiation is known to have negative impacts on fuel performance, such as mechanical integrity and dimensional stability. In order to eliminate/minimize the direct interaction between cladding and fuel meat, a thin zirconium diffusion barrier was introduced between the cladding and U-Mo fuel meat through a co-rolling process. A complex interface between the zirconium and U-Mo was developed during the co-rolling process. A predictable interface between zirconium and U-Mo is critical to achieve good fuel performance since the interfaces can be the weakest link in the monolithic fuel system. A post co-rolling annealing treatment is expected to create a well-controlled interface between zirconium and U-Mo. A systematic study utilizing post co-rolling annealing treatment has been carried out. Based on microscopy results, the impacts of the annealing treatment on the interface between zirconium and U-Mo will be presented and an optima annealing treatment schedule will be suggested. The effects of the annealing treatment on the fuel performance will also be discussed.

  2. Photoluminescent BaMoO{sub 4} nanopowders prepared by complex polymerization method (CPM)

    SciTech Connect (OSTI)

    Azevedo Marques, Ana Paula de [Laboratorio de Analise Termica e Materiais, Departamento de Quimica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil)]. E-mail: apamarques@liec.ufscar.br; Melo, Dulce M.A. de [Laboratorio de Analise Termica e Materiais, Departamento de Quimica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Paskocimas, Carlos A. [Departamento de Engenharia Mecanica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Pizani, Paulo S. [Laboratorio de Semicondutores, Departamento de Fisica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Joya, Miryam R. [Laboratorio de Semicondutores, Departamento de Fisica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Leite, Edson R. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, CMDMC, Departamento de Quimica, Universidade Federal de Sao Carlos 13565-905, Sao Carlos, SP (Brazil); Longo, Elson [CMDMC, LIEC, Instituto de Quimica, Universidade Estadual Paulista, 14801-907 Araraquara, SP (Brazil)

    2006-03-15T23:59:59.000Z

    The BaMoO{sub 4} nanopowders were prepared by the Complex Polymerization Method (CPM). The structure properties of the BaMoO{sub 4} powders were characterized by FTIR transmittance spectra, X-ray diffraction (XRD), Raman spectra, photoluminescence spectra (PL) and high-resolution scanning electron microscopy (HR-SEM). The XRD, FTIR and Raman data showed that BaMoO{sub 4} at 300 deg. C was disordered. At 400 deg. C and higher temperature, BaMoO{sub 4} crystalline scheelite-type phases could be identified, without the presence of additional phases, according to the XRD, FTIR and Raman data. The calculated average crystallite sizes, calculated by XRD, around 40 nm, showed the tendency to increase with the temperature. The crystallite sizes, obtained by HR-SEM, were around of 40-50 nm. The sample that presented the highest intensity of the red emission band was the one heat treated at 400 deg. C for 2 h, and the sample that displayed the highest intensity of the green emission band was the one heat treated at 700 deg. C for 2 h. The CPM was shown to be a low cost route for the production of BaMoO{sub 4} nanopowders, with the advantages of lower temperature, smaller time and reduced cost. The optical properties observed for BaMoO{sub 4} nanopowders suggested that this material is a highly promising candidate for photoluminescent applications.

  3. Synthesis and characterization of the ((CO)/sub 4/MoS/sub 2/MS/sub 2/)/sup 2 -/ and ((CO)/sub 4/MoS/sub 2/MS/sub 2/Mo(CO)/sub 4/)/sup 2 -/ ions (M = Mo, W): species containing group VI (6) metals in widely separated formal oxidation states

    SciTech Connect (OSTI)

    Rosenhein, L.D.; McDonald, J.W.

    1987-10-07T23:59:59.000Z

    Dinuclear and trinuclear sulfide-bridged complexes of the types (Et/sub 4/N)/sub 2/(MS/sub 4/(Mo(CO)/sub 4/)) and (Et/sub 4/N)/sub 2/(MS/sub 4/(Mo(CO)/sub 4/)/sub 2/) were prepared by the reaction of one or two equivalents of Mo(CO)/sub 4/(C/sub 7/H/sub 8/) (C/sub 7/H/sub 8/ = norbornadiene) with (Et/sub 4/N)/sub 2/(MS/sub 4/) (M = Mo, W) in methyl alcohol. Elemental analyses were consistent with the proposed formulae. Infrared spectra of all four compounds contain strong bands in the carbonyl region and low-energy bands characteristic of terminal and bridging M-S vibrations in linear, polynuclear, and sulfido-bridged species. Electrochemical experimental results support the hypothesis that the di- and trinuclear species contain both M(IV) (M = Mo, W) and Mo(0) oxidation states in the same complex. 33 references, 2 tables.

  4. Food and Drug Administration process validation activities to support 99Mo production at Sandia National Laboratories

    SciTech Connect (OSTI)

    McDonald, M.J.; Bourcier, S.C.; Talley, D.G.

    1997-07-01T23:59:59.000Z

    Prior to 1989 {sup 99}Mo was produced in the US by a single supplier, Cintichem Inc., Tuxedo, NY. Because of problems associated with operating its facility, in 1989 Cintichem elected to decommission the facility rather than incur the costs for repair. The demise of the {sup 99}Mo capability at Cintichem left the US totally reliant upon a single foreign source, Nordion International, located in Ottawa Canada. In 1992 the DOE purchased the Cintichem {sup 99}Mo Production Process and Drug Master File (DMF). In 1994 the DOE funded Sandia National Laboratories (SNL) to produce {sup 99}Mo. Although Cintichem produced {sup 99}Mo and {sup 99m}Tc generators for many years, there was no requirement for process validation which is now required by the Food and Drug Administration (FDA). In addition to the validation requirement, the requirements for current Good manufacturing Practices were codified into law. The purpose of this paper is to describe the process validation being conducted at SNL for the qualification of SNL as a supplier of {sup 99}Mo to US pharmaceutical companies.

  5. THE IMPACT OF TYPE Ia SUPERNOVA EXPLOSIONS ON HELIUM COMPANIONS IN THE CHANDRASEKHAR-MASS EXPLOSION SCENARIO

    SciTech Connect (OSTI)

    Liu Zhengwei; Wang, B.; Han, Z. W. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Pakmor, R. [Heidelberger Institut fuer Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Seitenzahl, I. R.; Hillebrandt, W.; Kromer, M.; Edelmann, P.; Taubenberger, S. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Roepke, F. K. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg, Am Hubland, D-97074 Wuerzburg (Germany); Maeda, K., E-mail: zwliu@ynao.ac.cn [Kavli Institute for the Physics and Mathematics of the Universe (Kavli-IPMU), Todai Institutes for Advanced Study (TODIAS), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)

    2013-09-01T23:59:59.000Z

    In the version of the single-degenerate scenario of Type Ia supernovae (SNe Ia) studied here, a carbon-oxygen white dwarf explodes close to the Chandrasekhar limit after accreting material from a non-degenerate helium (He) companion star. In the present study, we employ the STELLAR GADGET code to perform three-dimensional hydrodynamical simulations of the interaction of the SN Ia ejecta with the He companion star taking into account its orbital motion and spin. It is found that only 2%-5% of the initial companion mass is stripped off from the outer layers of He companion stars due to the supernova (SN) impact. The dependence of the unbound mass (or the kick velocity) on the orbital separation can be fitted to a good approximation by a power law for a given companion model. After the SN impact, the outer layers of a He donor star are significantly enriched with heavy elements from the low-expansion-velocity tail of SN Ia ejecta. The total mass of accumulated SN-ejecta material on the companion surface reaches about {approx}> 10{sup -3} M{sub Sun} for different companion models. This enrichment with heavy elements provides a potential way to observationally identify the surviving companion star in SN remnants. Finally, by artificially adjusting the explosion energy of the W7 explosion model, we find that the total accumulation of SN ejecta on the companion surface is also dependent on the explosion energy with a power-law relation to a good approximation.

  6. The Type Ia supernova 2004S, a clone of SN 2001el, and the optimal photometric bands for extinction estimation

    E-Print Network [OSTI]

    Kevin Krisciunas; Peter M. Garnavich; Vallery Stanishev; Nicholas B. Suntzeff; Jose Luis Prieto; Juan Espinoza; David Gonzalez; Maria Elena Salvo; Nancy Elias de la Rosa; Stephen J. Smartt; Justyn R. Maund; Rolf-Peter Kudritzki

    2006-09-10T23:59:59.000Z

    We present optical (UBVRI) and near-infrared (YJHK) photometry of the normal Type Ia supernova 2004S. We also present eight optical spectra and one near-IR spectrum of SN 2004S. The light curves and spectra are nearly identical to those of SN 2001el. This is the first time we have seen optical and IR light curves of two Type Ia supernovae match so closely. Within the one parameter family of light curves for normal Type Ia supernovae, that two objects should have such similar light curves implies that they had identical intrinsic colors and produced similar amounts of Ni-56. From the similarities of the light curve shapes we obtain a set of extinctions as a function of wavelength which allows a simultaneous solution for the distance modulus difference of the two objects, the difference of the host galaxy extinctions, and R_V. Since SN 2001el had roughly an order of magnitude more host galaxy extinction than SN 2004S, the value of R_V = 2.15 (+0.24 -0.22) pertains primarily to dust in the host galaxy of SN 2001el. We have also shown via Monte Carlo simulations that adding rest frame J-band photometry to the complement of BVRI photometry of Type Ia SNe decreases the uncertainty in the distance modulus by a factor of 2.7. A combination of rest frame optical and near-IR photometry clearly gives more accurate distances than using rest frame optical photometry alone.

  7. SPECTROSCOPIC OBSERVATIONS OF SN 2012fr: A LUMINOUS, NORMAL TYPE Ia SUPERNOVA WITH EARLY HIGH-VELOCITY FEATURES AND A LATE VELOCITY PLATEAU

    SciTech Connect (OSTI)

    Childress, M. J.; Scalzo, R. A.; Sim, S. A.; Tucker, B. E.; Yuan, F.; Schmidt, B. P. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Cenko, S. B.; Filippenko, A. V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Silverman, J. M. [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States); Contreras, C.; Hsiao, E. Y.; Phillips, M.; Morrell, N. [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Jha, S. W.; McCully, C. [Department of Physics and Astronomy, Rutgers, State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Anderson, J. P.; De Jaeger, T.; Forster, F. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Benetti, S. [INAF Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy); Bufano, F., E-mail: mjc@mso.anu.edu.au [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); and others

    2013-06-10T23:59:59.000Z

    We present 65 optical spectra of the Type Ia SN 2012fr, 33 of which were obtained before maximum light. At early times, SN 2012fr shows clear evidence of a high-velocity feature (HVF) in the Si II {lambda}6355 line that can be cleanly decoupled from the lower velocity ''photospheric'' component. This Si II {lambda}6355 HVF fades by phase -5; subsequently, the photospheric component exhibits a very narrow velocity width and remains at a nearly constant velocity of {approx}12,000 km s{sup -1} until at least five weeks after maximum brightness. The Ca II infrared triplet exhibits similar evidence for both a photospheric component at v Almost-Equal-To 12,000 km s{sup -1} with narrow line width and long velocity plateau, as well as an HVF beginning at v Almost-Equal-To 31,000 km s{sup -1} two weeks before maximum. SN 2012fr resides on the border between the ''shallow silicon'' and ''core-normal'' subclasses in the Branch et al. classification scheme, and on the border between normal and high-velocity Type Ia supernovae (SNe Ia) in the Wang et al. system. Though it is a clear member of the ''low velocity gradient'' group of SNe Ia and exhibits a very slow light-curve decline, it shows key dissimilarities with the overluminous SN 1991T or SN 1999aa subclasses of SNe Ia. SN 2012fr represents a well-observed SN Ia at the luminous end of the normal SN Ia distribution and a key transitional event between nominal spectroscopic subclasses of SNe Ia.

  8. Chameleon-like cosmology in light of SNeIa, CMB, BAO and OHD observational data sets

    E-Print Network [OSTI]

    Rabiei, Sayed Wrya; Saaidi, Khaled; Aghamohammadi, Ali

    2015-01-01T23:59:59.000Z

    During this work an interacting chameleon-like scalar field scenario, by considering SNeIa, CMB, BAO and OHD data sets is investigated. Some cosmological parameters includes of Hubble, deceleration and coincidence parameters in such mechanism are analysed. It is realized for estimation the free parameters of a theoretical model, it is better all mentioned observational data sets be considered. In fact if one considers SNeIa, CMB and BAO but ignores OHD it maybe leads to an incorrect result. Also it will find out, when we margin the free parameters, the $\\chi _{\\rm{T}}^2$ function should be re-weighted, this fact arises from the abundance of SNeIa and OHD sources in comparison to CMB and BAO data sets. We margin the likelihood $\\mathcal{L} (\\Omega_{\\rm{m0}} ,\\omega_1 , \\beta)$ with respect to $\\omega_1$, $\\beta$ and $\\Omega_{\\rm{m0}}$ respectively and by means of two dimensional confidence levels $68.3\\%$, $90\\%$ and $95.4\\%$, the relative probability functions are plotted. Also the quantities which maximize t...

  9. Explosion Models for Type Ia Supernovae: A Comparison with Observed Light Curves, distances, H_o and q_o

    E-Print Network [OSTI]

    P. Hoeflich; A. Khokkhlov

    1996-02-06T23:59:59.000Z

    Theoretical monochromatic light curves and photospheric expansion velocities are compared with observations of 27 Type Ia supernovae (SNe Ia). A set of 37 models has been considered which encompasses all currently discussed explosion scenarios for Type Ia supernovae including deflagrations, detonations, delayed detonations, pulsating delayed detonations and tamped detonations of Chandra- mass, and Helium detonations of low mass white dwarfs. The explosions are calculated using one-dimensional Lagrangian hydro and radiation-hydro codes with incorporated nuclear networks. Subsequently, light curves are constructed using our LC scheme which includes an implicit radiation transport, expansion opacities, a Monte-Carlo $\\gamma $-ray transport, and molecular and dust formation. For some supernovae, results of detailed non-LTE calculations have been considered. Observational properties of our series of models are discussed, the relation between the absolute brightness, post-maximum decline rates, the colors at several moments of time, etc. All models with a Ni production larger than 0.4 solar masses produce light curves of similar brightness. The influence of the cosmological red shift on the light curves and on the correction for interstellar reddening is discussed. Based on data rectification of the standard deviation, a quantitative procedure to fit the observations has been used to the determine the free parameters, i.e. the correct model, the distance, the reddening, and the time of the explosion. The results are discussed in detail and applied to determine Ho and qo.

  10. Spectroscopic Properties of Star-Forming Host Galaxies and Type Ia Supernova Hubble Residuals in a Nearly Unbiased Sample

    SciTech Connect (OSTI)

    D'Andrea, Chris B. [Univ. of Pennsylvania, Philadelphia, PA (United States); et al.

    2011-12-20T23:59:59.000Z

    We examine the correlation between supernova host galaxy properties and their residuals on the Hubble diagram. We use supernovae discovered during the Sloan Digital Sky Survey II - Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of -23 < M_r < -17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star-formation rates from host galaxies with active star formation. From a final sample of ~ 40 emission-line galaxies, we find that light-curve corrected Type Ia supernovae are ~ 0.1 magnitudes brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (> 3{\\sigma}) correlation between the Hubble residuals of Type Ia supernovae and the specific star-formation rate of the host galaxy. We comment on the importance of supernova/host-galaxy correlations as a source of systematic bias in future deep supernova surveys.

  11. Kepler's Supernova: An Overluminous Type Ia Event Interacting with a Massive Circumstellar Medium at a Very Late Phase

    E-Print Network [OSTI]

    Katsuda, Satoru; Maeda, Keiichi; Tanaka, Masaomi; Koyama, Katsuji; Tsunemi, Hiroshi; Nakajima, Hiroshi; Maeda, Yoshitomo; Ozaki, Masanobu; Petre, Robert

    2015-01-01T23:59:59.000Z

    We have analyzed XMM-Newton, Chandra, and Suzaku observations of Kepler's supernova remnant (SNR) to investigate the properties of both the SN ejecta and the circumstellar medium (CSM). For comparison, we have also analyzed two similarly-aged, ejecta-dominated SNRs: Tycho's SNR, thought to be the remnant of a typical Type Ia SN, and SNR 0509-67.5 in the Large Magellanic Cloud, thought to be the remnant of an overluminous Type Ia SN. By simply comparing the X-ray spectra, we find that line intensity ratios of iron-group elements (IGE) to intermediate-mass elements (IME) for Kepler's SNR and SNR 0509-67.5 are much higher than those for Tycho's SNR. We therefore argue that Kepler is the product of an overluminous Type Ia SN. This inference is supported by our spectral modeling, which reveals the IGE and IME masses respectively to be ~0.95 M_sun and ~0.12 M_sun (Kepler's SNR), ~0.75 M_sun and ~0.34 M_sun (SNR 0509-67.5), and ~0.35 M_sun and ~0.70 M_sun (Tycho's SNR). We find that the CSM component in Kepler's SNR...

  12. Evidence for Microvariability in the Optical Light Curve of the Type Ia SN 2014J

    E-Print Network [OSTI]

    Bonanos, A Z

    2015-01-01T23:59:59.000Z

    We present results of high-cadence monitoring of the optical light curve of the nearby, Type Ia SN 2014J in M82 using the 2.3m Aristarchos telescope. $B$ and $V$-band photometry on days 15-18 after $t_{max}(B)$, obtained with a cadence of 2 min per band, reveals evidence for variability at the 0.02-0.05 mag level on timescales of 15-60 min on all four nights. The decline slope was measured to be steeper in the $B$-band than in $V$-band, and to steadily decrease in both bands from 0.15 mag/day (night 1) to 0.04 mag/day (night 4) in V and from 0.19 mag/day (night 1) to 0.06 mag/day (night 4) in B, corresponding to the onset of the secondary maximum. We propose that microvariability could be due to one or a combination of the following scenarios: the clumpiness of the ejecta, their interaction with circumstellar material, the asymmetry of the explosion, or the mechanism causing the secondary maximum in the near-infrared light curve. We encourage the community to undertake high-cadence monitoring of future, nearb...

  13. Accelerating universe from gravitational leakage into extra dimensions: confrontation with SNeIa

    E-Print Network [OSTI]

    Zong-Hong Zhu; Jailson S. Alcaniz

    2004-11-01T23:59:59.000Z

    There is mounting observational evidence that the expansion of our universe is undergoing an acceleration. A dark energy component has usually been invoked as the most feasible mechanism for the acceleration. However, it is desirable to explore alternative possibilities motivated by particle physics before adopting such an untested entity. In this work, we focus our attention on an acceleration mechanism: one arising from gravitational leakage into extra dimensions. We confront this scenario with high-$z$ type Ia supernovae compiled by Tonry et al. (2003) and recent measurements of the X-ray gas mass fractions in clusters of galaxies published by Allen et al. (2002,2003). A combination of the two databases gives at a 99% confidence level that $\\Omega_m=0.29^{+0.04}_{-0.02}$, $\\Omega_{rc}=0.21^{+0.08}_{-0.08}$, and $\\Omega_k=-0.36^{+0.31}_{-0.35}$, indicating a closed universe. We then constrain the model using the test of the turnaround redshift, $z_{q=0}$, at which the universe switches from deceleration to acceleration. We show that, in order to explain that acceleration happened earlier than $z_{q=0} = 0.6$ within the framework of gravitational leakage into extra dimensions, a low matter density, $\\Omega_m < 0.27$, or a closed universe is necessary.

  14. Phenomenology for Supernova Ia Data Based on a New Cosmic Time

    E-Print Network [OSTI]

    Charles B. Leffert

    2007-07-26T23:59:59.000Z

    A new phenomenological theory for the expansion of our universe is presented. Because fundamental supporting theory is still in development, its discussion is not presented in this paper. The theory is based on a new algebraic expression for cosmic time G Rho t^2=3/32Pi, which correctly predicts the WMAP measured cosmological constants and the fundamental Hubble parameter H(t) for the expansion of the universe. A replacement for dark matter, called here "dark mass", is proposed which scales as with the expansion and incorporated. It does not react with ordinary matter, except gravitationally, and produces flat rotational curves for spiral galaxies. Also a new expression for the approaching velocity of radiation in a closed 3-sphere expanding universe is given that accounts for the early degrading negative approach of radiation for z > 1.7. The expression is v = Hr-c. Combining these three elements produces a luminosity distance dL that successfully predicts the apparent magnitude of exploding supernova Ia stars and even the new gamma ray bursts with no need for dark energy or acceleration of the expansion of the universe.

  15. Sub-millimeter emission from type Ia supernova host galaxies at z=0.5

    E-Print Network [OSTI]

    D. Farrah; M. Fox; M. Rowan-Robinson; D. Clements; J. Afonso

    2003-12-03T23:59:59.000Z

    We present deep sub-millimetre observations of seventeen galaxies at z=0.5, selected through being hosts of a type 1a supernova. Two galaxies are detected directly, and the sample is detected statistically with a mean 850 micron flux of 1.01mJy +/- 0.33mJy, which is 25% - 135% higher than locally. We infer that the mean value of A_v in normal galaxies at z=0.5 is comparable to or greater than the mean A_v in local normal galaxies, in agreement with galaxy chemical evolution models and indirect observational evidence. Scaling from the local value given by Rowan-Robinson (2003) gives a mean extinction at z=0.5 of A_v = 0.56 +/- 0.17. The dust in the brightest sub-mm object in our sample is best interpreted as normal `cirrus' dust similar to that seen locally. The detection rate of our sample suggests that some sources found in blank-field sub-mm surveys may not be high redshift starbursts, but rather cirrus galaxies at moderate redshifts and with lower star formation rates. Finally, an increase in host dust extinction with redshift may impact the cosmological results from distant supernova searches. This emphasizes the need to carefully monitor dust extinction when using type Ia supernovae to measure the cosmological parameters.

  16. Color dispersion and Milky-Way-like reddening among type Ia supernovae

    SciTech Connect (OSTI)

    Scolnic, Daniel M.; Riess, Adam G.; Rodney, Steven A.; Brout, Dillon J.; Jones, David O. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rest, Armin [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2014-01-01T23:59:59.000Z

    Past analyses of Type Ia supernovae have identified an irreducible scatter of 5%-10% in distance, widely attributed to an intrinsic dispersion in luminosity. Another equally valid source of this scatter is intrinsic dispersion in color. Misidentification of the true source of this scatter can bias both the retrieved color-luminosity relation and cosmological parameter measurements. The size of this bias depends on the magnitude of the intrinsic color dispersion relative to the distribution of colors that correlate with distance. We produce a realistic simulation of a misattribution of intrinsic scatter and find a negative bias in the recovered color-luminosity relation, ?, of ?? ? –1.0 (?33%) and a positive bias in the equation of state parameter, w, of ?w ? +0.04 (?4%). We re-analyze current published datasets with the assumption that the distance scatter is predominantly the result of color. Unlike previous analyses, we find that the data are consistent with a Milky-Way-like reddening law (R{sub V} = 3.1) and that a Milky-Way dust model better predicts the asymmetric color-luminosity trends than the conventional luminosity scatter hypothesis. We also determine that accounting for color variation reduces the correlation between various host galaxy properties and Hubble residuals by ?20%.

  17. Type Ia Supernovae: Can Coriolis force break the symmetry of the gravitational confined detonation explosion mechanism?

    E-Print Network [OSTI]

    García-Senz, D; Domínguez, I; Thielemann, F K

    2015-01-01T23:59:59.000Z

    Nowadays the number of models aimed at explaining the Type Ia supernova phenomenon is high and discriminating between them is a must-do. In this work we explore the influence of rotation in the evolution of the nuclear flame which drives the explosion in the so called gravitational confined detonation models. Assuming that the flame starts in a point-like region slightly above the center of the white dwarf (WD) and adding a moderate amount of angular velocity to the star we follow the evolution of the deflagration using a smoothed particle hydrodynamics code. We find that the results are very dependent on the angle between the rotational axis and the line connecting the initial bubble of burned material with the center of the white dwarf at the moment of the ignition. The impact of rotation is larger for angles close to 90{\\deg} because the Coriolis force on a floating element of fluid is maximum, and its principal effect is to break the symmetry of the deflagration. Such symmetry breaking weakens the converg...

  18. A Test of Tully-Fisher Distance Estimates Using Cepheids and Type Ia Supernovae

    E-Print Network [OSTI]

    T. Shanks

    1999-01-24T23:59:59.000Z

    We update and extend the results of Shanks (1997, MNRAS, 290, L77) by making a direct test of Tully-Fisher distance estimates to thirteen spiral galaxies with HST Cepheid distances and to ten spiral galaxies with Type Ia supernova (SNIa) distances. The results show that the Tully-Fisher distance moduli are too short with respect to the Cepheid distances by 0.46+-0.11mag and too short with respect to the SNIa distances by 0.49+-0.18mag. Combining the HST Cepheid and the best SNIa data suggests that, overall, previous Tully-Fisher distances at v~1000 kms-1 were too short by 0.43+-0.09mag, a result which is significant at the 4.6 sigma level. These data therefore indicate that previous Tully-Fisher distances should be revised upwards by 22+-5% implying, for example, a Virgo distance of 19.0+-1.8Mpc. The value of Ho from Tully-Fisher estimates is correspondingly revised downwards from Ho=84+-10kms-1Mpc-1 to Ho=69+-8kms-1Mpc-1. There is evidence that the Tully-Fisher relation at large distances is affected by Malmquist bias. In this case, we argue that Ho<50kms-1Mpc-1 cannot be ruled out by Tully-Fisher considerations.

  19. SN1994D in NGC4526: a normally bright type Ia supernova

    E-Print Network [OSTI]

    Georg Drenkhahn; Tom Richtler

    1999-09-07T23:59:59.000Z

    SN1994D of type Ia has been suspected not to fit into the relation between decline rate, colour, and brightness. However, an individual distance of its host galaxy, NGC4526, other than that of the Virgo cluster, has not yet been published. We determined the distance by the method of globular cluster luminosity functions on the basis of HST archive data. A maximum-likelihood fit returns apparent turn-over magnitudes of 23.16+-0.16mag in V and 21.96+-0.09mag in I. The corresponding distance modulus is 30.4+-0.3mag, where the error reflects our estimation of the absolute distance scale. The absolute magnitudes (not corrected for decline rate and colour) are -18.67+-0.30mag, -18.62+-0.30mag, and -18.40+-0.30mag for B, V, and I, respectively. The corrected magnitudes are -18.69+-0.31mag, -18.69+-0.31mag, and -18.44+-0.31mag. Compared with other supernovae with reliably determined distances, SN1994D fits within the errors. It is therefore not a counter-example against a uniform decline-rate-colour-brightness relation.

  20. Magnitude-Redshift Relation for SNe Ia, Time Dilation, and Plasma Redshift

    E-Print Network [OSTI]

    Ari Brynjolfsson

    2006-02-22T23:59:59.000Z

    We have previously shown that the type Ia supernovae data by Riess et al. match the prediction of the magnitude-redshift relation in the plasma-redshift cosmology. In this article, we also show that the recent SNLS data, which have a slightly narrower distribution as reported by Astier et al. in 2005, match the predictions of the plasma-redshift cosmology. The standard deviation of the SNLS-magnitude from the predicted curve is only about 0.14. The data indicate that there is no cosmic time dilation. The big-bang cosmology therefore appears false. The plasma redshift, which follows from exact evaluation of photons interaction with hot sparse electron plasma, leads to a quasi-static, infinite, and everlasting universe. It does not need big bang, dark energy, or dark matter for describing the observations. It predicts intrinsic redshifts of galaxies consistent with what is observed. The Hubble constant that best fits the SNLS data is about 63 km per sec per Mpc. This corresponds to an average electron density of about 0.0002 per cubic centimeter in intergalactic space. This density together with the plasma redshift heating to an average plasma temperature in intergalactic space of about 3 million K explains the observed isotropic cosmic microwave background (CMB) and the cosmic X-ray background.

  1. Mechanistic study of methanol synthesis from CO? and H? on a modified model Mo?S? cluster

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Cheng [Yangzhou Univ., Yangzhou, Jiangsu (China); Liu, Ping [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-02-06T23:59:59.000Z

    We report the methanol synthesis from CO? and H? on metal (M = K, Ti, Co, Rh, Ni, and Cu)-modified model Mo?S? catalyst using density functional theory (DFT). The results show that the catalytic behavior of a Mo?S? cluster is changed significantly due to the modifiers, via the electron transfer from M to Mo?S? and therefore the reduction of the Mo cation (ligand effect) and the direct participation of M in the reaction (ensemble effect) to promote some elementary steps. With the most positively charged modifier, the ligand effect in the case of K-Mo?S? is the most obvious among the systems studied; however it cannot compete with the ensemble effect, which plays a dominate role in determining activity via the electrostatic attraction in particular to stabilize the CHxOy species adsorbed at the Mo sites of Mo?S?. In comparison, the ligand effect is weaker and the ensemble effect is more important when the other modifiers are used. In addition, the modifiers also vary the optimal reaction pathway for methanol synthesis on Mo?S?, ranging from the reverse water-gas shift (RWGS) + CO hydrogenation as that of Mo?S? to the formate pathway. Finally, K is able to accelerate the methanol synthesis on Mo?S? the most; while the promotion by Rh is relatively small. Using the modifiers like Ti, Co, Ni, and Cu, the activity of Mo?S? is decreased instead. The relative stability between *HCOO and *HOCO is identified as a descriptor to capture the variation in mechanism and scales well with the estimated activity. Our study not only provides better understanding of the reaction mechanism and actives on the modified Mo?S?, but also predicts some possible candidates, which can be used a promoter to facilitate the CH?OH synthesis on Mo sulfides.

  2. Mechanistic study of methanol synthesis from CO? and H? on a modified model Mo?S? cluster

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Cheng; Liu, Ping

    2015-02-06T23:59:59.000Z

    We report the methanol synthesis from CO? and H? on metal (M = K, Ti, Co, Rh, Ni, and Cu)-modified model Mo?S? catalyst using density functional theory (DFT). The results show that the catalytic behavior of a Mo?S? cluster is changed significantly due to the modifiers, via the electron transfer from M to Mo?S? and therefore the reduction of the Mo cation (ligand effect) and the direct participation of M in the reaction (ensemble effect) to promote some elementary steps. With the most positively charged modifier, the ligand effect in the case of K-Mo?S? is the most obvious among themore »systems studied; however it cannot compete with the ensemble effect, which plays a dominate role in determining activity via the electrostatic attraction in particular to stabilize the CHxOy species adsorbed at the Mo sites of Mo?S?. In comparison, the ligand effect is weaker and the ensemble effect is more important when the other modifiers are used. In addition, the modifiers also vary the optimal reaction pathway for methanol synthesis on Mo?S?, ranging from the reverse water-gas shift (RWGS) + CO hydrogenation as that of Mo?S? to the formate pathway. Finally, K is able to accelerate the methanol synthesis on Mo?S? the most; while the promotion by Rh is relatively small. Using the modifiers like Ti, Co, Ni, and Cu, the activity of Mo?S? is decreased instead. The relative stability between *HCOO and *HOCO is identified as a descriptor to capture the variation in mechanism and scales well with the estimated activity. Our study not only provides better understanding of the reaction mechanism and actives on the modified Mo?S?, but also predicts some possible candidates, which can be used a promoter to facilitate the CH?OH synthesis on Mo sulfides.« less

  3. Region 2007 2008 2009 2010 2011 2012 New England 183 140 138 140 127 136 -26%

    E-Print Network [OSTI]

    Fernandez, Eduardo

    17% Plains 45 48 50 60 53 59 31% Rocky Mountains 18 18 27 21 21 19 6% Southwest 56 61 61 57 64 83 48 Region Florida Atlantic University CO TX NMAZ UT NV CA OR WA WY ND SD NE KS OK MN WI MI IA MO IL AR AL AK New England Great Lakes Plains Rocky Mountains Far West Florida South west #12;

  4. Enriched Zn$^{100}$MoO$_4$ scintillating bolometers to search for $0 ? 2?$ decay of $^{100}$Mo with the LUMINEU experiment

    E-Print Network [OSTI]

    A. S. Barabash; D. M. Chernyak; F. A. Danevich; A. Giuliani; I. M. Ivanov; E. P. Makarov; M. Mancuso; S. Marnieros; S. G. Nasonov; C. Nones; E. Olivieri; G. Pessina; D. V. Poda; V. N. Shlegel; M. Tenconi; V. I. Tretyak; Ya. V. Vasiliev; M. Velazquez; V. N. Zhdankov

    2014-07-05T23:59:59.000Z

    The LUMINEU project aims at performing a demonstrator underground experiment searching for the neutrinoless double beta decay of the isotope $^{100}$Mo embedded in zinc molybdate (ZnMoO$_4$) scintillating bolometers. In this context, a zinc molybdate crystal boule enriched in $^{100}$Mo to 99.5\\% with a mass of 171 g was grown for the first time by the low-thermal-gradient Czochralski technique. The production cycle provided a high yield (the crystal boule mass was 84\\% of initial charge) and an acceptable level -- around 4\\% -- of irrecoverable losses of the costy enriched material. Two crystals of 59 g and 63 g, obtained from the enriched boule, were tested aboveground at milli-Kelvin temperature as scintillating bolometers. They showed a high detection performance, equivalent to that of previously developed natural ZnMoO$_4$ detectors. These results pave the way to future sensitive searches based on the LUMINEU technology, capable to approach and explore the inverted hierarchy region of the neutrino mass pattern.

  5. Magnetic field-induced phase transformation and variant reorientation in Ni2MnGa and NiMnCoIn magnetic shape memory alloys

    E-Print Network [OSTI]

    Karaca, Haluk Ersin

    2009-05-15T23:59:59.000Z

    The purpose of this work is to reveal the governing mechanisms responsible for the magnetic field-induced i) martensite reorientation in Ni2MnGa single crystals, ii) stress-assisted phase transformation in Ni2MnGa single crystals and iii) phase...

  6. Ferromagnetic Mn moments at SrRuO3/SrMnO3 interfaces Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439

    E-Print Network [OSTI]

    Haskel, Daniel

    Ferromagnetic Mn moments at SrRuO3/SrMnO3 interfaces Y. Choia Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 Y. Z. Yoo, O. Chmaissem, A. Ullah, S. Kolesnik, and C. W University, DeKalb, Illinois 60115 D. Haskel Advanced Photon Source, Argonne National Laboratory, Argonne

  7. Charge transport properties of CdMnTe radiation detectors

    SciTech Connect (OSTI)

    Kim K.; Rafiel, R.; Boardman, M.; Reinhard, I.; Sarbutt, A.; Watt, G.; Watt, C.; Uxa, S.; Prokopovich, D.A.; Belas, E.; Bolotnikov, A.E.; James, R.B.

    2012-04-11T23:59:59.000Z

    Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe)radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading chargecollection is reduced with increasing values of bias voltage. The electron transit time was determined from time of flight measurements. From the dependence of drift velocity on applied electric field the electron mobility was found to be n = (718 55) cm2/Vs at room temperature.

  8. The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey

    SciTech Connect (OSTI)

    Hayden, Brian T.; /Notre Dame U.; Garnavich, Peter M.; /Notre Dame U.; Kessler, Richard; /KICP, Chicago /Chicago U., EFI; Frieman, Joshua A.; /KICP, Chicago /Chicago U. /Fermilab; Jha, Saurabh W.; /Stanford U., Phys. Dept. /Rutgers U., Piscataway; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Cinabro, David; /Wayne State U.; Dilday, Benjamin; /Rutgers U., Piscataway; Kasen, Daniel; /UC, Santa Cruz; Marriner, John; /Fermilab; Nichol, Robert C.; /Portsmouth U., ICG /Baltimore, Space Telescope Sci. /Johns Hopkins U.

    2010-01-01T23:59:59.000Z

    We analyze the rise and fall times of Type Ia supernova (SN Ia) light curves discovered by the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. From a set of 391 light curves k-corrected to the rest-frame B and V bands, we find a smaller dispersion in the rising portion of the light curve compared to the decline. This is in qualitative agreement with computer models which predict that variations in radioactive nickel yield have less impact on the rise than on the spread of the decline rates. The differences we find in the rise and fall properties suggest that a single 'stretch' correction to the light curve phase does not properly model the range of SN Ia light curve shapes. We select a subset of 105 light curves well observed in both rise and fall portions of the light curves and develop a '2-stretch' fit algorithm which estimates the rise and fall times independently. We find the average time from explosion to B-band peak brightness is 17.38 {+-} 0.17 days, but with a spread of rise times which range from 13 days to 23 days. Our average rise time is shorter than the 19.5 days found in previous studies; this reflects both the different light curve template used and the application of the 2-stretch algorithm. The SDSS-II supernova set and the local SNe Ia with well-observed early light curves show no significant differences in their average rise-time properties. We find that slow-declining events tend to have fast rise times, but that the distribution of rise minus fall time is broad and single peaked. This distribution is in contrast to the bimodality in this parameter that was first suggested by Strovink (2007) from an analysis of a small set of local SNe Ia. We divide the SDSS-II sample in half based on the rise minus fall value, t{sub r} - t{sub f} {approx}< 2 days and t{sub r} - t{sub f} > 2 days, to search for differences in their host galaxy properties and Hubble residuals; we find no difference in host galaxy properties or Hubble residuals in our sample.

  9. Large exchange bias enhancement in (Pt(or Pd)/Co)/IrMn/Co trilayers with ultrathin IrMn thanks to interfacial Cu dusting

    SciTech Connect (OSTI)

    Vinai, G. [SPINTEC, UMR 8191 CEA/CNRS/UJF/Grenoble-INP, CEA/INAC, 17, rue des Martyrs, 38054 Grenoble (France); Crocus Technology, 4 Place Robert Schuman, 38054 Grenoble (France); Moritz, J. [Institut Jean Lamour, UMR 7198 CNRS - Université de Lorraine, Bd des Aiguillettes, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Bandiera, S. [Crocus Technology, 4 Place Robert Schuman, 38054 Grenoble (France); Prejbeanu, I. L.; Dieny, B. [SPINTEC, UMR 8191 CEA/CNRS/UJF/Grenoble-INP, CEA/INAC, 17, rue des Martyrs, 38054 Grenoble (France)

    2014-04-21T23:59:59.000Z

    The magnitude of exchange bias (H{sub ex}) at room temperature can be significantly enhanced in IrMn/Co and (Pt(or Pd)/Co)/IrMn/Co structures thanks to the insertion of an ultrathin Cu dusting layer at the IrMn/Co interface. The combination of trilayer structure and interfacial Cu dusting leads to a three-fold increase in H{sub ex} as compared to the conventional IrMn/Co bilayer structure, with an increased blocking temperature (T{sub B}) and a concave curvature of the temperature dependence H{sub ex}(T), ideal for improved Thermally Assisted-Magnetic Random Access Memory storage layer. This exchange bias enhancement is ascribed to a reduction of the spin frustration at the IrMn/Co interface thanks to interfacial Cu addition.

  10. Control of absorption of monolayer MoS$_{2}$ thin-film transistor in one-dimensional defective photonic crystal

    E-Print Network [OSTI]

    Yang, Fang-Fang; Xiao, Wen-bo; Liu, Jiang-Tao; Liu, Nian-Hua

    2014-01-01T23:59:59.000Z

    The light absorption and transmission of monolayer MoS$_{2}$ in a one-dimensional defective photonic crystal (d-1DPC) is theoretically investigated. The study shows that the strong interference effect decreases photon density in particular areas of the microcavity. The d-1DPC can reduce light absorption of monolayer MoS$_{2}$ and enhance light transmission. The impact of monolayer MoS$_{2}$ light absorption on the localization effect of photon is investigated when monolayer MoS$_{2}$ and the organic light-emitting diode are located in the same microcavity. However, monolayer MoS$_{2}$ does not reduce the localization effect of light by regulating the position of monolayer MoS$_{2}$ in the microcavity.

  11. The deflagration stage of Chandrasekhar mass models for type Ia supernovae. I. Early evolution

    SciTech Connect (OSTI)

    Malone, C. M.; Woosley, S. E.; Dong, S. [Department of Astronomy and Astrophysics, The University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Nonaka, A.; Almgren, A. S.; Bell, J. B. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Zingale, M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2014-02-10T23:59:59.000Z

    We present high-resolution, full-star simulations of the post-ignition phase of Type Ia supernovae using the compressible hydrodynamics code Castro. Initial conditions, including the turbulent velocity field and ignition site, are imported directly from a simulation of the last few hours of presupernova convection using a low Mach number code, Maestro. Adaptive mesh refinement allows the initial burning front to be modeled with an effective resolution of 36,864{sup 3} zones (136 m zone{sup –1}). The initial rise and expansion of the deflagration front are tracked until burning reaches the star's edge and the role of the background turbulence on the flame is investigated. The effect of artificially moving the ignition location closer to the star's center is explored. The degree to which turbulence affects the burning front decreases with increasing ignition radius since the buoyancy force is stronger at larger radii. Even central ignition—in the presence of a background convective flow field—is rapidly carried off-center as the flame is carried by the flow field. We compare our results to analytic models for burning thermals, and find that they reproduce the general trends of the bubble's size and mass, but underpredict the amount of buoyant acceleration due to simplifying assumptions of the bubble's properties. Overall, we find that the amount of mass that burns prior to flame break out is small, consistent with a gravitationally confined detonation' occurring at a later epoch, but additional burning will occur following breakout that may modify this conclusion.

  12. Persistent C II absorption in the normal type Ia supernova 2002fk

    SciTech Connect (OSTI)

    Cartier, Régis; Zelaya, Paula [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hamuy, Mario; Maza, José; González, Luis; Huerta, Leonor [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Pignata, Giuliano [Departamento Ciencias Fisicas, Universidad Andres Bello, Av. República 252, Santiago (Chile); Förster, Francisco [Center for Mathematical Modelling, Universidad de Chile, Avenida Blanco Encalada 2120, Piso 7, Santiago (Chile); Folatelli, Gaston [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Phillips, Mark M.; Morrell, Nidia; Contreras, Carlos; Roth, Miguel; González, Sergio [Carnegie Institution of Washington, Las Campanas Observatory, Colina el Pino s/n, Casilla 601 (Chile); Krisciunas, Kevin; Suntzeff, Nicholas B. [Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843 (United States); Clocchiatti, Alejandro [Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago (Chile); Coppi, Paolo [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Koviak, Kathleen, E-mail: rcartier@das.uchile.cl [Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 911901 (United States)

    2014-07-01T23:59:59.000Z

    We present well-sampled UBVRIJHK photometry of SN 2002fk starting 12 days before maximum light through 122 days after peak brightness, along with a series of 15 optical spectra from –4 to +95 days since maximum. Our observations show the presence of C II lines in the early-time spectra of SN 2002fk, expanding at 11,000 km s{sup –1} and persisting until 8 days past maximum light with a velocity of ?9000 km s{sup –1}. SN 2002fk is characterized by a small velocity gradient of v-dot {sub Si} {sub II}=26 km s{sup –1} day{sup –1}, possibly caused by an off-center explosion with the ignition region oriented toward the observer. The connection between the viewing angle of an off-center explosion and the presence of C II in the early-time spectrum suggests that the observation of C II could be also due to a viewing angle effect. Adopting the Cepheid distance to NGC 1309 we provide the first H {sub 0} value based on near-infrared (near-IR) measurements of a Type Ia supernova (SN) between 63.0 ± 0.8 (±3.4 systematic) and 66.7 ± 1.0 (±3.5 systematic) km s{sup –1} Mpc{sup –1}, depending on the absolute magnitude/decline rate relationship adopted. It appears that the near-IR yields somewhat lower (6%-9%) H {sub 0} values than the optical. It is essential to further examine this issue by (1) expanding the sample of high-quality near-IR light curves of SNe in the Hubble flow, and (2) increasing the number of nearby SNe with near-IR SN light curves and precise Cepheid distances, which affords the promise to deliver a more precise determination of H {sub 0}.

  13. Evaluating systematic dependencies of type Ia supernovae : the influence of deflagration to detonation density.

    SciTech Connect (OSTI)

    Jackson, A. P.; Calder, A. C.; Townsley, D. M.; Chamulak, D. A.; Brown, E. F.; Timmes, F. X. (Physics); (State Univ. of New York); (Univ. of Alabama); (Michigan State Univ.); (Arizona State Univ.); (Joint Inst. for Nuclear Astrophysics)

    2010-09-01T23:59:59.000Z

    We explore the effects of the deflagration to detonation transition (DDT) density on the production of {sup 56}Ni in thermonuclear supernova (SN) explosions (Type Ia supernovae). Within the DDT paradigm, the transition density sets the amount of expansion during the deflagration phase of the explosion and therefore the amount of nuclear statistical equilibrium (NSE) material produced. We employ a theoretical framework for a well-controlled statistical study of two-dimensional simulations of thermonuclear SNe with randomized initial conditions that can, with a particular choice of transition density, produce a similar average and range of {sup 56}Ni masses to those inferred from observations. Within this framework, we utilize a more realistic 'simmered' white dwarf progenitor model with a flame model and energetics scheme to calculate the amount of {sup 56}Ni and NSE material synthesized for a suite of simulated explosions in which the transition density is varied in the range (1-3) x 10{sup 7} g cm{sup -3}. We find a quadratic dependence of the NSE yield on the log of the transition density, which is determined by the competition between plume rise and stellar expansion. By considering the effect of metallicity on the transition density, we find the NSE yield decreases by 0.055 {+-} 0.004 M {circle_dot} for a 1 Z {circle_dot} increase in metallicity evaluated about solar metallicity. For the same change in metallicity, this result translates to a 0.067 {+-} 0.004 M {circle_dot} decrease in the {sup 56}Ni yield, slightly stronger than that due to the variation in electron fraction from the initial composition. Observations testing the dependence of the yield on metallicity remain somewhat ambiguous, but the dependence we find is comparable to that inferred from some studies.

  14. EVALUATING SYSTEMATIC DEPENDENCIES OF TYPE Ia SUPERNOVAE: THE INFLUENCE OF DEFLAGRATION TO DETONATION DENSITY

    SciTech Connect (OSTI)

    Jackson, Aaron P.; Calder, Alan C. [Department of Physics and Astronomy, State University of New York-Stony Brook, Stony Brook, NY (United States); Townsley, Dean M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL (United States); Chamulak, David A. [Argonne National Laboratory, Argonne, IL (United States); Brown, Edward F.; Timmes, F. X. [Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States)

    2010-09-01T23:59:59.000Z

    We explore the effects of the deflagration to detonation transition (DDT) density on the production of {sup 56}Ni in thermonuclear supernova (SN) explosions (Type Ia supernovae). Within the DDT paradigm, the transition density sets the amount of expansion during the deflagration phase of the explosion and therefore the amount of nuclear statistical equilibrium (NSE) material produced. We employ a theoretical framework for a well-controlled statistical study of two-dimensional simulations of thermonuclear SNe with randomized initial conditions that can, with a particular choice of transition density, produce a similar average and range of {sup 56}Ni masses to those inferred from observations. Within this framework, we utilize a more realistic 'simmered' white dwarf progenitor model with a flame model and energetics scheme to calculate the amount of {sup 56}Ni and NSE material synthesized for a suite of simulated explosions in which the transition density is varied in the range (1-3) x10{sup 7} g cm{sup -3}. We find a quadratic dependence of the NSE yield on the log of the transition density, which is determined by the competition between plume rise and stellar expansion. By considering the effect of metallicity on the transition density, we find the NSE yield decreases by 0.055 {+-} 0.004 M {sub sun} for a 1 Z{sub sun} increase in metallicity evaluated about solar metallicity. For the same change in metallicity, this result translates to a 0.067 {+-} 0.004 M{sub sun} decrease in the {sup 56}Ni yield, slightly stronger than that due to the variation in electron fraction from the initial composition. Observations testing the dependence of the yield on metallicity remain somewhat ambiguous, but the dependence we find is comparable to that inferred from some studies.

  15. Effects of rhenium alloying on the microstructures and mechanical properties of directionally solidified NiAl-Mo eutectic alloy

    SciTech Connect (OSTI)

    Misra, A.; Wu, Z.L.; Gibala, R. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering

    1997-12-31T23:59:59.000Z

    Low ductility of the reinforcing bcc metal phase at room temperature and weak interfaces can limit the intrinsic toughness and ductility of NiAl-bcc metal eutectic composites. The potential of rhenium (Re) addition, which is known to solid solution soften and lower the ductile-to-brittle transition temperature of various bcc metals, to enhance the ductility and toughness of a directionally solidified NiAl-9 at.% Mo eutectic alloy was investigated. Re partitioned to the bcc metal phase and formed a substitutional solid solution. The interface morphology was changed from a faceted to a non-faceted one. Re alloying caused softening of the Mo fibers, and as a result NiAl-Mo(Re) alloys were softer in compression and flexure and had {approximately}20% higher fracture toughness values as compared to the transverse orientation toughness of NiAl-9Mo alloy. The toughness of the NiAl-Mo(Re) alloys was lower than the longitudinal orientation toughness of the NiAl-9Mo alloy due to the poor alignment of the Mo(Re) phase with the growth direction. The toughening mechanisms have been evaluated and schemes for processing NiAl-Mo(Re) alloys for higher toughness in the longitudinal orientation are suggested. The role of the residual interstitial impurities and partitioning of Ni and Al to Mo fibers on the mechanical properties are highlighted.

  16. Method for the production of {sup 99m}Tc compositions from {sup 99}Mo-containing materials

    DOE Patents [OSTI]

    Bennett, R.G.; Christian, J.D.; Grover, S.B.; Petti, D.A.; Terry, W.K.; Yoon, W.Y.

    1998-09-01T23:59:59.000Z

    An improved method is described for producing {sup 99m}Tc compositions from {sup 99}Mo compounds. {sup 100}Mo metal or {sup 100}MoO{sub 3} is irradiated with photons in a particle (electron) accelerator to ultimately produce {sup 99}MoO{sub 3}. This composition is then heated in a reaction chamber to form a pool of molten {sup 99}MoO{sub 3} with an optimum depth of 0.5--5 mm. A gaseous mixture thereafter evolves from the molten {sup 99}MoO{sub 3} which contains vaporized {sup 99}MoO{sub 3}, vaporized {sup 99m}TcO{sub 3}, and vaporized {sup 99m}TcO{sub 2}. This mixture is then combined with an oxidizing gas (O{sub 2(g)}) to generate a gaseous stream containing vaporized {sup 99m}Tc{sub 2}O{sub 7} and vaporized {sup 99}MoO{sub 3}. Next, the gaseous stream is cooled in a primary condensation stage in the reaction chamber to remove vaporized {sup 99}MoO{sub 3}. Cooling is undertaken at a specially-controlled rate to achieve maximum separation efficiency. The gaseous stream is then cooled in a sequential secondary condensation stage to convert vaporized {sup 99m}Tc{sub 2}O{sub 7} into a condensed {sup 99m}Tc-containing reaction product which is collected. 1 fig.

  17. Method for the production of .sup.99m Tc compositions from .sup.99 Mo-containing materials

    DOE Patents [OSTI]

    Bennett, Ralph G. (Idaho Falls, ID); Christian, Jerry D. (Idaho Falls, ID); Grover, S. Blaine (Idaho Falls, ID); Petti, David A. (Idaho Falls, ID); Terry, William K. (Idaho Falls, ID); Yoon, Woo Y. (Idaho Falls, ID)

    1998-01-01T23:59:59.000Z

    An improved method for producing .sup.99m Tc compositions from .sup.99 Mo compounds. .sup.100 Mo metal or .sup.100 MoO.sub.3 is irradiated with photons in a particle (electron) accelerator to ultimately produce .sup.99 MoO.sub.3. This composition is then heated in a reaction chamber to form a pool of molten .sup.99 MoO.sub.3 with an optimum depth of 0.5-5 mm. A gaseous mixture thereafter evolves from the molten .sup.99 MoO.sub.3 which contains vaporized .sup.99 MoO.sub.3, vaporized .sup.99m TcO.sub.3, and vaporized .sup.99m TcO.sub.2. This mixture is then combined with an oxidizing gas (O.sub.2(g)) to generate a gaseous stream containing vaporized .sup.99m Tc.sub.2 O.sub.7 and vaporized .sup.99 MoO.sub.3. Next, the gaseous stream is cooled in a primary condensation stage in the reaction chamber to remove vaporized .sup.99 MoO.sub.3. Cooling is undertaken at a specially-controlled rate to achieve maximum separation efficiency. The gaseous stream is then cooled in a sequential secondary condensation stage to convert vaporized .sup.99m Tc.sub.2 O.sub.7 into a condensed .sup.99m Tc-containing reaction product which is collected.

  18. An in situ x-ray spectroscopic study of Mo?{sup +} speciation in supercritical aqueous solutions

    SciTech Connect (OSTI)

    Yan, Hao [Missouri State University, Springfield, MO (United States); Mayanovic, Robert A. [Missouri State University, Springfield, MO (United States); Anderson, Alan J. [St. Francis Xavier Univ., Antigonish, NS (Canada); Meredith, Peter R. [St. Francis Xavier Univ., Antigonish, NS (Canada)

    2011-09-01T23:59:59.000Z

    In situ XRF and Mo K-edge XAS measurements were made on the ID20-B beam line at the APS on MoO? in 1 M H?O? aqueous solution, at temperatures between 400 and 600 °C. The samples were analyzed using a modified Bassett-type hydrothermal diamond anvil cell. Our XRF measurements show that MoO? is highly soluble in the supercritical H?O? aqueous fluid. Analysis of XAS spectra shows that the Mo?{sup +} ion exhibits consistent speciation in the H?O? aqueous solution at temperatures ranging from 400 to 600 °C.

  19. Mechanical properties of MoS2/graphene heterostructures Jin-Wu Jiang and Harold S. Park

    E-Print Network [OSTI]

    of the heterostructure is considerably smaller than the MoS2 due to lateral buckling of the outer graphene layers owning

  20. Ge{sub 1-x}Mn{sub x} heteroepitaxial quantum dots: Growth, morphology, and magnetism

    SciTech Connect (OSTI)

    Kassim, J.; Nolph, C.; Reinke, P.; Floro, J. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Jamet, M. [Institut Nanosciences et Cryogenie/SP2M, CEA-UJF, F-38054 Grenoble (France)

    2013-02-21T23:59:59.000Z

    Heteroepitaxial Ge{sub 1-x}Mn{sub x} quantum dots (QDs) were grown on Si (001) by molecular beam epitaxial co-deposition, with x = 0 to 0.10, in order to explore the interaction between Mn content, surface morphological evolution, and magnetism. Morphological evolution typical of the Ge/Si (001) system was observed, where the effect of Mn on surface morphology is surprisingly minimal at low Mn content, with no obvious surface morphological indicators of second phase formation. As the Mn content increases, secondary phase formation becomes evident, appearing to heterogeneously nucleate on or within Ge QDs. Still higher Mn concentrations lead to extensive second phase formation interspersed with an array of Ge QDs. Although ferromagnetism up to 220 K is observed, likely arising from intermetallic precipitates, there is no clear evidence for room-temperature ferromagnetism associated with a dilute magnetic solution phase.

  1. Time resolved magneto-optical studies of ferromagnetic InMnSb films

    SciTech Connect (OSTI)

    Frazier, M.; Kini, R. N.; Nontapot, K.; Khodaparast, G. A. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Wojtowicz, T. [Institute of Physics, Polish Academy of Sciences 02-668 Warsaw (Poland); Liu, X.; Furdyna, J. K. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2008-02-11T23:59:59.000Z

    We report time resolved magneto-optical measurements in InMnSb ferromagnetic films with 2% and 2.8% Mn contents grown by low temperature molecular beam epitaxy. In order to probe a possible interaction between the spins of photoexcited carriers and the Mn ions, we measured spin dynamics before and after aligning the Mn ions by applying an external magnetic field at temperatures above and below the samples' Curie temperatures. We observed no significant temperature or magnetic field dependence in the relaxation times and attribute the observed dynamics entirely to the relaxation of photoexcited electrons in the conduction band where the s-d coupling with the localized Mn ions is significantly weaker compared to the p-d exchange coupling. We observed several differences in the optical response of our InMnSb samples which could have been influenced mainly by the samples' growth conditions.

  2. Elementary Steps of Syngas Reactions on Mo2C(001): Adsorption Thermochemistry and Bond Dissociation

    SciTech Connect (OSTI)

    Medford, Andrew

    2012-02-16T23:59:59.000Z

    Density functional theory (DFT) and ab initio thermodynamics are applied in order to investigate the most stable surface and subsurface terminations of Mo{sub 2}C(001) as a function of chemical potential and in the presence of syngas. The Mo-terminated (001) surface is then used as a model surface to evaluate the thermochemistry and energetic barriers for key elementary steps in syngas reactions. Adsorption energy scaling relations and Broensted-Evans-Polanyi relationships are established and used to place Mo{sub 2}C into the context of transition metal surfaces. The results indicate that the surface termination is a complex function of reaction conditions and kinetics. It is predicted that the surface will be covered by either C{sub 2}H{sub 2} or O depending on conditions. Comparisons to transition metals indicate that the Mo-terminated Mo{sub 2}C(001) surface exhibits carbon reactivity similar to transition metals such as Ru and Ir, but is significantly more reactive towards oxygen.

  3. TEM Characterization of High Burn-up Microstructure of U-7Mo Alloy

    SciTech Connect (OSTI)

    Jian Gan; Brandon Miller; Dennis Keiser; Adam Robinson; James Madden; Pavel Medvedev; Daniel Wachs

    2014-04-01T23:59:59.000Z

    As an essential part of global nuclear non-proliferation effort, the RERTR program is developing low enriched U-Mo fuels (< 20% U-235) for use in research and test reactors that currently employ highly enriched uranium fuels. One type of fuel being developed is a dispersion fuel plate comprised of U-7Mo particles dispersed in Al alloy matrix. Recent TEM characterizations of the ATR irradiated U-7Mo dispersion fuel plates include the samples with a local fission densities of 4.5, 5.2, 5.6 and 6.3 E+21 fissions/cm3 and irradiation temperatures of 101-136?C. The development of the irradiated microstructure of the U-7Mo fuel particles consists of fission gas bubble superlattice, large gas bubbles, solid fission product precipitates and their association to the large gas bubbles, grain subdivision to tens or hundreds of nanometer size, collapse of bubble superlattice, and amorphisation. This presentation will describe the observed microstructures specifically focusing on the U-7Mo fuel particles. The impact of the observed microstructure on the fuel performance and the comparison of the relevant features with that of the high burn-up UO2 fuels will be discussed.

  4. Beta. -MoO sub 3 produced from a novel freeze drying route

    SciTech Connect (OSTI)

    Parise, J.B. (State Univ. of New York, Stony Brook (United States)); McCarron, E.M. III (E.I. Dupont de Nemours and Co., Inc., Wilmington, DE (United States)); Von Dreele, R.; Goldstone, J.A. (Los Alamos National Lab., NM (United States))

    1991-07-01T23:59:59.000Z

    Powdered samples of {beta}-MoO{sub 3} have been produced by the gentle heat treatment of freeze-dried molybdic acid at 350{degree}C for 1 hr. The samples, yellow-green in appearance, contained varying amounts of the thermodynamically stable {alpha}-MoO{sub 3}, depending upon the time and temperature of heat treatment. Neutron diffraction data were collected at 300 K. all peaks, not attributable to {alpha}-MoO{sub 3}, were indexed on the basis of a monoclinic cell, P2{sub 1}/c, {alpha} = 7.1228(7), b = 5.3660(6), c = 5.5665(6), {beta} = 92.01(1){degree}, V = 212.62(6){angstrom}{sup 3}. The structure, which is related to ReO{sub 3}, contains two crystallographically independent octahedra. Both show evidence of disorder at the Mo and O sites. Two distinct orientations of a short mo-O distance, suggestive of the type of molybdenyl bond observed in both the {alpha} and {beta}{prime}-forms, are primarily responsible for the observed disordering.

  5. Oxidation and creep behavior of Mo*5*Si*3* based materials

    SciTech Connect (OSTI)

    Meyer, M.

    1995-06-19T23:59:59.000Z

    Mo{sub 5}Si{sub 3} shows promise as a high temperature creep resistant material. The high temperature oxidation resistance of Mo{sub 5}Si{sub 3} has been found to be poor, however, limiting its use in oxidizing atmospheres. Undoped Mo{sub 5}Si{sub 3} exhibits mass loss in the temperature range 800{degrees}-1200{degrees}C due to volatilization of molybdenum oxide, indicating that the silica scale does not provide a passivating layer. The addition of boron results in protective scale formation and parabolic oxidation kinetics in the temperature range of 1050{degrees}-1300{degrees}C. The oxidation rate of Mo{sub 5}Si{sub 3} was decreased by 5 orders of magnitude at 1200{degrees}C by doping with less than two weight percent boron. Boron doping eliminates catastrophic {open_quote}pest{close_quote} oxidation at 800{degrees}C. The mechanism for improved oxidation resistance of boron doped Mo{sub 5}Si{sub 3} is due to scale modification by boron.

  6. Liquid generation during sintering of Fe-3.5%Mo powder compacts with elemental boron additions

    SciTech Connect (OSTI)

    Sarasola, M.; Gomez-Acebo, T.; Castro, F

    2004-09-06T23:59:59.000Z

    The mechanisms for liquid generation and the microstructural development during sintering of a Fe-3.5Mo-0.3B alloy were studied. Interrupted sintering experiments followed by water quenching from specific temperatures within the sintering cycle have been carried out. The influence of Mo, both, on the final microstructure and on the behaviour of boron prior to, during and after the formation of the liquid phase, was studied through observation of the quenched samples under LOM and SEM. The study shows that prior to the formation of the liquid phase, boron diffuses into the metallic particles forming inter and intragranular precipitates of the (Fe,Mo){sub 2}B type. At higher temperatures a continuous Fe/Mo/B liquid phase, with excellent wetting characteristics, is formed thus leading to near fully dense materials. The generation of the liquid is based on a eutectic reaction involving the mixed (Fe,Mo){sub 2}B borides previously formed. The development of the microstructure after liquid formation is described.

  7. argillacea huebner caterpillars: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Des Moines, IA Caterpillar Mossville, IL Caterpillar Peoria, IL Cerner Kansas City, MO Eaton Naperville, IL Procter &Gamble (Oral B) Iowa City, IA RISE-Cancer Research Center...

  8. IV. -PHOTOMAGNETISM AND CONDUCT I W r PHOTOMAGNETIC EFFECT IN A Li-Mn FERRITE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    IV. - PHOTOMAGNETISM AND CONDUCT I W r PHOTOMAGNETIC EFFECT IN A Li-Mn FERRITE P. BERNSTEIN and T'effet photomagnCtique dans le ferrite Fez,I oLi0.45Mn0.4504 au moyen de la variation de la perm investigated in a Fez.loLi0.45Mn0.4504ferrite by looking at the variations of the permeability under light

  9. Doping-level-dependent optical properties of GaN:Mn O. Gelhausen,a)

    E-Print Network [OSTI]

    Nabben, Reinhard

    for system response. The optical absorption spectra recorded at 2 K of nomi- nally undoped GaN, GaN:Mn, and GaN:Mn:Si are presented in Fig. 1. An absorption band with a zero phonon line ZPL at 1.414 0.002 eDoping-level-dependent optical properties of GaN:Mn O. Gelhausen,a) E. Malguth, and M. R. Phillips

  10. Optical Properties of Mn-doped GaN O. Gelhausen1

    E-Print Network [OSTI]

    Nabben, Reinhard

    measurements. In the GaN:Mn, an intense absorption peak at 1.414 +/- 0.002 eV was observed. This peakOptical Properties of Mn-doped GaN O. Gelhausen1 , E. Malguth1,3 , M. R. Phillips1 , E. M. Goldys2, Germany ABSTRACT Molecular beam epitaxy-grown GaN with different Mn concentrations (5-23 x 1019 cm-3

  11. Strain mediated coupling in magnetron sputtered multiferroic PZT/Ni-Mn-In/Si thin film heterostructure

    SciTech Connect (OSTI)

    Singh, Kirandeep; Kaur, Davinder, E-mail: dkaurfph@iitr.ernet.in [Functional Nanomaterials Research Lab, Department of Physics and Centre of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee-247667, Uttarakhand (India); Singh, Sushil Kumar [Functional Materials Division, Solid State Physics Lab (SSPL), DRDO, Lucknow Road, Timarpur, Delhi 110054 (India)

    2014-09-21T23:59:59.000Z

    The strain mediated electrical and magnetic properties were investigated in PZT/Ni-Mn-In heterostructure deposited on Si (100) by dc/rf magnetron sputtering. X-ray diffraction pattern revealed that (220) orientation of Ni-Mn-In facilitate the (110) oriented tertragonal phase growth of PZT layer in PZT/Ni-Mn-In heterostructure. A distinctive peak in dielectric constant versus temperature plots around martensitic phase transformation temperature of Ni-Mn-In showed a strain mediated coupling between Ni-Mn-In and PZT layers. The ferroelectric measurement taken at different temperatures exhibits a well saturated and temperature dependent P-E loops with a highest value of P{sub sat}???55 ?C/cm{sup 2} obtained during martensite-austenite transition temperature region of Ni-Mn-In. The stress induced by Ni-Mn-In layer on upper PZT film due to structural transformation from martensite to austenite resulted in temperature modulated Tunability of PZT/Ni-Mn-In heterostructure. A tunability of 42% was achieved at 290?K (structural transition region of Ni-Mn-In) in these heterostructures. I-V measurements taken at different temperatures indicated that ohmic conduction was the main conduction mechanism over a large electric field range in these heterostructures. Magnetic measurement revealed that heterostructure was ferromagnetic at room temperature with a saturation magnetization of ?123?emu/cm{sup 3}. Such multiferroic heterostructures exhibits promising applications in various microelectromechanical systems.

  12. Mn(II) Oxidation by an Ascomycete Fungus is Linked to Superoxide...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Asexual Reproduction. Abstract: Manganese (Mn) oxides are among the most reactive minerals within the environment, where they control the bioavailability of carbon, nutrients,...

  13. Enhancing SMM properties via axial distortion of Mn-3(III) clusters 

    E-Print Network [OSTI]

    Parsons S.; Brechin, E.K.; Collins A.; Karotsis G.; Jones L.F.; Inglis R.; Wernsdorfer W.; Perlepes S.P.

    2008-01-01T23:59:59.000Z

    Replacement of carboxylate and solvent with facially capping tripodal ligands enhances the single-molecule magnet (SMM) properties of [Mn-3(III)] triangles.

  14. Metastable phase boundaries of quasicrystalline phases. [Al-Mn; Al-Ru

    SciTech Connect (OSTI)

    Follstaedt, D.M.; Knapp, J.A.

    1987-01-01T23:59:59.000Z

    The melting curve (T/sub 0/) of the metastable icosahedral phase and the liquidus of the decagonal phase of Al-Mn have been obtained for 14 to 22 at. % Mn. Icosahedral Al-Mn has a congruent melting point of 910 +- 20/sup 0/C at 20 at. % Mn, and melts approx.30/sup 0/C lower than crystalline compounds with the same composition. Icosahedral Al/sub 82/Ru/sub 18/ was determined to melt at 1260 +- 30/sup 0/C. These results were obtained by forming single-phase icosahedral alloys with ion beam mixing, and by rapid heating to accurately known temperatures with electron beams.

  15. HIGH RESOLUTION SCANNING AUGER MICROSCOPIC INVESTIGATION OF INTERGRANULAR FRACTURE IN AS-QUENCHED Fe-12Mn

    E-Print Network [OSTI]

    Lee, H.J.

    2013-01-01T23:59:59.000Z

    contents in Fe-Mn alloys. Scanning electron fractographsTransactions HIGH RESOLUTION SCANNING AUGER MICROSCOPICof Califomia. HIGH RESOLUTION SCANNING AUGER MICROSCOPIC

  16. Preparation and electrochemical properties of lamellar MnO{sub 2} for supercapacitors

    SciTech Connect (OSTI)

    Yan, Jun; Wei, Tong [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Cheng, Jie [Research Institute of Chemical Defense, Beijing 100083 (China)] [Research Institute of Chemical Defense, Beijing 100083 (China); Fan, Zhuangjun, E-mail: fanzhj666@163.com [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang, Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)] [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2010-02-15T23:59:59.000Z

    Lamellar birnessite-type MnO{sub 2} materials were prepared by changing the pH of the initial reaction system via hydrothermal synthesis. The interlayer spacing of MnO{sub 2} with a layered structure increased gradually when the initial pH value varied from 12.43 to 2.81, while the MnO{sub 2}, composed of {alpha}-MnO{sub 2} and {gamma}-MnO{sub 2}, had a rod-like structure at pH 0.63. Electrochemical studies indicated that the specific capacitance of birnessite-type MnO{sub 2} was much higher than that of rod-like MnO{sub 2} at high discharge current densities due to the lamellar structure with fast intercalation/deintercalation of protons and high utilization of MnO{sub 2}. The initial specific capacitance of MnO{sub 2} prepared at pH 2.81 was 242.1 F g{sup -1} at 2 mA cm{sup -2} in 2 mol L{sup -1} (NH{sub 4}){sub 2}SO{sub 4} aqueous electrolyte. The capacitance increased by about 8.1% of initial capacitance after 200 cycles at a current density of 100 mA cm{sup -2}.

  17. Magnetization relaxation in (Ga,Mn)As ferromagnetic semiconductors 

    E-Print Network [OSTI]

    Sinova, Jairo; Jungwirth, T.; Liu, X.; Sasaki, Y.; Furdyna, JK; Atkinson, WA; MacDonald, AH.

    2004-01-01T23:59:59.000Z

    description of ferromagnetism in many diluted magnetic semiconductors ~DMS?s!, ~Ga,M- n!As in particular.2,3 Exchange-coupling between local mo- ments and itinerant electrons should also contribute signifi- 0163-1829/2004/69~8!/085209~6!/$22.50 69 085209... suggests g contributes significantly to the damping rate of the g the theoretical Gilbert coefficient with the values typical critical current for spin-transfer magnetization s low as ;105 A cm22. PACS number~s!: 73.20.Mf, 73.40.2c, 85.75.2d curate...

  18. Atomistic full-band simulations of monolayer MoS{sub 2} transistors

    SciTech Connect (OSTI)

    Chang, Jiwon; Register, Leonard F.; Banerjee, Sanjay K. [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)] [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)

    2013-11-25T23:59:59.000Z

    We study the transport properties of deeply scaled monolayer MoS{sub 2} n-channel metal-oxide-semiconductor field effect transistors (MOSFETs), using full-band ballistic quantum transport simulations, with an atomistic tight-binding Hamiltonian obtained from density functional theory. Our simulations suggest that monolayer MoS{sub 2} MOSFETs can provide near-ideal subthreshold slope, suppression of drain-induced barrier lowering, and gate-induced drain leakage. However, these full-band simulations exhibit limited transconductance. These ballistic simulations also exhibit negative differential resistance (NDR) in the output characteristics associated with the narrow width in energy of the lowest conduction band, but this NDR may be substantially reduced or eliminated by scattering in MoS{sub 2}.

  19. Highly conducting SrMoO{sub 3} thin films for microwave applications

    SciTech Connect (OSTI)

    Radetinac, Aldin, E-mail: aldin@oxide.tu-darmstadt.de; Mani, Arzhang; Ziegler, Jürgen; Alff, Lambert; Komissinskiy, Philipp, E-mail: komissinskiy@oxide.tu-darmstadt.de [Institute of Materials Science, TU Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany); Melnyk, Sergiy; Nikfalazar, Mohammad; Zheng, Yuliang; Jakoby, Rolf [Institute for Microwave Engineering and Photonics, TU Darmstadt, Merckstraße 25, 64283 Darmstadt (Germany)

    2014-09-15T23:59:59.000Z

    We have measured the microwave resistance of highly conducting perovskite oxide SrMoO{sub 3} thin film coplanar waveguides. The epitaxial SrMoO{sub 3} thin films were grown by pulsed laser deposition and showed low mosaicity and smooth surfaces with a root mean square roughness below 0.3?nm. Layer-by-layer growth could be achieved for film thicknesses up to 400?nm as monitored by reflection high-energy electron diffraction and confirmed by X-ray diffraction. We obtained a constant microwave resistivity of 29???·cm between 0.1 and 20?GHz by refining the frequency dependence of the transmission coefficients. Our result shows that SrMoO{sub 3} is a viable candidate as a highly conducting electrode material for all-oxide microwave electronic devices.

  20. Time exposure performance of Mo-Au Gibbsian segregating alloys for extreme ultraviolet collector optics

    SciTech Connect (OSTI)

    Qiu Huatan; Srivastava, Shailendra N.; Thompson, Keith C.; Neumann, Martin J.; Ruzic, David N

    2008-05-01T23:59:59.000Z

    Successful implementation of extreme ultraviolet (EUV) lithography depends on research and progress toward minimizing collector optics degradation from intense plasma erosion and debris deposition. Thus studying the surface degradation process and implementing innovative methods, which could enhance the surface chemistry causing the mirrors to suffer less damage, is crucial for this technology development. A Mo-Au Gibbsian segregation (GS) alloy is deposited on Si using a dc dual-magnetron cosputtering system and the damage is investigated as a result of time dependent exposure in an EUV source. A thin Au segregating layer is maintained through segregation during exposure, even though overall erosion in the Mo-Au sample is taking place in the bulk. The reflective material, Mo, underneath the segregating layer is protected by this sacrificial layer, which is lost due to preferential sputtering. In addition to theoretical work, experimental results are presented on the effectiveness of the GS alloys to be used as potential EUV collector optics material.