Sample records for limits matter ge

  1. Limited-area growth of Ge and SiGe on Si

    E-Print Network [OSTI]

    Kim, Meekyung, Ph. D. Massachusetts Institute of Technology

    2011-01-01T23:59:59.000Z

    The goal of this thesis is to develop and understand processing conditions that improve the surface morphology and reduce the dislocation density in limited-area heteroepitaxy of Ge and SiGe on Si (100) substrates. Low ...

  2. Reducing 68Ge Background in Dark Matter Experiments

    SciTech Connect (OSTI)

    Kouzes, Richard T.; Orrell, John L.

    2011-03-01T23:59:59.000Z

    Experimental searches for dark matter include experiments with sub-0.5 keV-energy threshold high purity germanium detectors. Experimental efforts, in partnership with the CoGeNT Collaboration operating at the Soudan Underground Laboratory, are focusing on energy threshold reduction via noise abatement, reduction of backgrounds from cosmic ray generated isotopes, and ubiquitous environmental radioactive sources. The most significant cosmic ray produced radionuclide is 68Ge. This paper evaluates reducing this background by freshly mining and processing germanium ore. The most probable outcome is a reduction of the background by a factor of two, and at most a factor of four. A very cost effective alternative is to obtain processed Ge as soon as possible and store it underground for 18 months.

  3. Deviations from ideal nucleation-limited relaxation in high-Ge content compositionally graded SiGe/Si*

    E-Print Network [OSTI]

    Deviations from ideal nucleation-limited relaxation in high-Ge content compositionally graded SiGe the sudden rise in threading dislocation density in Ge-rich relaxed graded SiGe layers grown at higher growth systems, including relaxed graded SiGe on Si substrates i.e., x Si1-xGex /Si ,1,2 InGaP on GaP substrates

  4. Limits on supersymmetric dark matter from EGRET observations of the Galactic center region

    SciTech Connect (OSTI)

    Hooper, Dan [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, Wisconsin, 53706 (United States); Dingus, Brenda L. [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, Wisconsin, 53706 (United States); Los Alamos National Lab, Mississippi H803 P-23, Los Alamos, New Mexico 87545 (United States)

    2004-12-01T23:59:59.000Z

    In most supersymmetic models, neutralino dark matter particles are predicted to accumulate in the Galactic center and annihilate generating, among other products, gamma rays. The Energetic Gamma Ray Experiment Telescope has made observations in this region, and is sensitive to gamma rays from 30 MeV to {approx}30 GeV. We have used an improved point source analysis including an energy dependent point spread function and an unbinned maximum likelihood technique, which has allowed us to lower the limits on gamma ray flux from the Galactic center by more than 1 order of magnitude. We find that the present Energetic Gamma Ray Experiment Telescope data can limit many supersymmetric models if the density of the Galactic dark matter halo is cuspy or spiked toward the Galactic center. We also discuss the ability of the Gamma ray Large Area Space Telescope to test these models.

  5. Limits on Supersymmetric Dark Matter From EGRET Observations of the Galactic Center Region

    E-Print Network [OSTI]

    Dan Hooper; Brenda Dingus

    2002-10-29T23:59:59.000Z

    In most supersymmetic models, neutralino dark matter particles are predicted to accumulate in the Galactic center and annihilate generating, among other products, gamma rays. The EGRET experiment has made observations in this region, and is sensitive to gamma rays from 30 MeV to $\\sim$30 GeV. We have used an improved point source analysis including an energy dependent point spread function and an unbinned maximum likelihood technique, which has allowed us to significantly lower the limits on gamma ray flux from the Galactic center. We find that the present EGRET data can limit many supersymmetric models if the density of the Galactic dark matter halo is cuspy or spiked toward the Galactic center. We also discuss the ability of GLAST to test these models.

  6. Limits on Supersymmetric Dark Matter From EGRET Observations of the Galactic Center Region

    E-Print Network [OSTI]

    Hooper, D; Hooper, Dan; Dingus, Brenda

    2002-01-01T23:59:59.000Z

    In most supersymmetic models, neutralino dark matter particles are predicted to accumulate in the Galactic center and annihilate generating, among other products, gamma rays. The EGRET experiment has made observations in this region, and is sensitive to gamma rays from 30 MeV to $\\sim$30 GeV. We have used an improved point source analysis including an energy dependent point spread function and an unbinned maximum likelihood technique, which has allowed us to significantly lower the limits on gamma ray flux from the Galactic center. We find that the present EGRET data can limit many supersymmetric models if the density of the Galactic dark matter halo is cuspy or spiked toward the Galactic center. We also discuss the ability of GLAST to test these models.

  7. Improved Spin Dependent Limits from the PICASSO Dark Matter Search Experiment

    E-Print Network [OSTI]

    Barnabe-Heider, M; Clark, K; Marco, M D; Doane, P; Feighery, W; Genest, M H; Gornea, R; Guenette, R; Kanagalingam, S; Krauss, C; Leroy, C; Lessard, L; Levine, I; Martin, J P; Mathusi, C; Noble, A; Noulty, R; Wichoski, U; Zacek, V

    2005-01-01T23:59:59.000Z

    The PICASSO experiment reports an improved limit for the existence of cold dark matter WIMPs interacting via spin-dependent interactions with nuclei. The experiment is installed in the Sudbury Neutrino Observatory at a depth of 2070 m. With superheated C4F10 droplets as the active material, and an exposure of 1.98+-0.19 kgd, no evidence for a WIMP signal was found. For a WIMP mass of 29 GeV/c2, limits on the spin-dependent cross section on protons of sigma_p = 1.31 pb and on neutrons of sigma_n = 21.5 pb have been obtained at 90% C.L. In both cases, some new parameter space in the region of WIMP masses below 20 GeV/c2 has now been ruled out. The results of these measurements are also presented in terms of limits on the effective WIMP-proton and neutron coupling strengths a_p and a_n.

  8. Improved Spin Dependent Limits from the PICASSO Dark Matter Search Experiment

    E-Print Network [OSTI]

    The PICASSO Collaboration; M. Barnabe-Heider; E. Behnke; K. Clark; M. Di Marco; P. Doane; W. Feighery; M. -H. Genest; R. Gornea; R. Guenette; S. Kanagalingam; C. B. Krauss; C. Leroy; L. Lessard; I. Levine; J. -P. Martin; C. Muthusi; A. J. Noble; R. Noulty; U. Wichoski; V. Zacek

    2005-08-09T23:59:59.000Z

    The PICASSO experiment reports an improved limit for the existence of cold dark matter WIMPs interacting via spin-dependent interactions with nuclei. The experiment is installed in the Sudbury Neutrino Observatory at a depth of 2070 m. With superheated C4F10 droplets as the active material, and an exposure of 1.98+-0.19 kgd, no evidence for a WIMP signal was found. For a WIMP mass of 29 GeV/c2, limits on the spin-dependent cross section on protons of sigma_p = 1.31 pb and on neutrons of sigma_n = 21.5 pb have been obtained at 90% C.L. In both cases, some new parameter space in the region of WIMP masses below 20 GeV/c2 has now been ruled out. The results of these measurements are also presented in terms of limits on the effective WIMP-proton and neutron coupling strengths a_p and a_n.

  9. Exclusion limits on the WIMP-nucleon cross-section from the Cryogenic Dark Matter Search

    E-Print Network [OSTI]

    CDMS Collaboration

    2002-08-16T23:59:59.000Z

    The Cryogenic Dark Matter Search (CDMS) employs low-temperature Ge and Si detectors to search for Weakly Interacting Massive Particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with >99.9% efficiency, and surface events are rejected with >95% efficiency. The estimate of the background due to neutrons is based primarily on the observation of multiple-scatter events that should all be neutrons. Data selection is determined primarily by examining calibration data and vetoed events. Resulting efficiencies should be accurate to about 10%. Results of CDMS data from 1998 and 1999 with a relaxed fiducial-volume cut (resulting in 15.8 kg-days exposure on Ge) are consistent with an earlier analysis with a more restrictive fiducial-volume cut. Twenty-three WIMP candidate events are observed, but these events are consistent with a background from neutrons in all ways tested. Resulting limits on the spin-independent WIMP-nucleon elastic-scattering cross-section exclude unexplored parameter space for WIMPs with masses between 10-70 GeV c^{-2}. These limits border, but do not exclude, parameter space allowed by supersymmetry models and accelerator constraints. Results are compatible with some regions reported as allowed at 3-sigma by the annual-modulation measurement of the DAMA collaboration. However, under the assumptions of standard WIMP interactions and a standard halo, the results are incompatible with the DAMA most likely value at >99.9% CL, and are incompatible with the model-independent annual-modulation signal of DAMA at 99.99% CL in the asymptotic limit.

  10. Dark matter limits froma 15 kg windowless bubble chamber

    SciTech Connect (OSTI)

    Szydagis, Matthew Mark; /Chicago U.

    2010-12-01T23:59:59.000Z

    The COUPP collaboration has successfully used bubble chambers, a technology previously applied only to high-energy physics experiments, as direct dark matter detectors. It has produced the world's most stringent spin-dependent WIMP limits, and increasingly competitive spin-independent limits. These limits were achieved by capitalizing on an intrinsic rejection of the gamma background that all other direct detection experiments must address through high-density shielding and empirically-determined data cuts. The history of COUPP, including its earliest prototypes and latest results, is briefly discussed in this thesis. The feasibility of a new, windowless bubble chamber concept simpler and more inexpensive in design is discussed here as well. The dark matter limits achieved with a 15 kg windowless chamber, larger than any previous COUPP chamber (2 kg, 4 kg), are presented. Evidence of the greater radiopurity of synthetic quartz compared to natural is presented using the data from this 15 kg device, the first chamber to be made from synthetic quartz. The effective reconstruction of the three-dimensional positions of bubbles in a highly distorted optical field, with ninety-degree bottom lighting similar to cloud chamber lighting, is demonstrated. Another innovation described in this thesis is the use of the sound produced by bubbles recorded by an array of piezoelectric sensors as the primary means of bubble detection. In other COUPP chambers, cameras have been used as the primary trigger. Previous work on bubble acoustic signature differentiation using piezos is built upon in order to further demonstrate the ability to discriminate between alpha- and neutron-induced events.

  11. Baryonic Dark Matter: Limits from HST and ISO

    E-Print Network [OSTI]

    Gerard Gilmore; IoA Cambridge; UK

    1998-12-15T23:59:59.000Z

    Recent HST and ISO observations provide very severe limits on any compact baryonic contributions to galactic (dark) halos. When combined with Milky Way Galaxy microlensing results, almost the entire plausible range of massive compact baryonic objects is excluded by direct observation. Deep direct imaging at 7mu and 15mu with ISOCAM on the ISO spacecraft directly excludes hydrogen-burning stars of any mass above the hydrogen-burning limit, and of any chemical abundance, from being the predominant explanation of the dark halos of external spiral galaxies. In the Milky Way Galaxy, HST has provided luminosity functions to the hydrogen-burning limit in several globular clusters. The resulting mass functions do not provide any support for dominance by very low-mass stars. This is consistent with field surveys for sub-stellar mass brown dwarfs, which show such objects to be relatively rare. These results are complemented by very deep HST luminosity functions in the Large Magellanic Cloud, providing strong support for the (near)-universality of the stellar mass function. Very recent HST results are available for the nearby dSph galaxy UMi. This galaxy, the most dark-matter dominated object known on kpc scales, has a normal stellar mass function at low masses. The prospects are bright for dark elementary particles.

  12. GeV Gamma-ray Flux Upper Limits from Clusters of Galaxies

    E-Print Network [OSTI]

    al., M Ackermann et

    2010-01-01T23:59:59.000Z

    The detection of diffuse radio emission associated with clusters of galaxies indicates populations of relativistic leptons infusing the intracluster medium. Those electrons and positrons are either injected into and accelerated directly in the intracluster medium, or produced as secondary pairs by cosmic-ray ions scattering on ambient protons. Radiation mechanisms involving the energetic leptons together with decay of neutral pions produced by hadronic interactions have the potential to produce abundant GeV photons. Here, we report on the search for GeV emission from clusters of galaxies using data collected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi) from August 2008 to February 2010. Thirty-three galaxy clusters have been selected according to their proximity and high mass, X-ray flux and temperature, and indications of non-thermal activity for this study. We report upper limits on the photon flux in the range 0.2-100 GeV towards a sample of observed clusters (typical va...

  13. Gravitational Lensing Limits on Cold Dark Matter and Its Variants

    E-Print Network [OSTI]

    Christopher S. Kochanek

    1994-11-19T23:59:59.000Z

    Standard $\\Omega_0=1$ cold dark matter (CDM) needs $0.27 < \\sigma_8 < 0.63$ ($2\\sigma$) to fit the observed number of large separation lenses, and the constraint is nearly independent of $H_0=100h^{-1}\\kms$ Mpc$^{-1}$. This range is strongly inconsistent with the COBE estimate of $\\sigma_8=(2.8\\pm0.2)h$. Tilting the primordial spectrum $\\propto k^n$ from $n=1$ to $0.3 \\ltorder n \\ltorder 0.7$, using an effective Hubble constant of $0.15 \\ltorder \\Gamma=h \\ltorder 0.30$, or reducing the matter density to $0.15 \\ltorder \\Omega_0 h \\ltorder 0.3$ either with no cosmological constant ($\\lambda_0=0$) or in a flat universe with a cosmological constant ($\\Omega_0+\\lambda_0=1$) can bring the lensing estimate of $\\sigma_8$ into agreement with the COBE estimates. The models and values for $\\sigma_8$ consistent with both lensing and COBE match the estimates from the local number density of clusters and correlation functions. The conclusions are insensitive to systematic errors except for the assumption that cluster core radii are singular. If clusters with $\\rho\\propto(r^2+s^2)^{-1}$ have core radii exceeding $s = 15h^{-1}\\sigma_3^2$ kpc for a cluster with velocity dispersion $\\sigma=10^3\\sigma_3 \\kms$ then the estimates are invalid. There is, however, a fine tuning problem in making the cluster core radii large enough to invalidate the estimates of $\\sigma_8$ while producing several lenses that do not have central or ``odd images.'' The estimated completeness of the current samples of lenses larger than $5\\parcs0$ is 20\\%, because neither quasar surveys nor lens surveys are optimized to this class of lenses.

  14. General relativity limit of the scalar-tensor theories for traceless matter field

    E-Print Network [OSTI]

    A. Bhadra

    2002-04-03T23:59:59.000Z

    $\\omega(\\phi) \\to \\infty$ limit of scalar tensor theories are studied for traceless matter source. It is shown that the limit $\\omega(\\phi) \\to \\infty$ does not reduce a scalar tensor theory to general relativity. An exact radiation solution of scalar tensor cosmology under Nordtvedt conditions is obtained for flat Friedmann universe.

  15. Nuclear spin structure in dark matter search: The finite momentum transfer limit

    E-Print Network [OSTI]

    V. A. Bednyakov; F. Simkovic

    2006-08-09T23:59:59.000Z

    Spin-dependent elastic scattering of weakly interacting massive dark matter particles (WIMP) off nuclei is reviewed. All available, within different nuclear models, structure functions S(q) for finite momentum transfer (q>0) are presented. These functions describe the recoil energy dependence of the differential event rate due to the spin-dependent WIMP-nucleon interactions. This paper, together with the previous paper ``Nuclear spin structure in dark matter search: The zero momentum transfer limit'', completes our review of the nuclear spin structure calculations involved in the problem of direct dark matter search.

  16. Limits in late time conversion of cold dark matter into dark radiation

    SciTech Connect (OSTI)

    Boriero, D.; Holanda, P. C. de; Motta, M., E-mail: danielb@ifi.unicamp.br, E-mail: holanda@ifi.unicamp.br, E-mail: mmota@ifi.unicamp.br [Instituto de Física Gleb Wataghin – UNICAMP, 13083-859, Campinas SP (Brazil)

    2013-06-01T23:59:59.000Z

    Structure formation creates high temperature and density regions in the Universe that allow the conversion of matter into more stable states, with a corresponding emission of relativistic matter and radiation. An example of such a mechanism is the supernova event, that releases relativistic neutrinos corresponding to 99% of the binding energy of remnant neutron star. We take this phenomena as a starting point for an assumption that similar processes could occur in the dark sector, where structure formation would generate a late time conversion of cold dark matter into a relativistic form of dark matter. We performed a phenomenological study about the limits of this conversion, where we assumed a transition profile that is a generalized version of the neutrino production in supernovae events. With this assumption, we obtained an interesting modification for the constraint over the cold dark matter density. We show that when comparing with the standard ?CDM cosmology, there is no preference for conversion, although the best fit is within 1? from the standard model best fit. The methodology and the results obtained qualify this conversion hypothesis, from the large scale structure point of view, as a viable and interesting model to be tested in the future with small scale data, and mitigate discrepancies between observations at this scale and the pure cold dark matter model.

  17. Nuclear matter effects on J/? production in asymmetric Cu+Au collisions at ?SNN=200 GeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adare, A.

    2014-12-01T23:59:59.000Z

    We report on J/? production from asymmetric Cu+Au heavy-ion collisions at ?sNN =200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/? yields in Cu+Au collisions in the Au-going direction is found to be comparable to that in Au+Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/? production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression in themore »larger Au nucleus. The relative suppression is opposite to that expected from hot nuclear matter dissociation, since a higher energy density is expected in the Au-going direction.« less

  18. Light NMSSM Neutralino Dark Matter in the Wake of CDMS II and a 126 GeV Higgs

    E-Print Network [OSTI]

    Kozaczuk, Jonathan

    2013-01-01T23:59:59.000Z

    Recent results from the Cryogenic Dark Matter Search (CDMS) experiment have renewed interest in light dark matter with a large spin-independent neutralino-nucleon scattering cross-section. Here, we examine the regions of the NMSSM capable of producing a light neutralino with a large direct detection cross-section, with scattering mediated by a light singlet-like scalar, and a 126 GeV Higgs consistent with the LHC results. We focus on two different scenarios for annihilation in the early universe, namely annihilation mediated by (1) a light scalar or by (2) a light pseudoscalar. We find that there exists viable parameter space in which a very light CP-even Higgs boson mediates both the neutralino-nucleon spin-independent elastic scattering and the neutralino pair-annihilation in the early universe. These regions can feature significant tree-level contributions to the SM-like Higgs mass and hence not require very heavy or highly-mixed stops. The strongest constraints in this case come from the decays of the SM-...

  19. Exclusion limits on the WIMP-nucleon cross section from the first run of the Cryogenic Dark Matter Search in the Soudan Underground Laboratory

    SciTech Connect (OSTI)

    Armel-Funkhouser, M.S.; /UC, Berkeley; Attisha, M.J.; /Case Western Reserve U.; Bailey, C.N.; /Case Western Reserve U.; Baudis, L.; /Florida U.; Bauer, Daniel A.; /Fermilab; Brink, P.L.; /Case Western Reserve U.; Bunker, R.; /UC, Santa Barbara; Cabrera, B.; /Case Western Reserve U.; Caldwell, D.O.; /UC, Santa Barbara; Chang, C.L.; /Case Western Reserve U.; Crisler, M.B.; /Fermilab; Cushman, P.; /Minnesota U.; Daal, M.; /UC, Berkeley; Dixon, R.; /Fermilab; Dragowsky, M.R.; Driscoll, D.D.; /Case Western Reserve U.; Duong, L.; /Minnesota U.; Ferril, R.; /UC, Santa Barbara; Filippini, J.; /UC, Berkeley; Gaitskell, R.J.; /Case Western Reserve U.; Hennings-Yeomans, R.; /Case Western Reserve U. /Fermilab /Case Western Reserve

    2005-07-01T23:59:59.000Z

    The Cryogenic Dark Matter Search (CDMS-II) employs low-temperature Ge and Si detectors to seek Weakly Interacting Massive Particles (WIMPs) via their elastic scattering interactions with nuclei. Simultaneous measurements of both ionization and phonon energy provide discrimination against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with > 99.99% efficiency. Electromagnetic events very near the detector surface can mimic nuclear recoils because of reduced charge collection, but these surface events are rejected with > 96% efficiency by using additional information from the phonon pulse shape. Efficient use of active and passive shielding, combined with the 2090 m.w.e. overburden at the experimental site in the Soudan mine, makes the background from neutrons negligible for this first exposure. All cuts are determined in a blind manner from in situ calibrations with external radioactive sources without any prior knowledge of the event distribution in the signal region. Resulting efficiencies are known to {approx}10%. A single event with a recoil of 64 keV passes all of the cuts and is consistent with the expected misidentification rate of surface-electron recoils. Under the assumptions for a standard dark matter halo, these data exclude previously unexplored parameter space for both spin-independent and spin-dependent WIMP-nucleon elastic scattering. The resulting limit on the spin-independent WIMP-nucleon elastic-scattering cross-section has a minimum of 4 x 10{sup -43} cm{sup 2} at a WIMP mass of 60 GeV c{sup -2}. The minimum of the limit for the spin-dependent WIMP-neutron elastic-scattering cross-section is 2 x 10{sup -37} cm{sup 2} at a WIMP mass of 50 GeV c{sup -2}.

  20. Cold dilute neutron matter on the lattice II: Results in the unitary limit

    E-Print Network [OSTI]

    Dean Lee; Thomas Schaefer

    2005-09-07T23:59:59.000Z

    This is the second of two papers which investigate cold dilute neutron matter on the lattice using pionless effective field theory. In the unitary limit, where the effective range is zero and scattering length is infinite, simple scaling relations relate thermodynamic functions at different temperatures. When the second virial coefficient is properly tuned, we find that the lattice results obey these scaling relations. We compute the energy per particle, pressure, spin susceptibility, dineutron correlation function, and an upper bound for the superfluid critical temperature.

  1. Static and high-frequency hole transport in p-Si/SiGe heterostructures in the ultra-quantum limit.

    SciTech Connect (OSTI)

    Drichko, I. L.; Smirnov, I. Yu.; Suslov, A. V.; Galperin, Y. M.; Vinokur, V.; Myronov, M.; Mironov, O. A.; Materials Science Division; A.F. Ioffe Physico-Technical Inst. of Russian Academy of Sciences; National High Magnetic Field Lab.; Univ. Oslo; Musashi Inst. of Tech.; Univ. Warwick; International Lab. of High Magnetic Fields and Low Temperature

    2007-10-01T23:59:59.000Z

    Complex high-frequency (HF), {sigma}{sup AC} = {sigma}{sub 1} - i{sigma}{sub 2}, and static, {sigma}{sup DC}, conductivities, as well as current-voltage characteristics, have been measured in p-Si/SiGe heterostructures with a low hole density (p = 8.2 x 10{sup 10} cm{sup -2}) at temperatures T = 0.3-4.2 K in the ultraquantum limit, when the filling factor is v < 1. In order to determine the components of the HF conductivity, the acoustic contactless method in the 'hybrid configuration' is used, when the surface acoustic wave propagates on the surface of the LiNbO{sub 3} piezoelectric and the heterostructure is pressed to the surface by a spring. The conductivities {sigma}{sub 1} and {sigma}{sub 2} are determined from the damping and velocity of the surface acoustic waves that are measured simultaneously with varying the magnetic field. The revealed HF conductivity features - {sigma}{sub 1} >> |{sigma}{sub 2}|, the negative sign of {sigma}{sub 2}, the threshold behavior of the current-voltage characteristic, and the dependence I {proportional_to} exp(-A/V{sup 0.3}) in the subthreshold region - indicate the formation of a pinned Wigner crystal (glass) in the ultraquantum limit (T = 0.3-0.8 K, B > 14 T).

  2. WIMP Dark Matter Limit-Direct Detection Data and Sensitivity Plots from the Cryogenic Dark Matter Search II and the University of California at Santa Barbara

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

    Expectations for non-baryonic dark matter are founded principally in Big Bang nucleosynthesis calculations, which indicate that the missing mass of the universe is not likely to be baryonic. The supersymmetric standard model (SUSY) offers a promising framework for expectations of particle species which could satisfy the observed properties of dark matter. WIMPs are the most likely SUSY candidate for a dark matter particle. The High Energy Physics Group at University of California, Santa Barbara, is part of the CDMSII Collaboration and have provided the Interactive Plotter for WIMP Dark Matter Limit-Direct Detection Data on their website. They invite other collaborations working on dark matter research to submit datasets and, as a result, have more than 150 data sets now available for use with the plotting tool. The published source of the data is provided with each data set.

  3. Improved Limits on Sterile Neutrino Dark Matter using Full-Sky Fermi-GBM Data

    E-Print Network [OSTI]

    Ng, Kenny C Y; Gaskins, Jennifer M; Smith, Miles; Preece, Robert

    2015-01-01T23:59:59.000Z

    A sterile neutrino of ~keV mass is a well motivated dark matter candidate. Its decay generates a X-ray line which offers a unique target for X-ray telescopes. For the first time, we use the Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-Ray Space Telescope to search for sterile neutrino decay lines; our analysis covers the energy range 10-25 keV (sterile neutrino mass 20-50 keV), which is inaccessible to X-ray and gamma-ray satellites such as Chandra, Suzaku, XMM-Newton, and INTEGRAL. The extremely wide field of view of the GBM enables a large fraction of the Milky Way dark matter halo to be probed. After implementing careful data cuts, we obtain ~53 days of full sky observational data. We search for sterile neutrino decay lines in the energy spectrum, and find no significant signal. From this, we obtain upper limits on the sterile neutrino mixing angle as a function of mass. In the sterile neutrino mass range 25-40 keV, we improve upon previous upper limits by approximately an order of magnitude. Bett...

  4. Technology Limits and compact model for SiGe Scaled FETs Robert W. Dutton and Chang-Hoon Choi

    E-Print Network [OSTI]

    Dutton, Robert W.

    conductivity of Si0.8Ge0.2 is 15 times lower than that of bulk-Si, such that self-heating problems similar restrict the use of strained-Si MOSFETs for technology nodes beyond 25 nm. Electrical and thermal

  5. Improving the Angular Resolution of EGRET and New Limits on Supersymmetric Dark Matter Near the Galactic Center

    E-Print Network [OSTI]

    Dan Hooper; Brenda Dingus

    2002-12-20T23:59:59.000Z

    Using the EGRET data and an improved point source analysis, including an energy dependent point spread function and an unbinned maximum likelihood technique, we have been able to place considerably lower limits on the gamma ray flux from the galactic center region. We also test this method on known sources, the Crab and Vela pulsars. In both cases, we find that our method improves the angular precision of EGRET data over the 3EG catalog. This new limit on gamma rays from the galactic center can be used to test models of annihilating supersymmetric dark matter and galactic halo profiles. We find that the present EGRET data can limit many supersymmetric models if the density of the galactic dark matter halo is cuspy or spiked toward the galactic center. We also discuss the ability of GLAST to test these models.

  6. Improving the Angular Resolution of EGRET and New Limits on Supersymmetric Dark Matter Near the Galactic Center

    E-Print Network [OSTI]

    Hooper, D; Hooper, Dan; Dingus, Brenda

    2002-01-01T23:59:59.000Z

    Using the EGRET data and an improved point source analysis, including an energy dependent point spread function and an unbinned maximum likelihood technique, we have been able to place considerably lower limits on the gamma ray flux from the galactic center region. We also test this method on known sources, the Crab and Vela pulsars. In both cases, we find that our method improves the angular precision of EGRET data over the 3EG catalog. This new limit on gamma rays from the galactic center can be used to test models of annihilating supersymmetric dark matter and galactic halo profiles. We find that the present EGRET data can limit many supersymmetric models if the density of the galactic dark matter halo is cuspy or spiked toward the galactic center. We also discuss the ability of GLAST to test these models.

  7. Features of the stress-strain state of Si/SiO{sub 2}/Ge heterostructures with germanium nanoislands of a limited density

    SciTech Connect (OSTI)

    Kuryliuk, V. V., E-mail: kuryluk@univ.kiev.ua; Korotchenkov, O. A., E-mail: olegk@univ.kiev.ua [Kyiv National University, Physics Faculty (Ukraine)

    2013-08-15T23:59:59.000Z

    Within the elastic continuum model, with the use of the finite-element method, the stress-strain state of silicon-germanium heterostructures with semispherical germanium islands grown on an oxidized silicon surface is calculated. It is shown that as the density of islands is increased to limiting values, in the SiGe structure with open quantum dots the value and spatial distribution of the elastic-strain fields significantly change. The results of theoretical calculation allow the heterostructure portions with the maximum variation in the stress-strain state to be determined. The position of such a portions can be controlled by changing the density of islands.

  8. HSE 1 HSE 2 HSE 3 GE 1 GE 2 GE 3 Residual effects of Large Vessels in GE BOLD Differential Mapping of Ocular Dominance Columns

    E-Print Network [OSTI]

    HSE 1 HSE 2 HSE 3 GE 1 GE 2 GE 3 Residual effects of Large Vessels in GE BOLD Differential Mapping these techniques in humans. Previous human studies (4-6) instead used the conventional GE BOLD technique, combined and limitations of GE BOLD differential mapping as compared to HSE BOLD differential mapping of ocular dominance

  9. Knudsen number, ideal hydrodynamic limit for elliptic flow and QGP viscosity in $\\sqrt{s}$=62 and 200 GeV Cu+Cu/Au+Au collisions

    E-Print Network [OSTI]

    A. K. Chaudhuri

    2010-09-27T23:59:59.000Z

    Taking into account of entropy generation during evolution of a viscous fluid, we have estimated inverse Knudsen number, ideal hydrodynamic limit for elliptic flow and QGP viscosity to entropy ratio in $\\sqrt{s}$=62 and 200 GeV Cu+Cu/Au+Au collisions. Viscosity to entropy ratio is estimated as $\\eta/s=0.17\\pm 0.10\\pm 0.20$, the first error is statistical, the second one is systematic. In a central Au+Au collision, inverse Knudsen number is $\\approx 2.80\\pm 1.63$, which presumably small for complete equilibration. In peripheral collisions it is even less. Ideal hydrodynamic limit for elliptic flow is $\\sim$40% more than the experimental flow in a central collision.

  10. Limits on Low-Mass WIMP Dark Matter with an Ultra-Low-Energy Germanium Detector at 220 eV Threshold

    E-Print Network [OSTI]

    Shin-Ted Lin; H. T. Wong; for the TEXONO Collaboration

    2008-10-20T23:59:59.000Z

    An energy threshold of (220$\\pm$10) eV was achieved at an efficiency of 50% with a four-channel ultra-low-energy germanium detector each with an active mass of 5 g\\cite{wimppaper}. This provides a unique probe to WIMP dark matter with mass below 10 GeV. With low background data taken at the Kuo-Sheng Laboratory, constraints on WIMPs in the galactic halo were derived. Both spin-independent WIMP-nucleon and spin-dependent WIMP-neutron bounds improve over previous results for WIMP mass between 3$-$6 GeV. These results, together with those on spin-dependent couplings, will be presented. Sensitivities for full-scale experiments were projected. This detector technique makes the unexplored sub-keV energy window accessible for new neutrino and dark matter experiments.

  11. The Mass-Function of Low Mass Halo Stars: Limits on Baryonic Halo Dark Matter

    E-Print Network [OSTI]

    David S. Graff; Katherine Freese

    1996-06-18T23:59:59.000Z

    We derive mass functions (MF) for halo red dwarfs (the faintest hydrogen burning stars) and then extrapolate to place limits on the total mass of halo brown dwarfs (stars not quite massive enough to burn hydrogen). The mass functions are obtained from the luminosity function of a sample of 114 local halo stars in the USNO parallax survey (Dahn \\etal 1995). We use stellar models of Alexander \\etal (1996) and make varying assumptions about metallicity and about possible unresolved binaries in the sample. We find that the MF for halo red dwarfs cannot rise more quickly than $1/m^2$ as one approaches the hydrogen burning limit. Using recent results from star formation theory, we extrapolate the MF into the brown-dwarf regime. We see that likely extrapolations imply that the total mass of brown dwarfs in the halo is less than $\\sim 3\\%$ of the local mass density of the halo ($\\sim 0.3\\%$ for the more realistic models we consider). Our limits apply to brown dwarfs in the halo that come from the same stellar population as the red dwarfs.

  12. Modular Invariant Soft Breaking, WMAP, Dark Matter and Sparticle Mass Limits

    E-Print Network [OSTI]

    Chattopadhyay, Utpal; Chattopadhyay, Utpal; Nath, Pran

    2004-01-01T23:59:59.000Z

    An analysis of soft breaking under the constraint of modular invariance is given. The role of dilaton and moduli dependent front factors in achieving a modular invariant $V_{soft}$ is emphasized. Further, it is shown that in string models $\\tan\\beta$ is no longer a free parameter but is determined in terms of $\\alpha_{string}$ and the other soft parameters by the constraints of modular invariance and radiative electroweak symmetry breaking. The above framework is then used to analyze the neutralino relic density consistent with the WMAP data at self dual points in the Kahler and complex structure moduli. One finds that the combined set of constraints arising from modular invariant soft breaking, radiative electroweak symmetry breaking and WMAP lead to upper limits on sparticle masses for $\\mu>0$. These limits are investigated for a class of models and found to lie within reach of the Tevatron and of the Large Hadron Collider (LHC). Further, an analysis of the neutralino-proton cross section shows that dark ma...

  13. Improved limits on sterile neutrino dark matter from full-sky observations by the Fermi-GBM

    E-Print Network [OSTI]

    Horiuchi, Shunsaku; Gaskins, Jennifer M; Smith, Miles; Preece, Robert

    2015-01-01T23:59:59.000Z

    For the first time, we use the Gamma-ray Burst Monitor (GBM) on-board the Fermi satellite to search for sterile neutrino decay lines in the energy range 10-25 keV corresponding to sterile neutrino mass range 20-50 keV. This energy range has been out of reach of traditional X-ray satellites such as Chandra, Suzaku, XMM-Newton, and gamma-ray satellites such as INTEGRAL. Furthermore, the extremely wide field of view of the GBM opens a large fraction of the Milky Way dark matter halo to be probed. We start with 1601 days worth of GBM data, implement stringent data cuts, and perform two simple line search analyses on the reduced data: in the first, the line flux is limited without background modeling, and in the second, the background is modeled as a power-law. We find no significant excess lines in both our searches. We set new limits on sterile neutrino mixing angles, improving on previous limits by approximately an order of magnitude. Better understanding of detector and astrophysical backgrounds, as well as de...

  14. First limits on WIMP nuclear recoil signals in ZEPLIN-II: a two phase xenon detector for dark matter detection

    E-Print Network [OSTI]

    G. J. Alner; H. M. Araujo; A. Bewick; C. Bungau; B. Camanzi; M. J. Carson; R. J. Cashmore; H. Chagani; V. Chepel; D. Cline; D. Davidge; J. C. Davies; E. Daw; J. Dawson; T. Durkin; B. Edwards; T. Gamble; J. Gao; C. Ghag; A. S. Howard; W. G. Jones; M. Joshi; E. V. Korolkova; V. A. Kudryavtsev; T. Lawson; V. N. Lebedenko; J. D. Lewin; P. Lightfoot; A. Lindote; I. Liubarsky; M. I. Lopes; R. Luscher; P. Majewski; K Mavrokoridis; J. E. McMillan; B. Morgan; D. Muna; A. St. J. Murphy; F. Neves; G. G. Nicklin; W. Ooi; S. M. Paling; J. Pinto da Cunha; S. J. S. Plank; R. M. Preece; J. J. Quenby; M. Robinson; F. Sergiampietri; C. Silva; V. N. Solovov; N. J. T. Smith; P. F. Smith; N. J. C. Spooner; T. J. Sumner; C. Thorne; D. R. Tovey; E. Tziaferi; R. J. Walker; H. Wang; J. White; F. L. H. Wolfs

    2007-01-31T23:59:59.000Z

    Results are presented from the first underground data run of ZEPLIN-II, a 31 kg two phase xenon detector developed to observe nuclear recoils from hypothetical weakly interacting massive dark matter particles. Discrimination between nuclear recoils and background electron recoils is afforded by recording both the scintillation and ionisation signals generated within the liquid xenon, with the ratio of these signals being different for the two classes of event. This ratio is calibrated for different incident species using an AmBe neutron source and Co-60 gamma-ray sources. From our first 31 live days of running ZEPLIN-II, the total exposure following the application of fiducial and stability cuts was 225 kgxdays. A background population of radon progeny events was observed in this run, arising from radon emission in the gas purification getters, due to radon daughter ion decays on the surfaces of the walls of the chamber. An acceptance window, defined by the neutron calibration data, of 50% nuclear recoil acceptance between 5 keVee and 20 keVee, had an observed count of 29 events, with a summed expectation of 28.6+/-4.3 gamma-ray and radon progeny induced background events. These figures provide a 90% c.l. upper limit to the number of nuclear recoils of 10.4 events in this acceptance window, which converts to a WIMP-nucleon spin-independent cross-section with a minimum of 6.6x10^-7 pb following the inclusion of an energy dependent, calibrated, efficiency. A second run is currently underway in which the radon progeny will be eliminated, thereby removing the background population, with a projected sensitivity of 2x10^-7 pb for similar exposures as the first run.

  15. A Comprehensive Search for Dark Matter Annihilation in Dwarf Galaxies

    E-Print Network [OSTI]

    Alex Geringer-Sameth; Savvas M. Koushiappas; Matthew G. Walker

    2015-03-11T23:59:59.000Z

    We present a new formalism designed to discover dark matter annihilation occurring in the Milky Way's dwarf galaxies. The statistical framework extracts all available information in the data by simultaneously combining observations of all the dwarf galaxies and incorporating the impact of particle physics properties, the distribution of dark matter in the dwarfs, and the detector response. The method performs maximally powerful frequentist searches and produces confidence limits on particle physics parameters. Probability distributions of test statistics under various hypotheses are constructed exactly, without relying on large sample approximations. The derived limits have proper coverage by construction and claims of detection are not biased by imperfect background modeling. We implement this formalism using data from the Fermi Gamma-ray Space Telescope to search for an annihilation signal in the complete sample of Milky Way dwarfs whose dark matter distributions can be reliably determined. We find that the observed data is consistent with background for each of the dwarf galaxies individually as well as in a joint analysis. The strongest constraints are at small dark matter particle masses. Taking the median of the systematic uncertainty in dwarf density profiles, the cross section upper limits are below the pure s-wave weak scale relic abundance value (2.2 x 10^-26 cm^3/s) for dark matter masses below 26 GeV (for annihilation into b quarks), 29 GeV (tau leptons), 35 GeV (up, down, strange, and charm quarks and gluons), 6 GeV (electrons/positrons), and 114 GeV (two-photon final state). For dark matter particle masses less than 1 TeV, these represent the strongest limits obtained to date using dwarf galaxies.

  16. Propagation In Matter Of Currents Of Relativistic Electrons Beyond The Alfven Limit, Produced In Ultra-High-Intensity Short-Pulse Laser-Matter Interactions

    SciTech Connect (OSTI)

    Batani, D.; Manclossi, M. [Dipartimento di Fisica 'G.Occhialini', Universita di Milano-Bicocca (Italy); INFM, Universita di Milano-Bicocca (Italy); Laboratoire d'Optique Appliquee, UMR ENSTA-CNRS-Ecole Polytechnique, Palaiseau (France); Baton, S.D.; Amiranoff, F.; Koenig, M.; Gremillet, L.; Popescu, H. [Laboratoire pour l'Utilisation des Lasers Intenses, UMR 7605 CNRS-CEA-X-Paris VI, Ecole Polytechnique, Palaiseau (France); Santos, J.J. [Laboratoire d'Optique Appliquee, UMR ENSTA-CNRS-Ecole Polytechnique, Palaiseau (France); Laboratoire pour l'Utilisation des Lasers Intenses, UMR 7605 CNRS-CEA-X-Paris VI, Ecole Polytechnique, Palaiseau (France); Martinolli, E. [Dipartimento di Fisica 'G.Occhialini', Universita di Milano-Bicocca (Italy); INFM, Universita di Milano-Bicocca (Italy); Laboratoire pour l'Utilisation des Lasers Intenses, UMR 7605 CNRS-CEA-X-Paris VI, Ecole Polytechnique, Palaiseau (France); Antonicci, A. [Dipartimento di Fisica 'G.Occhialini', Universita di Milano-Bicocca (Italy); INFM, Universita di Milano-Bicocca (Italy); Rousseaux, C.; Rabec Le Gloahec, M. [Commissariat a l'Energie Atomique, Bruyeres-le-Chatel (France); Hall, T. [University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ (United Kingdom); Malka, V. [Laboratoire d'Optique Appliquee, UMR ENSTA-CNRS-Ecole Polytechnique, Palaiseau (France); Cowan, T.E.; Stephens, R. [Inertial Fusion Technology Division, Fusion Group, General Atomics, San Diego, CA (United States); Key, M. [Lawrence Livermore National Laboratory, Livermore CA (United States); King, J.; Freeman, R. [Department of Applied Sciences, University of California Davis, CA 95616 (United States)

    2004-12-01T23:59:59.000Z

    This paper reports the results of several experiments performed at the LULI laboratory (Palaiseau, France) concerning the propagation of large relativistic currents in matter from ultra-high-intensity laser pulse interaction with target. We present our results according to the type of diagnostics used in the experiments: 1) K{alpha} emission and K{alpha} imaging, 2) study of target rear side emission in the visible region, 3) time resolved optical shadowgraphy.

  17. Characteristics of Sn segregation in Ge/GeSn heterostructures

    SciTech Connect (OSTI)

    Li, H.; Chang, C.; Chen, T. P.; Cheng, H. H., E-mail: hhcheng@ntu.edu.tw [Center for Condensed Matter Sciences and Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Shi, Z. W.; Chen, H. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-10-13T23:59:59.000Z

    We report an investigation of Sn segregation in Ge/GeSn heterostructures occurred during the growth by molecular beam epitaxy. The measured Sn profile in the Ge layer shows that: (a) the Sn concentration decreases rapidly near the Ge/GeSn interface, and (b) when moving away from the interface, the Sn concentration reduced with a much slower rate. The 1/e decay lengths of the present system are much longer than those of the conventional group IV system of Ge segregation in the Si overlayer because of the smaller kinetic potential as modeled by a self-limited two-state exchange scheme. The demonstration of the Sn segregation shows the material characteristics of the heterostructure, which are needed for the investigation of its optical properties.

  18. Combined CDF and Dzero Upper Limits on Standard Model Higgs Boson Production at High Mass (155-200 GeV/c2) with 3 fb-1 of data

    E-Print Network [OSTI]

    Tevatron New Phenomena; Higgs working group; CDF Collaboration; D0 Collaboration

    2008-08-05T23:59:59.000Z

    We combine results from CDF and DO searches for a standard model Higgs boson in ppbar collisions at the Fermilab Tevatron, at sqrt{s}=1.96 TeV. With 3.0 fb-1 of data analyzed at CDF, and at DO, the 95% C.L. upper limits on Higgs boson production are a factor of 1.2, 1.0 and 1.3 higher than the SM cross section for a Higgs boson mass of m_{H}=$165, 170 and 175 GeV, respectively. We exclude at 95% C.L. a standard model Higgs boson of m_H=170 GeV. Based on simulation, the ratios of the corresponding median expected upper limit to the Standard Model cross section are 1.2, 1.4 and 1.7. Compared to the previous Higgs Tevatron combination, more data and refined analysis techniques have been used. These results extend significantly the individual limits of each experiment and provide new knowledge on the mass of the standard model Higgs boson beyond the LEP direct searches.

  19. Direct Dark Matter Search with the CRESST-II Experiment

    E-Print Network [OSTI]

    ,

    2015-01-01T23:59:59.000Z

    The quest for the particle nature of dark matter is one of the big open questions of modern physics. The CRESST-II experiment, located at the Gran Sasso laboratory in Italy, is optimised for the detection of the elastic scattering of dark matter particles with ordinary matter. We present the result obtained with an improved detector setup with increased radiopurity and enhanced background rejection. The limit obtained in the so-called low mass region between one and three GeV/c2 is at the present among the best limits obtained for direct dark matter experiments. In addition we give an outlook of the future potential for direct dark matter detection using further improved CRESST CaWO4 cryogenic detectors.

  20. approaching cryogenic ge: Topics by E-print Network

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

    Very low Weinreb, Sander 2 Draft 040509 A new high-background-rejection dark matter Ge cryogenic Computer Technologies and Information Sciences Websites Summary: Draft...

  1. Gluon condensation and deconfinement critical density in nuclear matter

    E-Print Network [OSTI]

    M. Baldo; P. Castorina; D. Zappala'

    2004-10-07T23:59:59.000Z

    An upper limit to the critical density for the transition to the deconfined phase, at zero temperature, has been evaluated by analyzing the behavior of the gluon condensate in nuclear matter. Due to the non linear baryon density effects, the upper limit to the critical density, \\rho_c turns out about nine times the saturation density, rho_0 for the value of the gluon condensate in vacuum =0.012 GeV^4. For neutron matter \\rho_c \\simeq 8.5 \\rho_0. The dependence of the critical density on the value of the gluon condensate in vacuum is studied.

  2. On the minimum dark matter mass testable by neutrinos from the Sun

    SciTech Connect (OSTI)

    Busoni, Giorgio; Simone, Andrea De; Huang, Wei-Chih, E-mail: giorgio.busoni@sissa.it, E-mail: andrea.desimone@sissa.it, E-mail: wei-chih.huang@sissa.it [SISSA and INFN, Sezione di Trieste, via Bonomea 265, I-34136 Trieste (Italy)

    2013-07-01T23:59:59.000Z

    We discuss a limitation on extracting bounds on the scattering cross section of dark matter with nucleons, using neutrinos from the Sun. If the dark matter particle is sufficiently light (less than about 4 GeV), the effect of evaporation is not negligible and the capture process goes in equilibrium with the evaporation. In this regime, the flux of solar neutrinos of dark matter origin becomes independent of the scattering cross section and therefore no constraint can be placed on it. We find the minimum values of dark matter masses for which the scattering cross section on nucleons can be probed using neutrinos from the Sun. We also provide simple and accurate fitting functions for all the relevant processes of GeV-scale dark matter in the Sun.

  3. Low surface brightness galaxies rotation curves in the low energy limit of $R^n$ gravity : no need for dark matter?

    E-Print Network [OSTI]

    S. Capozziello; V. F. Cardone; A. - Troisi

    2006-12-13T23:59:59.000Z

    We investigate the possibility that the observed flatness of the rotation curves of spiral galaxies is not an evidence for the existence of dark matter haloes, but rather a signal of the breakdown of General Relativity. To this aim, we consider power - law fourth order theories of gravity obtained by replacing the scalar curvature $R$ with $f(R) = f_0 R^n$ in the gravity Lagrangian. We show that, in the low energy limit, the gravitational potential generated by a pointlike source may be written as $\\Phi(r) \\propto r^{-1} \\left [ 1 + (r/r_c)^{\\beta} \\right ]$ with $\\beta$ a function of the slope $n$ of the gravity Lagrangian and $r_c$ a scalelength depending on the gravitating system properties. In order to apply the model to realistic systems, we compute the modified potential and the rotation curve for spherically symmetric and for thin disk mass distributions. It turns out that the potential is still asymptotically decreasing, but the corrected rotation curve, although not flat, is higher than the Newtonian one thus offering the possibility to fit rotation curves without dark matter. To test the viability of the model, we consider a sample of 15 low surface brightness (LSB) galaxies with combined HI and H$\\alpha$ measurements of the rotation curve extending in the putative dark matter dominated region. We find a very good agreement between the theoretical rotation curve and the data using only stellar disk and interstellar gas.

  4. Dark Matter Directionality Revisited with a High Pressure Xenon Gas Detector

    E-Print Network [OSTI]

    Gopolang Mohlabeng; Kyoungchul Kong; Jin Li; Adam Para; Jonghee Yoo

    2015-03-13T23:59:59.000Z

    An observation of the anisotropy of dark matter interactions in a direction-sensitive detector would provide decisive evidence for the discovery of galactic dark matter. Directional information would also provide a crucial input to understanding its distribution in the local Universe. Most of the existing directional dark matter detectors utilize particle tracking methods in a low-pressure gas time projection chamber. These low pressure detectors require excessively large volumes in order to be competitive in the search for physics beyond the current limit. In order to avoid these volume limitations, we consider a novel proposal, which exploits a columnar recombination effect in a high-pressure gas time projection chamber. The ratio of scintillation to ionization signals observed in the detector carries the angular information of the particle interactions. In this paper, we investigate the sensitivity of a future directional detector focused on the proposed high-pressure Xenon gas time projection chamber. We study the prospect of detecting an anisotropy in the dark matter velocity distribution. We find that tens of events are needed to exclude an isotropic distribution of dark matter interactions at 95% confidence level in the most optimistic case with head-to-tail information. However, one needs at least 10-20 times more events without head-to-tail information for light dark matter below 50 GeV or one between 200 GeV and 400 GeV. For an intermediate mass range, we find it challenging to observe anisotropy of dark matter distribution.

  5. Diffusion in SiGe and Ge

    E-Print Network [OSTI]

    Liao, Christopher Yuan Ting

    2010-01-01T23:59:59.000Z

    Claeys, et al. , "Si versus Ge for future microelectronics,"in Selectively Doped Si/Si x Ge 1-x Superlattices," PhysicalA. Fitzgerald, et al. , "Relaxed Ge x Si 1-x structures for

  6. Diffusion in SiGe and Ge

    E-Print Network [OSTI]

    Liao, Christopher Yuan Ting

    2010-01-01T23:59:59.000Z

    High-electron-mobility Si/SiGe heterostructures: influenceof the relaxed SiGe buffer layer," Semiconductor Science andFrom its discovery to SiGe devices," Materials Science in

  7. Limit on Neutrinoless ?? Decay of Xe-136 from the First Phase of KamLAND-Zen and Comparison with the Positive Claim in Ge-76

    E-Print Network [OSTI]

    KamLAND-Zen Collaboration

    2013-02-19T23:59:59.000Z

    We present results from the first phase of the KamLAND-Zen double-beta decay experiment, corresponding to an exposure of 89.5 kg yr of Xe-136. We obtain a lower limit for the neutrinoless double-beta decay half-life of T_{1/2}^{0{\

  8. Consideration of gravitational time delay and limitation of equivalence principle of inert and gravitational masses erases the problem of dark matter

    E-Print Network [OSTI]

    Mikhail A. Samokhvalov

    2014-04-01T23:59:59.000Z

    The work is based on the equation of relativistic dynamics, the law of mass conservation of material body moving in gravitational field and the influence of gravitation on time passage discovered by Einstein. The formulae describing changes of inert and gravitational masses of material body were found. A new formula for the power of gravitational interaction of material bodies was derived. Newtons formula was shown to be the approximation of the new formula. It was determined that the equivalence principle of inert and gravitational masses is not universal. This principle is true with definite accuracy within the Solar system, when the sum of kinetic and potential energies of a material body is equal to zero. Limitation of the equivalence principle of inert and gravitational masses for galactic star systems erases the problem of dark matter.

  9. Understanding of interface structures and reaction mechanisms induced by Ge or GeO diffusion in Al{sub 2}O{sub 3}/Ge structure

    SciTech Connect (OSTI)

    Shibayama, Shigehisa [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan) [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); JSPS, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Kato, Kimihiko; Sakashita, Mitsuo; Takeuchi, Wakana; Taoka, Noriyuki; Nakatsuka, Osamu; Zaima, Shigeaki [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)] [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2013-08-19T23:59:59.000Z

    The reaction mechanisms at Al{sub 2}O{sub 3}/Ge interfaces with thermal oxidation through the Al{sub 2}O{sub 3} layer have been investigated. X-ray photoelectron spectroscopy reveals that an Al{sub 6}Ge{sub 2}O{sub 13} layer is formed near the interface, and a GeO{sub 2} layer is formed on the Al{sub 2}O{sub 3} surface, suggesting Ge or GeO diffusion from the Ge surface. It is also clarified that the Al{sub 6}Ge{sub 2}O{sub 13} layer is formed by the different mechanism with a small activation energy of 0.2 eV, compared with the GeO{sub 2} formation limited by oxygen diffusion. Formation of Al-O-Ge bonds due to the AlGeO formation could lead appropriate interface structures with high interface qualities.

  10. Testing the Dark Matter Interpretation of the DAMA/LIBRA Result with Super-Kamiokande

    E-Print Network [OSTI]

    Jonathan L. Feng; Jason Kumar; John Learned; Louis E. Strigari

    2009-03-10T23:59:59.000Z

    We consider the prospects for testing the dark matter interpretation of the DAMA/LIBRA signal with the Super-Kamiokande experiment. The DAMA/LIBRA signal favors dark matter with low mass and high scattering cross section. We show that these characteristics imply that the scattering cross section that enters the DAMA/LIBRA event rate determines the annihilation rate probed by Super-Kamiokande. Current limits from Super-Kamiokande through-going events do not test the DAMA/LIBRA favored region. We show, however, that upcoming analyses including fully-contained events with sensitivity to dark matter masses from 5 to 10 GeV may corroborate the DAMA/LIBRA signal. We conclude by considering three specific dark matter candidates, neutralinos, WIMPless dark matter, and mirror dark matter, which illustrate the various model-dependent assumptions entering our analysis.

  11. Direct and indirect detection of dissipative dark matter

    E-Print Network [OSTI]

    JiJi Fan; Andrey Katz; Jessie Shelton

    2014-07-02T23:59:59.000Z

    We study the constraints from direct detection and solar capture on dark matter scenarios with a subdominant dissipative component. This dissipative dark matter component in general has both a symmetric and asymmetric relic abundance. Dissipative dynamics allow this subdominant dark matter component to cool, resulting in its partial or total collapse into a smaller volume inside the halo (e.g., a dark disk) as well as a reduced thermal velocity dispersion compared to that of normal cold dark matter. We first show that these features considerably relax the limits from direct detection experiments on the couplings between standard model (SM) particles and dissipative dark matter. On the other hand, indirect detection of the annihilation of the symmetric dissipative dark matter component inside the Sun sets stringent and robust constraints on the properties of the dissipative dark matter. In particular, IceCube observations force dissipative dark matter particles with mass above 50 GeV to either have a small coupling to the SM or a low local density in the solar system, or to have a nearly asymmetric relic abundance. Possible helioseismology signals associated with purely asymmetric dissipative dark matter are discussed, with no present constraints.

  12. Low surface brightness galaxies rotation curves in the low energy limit of $R^n$ gravity no need for dark matter?

    E-Print Network [OSTI]

    Capozziello, S; Troisi, A

    2006-01-01T23:59:59.000Z

    We investigate the possibility that the observed flatness of the rotation curves of spiral galaxies is not an evidence for the existence of dark matter haloes, but rather a signal of the breakdown of General Relativity. To this aim, we consider power - law fourth order theories of gravity obtained by replacing the scalar curvature $R$ with $f(R) = f_0 R^n$ in the gravity Lagrangian. We show that, in the low energy limit, the gravitational potential generated by a pointlike source may be written as $\\Phi(r) \\propto r^{-1} \\left [ 1 + (r/r_c)^{\\beta} \\right ]$ with $\\beta$ a function of the slope $n$ of the gravity Lagrangian and $r_c$ a scalelength depending on the gravitating system properties. In order to apply the model to realistic systems, we compute the modified potential and the rotation curve for spherically symmetric and for thin disk mass distributions. It turns out that the potential is still asymptotically decreasing, but the corrected rotation curve, although not flat, is higher than the Newtonian...

  13. What Does The PAMELA Antiproton Spectrum Tell Us About Dark Matter?

    E-Print Network [OSTI]

    Dan Hooper; Tim Linden; Philipp Mertsch

    2014-10-06T23:59:59.000Z

    Measurements of the cosmic ray antiproton spectrum can be used to search for contributions from annihilating dark matter and to constrain the dark matter annihilation cross section. Depending on the assumptions made regarding cosmic ray propagation in the Galaxy, such constraints can be quite stringent. We revisit this topic, utilizing a set of propagation models fit to the cosmic ray boron, carbon, oxygen and beryllium data. We derive upper limits on the dark matter annihilation cross section and find that when the cosmic ray propagation parameters are treated as nuisance parameters (as we argue is appropriate), the resulting limits are significantly less stringent than have been previously reported. We also note (as have several previous groups) that simple GALPROP-like diffusion-reacceleration models predict a spectrum of cosmic ray antiprotons that is in good agreement with PAMELA's observations above ~5 GeV, but that significantly underpredict the flux at lower energies. Although the complexity of modeling cosmic ray propagation at GeV-scale energies makes it difficult to determine the origin of this discrepancy, we consider the possibility that the excess antiprotons are the result of annihilating dark matter. Suggestively, we find that this excess is best fit for a dark matter mass of approximately 35 GeV and annihilation cross section of approximately 1e-26 cm^3/s (to b-bbar), in good agreement with the mass and cross section previously shown to be required to generate the gamma-ray excess observed from the Galactic Center.

  14. Search for Dark Matter in Events with One Jet and Missing Transverse Energy in pp? Collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; et al

    2012-05-01T23:59:59.000Z

    We present the results of a search for dark matter production in the monojet signature. We analyze a sample of Tevatron pp? collisions at ?s=1.96 TeV corresponding to an integrated luminosity of 6.7 fb?ą recorded by the CDF II detector. In events with large missing transverse energy and one energetic jet, we find good agreement between the standard model prediction and the observed data. We set 90% confidence level upper limits on the dark matter production rate. The limits are translated into bounds on nucleon-dark matter scattering rates which are competitive with current direct detection bounds on spin-independent interaction belowmore »a dark matter candidate mass of 5 GeV/c˛, and on spin-dependent interactions up to masses of 200 GeV/c˛.« less

  15. Search for Dark Matter in Events with One Jet and Missing Transverse Energy in pp? Collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Bai, Y.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; d’Ascenzo, N.; Datta, M.; de Barbaro, P.; Dell’Orso, M.; Demortier, L.; Deninno, M.; Devoto, F.; d’Errico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; D’Onofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Fox, P. J.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harnik, R.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C.-J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Martínez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.

    2012-05-01T23:59:59.000Z

    We present the results of a search for dark matter production in the monojet signature. We analyze a sample of Tevatron pp? collisions at ?s=1.96 TeV corresponding to an integrated luminosity of 6.7 fb?ą recorded by the CDF II detector. In events with large missing transverse energy and one energetic jet, we find good agreement between the standard model prediction and the observed data. We set 90% confidence level upper limits on the dark matter production rate. The limits are translated into bounds on nucleon-dark matter scattering rates which are competitive with current direct detection bounds on spin-independent interaction below a dark matter candidate mass of 5 GeV/c˛, and on spin-dependent interactions up to masses of 200 GeV/c˛.

  16. J. Phys.: Condens. Matter 10 (1998) 55255533. Printed in the UK PII: S0953-8984(98)90657-9 A theoretical study of native acceptors in CdGeAs2

    E-Print Network [OSTI]

    Pandey, Ravi

    1998-01-01T23:59:59.000Z

    of CdGeAs2 and will calculate formation energies of native defects and binding energies of the acceptor-8984(98)90657-9 A theoretical study of native acceptors in CdGeAs2 Ravindra Pandey, Melvin C Ohmer and Julian D Gale§ Department of Physics, Michigan Technological University, Houghton, MI 49931, USA Air Force Research

  17. Indirect Search for Dark Matter in M31 with the CELESTE Experiment

    E-Print Network [OSTI]

    Lavalle, J; Britto, R; Bruel, P; Bussons-Gordo, J; Dumora, D; Durand, E; Giraud, E; Jacholkowska, A; Lott, B; M"unz, F; Manseri, H; Nuss, E; Piron, Frédéric; Reposeur, T; Smith, D A

    2006-01-01T23:59:59.000Z

    If dark matter is made of neutralinos, annihilation of such Majorana particles should produce high energy cosmic rays, especially in galaxy halo high density regions like galaxy centres. M31 (Andromeda) is our nearest neighbour spiral galaxy, and both its high mass and its low distance make it a source of interest for the indirect search for dark matter through gamma-ray detection. The ground based atmospheric Cherenkov telescope CELESTE observed M31 from 2001 to 2003, in the mostly unexplored energy range 50-500 GeV. These observations provide an upper limit on the flux above 50 GeV around $10^{-10}\\rm{cm}^{-2}\\rm{s}^{-1}$ in the frame of supersymmetric dark matter, and more generally on any gamma emission from M31.

  18. Indirect Search for Dark Matter in M31 with the CELESTE Experiment

    E-Print Network [OSTI]

    J. Lavalle; H. Manseri; A. Jacholkowska; E. Brion; R. Britto; P. Bruel; J. Bussons-Gordo; D. Dumora; E. Durand; E. Giraud; B. Lott; F. Münz; E. Nuss; F. Piron; T. Reposeur; D. A. Smith

    2006-01-13T23:59:59.000Z

    If dark matter is made of neutralinos, annihilation of such Majorana particles should produce high energy cosmic rays, especially in galaxy halo high density regions like galaxy centres. M31 (Andromeda) is our nearest neighbour spiral galaxy, and both its high mass and its low distance make it a source of interest for the indirect search for dark matter through gamma-ray detection. The ground based atmospheric Cherenkov telescope CELESTE observed M31 from 2001 to 2003, in the mostly unexplored energy range 50-500 GeV. These observations provide an upper limit on the flux above 50 GeV around $10^{-10}\\rm{cm}^{-2}\\rm{s}^{-1}$ in the frame of supersymmetric dark matter, and more generally on any gamma emission from M31.

  19. Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud

    E-Print Network [OSTI]

    Alex Drlica-Wagner; German A. Gomez-Vargas; John W. Hewitt; Tim Linden; Luigi Tibaldo

    2014-06-30T23:59:59.000Z

    Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use gamma-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant gamma-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially-extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section ($\\sim 3\\times10^{-26}{\\rm cm}^{3}{\\rm s}^{-1}$) for dark matter masses $\\lesssim 30$ GeV annihilating via the $b \\bar b$ or $\\tau^{+}\\tau^{-}$ channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

  20. Limits on a muon flux from Kaluza-Klein dark matter annihilations in the Sun from the IceCube 22-string detector

    E-Print Network [OSTI]

    Abbasi, R.

    2010-01-01T23:59:59.000Z

    matter annihilations in the Sun from the IceCube 22-stringmatter annihilations in the Sun from the IceCube 22-stringmatter annihilations in the Sun has been performed with the

  1. A Model of Asymmetric Hadronic Dark Matter and Leptogenesis

    E-Print Network [OSTI]

    Yang, Wei-Min

    2015-01-01T23:59:59.000Z

    The paper suggests a model to account for the common origins of the asymmetric dark matter (ADM) and matter-antimatter asymmetry. The ADM nature is a stable hadronic particle consisting of a heavy color scalar and a light $u$ quark, which is formed after the QCD phase transition. At the early stage the ADM are in thermal equilibrium through collisions with the nucleons, moreover, they can emit the $\\gamma$ photons with $0.32$ MeV energy. However they are decoupling and become the dark matter at the temperature about $130$ MeV. The mass upper limit of the ADM is predicted as $M_{D}<1207$ GeV. It is feasible and promising to test the model in future experiments.

  2. A Search for dark matter in events with one jet and missing transverse energy in $p\\bar{p}$ collisions at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-03-01T23:59:59.000Z

    We present the results of a search for dark matter production in the monojet signature. We analyze a sample of Tevatron pp collisions at {radical}s = 1.96 TeV corresponding to an integrated luminosity of 6.7 fb{sup -1} recorded by the CDF II detector. In events with large missing transverse energy and one energetic jet, we find good agreement between the standard model prediction and the observed data. We set 90% confidence level upper limits on the dark matter production rate. The limits are translated into bounds on nucleon-dark matter scattering rates which are competitive with current direct detection bounds on spin-independent interaction below a dark matter candidate mass of 5 GeV/c{sup 2}, and on spin-dependent interactions up to masses of 200 GeV/c{sup 2}.

  3. CHEM 114 GE 124 MATH 110 GE 110 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120

    E-Print Network [OSTI]

    Saskatchewan, University of

    2006-07 CHEM 114 GE 124 MATH 110 GE 110 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120 GE 210 MATH 223CE 212 CMPT 116 Hum/SocSci Jr. GEOE 218 CE 225 MATH 224GE 213# GE 348# CE 295 English 11x# CE 315 CE 311 CE 318 CE 319 CE 317 CE 316CE 327 CE 321 Sr Sci elect#CE 329 CE 328 GE 300# Eng/Sr Sci Elec# CE Elec

  4. Stealth Dark Matter: Dark scalar baryons through the Higgs portal

    E-Print Network [OSTI]

    Thomas Appelquist; Richard C. Brower; Michael I. Buchoff; George T. Fleming; Xiao-Yong Jin; Joe Kiskis; Graham D. Kribs; Ethan T. Neil; James C. Osborn; Claudio Rebbi; Enrico Rinaldi; David Schaich; Chris Schroeder; Sergey Syritsyn; Pavlos Vranas; Evan Weinberg; Oliver Witzel

    2015-03-13T23:59:59.000Z

    We present a new model of "Stealth Dark Matter": a composite baryonic scalar of an $SU(N_D)$ strongly-coupled theory with even $N_D \\geq 4$. All mass scales are technically natural, and dark matter stability is automatic without imposing an additional discrete or global symmetry. Constituent fermions transform in vector-like representations of the electroweak group that permit both electroweak-breaking and electroweak-preserving mass terms. This gives a tunable coupling of stealth dark matter to the Higgs boson independent of the dark matter mass itself. We specialize to $SU(4)$, and investigate the constraints on the model from dark meson decay, electroweak precision measurements, basic collider limits, and spin-independent direct detection scattering through Higgs exchange. We exploit our earlier lattice simulations that determined the composite spectrum as well as the effective Higgs coupling of stealth dark matter in order to place bounds from direct detection, excluding constituent fermions with dominantly electroweak-breaking masses. A lower bound on the dark baryon mass $m_B \\gtrsim 300$ GeV is obtained from the indirect requirement that the lightest dark meson not be observable at LEP II. We briefly survey some intriguing properties of stealth dark matter that are worthy of future study, including: collider studies of dark meson production and decay; indirect detection signals from annihilation; relic abundance estimates for both symmetric and asymmetric mechanisms; and direct detection through electromagnetic polarizability, a detailed study of which will appear in a companion paper.

  5. CHEM 114 GE 124 MATH 110 COMM 102GE 110 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120

    E-Print Network [OSTI]

    Saskatchewan, University of

    CHEM 114 GE 124 MATH 110 COMM 102GE 110 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120 CMPT 116CHEM 250# MATH 223 EE 201 GE 213 Grp. A elective*CHE 223 Hum/SocSci Jr. MATH 224 English 11x CHE 220CHE 210 CHECHE 413 Grp. B elective#* Grp. B elective*#CHE 424 CHE 421 CHE 422 GE 348# CHE 423 GE 449# CH E 470

  6. CHEM 114 GE 124 MATH 110 COMM 102GE 110 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120

    E-Print Network [OSTI]

    Saskatchewan, University of

    CHEM 114 GE 124 MATH 110 COMM 102GE 110 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120 CMPT 116CHEM 250# MATH 223 EE 201 GE 213 Grp. A elective*CHE 223 HSS@# MATH 224 English 11x CHE 220CHE 210 CHE 323 CHE Grp. B elective#* Grp. B elective*#CHE 424 CHE 421 CHE 422 GE 348# CHE 423 GE 449# CH E 470^ Chemical

  7. CHEM 114 GE 124 MATH 110 GE 110 COMM 102 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120

    E-Print Network [OSTI]

    Saskatchewan, University of

    CHEM 114 GE 124 MATH 110 GE 110 COMM 102 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120 ME 227 GE 213# MATH 223 EE 201ME 214 CMPT 116 ME 215 GE 226 MATH 224 Hum/SocSci@# ME 251 ME 229 ME 318 ME 335 ME 313 ME 316 ME 352ME 330 GE 348# ME 328 ME 327 ME 323 ME 321ME 324 RCM 300# ME 418 ME 417 ME 450 ME 431

  8. GE ?????????????????4G?????...

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

    GE 4G Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click...

  9. The Sensitivity of HAWC to High-Mass Dark Matter Annihilations

    E-Print Network [OSTI]

    A. U. Abeysekara; R. Alfaro; C. Alvarez; J. D. Alvarez; R. Arceo; J. C. Arteaga-Velazquez; H. A. Ayala Solares; A. S. Barber; B. M. Baughman; N. Bautista-Elivar; J. Becerra Gonzalez; E. Belmont; S. Y. BenZvi; D. Berley; M. Bonilla Rosales; J. Braun; R. A. Caballero-Lopez; K. S. Caballero-Mora; A. Carraminana; M. Castillo; U. Cotti; J. Cotzomi; E. de la Fuente; C. De Leon; T. DeYoung; R. Diaz Hernandez; L. Diaz-Cruz; J. C. Diaz-Velez; B. L. Dingus; M. A. DuVernois; R. W. Ellsworth; S. F. E.; D. W. Fiorino; N. Fraija; A. Galindo; F. Garfias; M. M. Gonzalez; J. A. Goodman; V. Grabski; M. Gussert; Z. Hampel-Arias; J. P. Harding; C. M. Hui; P. Huentemeyer; A. Imran; A. Iriarte; P. Karn; D. Kieda; G. J. Kunde; A. Lara; R. J. Lauer; W. H. Lee; D. Lennarz; H. Leon Vargas; E. C. Linares; J. T. Linnemann; M. Longo; R. Luna-Garcia; A. Marinelli; H. Martinez; O. Martinez; J. Martinez-Castro; J. A. J. Matthews; J. McEnery; E. Mendoza Torres; P. Miranda-Romagnoli; E. Moreno; M. Mostafa; L. Nellen; M. Newbold; R. Noriega-Papaqui; T. Oceguera-Becerra; B. Patricelli; R. Pelayo; E. G. Perez-Perez; J. Pretz; C. Riviere; D. Rosa-Gonzalez; J. Ryan; H. Salazar; F. Salesa; A. Sandoval; M. Schneider; S. Silich; G. Sinnis; A. J. Smith; K. Sparks Woodle; R. W. Springer; I. Taboada; P. A. Toale; K. Tollefson; I. Torres; T. N. Ukwatta; L. Villasenor; T. Weisgarber; S. Westerhoff; I. G. Wisher; J. Wood; G. B. Yodh; P. W. Younk; D. Zaborov; A. Zepeda; H. Zhou; K. N. Abazajian

    2014-12-09T23:59:59.000Z

    The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from non-luminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross-section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross-sections below thermal. HAWC should also be sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross-section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.

  10. GE Healthcare Introduction

    E-Print Network [OSTI]

    Lebendiker, Mario

    GE Healthcare Introduction HR 16 columns are designed for high resolution liquid chromatography your local GE Healthcare office. System compatibility HR 16 columns are designed to be used with ÄKTATM. Wash the parts thoroughly in distilled water. 4. Reassemble the column (see Assembling the column above

  11. The status of neutralino dark matter

    SciTech Connect (OSTI)

    Shakya, Bibhushan [Laboratory for Elementary Particle Physics, Cornell University, Ithaca, NY 14853 (United States)

    2014-06-24T23:59:59.000Z

    The lightest neutralino in supersymmetry is the most studied dark matter candidate. This writeup reviews the status of neutralino dark matter in minimal and nonminimal supersymmetric models in light of recent null results at the XENON100 experiment and the observation of a 130 GeV gamma ray signal from the Galactic Center by the Fermi LAT.

  12. Chevron, GE form Technology Alliance

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

    form Technology Alliance February 3, 2014 HOUSTON, TX, Feb. 3, 2014-Chevron Energy Technology Company and GE Oil & Gas announced today the creation of the Chevron GE Technology...

  13. Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in pp? Collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anzá, F.; Apollinari, G.; Appel, J. A.; et al

    2012-05-01T23:59:59.000Z

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb?ą of Tevatron ppŻ collisions at ?s=1.96 TeV, collected by the CDF II detector. We search for production of a dark-matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process pp??t+D as a function of the massmore »of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0–150 GeV/c˛.« less

  14. Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in pp? Collisions at ?s=1.96 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anzá, F.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; d’Ascenzo, N.; Datta, M.; de Barbaro, P.; Dell’Orso, M.; Demortier, L.; Deninno, M.; Devoto, F.; d’Errico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; D’Onofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Fuks, B.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C.-J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Martínez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.

    2012-05-01T23:59:59.000Z

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb?ą of Tevatron ppŻ collisions at ?s=1.96 TeV, collected by the CDF II detector. We search for production of a dark-matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process pp??t+D as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0–150 GeV/c˛.

  15. Noble Travails: Noble Liquid Dark Matter Detectors

    E-Print Network [OSTI]

    Golwala, Sunil

    , or water, 0.1x flux per 10 cm Cosmic Ray Muons generate high energy neutrons 50 MeV - 3 GeV which are toughGaitskell Noble Travails: Noble Liquid Dark Matter Detectors Rick Gaitskell Particle Astrophysics://particleastro.brown.edu/ http://gaitskell.brown.edu v1 #12;LUX Dark Matter Collaboration 2007 v01_7mm Dark Matter Theory

  16. Environmentally selected WIMP dark matter with high-scale supersymmetry breaking

    SciTech Connect (OSTI)

    Elor, Gilly; Goh, Hock-Seng; Kumar, Piyush [Berkeley Center for Theoretical Physics, and Theoretical Physics Group, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Hall, Lawrence J.; Nomura, Yasunori [Berkeley Center for Theoretical Physics, and Theoretical Physics Group, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8568 (Japan)

    2010-05-01T23:59:59.000Z

    We explore the possibility that both the weak scale and the thermal relic dark matter abundance are environmentally selected in a multiverse. An underlying supersymmetric theory containing the states of the minimal supersymmetric standard model (MSSM) and singlets, with supersymmetry and R symmetry broken at unified scales, has just two realistic low-energy effective theories. One theory (SM+w-tilde) is the standard model augmented only by the wino, having a mass near 3 TeV, and has a Higgs boson mass in the range of (127-142) GeV. The other theory (SM+h-tilde/s-tilde) has Higgsinos and a singlino added to the standard model. The Higgs boson mass depends on the single new Yukawa coupling of the theory, y, and is near 141 GeV for small y but grows to be as large as 210 GeV as this new coupling approaches strong coupling at high energies. Much of the parameter space of this theory will be probed by direct detection searches for dark matter that push 2 orders of magnitude below the present bounds; furthermore, the dark matter mass and cross section on nucleons are correlated with the Higgs boson mass. The indirect detection signal of monochromatic photons from the Galactic center is computed, and the range of parameters that may be accessible to LHC searches for trilepton events is explored. Taking a broader view, allowing the possibility of R symmetry protection to the TeV scale or axion dark matter, we find four more theories: (SM+axion), two versions of split supersymmetry, and the E-MSSM, where a little supersymmetric hierarchy is predicted. The special Higgs mass value of (141{+-}2) GeV appears in symmetry limits of three of the six theories, (SM+axion), (SM+w-tilde), and (SM+h-tilde/s-tilde), motivating a comparison of other signals of these three theories.

  17. Dark matter and cosmology

    SciTech Connect (OSTI)

    Schramm, D.N.

    1992-03-01T23:59:59.000Z

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold`` and ``hot`` non-baryonic candidates is shown to depend on the assumed ``seeds`` that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  18. Dark matter and cosmology

    SciTech Connect (OSTI)

    Schramm, D.N.

    1992-03-01T23:59:59.000Z

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between cold'' and hot'' non-baryonic candidates is shown to depend on the assumed seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  19. GE Global Research Locations | GE Global Research

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

    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 742EnergyOnItem NotEnergy,ARMFormsGasReleaseSpeechesHall ATours,Dioxide and MethaneLocations GE

  20. GE Global Research Leadership | GE Global Research

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

    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 for4,645U.S. DOE Office of Science (SC) Environmental AssessmentsGeoffrey Campbell is theOpportunitiesTheGAOHome >About GE

  1. GE Researcher Discusses Leadership | GE Global Research

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

    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 for4,645U.S. DOEThe Bonneville Power AdministrationField8,Dist.Newof EnergyFunding OpportunityF G F ! ( ! ( ! ( !ProgressGE

  2. Dark Matter Directionality Revisited with a High Pressure Xenon Gas Detector

    E-Print Network [OSTI]

    Gopolang Mohlabeng; Kyoungchul Kong; Jin Li; Adam Para; Jonghee Yoo

    2015-04-29T23:59:59.000Z

    An observation of the anisotropy of dark matter interactions in a direction-sensitive detector would provide decisive evidence for the discovery of galactic dark matter. Directional information would also provide a crucial input to understanding its distribution in the local Universe. Most of the existing directional dark matter detectors utilize particle tracking methods in a low-pressure gas time projection chamber. These low pressure detectors require excessively large volumes in order to be competitive in the search for physics beyond the current limit. In order to avoid these volume limitations, we consider a novel proposal, which exploits a columnar recombination effect in a high-pressure gas time projection chamber. The ratio of scintillation to ionization signals observed in the detector carries the angular information of the particle interactions. In this paper, we investigate the sensitivity of a future directional detector focused on the proposed high-pressure Xenon gas time projection chamber. We study the prospect of detecting an anisotropy in the dark matter velocity distribution. We find that tens of events are needed to exclude an isotropic distribution of dark matter interactions at 95% confidence level in the most optimistic case with head-to-tail information. However, one needs at least 10-20 times more events without head-to-tail information for light dark matter below 50 GeV. For an intermediate mass range, we find it challenging to observe an anisotropy of the dark matter distribution. Our results also show that the directional information significantly improves precision measurements of dark matter mass and the elastic scattering cross section for a heavy dark matter.

  3. Quantitative Constraints on the Transport Properties of Hot Partonic Matter from Semi-Inclusive Single High Transverse Momentum Pion Suppression in Au+Au collisions at sqrt(s_NN) = 200 GeV

    E-Print Network [OSTI]

    PHENIX Collaboration; A. Adare

    2008-09-26T23:59:59.000Z

    The PHENIX experiment has measured the suppression of semi-inclusive single high transverse momentum pi^0's in Au+Au collisions at sqrt(s_NN) = 200 GeV. The present understanding of this suppression is in terms of energy-loss of the parent (fragmenting) parton in a dense color-charge medium. We have performed a quantitative comparison between various parton energy-loss models and our experimental data. The statistical point-to-point uncorrelated as well as correlated systematic uncertainties are taken into account in the comparison. We detail this methodology and the resulting constraint on the model parameters, such as the initial color-charge density dN^g/dy, the medium transport coefficient , or the initial energy-loss parameter epsilon_0. We find that high transverse momentum pi^0 suppression in Au+Au collisions has sufficient precision to constrain these model dependent parameters at the +/1 20%-25% (one standard deviation) level. These constraints include only the experimental uncertainties, and further studies are needed to compute the corresponding theoretical uncertainties.

  4. CONSTRAINTS ON DARK MATTER ANNIHILATION IN CLUSTERS OF GALAXIES FROM DIFFUSE RADIO EMISSION

    SciTech Connect (OSTI)

    Storm, Emma; Jeltema, Tesla E.; Profumo, Stefano [Department of Physics, University of California, 1156 High St., Santa Cruz, CA 95064 (United States); Rudnick, Lawrence [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)

    2013-05-10T23:59:59.000Z

    Annihilation of dark matter can result in the production of stable Standard Model particles including electrons and positrons that, in the presence of magnetic fields, lose energy via synchrotron radiation, observable as radio emission. Galaxy clusters are excellent targets to search for or to constrain the rate of dark matter annihilation, as they are both massive and dark matter dominated. In this study, we place limits on dark matter annihilation in a sample of nearby clusters using upper limits on the diffuse radio emission, low levels of observed diffuse emission, or detections of radio mini-halos. We find that the strongest limits on the annihilation cross section are better than limits derived from the non-detection of clusters in the gamma-ray band by a factor of {approx}3 or more when the same annihilation channel and substructure model, but different best-case clusters, are compared. The limits on the cross section depend on the assumed amount of substructure, varying by as much as two orders of magnitude for increasingly optimistic substructure models as compared to a smooth Navarro-Frenk-White profile. In our most optimistic case, using the results of the Phoenix Project, we find that the derived limits reach below the thermal relic cross section of 3 Multiplication-Sign 10{sup -26} cm{sup 3} s{sup -1} for dark matter masses as large as 400 GeV, for the b b-bar annihilation channel. We discuss uncertainties due to the limited available data on the magnetic field structure of individual clusters. We also report the discovery of diffuse radio emission from the central 30-40 kpc regions of the groups M49 and NGC 4636.

  5. Constraining Light Dark Matter with Low-Energy e+e- Colliders

    E-Print Network [OSTI]

    Rouven Essig; Jeremy Mardon; Michele Papucci; Tomer Volansky; Yi-Ming Zhong

    2015-02-21T23:59:59.000Z

    We investigate the power of low-energy, high-luminosity electron--positron colliders to probe hidden sectors with a mass below ~10 GeV that couple to Standard Model particles through a light mediator. Such sectors provide well-motivated dark matter candidates, and can give rise to distinctive mono-photon signals at B-factories and similar experiments. We use data from an existing mono-photon search by BaBar to place new constraints on this class of models, and give projections for the sensitivity of a similar search at a future B-factory such as Belle II. We find that the sensitivity of such searches are more powerful than searches at other collider or fixed-target facilities for hidden-sector mediators and particles with masses between a few hundred MeV and 10 GeV. Mediators produced on-shell and decaying invisibly to hidden-sector particles such as dark matter can be probed particularly well. Sensitivity to light dark matter produced through an off-shell mediator is more limited, but may be improved with a better control of backgrounds, allowing background estimation and a search for kinematic edges. We compare our results to existing and future direct detection experiments and show that low-energy colliders provide an indispensable and complementary avenue to search for light dark matter. The implementation of a mono-photon trigger at Belle II would provide an unparalleled window into such light hidden sectors.

  6. Implications of Direct Dark Matter Constraints for Minimal Supersymmetric Standard Model Higgs Boson Searches at the Tevatron

    E-Print Network [OSTI]

    Marcela Carena; Dan Hooper; Peter Skands

    2006-08-22T23:59:59.000Z

    Searches for the Minimal Supersymmetric Standard Model (MSSM) Higgs bosons are among the most promising channels for exploring new physics at the Tevatron. In particular, interesting regions of large $\\tan \\beta$ and small $m_A$ are probed by searches for heavy neutral Higgs bosons, A and H, when they decay to $\\tau^+ \\tau^-$ and $b\\bar{b}$. At the same time, direct searches for dark matter, such as CDMS, attempt to observe neutralino dark matter particles scattering elastically off nuclei. This can occur through t-channel Higgs exchange, which has a large cross section in the case of large $\\tan \\beta$ and small $m_A$. As a result, there is a natural interplay between the heavy, neutral Higgs searches at the Tevatron and the region of parameter space explored by CDMS. We show that if the lightest neutralino makes up the dark matter of our universe, current limits from CDMS strongly constrain the prospects of heavy, neutral MSSM Higgs discovery at the Tevatron (at 3 sigma with 4 fb^-1 per experiment) unless $|\\mu| \\gsim$ 400 GeV. The limits of CDMS projected for 2007 will increase this constraint to $|\\mu| \\gsim$ 800 GeV. On the other hand, if CDMS does observe neutralino dark matter in the near future, it will make the discovery of heavy, neutral MSSM Higgs bosons far more likely at the Tevatron.

  7. Ultra-Low-Energy Germanium Detector for Neutrino-Nucleus Coherent Scattering and Dark Matter Searches

    E-Print Network [OSTI]

    Henry T. Wong

    2008-03-01T23:59:59.000Z

    The status and plans of a research program on the development of ultra-low-energy germanium detectors with sub-keV sensitivities are reported. We survey the scientific goals which include the observation of neutrino-nucleus coherent scattering, the studies of neutrino magnetic moments, as well as the searches of WIMP dark matter. In particular, a threshold of 100-200 eV and a sub-keV background comparable to underground experiments were achieved with prototype detectors. New limits were set for WIMPs with mass between 3-6 GeV. The prospects of the realization of full-scale experiments are discussed.

  8. Thermoelectric properties of nanoporous Ge

    E-Print Network [OSTI]

    Lee, Joo-Hyoung

    We computed thermoelectric properties of nanoporous Ge (np-Ge) with aligned pores along the [001] direction through a combined classical molecular dynamics and first-principles electronic structure approach. A significant ...

  9. On The Origin of Light Dark Matter Species

    SciTech Connect (OSTI)

    Essig, Rouven; Kaplan, Jared; Schuster, Philip; /SLAC; Toro, Natalia; /Stanford U., Phys. Dept.

    2010-06-04T23:59:59.000Z

    TeV-mass dark matter charged under a new GeV-scale gauge force can explain electronic cosmic-ray anomalies. We propose that the CoGeNT and DAMA direct detection experiments are observing scattering of light stable states 'GeV-Matter' that are charged under this force and constitute a small fraction of the dark matter halo. Dark higgsinos in a supersymmetric dark sector are natural candidates for GeV-Matter that scatter off protons with a universal cross-section of 5 x 10{sup -38} cm{sup 2} and can naturally be split by 10-30 keV so that their dominant interaction with protons is down-scattering. As an example, down-scattering of an O(5) GeV dark higgsino can simultaneously explain the spectra observed by both CoGeNT and DAMA. The event rates in these experiments correspond to a GeV-Matter abundance of 0.2-1% of the halo mass density. This abundance can arise directly from thermal freeze-out at weak coupling, or from the late decay of an unstable TeV-scale WIMP. Our proposal can be tested by searches for exotics in the BaBar and Belle datasets.

  10. Gamma-ray boxes from axion-mediated dark matter

    SciTech Connect (OSTI)

    Ibarra, Alejandro; Gehler, Sergio López; Pato, Miguel [Physik-Department T30d, Technische Universität München, James-Franck-Strasse, 85748 Garching (Germany); Lee, Hyun Min; Park, Wan-Il, E-mail: ibarra@tum.de, E-mail: hyun.min.lee@cern.ch, E-mail: sergio.lopez@ph.tum.de, E-mail: wipark@kias.re.kr, E-mail: miguel.pato@tum.de [School of Physics, KIAS, Seoul 130-722 (Korea, Republic of)

    2013-05-01T23:59:59.000Z

    We compute the gamma-ray output of axion-mediated dark matter and derive the corresponding constraints set by recent data. In such scenarios the dark matter candidate is a Dirac fermion that pair-annihilates into axions and/or scalars. Provided that the axion decays (at least partly) into photons, these models naturally give rise to a box-shaped gamma-ray spectrum that may present two distinct phenomenological behaviours: a narrow box, resembling a line at half the dark matter mass, or a wide box, spanning an extensive energy range up to the dark matter mass. Remarkably, we find that in both cases a sizable gamma-ray flux is predicted for a thermal relic without fine-tuning the model parameters nor invoking boost factors. This large output is in line with recent Fermi-LAT observations towards the galactic centre region and is on the verge of being excluded. We then make use of the Fermi-LAT and H.E.S.S. data to derive robust, model-independent upper limits on the dark matter annihilation cross section for the narrow and wide box scenarios. H.E.S.S. constraints, in particular, turn out to match the ones from Fermi-LAT at hundreds of GeV and extend to multi-TeV masses. Future ?erenkov telescopes will likely probe gamma-ray boxes from thermal dark matter relics in the whole multi-TeV range, a region hardly accessible to direct detection, collider searches and other indirect detection strategies.

  11. Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

    SciTech Connect (OSTI)

    Ackermann, M.; Ajello, M.; /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC; Albert, A.; /Taiwan, Natl. Taiwan U. /Ohio State U.; Atwood, W.B.; /UC, Santa Cruz; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, G.; /INFN, Trieste /Trieste U.; Bastieri, D.; /INFN, Padua /Padua U.; Bechtol, K.; /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC; Bellazzini, R.; /INFN, Pisa; Berenji, B.; Blandford, R.D.; Bloom, E.D.; /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC; Bregeon, J.; /INFN, Pisa; Brigida, M.; /Bari Polytechnic /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Buehler, R.; /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC; Burnett, T.H.; /Washington U., Seattle; Buson, S.; /INFN, Padua /Padua U. /ICE, Bellaterra /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC /INFN, Rome /Rome U. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC /Artep Inc. /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC /ASDC, Frascati /Perugia U. /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC /Montpellier U. /Stockholm U. /Stockholm U., OKC /ASDC, Frascati /ASDC, Frascati /Udine U. /INFN, Trieste /Bari Polytechnic /INFN, Bari /Naval Research Lab, Wash., D.C. /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC /Montpellier U. /Bari Polytechnic /INFN, Bari /Ecole Polytechnique /NASA, Goddard /Hiroshima U. /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC /Bari Polytechnic /INFN, Bari /INFN, Bari /ASDC, Frascati /NASA, Goddard /INFN, Perugia /Perugia U. /Bari Polytechnic /INFN, Bari /Bologna Observ. /Stanford U., HEPL /Taiwan, Natl. Taiwan U. /SLAC /DAPNIA, Saclay /Alabama U., Huntsville; /more authors..

    2012-09-14T23:59:59.000Z

    Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10{sup -26} cm{sup 3} s{sup -1} at 5 GeV to about 5 x 10{sup -23} cm{sup 3} s{sup -1} at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section ({approx}3 x 10{sup -26} cm{sup 3} s{sup -1} for a purely s-wave cross section), without assuming additional boost factors.

  12. GE Anna Heijbel / The Storm

    E-Print Network [OSTI]

    Tian, Weidong

    1 / GE Anna Heijbel / The Storm® Confocal Optics 50, 100, 200 µm 5 IQTL · ·DNA ·DNA Gels, blots, tissue sections (not in situ), radio-TLC & X-Ray diffraction #12;2 / GE Anna Heijbel / Phosphor µm 1010 43 x 35 cm43 x 35 cm Scanning Technology #12;3 / GE Anna Heijbel / Confocal Optics PMTPMT

  13. ECS2003_#923_Fitzgerald ECS Meeting Proceedings, Paris, France April 29, 2003 MOSFET CHANNEL ENGINEERING USING STRAINED SI, SIGE, AND GE

    E-Print Network [OSTI]

    MOSFET channel designs in the SiGe/Relaxed SiGe/Si system to explore the limits of electron and hole. The largest improvement in both PMOS and NMOS drive current enhancements were achieved with a -Si/-Ge SiGe materials system possesses the potential to further reduce the power-delay product in CMOS far

  14. Dark Matter in Split SUSY with Intermediate Higgses

    E-Print Network [OSTI]

    Kingman Cheung; Ran Huo; Jae Sik Lee; Yue-Lin Sming Tsai

    2014-12-04T23:59:59.000Z

    The searches for heavy Higgs bosons and supersymmetric (SUSY) particles at the LHC have left the minimal supersymmetric standard model (MSSM) with an unusual spectrum of SUSY particles, namely, all squarks are beyond a few TeV while the Higgs bosons other than the one observed at 125 GeV could be relatively light. In light of this, we study a scenario characterized by two scales: the SUSY breaking scale or the squark-mass scale $(M_S)$ and the heavy Higgs-boson mass scale $(M_A)$. We perform a survey of the MSSM parameter space with $M_S \\lesssim 10^{10}$ GeV and $M_A \\lesssim 10^4$ GeV such that the lightest Higgs boson mass is within the range of the observed Higgs boson as well as satisfying a number of constraints. The set of constraints include the invisible decay width of the $Z$ boson and that of the Higgs boson, the chargino-mass limit, dark matter relic abundance from Planck, the spin-independent cross section of direct detection by LUX, and gamma-ray flux from dwarf spheroidal galaxies and gamma-ray line constraints measured by Fermi LAT. Survived regions of parameter space feature the dark matter with correct relic abundance, which is achieved through either coannihilation with charginos, $A/H$ funnels, or both. We show that future measurements, e.g., XENON1T and LZ, of spin-independent cross sections can further squeeze the parameter space.

  15. Axion Dark Matter Searches

    E-Print Network [OSTI]

    I. Stern

    2014-03-21T23:59:59.000Z

    Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a $\\mu$eV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 $\\mu$eV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.

  16. Axion dark matter searches

    SciTech Connect (OSTI)

    Stern, Ian P. [Department of Physics, Univerisity of Florida, Gainesville, FL 32611-8440 (United States); Collaboration: ADMX Collaboration; ADMX-HF Collaboration

    2014-06-24T23:59:59.000Z

    Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a ?eV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 ?eV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.

  17. Dark Matters

    ScienceCinema (OSTI)

    Joseph Silk

    2010-01-08T23:59:59.000Z

    One of the greatest mysteries in the cosmos is that it is mostly dark.  Astronomers and particle physicists today are seeking to unravel the nature of this mysterious, but pervasive dark matter which has profoundly influenced the formation of structure in the universe.  I will describe the complex interplay between galaxy formation and dark matter detectability and review recent attempts to measure particle dark matter by direct and indirect means.

  18. CTu2J.4.pdf CLEO Technical Digest OSA 2012 Selective-Area Growth of Ge and Ge/SiGe Quantum Wells

    E-Print Network [OSTI]

    Miller, David A. B.

    CTu2J.4.pdf CLEO Technical Digest © OSA 2012 Selective-Area Growth of Ge and Ge/SiGe Quantum Wells process for growing high-quality bulk Ge and Ge/SiGe quantum wells in selected areas of 3 µm thick silicon. Introduction and motivation Ge and especially Ge/SiGe quantum wells exhibit strong electroabsorption (Franz

  19. GE Wins Manufacturing Leadership Award |GE Global Research

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

    secured software platform that delivers data and visualizations to all major artificial lift functions at GE Oil & Gas. Several analytic modules were built to extract meaningful...

  20. GE Partners on Microgrid Project | GE Global Research

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

    and Academia Partner on Microgrid Project GE Awarded a 1.2M Department of Energy Grant to Design Technology to Keep Electricity Flowing after Catastrophic Weather Events...

  1. GE, Aavid Commercialize Dual Cool Jets Technology | GE Global...

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

    market. GE's broad array of industrial businesses requires highly advanced and reliable electronics that are increasingly driving the need for advanced cooling solutions to...

  2. GE, University of Washington Disease Detection | GE Global Research

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

    excited about this team's unique ability to combine new designs for paper-based microfluidics with new nucleic amplification methods and GE's novel paper chemistries to help...

  3. The GE Store

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

    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:Energy: Grid Integration Redefining What'sis Taking Over Our InstagramStructureProposedPAGESafetyTed5,AuditThe FiveBiofuelsGE Store for

  4. Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

    SciTech Connect (OSTI)

    Knowlton, W.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.

    1995-07-01T23:59:59.000Z

    This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

  5. FIRST STUDY OF DARK MATTER PROPERTIES WITH DETECTED SOLAR GRAVITY MODES AND NEUTRINOS

    SciTech Connect (OSTI)

    Turck-Chieze, S.; Garcia, R. A. [CEA/DSM/IRFU/SAp-AIM, CE Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette (France); Lopes, I. [Centro Multidisciplinar de Astrofisica, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Ballot, J. [Institut de Recherche en Astrophysique et Planetologie, CNRS, 14 avenue Edouard Belin and Universite de Toulouse, UPS-OMP, IRAP, 31400 Toulouse (France); Couvidat, S. [W.W. Hansen. E. P. L., Stanford University, Stanford, CA 94305 (United States); Mathur, S. [High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); Salabert, D. [CNRS, Observatoire de la Cote d'Azur, Universite de Nice Sophia-Antipolis, BP 4229, 06304 Nice Cedex 4 (France); Silk, J., E-mail: Sylvaine.Turck-Chieze@cea.fr [UPMC-CNRS, UMR7095, Institut d'Astrophysique de Paris, F-75014 Paris (France)

    2012-02-10T23:59:59.000Z

    We derive new limits on the cold dark matter properties for weakly interacting massive particles (WIMPs), potentially trapped in the solar core by using for the first time the central temperature constrained by boron neutrinos and the central density constrained by the dipolar gravity modes detected with the Global Oscillations at Low Frequency/Solar Helioseismic Observatory instrument. These detections disfavor the presence of non-annihilating WIMPs for masses {<=}10 GeV and spin dependent cross-sections >5 Multiplication-Sign 10{sup -36} cm{sup 2} in the solar core but cannot constrain WIMP annihilation models. We suggest that in the coming years helio- and asteroseismology will provide complementary probes of dark matter.

  6. GE Healthcare Product Guide 2007

    E-Print Network [OSTI]

    Lebendiker, Mario

    GE Healthcare BioProcess Product Guide 2007 #12;How to contact us Europe www.gehealthcare.com/bioprocess or by phone (T), fax (F), and Email Austria T: +43 1 57 606 1613 F: +43 1 57 606 1614 Email: cust.orderde@ge.com Belgium T: 0800 73890 F: 02 416 8206 Email: order.bnl@ge.com Central and East Europe (Austria) T: +43 1

  7. Magnetic Refrigeration | GE Global Research

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

    temperature," said Frank Johnson, a materials scientist and project leader on GE's magnetic refrigeration project. Developed over the past decade, these new magnetocaloric...

  8. Pushing Super Materials to the Limit | GE Global Research

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

    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 for4,645U.S. DOE Office of Science (SC)IntegratedSpeedingTechnicalPurchase, Delivery, and Storage of Gases

  9. Thermodynamics of clusterized matter

    E-Print Network [OSTI]

    Ad. R. Raduta; F. Gulminelli

    2009-08-26T23:59:59.000Z

    Thermodynamics of clusterized matter is studied in the framework of statistical models with non-interacting cluster degrees of freedom. At variance with the analytical Fisher model, exact Metropolis simulation results indicate that the transition from homogeneous to clusterized matter lies along the $\\rho=\\rho_0$ axis at all temperatures and the limiting point of the phase diagram is not a critical point even if the surface energy vanishes at this point. Sensitivity of the inferred phase diagram to the employed statistical framework in the case of finite systems is discussed by considering the grand-canonical and constant-pressure canonical ensembles. A Wigner-Seitz formalism in which the fragment charge is neutralized by an uniform electron distribution allows to build the phase diagram of neutron star matter.

  10. Results on neutrinoless double beta decay of 76 Ge from Gerda Phase I

    E-Print Network [OSTI]

    Results on neutrinoless double beta decay of 76 Ge from Gerda Phase I M. Agostini,14 M. Allardt,3 E and a lower limit is derived for the half-life of neutrinoless double beta decay of 76 Ge, T0 1/2> 2.1 · 1025 double beta decay of the isotope 76 Ge. Data con- sidered in the present analysis have been collected

  11. Serial and parallel Si, Ge, and SiGe direct-write with scanning...

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

    Serial and parallel Si, Ge, and SiGe direct-write with scanning probes and conducting stamps. Serial and parallel Si, Ge, and SiGe direct-write with scanning probes and conducting...

  12. How Will Mind Overcome Matter | GE Global Research

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

    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 for4,645U.S. DOE Office of Science (SC) EnvironmentalGyroSolé(tm) HarmonicbetandEnergy 2010 ABringof

  13. CHEM 114 GE 124 MATH 110 COMM 102 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120

    E-Print Network [OSTI]

    Saskatchewan, University of

    2006-07 CHEM 114 GE 124 MATH 110 COMM 102 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120 GEOL 245 MATH 223 CE 328 CE 212 CE 225 CE 295GE 213# MATH 224 GEOL 224 GEOE 218 GEOL 258 Hum/SocSci Jr. GEOE 315 GEOE 475 Grp C Elec.# GE 348#CE 318 CE 319 ENG 11X# GEOL 463 or Grp B Elec.# GEOL 226 GE 300# CE 316

  14. CHEM 114 GE 124 MATH 110 COMM 102 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120

    E-Print Network [OSTI]

    Saskatchewan, University of

    2005-2006 CHEM 114 GE 124 MATH 110 COMM 102 CHEM 115# GE 125 MATH 124 PHYS 155 GE 120 GEOL 245 MATH 223 CE 328 CE 212 CE 225 CE 295GE 213# MATH 224 GEOL 224 GEOE 218 GEOL 258 BusSci/HSS# GEOE 315 GEOE 475 Grp C Elec.# GE 348#CE 318 CE 319 ENG 11X# GEOL 463 or Grp B Elec.# GEOL 226 GE 300# CE 316 Grp

  15. Low-voltage broad-band electroabsorption from thin Ge/SiGe

    E-Print Network [OSTI]

    Miller, David A. B.

    Low-voltage broad-band electroabsorption from thin Ge/SiGe quantum wells epitaxially grown than 5 dB over the entire telecommunication S- and C-bands with only 1V drive using a new Ge/SiGe QW epitaxy design approach; further, this is demonstrated with the thinnest Ge/SiGe epitaxy to date, using

  16. Strained Si, SiGe, and Ge on-insulator: review of wafer bonding fabrication techniques

    E-Print Network [OSTI]

    Strained Si, SiGe, and Ge on-insulator: review of wafer bonding fabrication techniques Gianni was arranged by Prof. C.K. Maiti Abstract Techniques for fabricating strained Si, SiGe, and Ge on is presented, with a detailed discussion of wafer bonding approaches for strained Si, SiGe, and Ge on

  17. Dark matter particles

    E-Print Network [OSTI]

    V. Berezinsky

    1996-10-31T23:59:59.000Z

    The baryonic and cold dark matter are reviewed in the context of cosmological models. The theoretical search for the particle candidates is limited by supersymmetric extension of the Standard Model. Generically in such models there are just two candidates associated with each other: generalized neutralino, which components are usual neutralino and axino, and axion which is a partner of axino in supermultiplet. The status of these particles as DM candidates is described.

  18. CAST solar axion search with 3^He buffer gas: Closing the hot dark matter gap

    E-Print Network [OSTI]

    M. Arik; S. Aune; K. Barth; A. Belov; S. Borghi; H. Brauninger; G. Cantatore; J. M. Carmona; S. A. Cetin; J. I. Collar; E. Da Riva; T. Dafni; M. Davenport; C. Eleftheriadis; N. Elias; G. Fanourakis; E. Ferrer-Ribas; P. Friedrich; J. Galan; J. A. Garcia; A. Gardikiotis; J. G. Garza; E. N. Gazis; T. Geralis; E. Georgiopoulou; I. Giomataris; S. Gninenko; H. Gomez; M. Gomez Marzoa; E. Gruber; T. Guthorl; R. Hartmann; S. Hauf; F. Haug; M. D. Hasinoff; D. H. H. Hoffmann; F. J. Iguaz; I. G. Irastorza; J. Jacoby; K. Jakovcic; M. Karuza; K. Konigsmann; R. Kotthaus; M. Krcmar; M. Kuster; B. Lakic; P. M. Lang; J. M. Laurent; A. Liolios; A. Ljubicic; V. Lozza; G. Luzon; S. Neff; T. Niinikoski; A. Nordt; T. Papaevangelou; M. J. Pivovaroff; G. Raffelt; H. Riege; A. Rodriguez; M. Rosu; J. Ruz; I. Savvidis; I. Shilon; P. S. Silva; S. K. Solanki; L. Stewart; A. Tomas; M. Tsagri; K. van Bibber; T. Vafeiadis; J. Villar; J. K. Vogel; S. C. Yildiz; K. Zioutas

    2014-09-15T23:59:59.000Z

    The CERN Axion Solar Telescope (CAST) has finished its search for solar axions with 3^He buffer gas, covering the search range 0.64 eV < m_a <1.17 eV. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. From the absence of excess X-rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g_ag < 3.3 x 10^{-10} GeV^{-1} at 95% CL, with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of g_a, for example by the currently discussed next generation helioscope IAXO.

  19. GE, Berkeley Energy Storage for Electric Vehicles | GE Global...

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

    Just Add Water: GE, Berkeley Lab Explore Possible Key to Energy Storage for Electric Vehicles Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new...

  20. Cold Spray and GE Technology | GE Global Research

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

    difference of the work done at GE Global Research is the development of cold spray for additive manufacturing, where we adapt this novel coating process to build 3D shapes....

  1. GE Researcher Explores Science Behind Movie Chappie | GE Global...

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

    When Will We Have Robot Best Friends? A GE Researcher Explores the Science Behind Movie Magic Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new...

  2. Joining GE Global Research Thermal Systems | GE Global Research

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

    Alps. With more than 16 years working as an aerospace engineer in the development of gas turbine jet engines, I had GE on my radar screen right from the beginning when I was...

  3. Uniaxially stressed Ge:Ga and Ge:Be

    SciTech Connect (OSTI)

    Dubon, O.D. Jr.

    1992-12-01T23:59:59.000Z

    The application of a large uniaxial stress to p-type Ge single crystals changes the character of both the valence band and the energy levels associated with the acceptors. Changes include the splitting of the fourfold degeneracy of the valence band top and the reduction of the ionization energy of shallow acceptors. In order to study the effect of uniaxial stress on transport properties of photoexcited holes, a variable temperature photo-Hall effect system was built in which stressed Ge:Ga and Ge:Be could be characterized. Results indicate that stress increases the lifetime and Hall mobility of photoexcited holes. These observations may help further the understanding of fundamental physical processes that affect the performance of stressed Ge photoconductors including the capture of holes by shallow acceptors.

  4. Cosmology, Thermodynamics and Matter Creation

    E-Print Network [OSTI]

    J. A. S. Lima; M. O. Calvao; I. Waga

    2007-08-24T23:59:59.000Z

    Several approaches to the matter creation problem in the context of cosmological models are summarily reviewed. A covariant formulation of the general relativistic imperfect simple fluid endowed with a process of matter creation is presented. By considering the standard big bang model, it is shown how the recent results of Prigogine et alii \\cite{1} can be recovered and, at the same time their limits of validity are explicited.

  5. Superconducting Detectors for Super Light Dark Matter

    E-Print Network [OSTI]

    Yonit Hochberg; Yue Zhao; Kathryn M. Zurek

    2015-04-27T23:59:59.000Z

    We propose and study a new class of of superconducting detectors which are sensitive to O(meV) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark matter limit, mX > keV. We compute the rate of dark matter scattering off free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with all astrophysical and terrestrial constraints could be detected by such detectors with a moderate size exposure.

  6. Superconducting Detectors for Super Light Dark Matter

    E-Print Network [OSTI]

    Hochberg, Yonit; Zurek, Kathryn M

    2015-01-01T23:59:59.000Z

    We propose and study a new class of of superconducting detectors which are sensitive to O(meV) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark matter limit, mX > keV. We compute the rate of dark matter scattering off free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with all astrophysical and terrestrial constraints could be detected by such detectors with a moderate size exposure.

  7. Pseudo-Goldstone modes in isospin-asymmetric nuclear matter

    SciTech Connect (OSTI)

    Cohen, T.D. [Univ. of Washington, Seattle, WA (United States); Broniowski, W. [H. Niewodniczanski Institute of Nuclear Physics, Cracow (Poland)

    1995-01-01T23:59:59.000Z

    The authors analyze the chiral limit in dense isospin-asymmetric nuclear matter. It is shown that the pseudo-Goldstone modes in this system are qualitatively different from the case of isospin-symmetric matter.

  8. Contamination of Dark Matter Experiments from Atmospheric Magnetic Dipoles

    E-Print Network [OSTI]

    A. Bueno; M. Masip; P. Sánchez-Lucas; N. Setzer

    2013-10-14T23:59:59.000Z

    Dark matter collisions with heavy nuclei (Xe, Ge, Si, Na) may produce recoils observable at direct-search experiments. Given that some of these experiments are yielding conflicting information, however, it is worth asking if physics other than dark matter may produce similar nuclear recoils. We examine under what conditions an atmospherically-produced neutral particle with a relatively large magnetic dipole moment could fake a dark matter signal. We argue that a very definite flux could explain the signals seen at DAMA/LIBRA, CDMS/Si and CoGeNT consistently with the bounds from XENON100 and CDMS/Ge. To explore the plausibility of this scenario, we discuss a concrete model with 10-50 MeV sterile neutrinos that was recently proposed to explain the LSND and MiniBooNE anomalies.

  9. Recommended GE Curriculum for the BSEE Majors

    E-Print Network [OSTI]

    Ravikumar, B.

    Recommended GE Curriculum for the BSEE Majors Area Subjects Suggested GE Courses Courses Actual units GE Units A. Communication and Critical Thinking (9) A.2. Fund. of Communication ENGL 101 4 4 A.3, Theatre, Dance and Music and Film Select from the GE C.1 list in the SSU Catalog 3 3 C.2. Literature

  10. Commissioning Run of the CRESST-II Dark Matter Search

    E-Print Network [OSTI]

    G. Angloher; M. Bauer; I. Bavykina; A. Bento; A. Brown; C. Bucci; C. Ciemniak; C. Coppi; G. Deuter; F. von Feilitzsch; D. Hauff; S. Henry; P. Huff; J. Imber; S. Ingleby; C. Isaila; J. Jochum; M. Kiefer; M. Kimmerle; H. Kraus; J. -C. Lanfranchi; R. F. Lang; B. Majorovits; M. Malek; R. McGowan; V. B. Mikhailik; E. Pantic; F. Petricca; S. Pfister; W. Potzel; F. Proebst; W. Rau; S. Roth; K. Rottler; C. Sailer; K. Schaeffner; J. Schmaler; S. Scholl; W. Seidel; L. Stodolsky; A. J. B. Tolhurst; I. Usherov; W. Westphal

    2009-02-16T23:59:59.000Z

    The CRESST cryogenic direct dark matter search at Gran Sasso, searching for WIMPs via nuclear recoil, has been upgraded to CRESST-II by several changes and improvements.We present the results of a commissioning run carried out in 2007. The basic element of CRESST-II is a detector module consisting of a large (~ 300 g) CaWO_4 crystal and a very sensitive smaller (~ 2 g) light detector to detect the scintillation light from the CaWO_4.Information from light-quenching factor studies allows the definition of a region of the energy-light yield plane which corresponds to tungsten recoils. A neutron test is reported which supports the principle of using the light yield to identify the recoiling nucleus. Data obtained with two detector modules for a total exposure of 48 kg-days are presented. Judging by the rate of events in the "all nuclear recoils" acceptance region the apparatus shows a factor ~ten improvement with respect to previous results, which we attribute principally to the presence of the neutron shield. In the "tungsten recoils" acceptance region three events are found, corresponding to a rate of 0.063 per kg-day. Standard assumptions on the dark matter flux, coherent or spin independent interactions,then yield a limit for WIMP-nucleon scattering of 4.8 \\times 10^{-7}pb, at M{WIMP} ~50 GeV.

  11. Asymmetric condensed dark matter

    E-Print Network [OSTI]

    Aguirre, Anthony

    2015-01-01T23:59:59.000Z

    We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate can be very light, $10^{-22}\\,{\\rm eV} \\lesssim m \\lesssim 10^2\\,{\\rm eV}$; the lower limit arises from constraints on small-scale structure formation, while the upper bound ensures that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of deco...

  12. GeSi intermixing in Ge quantum dots on Si,,001... and Si,,111... F. Boscherinia)

    E-Print Network [OSTI]

    Ge­Si intermixing in Ge quantum dots on Si,,001... and Si,,111... F. Boscherinia) Laboratori December 1999 Exploiting Ge K-edge x-ray absorption spectroscopy we provide direct evidence of Si­Ge intermixing in self-organized strained and unstrained Ge quantum dots on Si, and provide a quantitative

  13. Nonlithographic epitaxial SnxGe1x dense nanowire arrays grown on Ge,,001...

    E-Print Network [OSTI]

    Atwater, Harry

    Nonlithographic epitaxial SnxGe1Ŕx dense nanowire arrays grown on Ge,,001... Regina Ragan-thick SnxGe1 x /Ge(001) epitaxial films with 0 x 0.085 by molecular-beam epitaxy. These films evolve during growth into a dense array of SnxGe1 x nanowires oriented along 001 , as confirmed by composition contrast

  14. Matter Field, Dark Matter and Dark Energy

    E-Print Network [OSTI]

    Masayasu Tsuge

    2009-03-24T23:59:59.000Z

    A model concerning particle theory and cosmology is proposed. Matter field, dark matter and dark energy are created by an energy flow from space to primordial matter fields at the phase transition in the early universe.

  15. 7-GeV Advanced Photon Source Conceptual Design Report

    SciTech Connect (OSTI)

    Not Available

    1987-04-01T23:59:59.000Z

    During the past decade, synchrotron radiation emitted by circulating electron beams has come into wide use as a powerful, versatile source of x-rays for probing the structure of matter and for studying various physical processes. Several synchrotron radiation facilities with different designs and characteristics are now in regular operation throughout the world, with recent additions in this country being the 0.8-GeV and 2.5-GeV rings of NSLS at Brookhaven National Laboratory. However, none of the operating facilities has been designed to use a low-emittance, high-energy stored beam, together with modern undulator devices, to produce a large number of hard x-ray beams of extremely high brilliance. This document is a proposal to the Department of Energy to construct and operate high-energy synchrotron radiation facility at Argonne National Laboratory. We have now chosen to set the design energy of this facility at 7.0 GeV, with the capability to operate at up to 7.5 GeV.

  16. GeV C. W. electron microtron design report

    SciTech Connect (OSTI)

    Not Available

    1982-05-01T23:59:59.000Z

    Rising interest in the nuclear physics community in a GeV C.W. electron accelerator reflects the growing importance of high-resolution short-range nuclear physics to future advances in the field. In this report major current problems are reviewed and the details of prospective measurements which could be made with a GeV C.W. electron facility are discussed, together with their impact on an understanding of nuclear forces and the structure of nuclear matter. The microtron accelerator has been chosen as the technology to generate the electron beams required for the research discussed because of the advantages of superior beam quality, low capital and operating cost and capability of furnishing beams of several energies and intensities simultaneously. A complete technical description of the conceptual design for a 2 GeV double-sided C.W. electron microtron is presented. The accelerator can furnish three beams with independently controlled energy and intensity. The maximum current per beam is 100 ..mu..amps. Although the precise objective for maximum beam energy is still a subject of debate, the design developed in this study provides the base technology for microtron accelerators at higher energies (2 to 6 GeV) using multi-sided geometries.

  17. Constraints on particle dark matter from cosmic-ray antiprotons

    E-Print Network [OSTI]

    N. Fornengo; L. Maccione; A. Vittino

    2015-01-30T23:59:59.000Z

    Cosmic-ray antiprotons represent an important channel for dark matter indirect-detection studies. Current measurements of the antiproton flux at the top of the atmosphere and theoretical determinations of the secondary antiproton production in the Galaxy are in good agreement, with no manifest deviation which could point to an exotic contribution in this channel. Therefore, antiprotons can be used as a powerful tool for constraining particle dark matter properties. By using the spectrum of PAMELA data from 50 MV to 180 GV in rigidity, we derive bounds on the dark matter annihilation cross section (or decay rate, for decaying dark matter) for the whole spectrum of dark matter annihilation (decay) channels and under different hypotheses of cosmic-rays transport in the Galaxy and in the heliosphere. For typical models of galactic propagation, the constraints are significantly strong, setting a lower bound on the dark matter mass of a "thermal" relic at about 50-90 GeV for hadronic annihilation channels. These bounds are enhanced to about 150 GeV on the dark matter mass, when large cosmic-rays confinement volumes in the Galaxy are considered, and are reduced to 4-5 GeV for annihilation to light quarks (no bound for heavy-quark production) when the confinement volume is small. Bounds for dark matter lighter than few tens of GeV are due to the low energy part of the PAMELA spectrum, an energy region where solar modulation is relevant: to this aim, we have implemented a detailed solution of the transport equation in the heliosphere, which allowed us not only to extend bounds to light dark matter, but also to determine the uncertainty on the constraints arising from solar modulation modeling. Finally, we estimate the impact of soon-to-come AMS-02 data on the antiproton constraints.

  18. The Jefferson Lab 12 GeV program on nucleon structure

    SciTech Connect (OSTI)

    Burkert, Volker D. [JLAB

    2013-10-01T23:59:59.000Z

    This slide-show presents the experiments planned at JLab with their 12 GeV upgrade. Experiments reported address: the use of hadron spectra as probes of QCD; the transverse structure of hadrons; the longitudinal structure of hadrons; the 3-dimensional structure of hadrons; hadrons and cold nuclear matter; and low-energy tests of the Standard Model and fundamental symmetries.

  19. Valley splitting theory of SiGe/Si/SiGe quantum wells Mark Friesen,1,

    E-Print Network [OSTI]

    Coppersmith, Susan N.

    Valley splitting theory of SiGe/Si/SiGe quantum wells Mark Friesen,1, * Sucismita Chutia,1 Charles an effective mass theory for SiGe/Si/SiGe quantum wells, with an emphasis on calculating the valley splitting interface, with characteristic energy splittings of order 0.1­1 meV for the case of SiGe/Si/SiGe quantum

  20. Growth of GaN on Ge(111) by molecular beam epitaxy

    SciTech Connect (OSTI)

    Lieten, R. R.; Degroote, S.; Cheng, K.; Leys, M.; Kuijk, M.; Borghs, G. [MCP/ART, IMEC, Kapeldreef 75, 3001 Leuven (Belgium) and ETRO, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium); MCP/ART, IMEC, Kapeldreef 75, 3001 Leuven (Belgium); ETRO, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium); MCP/ART, IMEC, Kapeldreef 75, 3001 Leuven (Belgium)

    2006-12-18T23:59:59.000Z

    The epitaxial growth of GaN on Ge is reported. The authors found that direct growth of GaN performs exceptionally well on Ge(111) with plasma assisted molecular beam epitaxy. A streaky reflection high energy electron diffraction pattern is observed during growth. X-ray diffraction showed a rocking curve full width at half maximum of only 371 arc sec for a 38 nm GaN layer and indicates an abrupt interface between the GaN and Ge. Secondary ion mass spectrometry shows limited diffusion of Ga atoms into the Ge substrate and Ge atoms into the GaN layers. Current-voltage measurements show rectifying behavior for n-GaN on p-Ge. Their results indicate that GaN growth on Ge does not require intermediate layers, allowing the Ge substrate to be used as back contact in vertical devices. A p-n junction formed between GaN and Ge can be used in heterojunction devices.

  1. Rolling up SiGe on insulator

    SciTech Connect (OSTI)

    Cavallo, F.; Songmuang, R.; Ulrich, C.; Schmidt, O. G. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    2007-05-07T23:59:59.000Z

    SiGe on insulator films of 10-50 nm thickness are fabricated by Ge condensation applying different oxidation times. The layers are released from the substrate by selectively etching the insulator film. Due to the varying Ge composition, the layers bend downward toward the substrate surface and roll up into microtubes. Depending on the Ge condensation, the strain distribution in the SiGe layers varies and allows a scaling of the tube diameters between 1 and 4 {mu}m. Assuming pseudomorphic SiGe layers, the tube diameters are smaller than expected from continuum mechanical theory. This suggests the occurrence of additional strain in the oxidized films.

  2. Direct Search for Low Mass Dark Matter Particles with CCDs

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Barreto, J [Rio de Janeiro Federal U.; Cease, H.; Diehl, H.T.; Estrada, J.; Flaugher, B.; Harrison, N.; Jones, J.; Kilminster, B [Fermilab; Molina, J [Asuncion Natl. U.; Smith, J.; Sonnenschein, A [Fermilab

    2012-05-15T23:59:59.000Z

    A direct dark matter search is performed using fully-depleted high-resistivity CCD detectors. Due to their low electronic readout noise (RMS ~7 eV) these devices operate with a very low detection threshold of 40 eV, making the search for dark matter particles with low masses (~5 GeV) possible. The results of an engineering run performed in a shallow underground site are presented, demonstrating the potential of this technology in the low mass region.

  3. Search for dark matter and large extra dimensions in monojet events in pp collisions at sqrt(s) = 7 TeV

    E-Print Network [OSTI]

    CMS Collaboration

    2014-11-07T23:59:59.000Z

    A search has been made for events containing an energetic jet and an imbalance in transverse momentum using a data sample of pp collisions at a center-of-mass energy of 7 TeV. This signature is common to both dark matter and extra dimensions models. The data were collected by the CMS detector at the LHC and correspond to an integrated luminosity of 5.0 inverse femtobarns. The number of observed events is consistent with the standard model expectation. Constraints on the dark matter-nucleon scattering cross sections are determined for both spin-independent and spin-dependent interaction models. For the spin-independent model, these are the most constraining limits for a dark matter particle with mass below 3.5 GeV, a region unexplored by direct detection experiments. For the spin-dependent model, these are the most stringent constraints over the 0.1-200 GeV mass range. The constraints on the Arkani-Hamed, Dimopoulos, and Dvali model parameter MD determined as a function of the number of extra dimensions are also an improvement over the previous results.

  4. Prospects of cold dark matter searches with an ultra-low-energy germanium detector

    E-Print Network [OSTI]

    H. T. Wong

    2007-11-08T23:59:59.000Z

    The report describes the research program on the development of ultra-low-energy germanium detectors, with emphasis on WIMP dark matter searches. A threshold of 100 eV is achieved with a 20 g detector array, providing a unique probe to the low-mas WIMP. Present data at a surface laboratory is expected to give rise to comparable sensitivities with the existing limits at the $\\rm{5 - 10 GeV}$ WIMP-mass range. The projected parameter space to be probed with a full-scale, kilogram mass-range experiment is presented. Such a detector would also allow the studies of neutrino-nucleus coherent scattering and neutrino magnetic moments.

  5. Thermal properties of hot and dense matter with finite range interactions

    E-Print Network [OSTI]

    Constantinou, Constantinos; Prakash, Madappa; Lattimer, James M

    2015-01-01T23:59:59.000Z

    We explore the thermal properties of hot and dense matter using a model that reproduces the empirical properties of isospin symmetric and asymmetric bulk nuclear matter, optical model fits to nucleon-nucleus scattering data, heavy-ion flow data in the energy range 0.5-2 GeV/A, and the largest well-measured neutron star mass of 2 $\\rm{M}_\\odot$. Results of this model which incorporates finite range interactions through Yukawa type forces are contrasted with those of a zero-range Skyrme model that yields nearly identical zero-temperature properties at all densities for symmetric and asymmetric nucleonic matter and the maximum neutron star mass, but fails to account for heavy-ion flow data due to the lack of an appropriate momentum dependence in its mean field. Similarities and differences in the thermal state variables and the specific heats between the two models are highlighted. Checks of our exact numerical calculations are performed from formulas derived in the strongly degenerate and non-degenerate limits....

  6. Glow in the Dark Matter: Observing galactic halos with scattered light

    E-Print Network [OSTI]

    Jonathan H. Davis; Joseph Silk

    2015-02-04T23:59:59.000Z

    We consider the observation of diffuse halos of light around the discs of spiral galaxies, as a probe of the interaction cross section between Dark Matter and photons. Using the galaxy M101 as an example, we show that for a scattering cross section at the level of 10^(-23) x (m/GeV) cm^2 or greater Dark Matter in the halo will scatter light out from the more luminous centre of the disc to larger radii, contributing to an effective increased surface brightness at the edges of the observed area on the sky. This allows us to set an upper limit on the DM-photon cross section using data from the Dragonfly instrument. We then show how to improve this constraint, and the potential for discovery, by combining the radial profile of DM-photon scattering with measurements at multiple wavelengths. Observation of diffuse light presents a new and potentially powerful way to probe the interactions of Dark Matter with photons, which is complimentary to existing searches.

  7. First Results from the DarkSide-50 Dark Matter Experiment at Laboratori Nazionali del Gran Sasso

    E-Print Network [OSTI]

    Agnes, P; Alton, A; Arisaka, K; Back, H O; Baldin, B; Biery, K; Bonfini, G; Bossa, M; Brigatti, A; Brodsky, J; Budano, F; Cadonati, L; Calaprice, F; Canci, N; Candela, A; Cao, H; Cariello, M; Cavalcante, P; Chavarria, A; Chepurnov, A; Cocco, A G; Crippa, L; D'Angelo, D; D'Incecco, M; Davini, S; De Deo, M; Derbin, A; Devoto, A; Di Eusanio, F; Di Pietro, G; Edkins, E; Empl, A; Fan, A; Fiorillo, G; Fomenko, K; Forster, G; Franco, D; Gabriele, F; Galbiati, C; Goretti, A; Grandi, L; Gromov, M; Guan, M Y; Guardincerri, Y; Hackett, B; Herner, K; Hungerford, E V; Ianni, Al; Ianni, An; Jollet, C; Keeter, K; Kendziora, C; Kidner, S; Kobychev, V; Koh, G; Korablev, D; Korga, G; Kurlej, A; Li, P X; Loer, B; Lombardi, P; Love, C; Ludhova, L; Luitz, S; Ma, Y Q; Machulin, I; Mandarano, A; Mari, S; Maricic, J; Marini, L; Martoff, C J; Meregaglia, A; Meroni, E; Meyers, P D; Milincic, R; Montanari, D; Montuschi, M; Monzani, M E; Mosteiro, P; Mount, B; Muratova, V; Musico, P; Nelson, A; Odrowski, S; Okounkova, M; Orsini, M; Ortica, F; Pagani, L; Pallavicini, M; Pantic, E; Papp, L; Parmeggiano, S; Parsells, R; Pelczar, K; Pelliccia, N; Perasso, S; Pocar, A; Pordes, S; Pugachev, D; Qian, H; Randle, K; Ranucci, G; Razeto, A; Reinhold, B; Renshaw, A; Romani, A; Rossi, B; Rossi, N; Rountree, S D; Sablone, D; Saggese, P; Saldanha, R; Sands, W; Sangiorgio, S; Segreto, E; Semenov, D; Shields, E; Skorokhvatov, M; Smirnov, O; Sotnikov, A; Stanford, C; Suvorov, Y; Tartaglia, R; Tatarowicz, J; Testera, G; Tonazzo, A; Unzhakov, E; Vogelaar, R B; Wada, M; Walker, S; Wang, H; Wang, Y; Watson, A; Westerdale, S; Wojcik, M; Wright, A; Xiang, X; Xu, J; Yang, C G; Yoo, J; Zavatarelli, S; Zec, A; Zhu, C; Zuzel, G

    2015-01-01T23:59:59.000Z

    We report the first results of DarkSide-50, a direct search for dark matter operating in the underground Laboratori Nazionali del Gran Sasso (LNGS) and searching for the rare nuclear recoils possibly induced by weakly interacting massive particles (WIMPs). The dark matter detector is a Liquid Argon Time Projection Chamber with a (46.4+-0.7) kg active mass, operated inside a 30 t organic liquid scintillator neutron veto, which is in turn installed at the center of a 1 kt water Cherenkov veto for the residual flux of cosmic rays. We report here the null results of a dark matter search for a (1422+-67) kg d exposure with an atmospheric argon fill. This is the most sensitive dark matter search performed with an argon target, corresponding to a 90% CL upper limit on the WIMP-nucleon spin-independent cross section of 6.1x10^-44 cm^2 for a WIMP mass of 100 GeV/c^2.

  8. First Results from the DarkSide-50 Dark Matter Experiment at Laboratori Nazionali del Gran Sasso

    E-Print Network [OSTI]

    P. Agnes; T. Alexander; A. Alton; K. Arisaka; H. O. Back; B. Baldin; K. Biery; G. Bonfini; M. Bossa; A. Brigatti; J. Brodsky; F. Budano; L. Cadonati; F. Calaprice; N. Canci; A. Candela; H. Cao; M. Cariello; P. Cavalcante; A. Chavarria; A. Chepurnov; A. G. Cocco; L. Crippa; D. D'Angelo; M. D'Incecco; S. Davini; M. De Deo; A. Derbin; A. Devoto; F. Di Eusanio; G. Di Pietro; E. Edkins; A. Empl; A. Fan; G. Fiorillo; K. Fomenko; G. Forster; D. Franco; F. Gabriele; C. Galbiati; A. Goretti; L. Grandi; M. Gromov; M. Y. Guan; Y. Guardincerri; B. Hackett; K. Herner; E. V. Hungerford; Al. Ianni; An. Ianni; C. Jollet; K. Keeter; C. Kendziora; S. Kidner; V. Kobychev; G. Koh; D. Korablev; G. Korga; A. Kurlej; P. X. Li; B. Loer; P. Lombardi; C. Love; L. Ludhova; S. Luitz; Y. Q. Ma; I. Machulin; A. Mandarano; S. Mari; J. Maricic; L. Marini; C. J. Martoff; A. Meregaglia; E. Meroni; P. D. Meyers; R. Milincic; D. Montanari; A. Monte; M. Montuschi; M. E. Monzani; P. Mosteiro; B. Mount; V. Muratova; P. Musico; A. Nelson; S. Odrowski; M. Okounkova; M. Orsini; F. Ortica; L. Pagani; M. Pallavicini; E. Pantic; L. Papp; S. Parmeggiano; R. Parsells; K. Pelczar; N. Pelliccia; S. Perasso; A. Pocar; S. Pordes; D. Pugachev; H. Qian; K. Randle; G. Ranucci; A. Razeto; B. Reinhold; A. Renshaw; A. Romani; B. Rossi; N. Rossi; S. D. Rountree; D. Sablone; P. Saggese; R. Saldanha; W. Sands; S. Sangiorgio; E. Segreto; D. Semenov; E. Shields; M. Skorokhvatov; O. Smirnov; A. Sotnikov; C. Stanford; Y. Suvorov; R. Tartaglia; J. Tatarowicz; G. Testera; A. Tonazzo; E. Unzhakov; R. B. Vogelaar; M. Wada; S. Walker; H. Wang; Y. Wang; A. Watson; S. Westerdale; M. Wojcik; A. Wright; X. Xiang; J. Xu; C. G. Yang; J. Yoo; S. Zavatarelli; A. Zec; C. Zhu; G. Zuzel

    2015-02-27T23:59:59.000Z

    We report the first results of DarkSide-50, a direct search for dark matter operating in the underground Laboratori Nazionali del Gran Sasso (LNGS) and searching for the rare nuclear recoils possibly induced by weakly interacting massive particles (WIMPs). The dark matter detector is a Liquid Argon Time Projection Chamber with a (46.4+-0.7) kg active mass, operated inside a 30 t organic liquid scintillator neutron veto, which is in turn installed at the center of a 1 kt water Cherenkov veto for the residual flux of cosmic rays. We report here the null results of a dark matter search for a (1422+-67) kg d exposure with an atmospheric argon fill. This is the most sensitive dark matter search performed with an argon target, corresponding to a 90% CL upper limit on the WIMP-nucleon spin-independent cross section of 6.1x10^-44 cm^2 for a WIMP mass of 100 GeV/c^2.

  9. Acoustoelectric effects in very high-mobility p-SiGe/Ge/SiGe heterostructure

    SciTech Connect (OSTI)

    Drichko, I. L.; Diakonov, A. M.; Lebedeva, E. V.; Smirnov, I. Yu. [A. F. Ioffe Physico-Technical Institute of Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Mironov, O. A. [Warwick SEMINANO R and D Centre, University of Warwick Science Park, Coventry CV4 7EZ (United Kingdom); Kummer, M.; Kaenel, H. von [Laboratorium fuer Festkoerperphysik ETH Zuerich, CH-8093 Zuerich (Switzerland); EpiSpeed SA, Technoparkstrasse 1, CH-8005 Zuerich (Switzerland)

    2009-11-01T23:59:59.000Z

    Measurement results of the acoustoelectric effects [surface acoustic waves (SAW) attenuation and velocity] in a high-mobility p-SiGe/Ge/SiGe structure are presented. The structure was low-energy plasma-enhanced chemical vapor deposition grown with a two-dimensional (2D) channel buried in the strained Ge layer. The measurements were performed as a function of temperature (1.5-4.2 K) and magnetic field (up to 8.4 T) at different SAW intensities at frequencies 28 and 87 MHz. Shubnikov-de Haas-like oscillations of both SAW attenuation and the velocity change have been observed. Hole density and mobility, effective mass, quantum and transport relaxation times, as well as the Dingle temperature were measured with a method free of electric contacts. The effect of heating of the 2D hole gas by the electric field of the SAW was investigated. Energy relaxation time tau{sub e}psilon and the deformation potential constant determined.

  10. PROBABILITY OF CORRECT SELECTION OF GAMMA VERSUS GE OR WEIBULL VERSUS GE BASED ON

    E-Print Network [OSTI]

    Kundu, Debasis

    PROBABILITY OF CORRECT SELECTION OF GAMMA VERSUS GE OR WEIBULL VERSUS GE BASED ON LIKELIHOOD RATIO proposes the use of likelihood ratio statistic in choosing between gamma and GE models or between Weibull and GE models. Probability of correct selec- tions are obtained using Monte Carlo simulations for various

  11. Explaining the Higgs boson $p_T$ distributions with a new heavy scalar boson and a dark matter candidate

    E-Print Network [OSTI]

    von Buddenbrock, Stefan; Cornell, Alan S; Kar, Deepak; Kumar, Mukesh; Mandal, Tanumoy; Mellado, Bruce; Mukhopadhyaya, Biswarup; Reed, Robert G

    2015-01-01T23:59:59.000Z

    We attempt a simultaneous fit of the excess in Higgs boson transverse momentum distributions in the $\\gamma\\gamma$ and $ZZ^*$ decay channels as well as certain excesses in the search for di-Higgs boson resonances observed with Run I data at the Large Hadron Collider. An answer is found in a scenario with a heavy scalar with mass in the range $275-285$~GeV, together with a scalar dark matter candidate with mass around $55-60$~GeV. This is consistent with all cosmological and direct dark matter search constraints, as well as the limit on the invisible decay width of the observed Higgs boson. In this scenario the producion of the heavy scalar in association with single top quark is not suppressed, compared to that of the Higgs boson. It is also important to look out for Higgs boson production in association with intermediate missing transverse energy. Another consequence is the possible decay of the heavy scalar into $VV$, where $V=Z$ and $W^{\\pm}$.

  12. Matter Wave Radiation Leading to Matter Teleportation

    E-Print Network [OSTI]

    Yong-Yi Huang

    2015-02-12T23:59:59.000Z

    The concept of matter wave radiation is put forward, and its equation is established for the first time. The formalism solution shows that the probability density is a function of displacement and time. A free particle and a two-level system are reinvestigated considering the effect of matter wave radiation. Three feasible experimental designs, especially a modified Stern-Gerlach setup, are proposed to verify the existence of matter wave radiation. Matter wave radiation effect in relativity has been formulated in only a raw formulae, which offers another explanation of Lamb shift. A possible mechanics of matter teleportation is predicted due to the effect of matter wave radiation.

  13. Understanding and engineering of NiGe/Ge junction formed by phosphorus ion implantation after germanidation

    SciTech Connect (OSTI)

    Oka, Hiroshi, E-mail: oka@asf.mls.eng.osaka-u.ac.jp; Minoura, Yuya; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji [Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-08-11T23:59:59.000Z

    Modulation of the effective electron Schottky barrier height (eSBH) of NiGe/Ge contacts induced by phosphorus ion implantation after germanide formation was investigated by considering local inhomogeneity in the eSBH. Systematic studies of NiGe/Ge contact devices having various germanide thicknesses and ion implantation areas indicated the threshold dopant concentration at the NiGe/Ge interface required for eSBH modulation and negligible dopant diffusion even at NiGe/Ge interface during drive-in annealing, leading to variation in the eSBH between the bottom and sidewall portions of the NiGe regions. Consequently, this method makes it possible to design source/drain contacts with low-resistivity Ohmic and ideal rectifying characteristics for future Ge-based transistors.

  14. Semiconductor Probes of Light Dark Matter

    E-Print Network [OSTI]

    Peter W. Graham; David E. Kaplan; Surjeet Rajendran; Matthew T. Walters

    2012-11-12T23:59:59.000Z

    Dark matter with mass below about a GeV is essentially unobservable in conventional direct detection experiments. However, newly proposed technology will allow the detection of single electron events in semiconductor materials with significantly lowered thresholds. This would allow detection of dark matter as light as an MeV in mass. Compared to other detection technologies, semiconductors allow enhanced sensitivity because of their low ionization energy around an eV. Such detectors would be particularly sensitive to dark matter with electric and magnetic dipole moments, with a reach many orders of magnitude beyond current bounds. Observable dipole moment interactions can be generated by new particles with masses as great as 1000 TeV, providing a window to scales beyond the reach of current colliders.

  15. Baryonic matter and beyond

    E-Print Network [OSTI]

    Kenji Fukushima

    2014-10-01T23:59:59.000Z

    We summarize recent developments in identifying the ground state of dense baryonic matter and beyond. The topics include deconfinement from baryonic matter to quark matter, a diquark mixture, topological effect coupled with chirality and density, and inhomogeneous chiral condensates.

  16. SiGe-On-Insulator (SGOI) Technology and MOSFET Fabrication

    E-Print Network [OSTI]

    SiGe-On-Insulator (SGOI) Technology and MOSFET Fabrication Zhiyuan Cheng, E. A. Fitzgerald, and D with less defects in SiGe film, but the SiGe film uniformity is inferior. "Smart-cut" approach has better control on the SiGe film thickness and uniformity, and is applicable to wider Ge content range of the SiGe

  17. Dark Matter Theory

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

    Dark Matter Theory Dark Matter Theory Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email Bruce Carlsten (505)...

  18. Analysis of X-Ray Diffraction as a Probe of Interdiffusion in Si/SiGe Heterostructures

    SciTech Connect (OSTI)

    Brennan, Sean M

    2003-08-20T23:59:59.000Z

    We investigate numerical simulations that utilize a non-linear interdiffusion solver and dynamical x-ray diffraction calculations to predict the local composition evolution in low Ge concentration Si/SiGe superlattices and their diffraction patterns during annealing. Superlattice satellite peak decay rates are compared with experimentally measured values and simulated diffraction patterns are matched directly to data with good success. The simulations are used to test the sensitivity of x-ray diffraction to various uncertainties commonly encountered when measuring interdiffusion at Si/SiGe interfaces. It is found that the most serious errors result from variations in the Ge content across the surface of the wafer. For example, the resolution limit of most experimental techniques used to measure Ge concentration in a SiGe film is -1 at.%, for a film with 11% mean Ge concentration annealed for 5 hours at 870 C, this level of error will cause the observed interdiffusivity values to deviate by -25% or +50%. The simulations are further used to show that for Si/SiGe interdiffusion, superlattice diffraction produces valid measurements when applied to 004 superlattice satellite peaks and square wave composition modulations even though it is only exactly applicable to satellite peaks about 000 reflection and to sinusoidal composition modulations. Finally, we show that proper interpretation of x-ray scattering data to extract Si/SiGe interdiffusivity values must account for the strong dependence of the interdiffusivity on Ge concentration.

  19. About GE Global Research Center | GE Global Research

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

    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 742EnergyOnItem NotEnergy,ARMForms About Become agovEducationWelcome toAboutAbout GE Global Research

  20. Heat Transfer in GE Jet Engines | GE Global Research

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

    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 for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cn SunnybankD.jpgHanfordDepartment ofHeat Transfer in GE Jet Engines Click to

  1. Lepton-flavored dark matter

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kile, Jennifer; Kobach, Andrew; Soni, Amarjit

    2015-05-01T23:59:59.000Z

    In this work, we address two paradoxes. The first is that the measured dark-matter relic density can be satisfied with new physics at O(100 GeV–1 TeV), while the null results from direct-detection experiments place lower bounds of O(10 TeV) on a new-physics scale. The second puzzle is that the severe suppression of lepton-flavor-violating processes involving electrons, e.g. ? ? 3e, ? ? e??, etc., implies that generic new-physics contributions to lepton interactions cannot exist below O(10–100 TeV), whereas the 3.6? deviation of the muon g – 2 from the standard model can be explained by a new physics scale matter thus interacts appreciably only with particles of ? and ? flavor at tree level and has loop-suppressed couplings to quarks and electrons. Remarkably, if such a gauged flavor interaction exists at a scale O(100 GeV–1 TeV), it allows for a consistent phenomenological framework, compatible with the muon g – 2, the relic density, direct detection, indirect detection, charged-lepton decays, neutrino trident production, and results from hadron and e?e? colliders. We suggest experimental tests for these ideas at colliders and for low-energy observables. (author)

  2. Lepton-flavored dark matter

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kile, Jennifer; Kobach, Andrew; Soni, Amarjit

    2015-05-01T23:59:59.000Z

    In this work, we address two paradoxes. The first is that the measured dark-matter relic density can be satisfied with new physics at O(100 GeV–1 TeV), while the null results from direct-detection experiments place lower bounds of O(10 TeV) on a new-physics scale. The second puzzle is that the severe suppression of lepton-flavor-violating processes involving electrons, e.g. ? ? 3e, ? ? e??, etc., implies that generic new-physics contributions to lepton interactions cannot exist below O(10–100 TeV), whereas the 3.6? deviation of the muon g – 2 from the standard model can be explained by a new physics scale more »TeV). Here, we suggest that it may not be a coincidence that both the muon g – 2 and the relic density can be satisfied by a new-physics scale ?1 TeV. We consider the possibility of a gauged lepton-flavor interaction that couples at tree level only to ?- and ?-flavored leptons and the dark sector. Dark matter thus interacts appreciably only with particles of ? and ? flavor at tree level and has loop-suppressed couplings to quarks and electrons. Remarkably, if such a gauged flavor interaction exists at a scale O(100 GeV–1 TeV), it allows for a consistent phenomenological framework, compatible with the muon g – 2, the relic density, direct detection, indirect detection, charged-lepton decays, neutrino trident production, and results from hadron and e?e? colliders. We suggest experimental tests for these ideas at colliders and for low-energy observables. (author)« less

  3. Photoconductivity of Si/Ge multilayer structures with Ge quantum dots pseudomorphic to the Si matrix

    SciTech Connect (OSTI)

    Talochkin, A. B., E-mail: tal@thermo.isp.nsc.ru; Chistokhin, I. B. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2011-07-15T23:59:59.000Z

    Longitudinal photoconductivity spectra of Si/Ge multilayer structures with Ge quantum dots grown pseudomorphically to the Si matrix are studied. Lines of optical transitions between hole levels of quantum dots and Si electronic states are observed. This allowed us to construct a detailed energy-level diagram of electron-hole levels of the structure. It is shown that hole levels of pseudomorphic Ge quantum dots are well described by the simplest 'quantum box' model using actual sizes of Ge islands. The possibility of controlling the position of the long-wavelength photosensitivity edge by varying the growth parameters of Si/Ge structures with Ge quantum dots is determined.

  4. Advanced Analytics | GE Global Research

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

    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 3,625govInstrumentstdmadapInactiveVisiting the TWP TWP Related LinksATHENAAdministrative80-AA (01-2015)GE

  5. Main sequence stars with asymmetric dark matter

    E-Print Network [OSTI]

    Fabio Iocco; Marco Taoso; Florent Leclercq; Georges Meynet

    2012-01-25T23:59:59.000Z

    We study the effects of feebly or non-annihilating weakly interacting Dark Matter (DM) particles on stars that live in DM environments denser than that of our Sun. We find that the energy transport mechanism induced by DM particles can produce unusual conditions in the core of Main Sequence stars, with effects which can potentially be used to probe DM properties. We find that solar mass stars placed in DM densities of rhochi>= e2 GeV/cm3 are sensitive to Spin-Dependent scattering cross-section sigmsd >= e-37 cm2 and a DM particle mass as low as mchi=5 GeV, accessing a parameter range weakly constrained by current direct detection experiments.

  6. Thermal Imaging Technologies | GE Global Research

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

    Enables Advanced Thermal Imaging An error occurred. Unable to execute Javascript. Bryan Whalen in the Electronics Cooling Lab at GE Global Research recorded this thermo...

  7. The cross-plane thermoelectric properties of p-Ge/Si{sub 0.5}Ge{sub 0.5} superlattices

    SciTech Connect (OSTI)

    Ferre Llin, L.; Samarelli, A.; Weaver, J. M. R.; Dobson, P. S.; Paul, D. J. [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT (United Kingdom)] [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT (United Kingdom); Cecchi, S.; Chrastina, D.; Isella, G. [L-NESS, Politecnico di Milano, Via Anzani 42, 22100 Como (Italy)] [L-NESS, Politecnico di Milano, Via Anzani 42, 22100 Como (Italy); Etzelstorfer, T.; Stangl, J. [Institute of Semiconductor and Solid State Physics, Johannes Kepler Universität, Linz (Austria)] [Institute of Semiconductor and Solid State Physics, Johannes Kepler Universität, Linz (Austria); Müller Gubler, E. [Electron Microscopy ETH Zurich, ETH Zurich, Wolfgang-Pauli-Str. 16, CH-8093 Zurich (Switzerland)] [Electron Microscopy ETH Zurich, ETH Zurich, Wolfgang-Pauli-Str. 16, CH-8093 Zurich (Switzerland)

    2013-09-30T23:59:59.000Z

    The electrical conductivity, Seebeck coefficients, and thermal conductivities of a range of p-type Ge/Si{sub 0.5}Ge{sub 0.5} superlattices designed for thermoelectric generation and grown by low energy plasma enhanced chemical vapor deposition have been measured using a range of microfabricated test structures. For samples with barriers around 0.5 nm in thickness, the measured Seebeck coefficients were comparable to bulk p-SiGe at similar doping levels suggesting the holes see the material as a random bulk alloy rather than a superlattice. The Seebeck coefficients for Ge quantum wells of 2.85 ± 0.85 nm increased up to 533 ± 25 ?V/K as the doping was reduced. The thermal conductivities are between 4.5 to 6.0 Wm{sup ?1}K{sup ?1} which are lower than comparably doped bulk Si{sub 0.3}Ge{sub 0.7} but higher than undoped Si/Ge superlattices. The highest measured figure of merit ZT was 0.080 ± 0.011 obtained for the widest quantum well studied. Analysis suggests that interface roughness is presently limiting the performance and a reduction in the strain between the quantum wells and barriers has the potential to improve the thermoelectric performance.

  8. SiGe/sSi quantum dot electron spin decoherence dependence on $^{73}$Ge

    E-Print Network [OSTI]

    Witzel, Wayne M; Carroll, Malcolm S

    2011-01-01T23:59:59.000Z

    We theoretically study the nuclear spin induced decoherence of a quantum dot in Si that is confined at a SiGe interface. We calculate decoherence time dependence on $^{73}$Ge in the barrier layer to evaluate the importance of Ge as well as Si enrichment for long decoherence times. We use atomistic tight-binding modeling for an accurate account of the electron wavefunction which is particularly important for determining the contact hyperfine interactions with the Ge nuclear spins. We find decoherence times due to Ge spins at natural concentrations to be milliseconds. This suggests SiGe/sSi quantum dot devices employing enriched Si will require enriched Ge as well in order to benefit from long coherence times. We provide a comparison of $T_2$ times for various fractions of nonzero spin isotopes of Si and Ge.

  9. SiGe/Si quantum dot electron spin decoherence dependence on $^{73}$Ge

    E-Print Network [OSTI]

    Wayne M. Witzel; Rajib Rahman; Malcolm S. Carroll

    2012-05-14T23:59:59.000Z

    We theoretically study the nuclear spin induced decoherence of a quantum dot in Si that is confined at a SiGe interface. We calculate decoherence time dependence on $^{73}$Ge in the barrier layer to evaluate the importance of Ge as well as Si enrichment for long decoherence times. We use atomistic tight-binding modeling for an accurate account of the electron wavefunction which is particularly important for determining the contact hyperfine interactions with the Ge nuclear spins. We find decoherence times due to Ge spins at natural concentrations to be milliseconds. This suggests SiGe/Si quantum dot devices employing enriched Si will require enriched Ge as well in order to benefit from long coherence times. We provide a comparison of $T_2$ times for various fractions of nonzero spin isotopes of Si and Ge.

  10. MOSFET Channel Engineering using Strained Si, SiGe, and Ge Channels

    E-Print Network [OSTI]

    Fitzgerald, Eugene A.

    Biaxial tensile strained Si grown on SiGe virtual substrates will be incorporated into future generations of CMOS technology due to the lack of performance increase with scaling. Compressively strained Ge-rich alloys with ...

  11. Structure and magnetism in strained Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy

    SciTech Connect (OSTI)

    Prestat, E. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Karlsruher Institut fuer Technologie (KIT), Laboratorium fuer Elektronenmikroskopie, D-76128 Karlsruhe (Germany); Barski, A.; Bellet-Amalric, E.; Morel, R.; Tainoff, D.; Jain, A.; Porret, C.; Bayle-Guillemaud, P.; Jamet, M. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Jacquot, J.-F. [INAC, SCIB, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

    2013-07-01T23:59:59.000Z

    In this letter, we study the structural and magnetic properties of Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy using X-ray diffraction, high resolution transmission electron microscopy, and superconducting quantum interference device. Like in Mn doped Ge films, Mn atoms diffuse during the growth and aggregate into vertically aligned Mn-rich nanocolumns of a few nanometers in diameter. Transmission electron microscopy observations in plane view clearly indicate that the Sn incorporation is not uniform with concentration in Mn rich vertical nanocolumns lower than the detection limit of electron energy loss spectroscopy. The matrix exhibits a GeSn solid solution while there is a Sn-rich GeSn shell around GeMn nanocolumns. The magnetization in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} layers is higher than in Ge{sub 1-x}Mn{sub x} films. This magnetic moment enhancement in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} is probably related to the modification of the electronic structure of Mn atoms in the nanocolumns by the Sn-rich shell, which is formed around the nanocolumns.

  12. Enhanced Hole Mobility in High Ge Content Asymmetrically Strained-SiGe p-MOSFETs

    E-Print Network [OSTI]

    Chléirigh, C. Ni

    The hole mobility characteristics of ?110? /(100)-oriented asymmetrically strained-SiGe p-MOSFETs are studied.

  13. Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab

    E-Print Network [OSTI]

    BDX Collaboration; M. Battaglieri; A. Celentano; R. De Vita; E. Izaguirre; G. Krnjaic; E. Smith; S. Stepanyan; A. Bersani; E. Fanchini; S. Fegan; P. Musico; M. Osipenko; M. Ripani; E. Santopinto; M. Taiuti; P. Schuster; N. Toro; M. Dalton; A. Freyberger; F. -X. Girod; V. Kubarovsky; M. Ungaro; G. De Cataldo; R. De Leo; D. Di Bari; L. Lagamba; E. Nappi; R. Perrino; M. Carpinelli; V. Sipala; S. Aiello; V. Bellini; M. De Napoli; A. Giusa; F. Mammoliti; E. Leonora; F. Noto; N. Randazzo; G. Russo; M. Sperduto; C. Sutera; C. Ventura; L. Barion; G. Ciullo; M. Contalbrigo; P. Lenisa; A. Movsisyan; F. Spizzo; M. Turisini; F. De Persio; E. Cisbani; C. Fanelli; F. Garibaldi; F. Meddi; G. M. Urciuoli; S. Anefalos Pereira; E. De Sanctis; D. Hasch; V. Lucherini; M. Mirazita; R. Montgomery; S. Pisano; G. Simi; A. D'Angelo; L. Colaneri L. Lanza; A. Rizzo; C. Schaerf; I. Zonta; D. Calvo; A. Filippi; M. Holtrop; R. Peremuzyan; D. Glazier; D. Ireland; B. McKinnon; D. Sokhan A. Afanasev; B. Briscoe; N. Kalantarians; L. El Fassi; L. Weinstein; P. Beltrame; A. Murphy; D. Watts; L. Zana; K. Hicks

    2014-06-11T23:59:59.000Z

    MeV-GeV dark matter (DM) is theoretically well motivated but remarkably unexplored. This Letter of Intent presents the MeV-GeV DM discovery potential for a 1 m$^3$ segmented plastic scintillator detector placed downstream of the beam-dump at one of the high intensity JLab experimental Halls, receiving up to 10$^{22}$ electrons-on-target (EOT) in a one-year period. This experiment (Beam-Dump eXperiment or BDX) is sensitive to DM-nucleon elastic scattering at the level of a thousand counts per year, with very low threshold recoil energies ($\\sim$1 MeV), and limited only by reducible cosmogenic backgrounds. Sensitivity to DM-electron elastic scattering and/or inelastic DM would be below 10 counts per year after requiring all electromagnetic showers in the detector to exceed a few-hundred MeV, which dramatically reduces or altogether eliminates all backgrounds. Detailed Monte Carlo simulations are in progress to finalize the detector design and experimental set up. An existing 0.036 m$^3$ prototype based on the same technology will be used to validate simulations with background rate estimates, driving the necessary R$\\&$D towards an optimized detector. The final detector design and experimental set up will be presented in a full proposal to be submitted to the next JLab PAC. A fully realized experiment would be sensitive to large regions of DM parameter space, exceeding the discovery potential of existing and planned experiments by two orders of magnitude in the MeV-GeV DM mass range.

  14. Improvements to the Calculation of Indirect Signals of Diffuse Gamma-rays and Neutrinos from Dark Matter Annihilation 

    E-Print Network [OSTI]

    Campbell, Sheldon Scott

    2012-10-19T23:59:59.000Z

    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1 Brief Review of FLRW Cosmology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2 Matter Collapse on Linear Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.2.1 The Linear... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Figure 22 The mean neutrino intensity for the focus point model . . . . . . . . . . . . . . 133 Figure 23 All-sky neutrino plus antineutrino detection rates for 150 GeV dark matter annihilation...

  15. Improvements to the Calculation of Indirect Signals of Diffuse Gamma-rays and Neutrinos from Dark Matter Annihilation

    E-Print Network [OSTI]

    Campbell, Sheldon Scott

    2012-10-19T23:59:59.000Z

    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1 Brief Review of FLRW Cosmology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2 Matter Collapse on Linear Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.2.1 The Linear... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Figure 22 The mean neutrino intensity for the focus point model . . . . . . . . . . . . . . 133 Figure 23 All-sky neutrino plus antineutrino detection rates for 150 GeV dark matter annihilation...

  16. Modeling of GE Appliances: Final Presentation

    SciTech Connect (OSTI)

    Fuller, Jason C.; Vyakaranam, Bharat; Leistritz, Sean M.; Parker, Graham B.

    2013-01-31T23:59:59.000Z

    This report is the final in a series of three reports funded by U.S. Department of Energy Office of Electricity Delivery and Energy Reliability (DOE-OE) in collaboration with GE Appliances’ through a Cooperative Research and Development Agreement (CRADA) to describe the potential of GE Appliances’ DR-enabled appliances to provide benefits to the utility grid.

  17. Relaxed SiGe Layers with High Ge Content by Compliant Substrates , R.L. Peterson1

    E-Print Network [OSTI]

    Relaxed SiGe Layers with High Ge Content by Compliant Substrates H. Yin1 , R.L. Peterson1 , K, high Ge content SiGe layers have been realized using stress balance on a compliant under compression. Upon equilibrium after an annealing, stress balance was formed between the SiGe films

  18. First Results from the Cryogenic Dark Matter Search Experiment at the Deep Site

    SciTech Connect (OSTI)

    Mandic, Vuk

    2004-06-01T23:59:59.000Z

    The Cryogenic Dark Matter Search (CDMS) experiment is designed to search for dark matter in the form of the Weakly Interacting Massive Particles (WIMPs). For this purpose, CDMS uses detectors based on crystals of Ge and Si, operated at the temperature of 20 mK, and providing a two-fold signature of an interaction: the ionization and the athermal phonon signals. The two signals, along with the passive and active shielding of the experimental setup, and with the underground experimental sites, allow very effective suppression and rejection of different types of backgrounds. This dissertation presents the commissioning and the results of the first WIMP-search run performed by the CDMS collaboration at the deep underground site at the Soudan mine in Minnesota. We develop different methods of suppressing the dominant background due to the electron-recoil events taking place at the detector surface and we apply these algorithms to the data set. These results place the world's most sensitive limits on the WIMP-nucleon spin-independent elastic-scattering cross-section. Finally, they examine the compatibility of the supersymmetric WIMP-models with the direct-detection experiments (such as CDMS) and discuss the implications of the new CDMS result on these models.

  19. Gamma-Ray Bursts Above 1 GeV

    E-Print Network [OSTI]

    Matthew G. Baring

    1997-11-21T23:59:59.000Z

    One of the principal results obtained by the Compton Gamma Ray Observatory relating to the study of gamma-ray bursts was the detection by the EGRET instrument of energetic ($>$100 MeV) photons from a handful of bright bursts. The most extreme of these was the single 18 GeV photon from the GRB940217 source. Given EGRET's sensitivity and limited field of view, the detection rate implies that such high energy emission may be ubiquitous in bursts. Hence expectations that bursts emit out to at least TeV energies are quite realistic, and the associated target-of-opportunity activity of the TeV gamma-ray community is well-founded. This review summarizes the observations and a handful of theoretical models for generating GeV--TeV emission in bursts sources, outlining possible ways that future positive detections could discriminate between different scenarios. The power of observations in the GeV--TeV range to distinguish between spectral structure intrinsic to bursts and that due to the intervening medium between source and observer is also discussed.

  20. Exclusive processes at JLab at 6 GeV

    SciTech Connect (OSTI)

    Kim, Andrey [University of Connecticut, JLAB

    2015-01-01T23:59:59.000Z

    Deeply virtual exclusive reactions provide a unique opportunity to probe the complex internal structure of the nucleon. They allow to access information about the correlations between parton transverse spatial and longitudinal momentum distributions from experimental observables. Dedicated experiments to study Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) have been carried out at Jefferson Lab using continuous electron beam with energies up to 6 GeV. Unpolarized cross sections, beam, target and double spin asymmetries have been measured for DVCS as well as for ?0 exclusive electroproduction. The data from Hall B provide a wide kinematic coverage with Q2=1-4.5 GeV2, xB=0.1-0.5, and ?t up to 2 GeV2. Hall A data have limited kinematic range partially overlapping with Hall B kinematics but provide a high accuracy measurements. Scaling tests of the DVCS cross sections provide solid evidence of twist-2 dominance, which makes chiral-even GPDs accessible even at modest Q2. We will discuss the interpretation of these data in terms of Generalized Parton Distributions (GPDs) model. Successful description of the recent CLAS ?0 exclusive production data within the framework of the GPD-based model provides a unique opportunity to access the chiral-odd GPDs.

  1. Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells

    E-Print Network [OSTI]

    Zhengping Jiang; Neerav Kharche; Timothy Boykin; Gerhard Klimeck

    2012-03-06T23:59:59.000Z

    A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We conclude that a single SiGe band offset and effective mass cannot comprehend the complex Si/SiGe interface interactions that dominate VS.

  2. Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells

    E-Print Network [OSTI]

    Jiang, Zhengping; Boykin, Timothy; Klimeck, Gerhard

    2011-01-01T23:59:59.000Z

    A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We conclude that a single SiGe band offset and effective mass cannot comprehend the complex Si/SiGe interface interactions that dominate VS.

  3. Monolithic Ge-on-Si lasers for integrated photonics

    E-Print Network [OSTI]

    Liu, Jifeng

    We report room temperature Ge-on-Si lasers with direct gap emission at 1590-1610 nm. Modeling of Ge/Si double heterojunction structures, which is supported by experimental results of Ge/Si LEDs, indicates the feasibility ...

  4. Ge-on-Si laser for silicon photonics

    E-Print Network [OSTI]

    Camacho-Aguilera, Rodolfo Ernesto

    2013-01-01T23:59:59.000Z

    Ge-on-Si devices are explored for photonic integration. Importance of Ge in photonics has grown and through techniques developed in our group we demonstrated low density of dislocations (Ge ...

  5. Is there a risk from not using GE animals?

    E-Print Network [OSTI]

    Murray, James D.; Maga, Elizabeth A.

    2010-01-01T23:59:59.000Z

    Is there a risk from not using GE animals? James D. Murray •rst genetically engi- neered (GE) plants and animals forthe debate often focuses on GE as a technique that is used

  6. Germanium: From Its Discovery to SiGe Devices

    E-Print Network [OSTI]

    Haller, E.E.

    2006-01-01T23:59:59.000Z

    From Its Discovery to SiGe Devices E.E. Haller Department ofrapidly rising interest in SiGe alloys, we are just startingstrained and unstrained SiGe multilayer structures [58]. 9.

  7. Design of programmable matter

    E-Print Network [OSTI]

    Knaian, Ara N. (Ara Nerses), 1977-

    2008-01-01T23:59:59.000Z

    Programmable matter is a proposed digital material having computation, sensing, actuation, and display as continuous properties active over its whole extent. Programmable matter would have many exciting applications, like ...

  8. Asymmetric dark matter

    SciTech Connect (OSTI)

    Kumar, Jason [Department of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

    2014-06-24T23:59:59.000Z

    We review the theoretical framework underlying models of asymmetric dark matter, describe astrophysical constraints which arise from observations of neutron stars, and discuss the prospects for detecting asymmetric dark matter.

  9. Exothermic dark matter

    E-Print Network [OSTI]

    Graham, Peter W.

    We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, ...

  10. Finding the Lower Stellar Mass Limit Observationally Justin Cantrell

    E-Print Network [OSTI]

    Wiita, Paul J.

    saying: "1. Objects with true masses below the limiting mass for thermonuclear fusion of deuterium masses above the limiting mass for thermonuclear fusion of deuterium are "brown dwarfs", no matter how below the limiting mass for thermonuclear fusion of deuterium are not "planets", but are "sub

  11. Hot-dark matter, cold dark matter and accelerating universe

    E-Print Network [OSTI]

    Abbas Farmany; Amin Farmany; Mohammad Mahmoodi

    2006-07-07T23:59:59.000Z

    The Friedman equation is solved for a universe contains hotdark matter and cold dark matter. In this scenario, hot-dark matter drives an accelerating universe no cold dark matter.

  12. Search for Dark Matter Satellites Using the FERMI-LAT

    SciTech Connect (OSTI)

    Ackermann, M.; /DESY; Albert, A.; /Ohio State U.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, G.; /INFN, Trieste /Trieste U.; Bastieri, D.; /INFN, Padua /Padua U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Blandford, R.D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, E.D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /SLAC; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bottacini, E.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Brandt, T.J.; /IRAP, Toulouse /Toulouse III U.; Bregeon, J.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Buehler, R.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Burnett, T.H.; /Washington U., Seattle; Caliandro, G.A.; /ICE, Bellaterra; Cameron, R.A.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /ASDC, Frascati /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /Stockholm U. /Stockholm U., OKC /ASDC, Frascati /Bari U. /INFN, Bari /Naval Research Lab, Wash., D.C. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Hiroshima U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Bari U. /INFN, Bari /INFN, Bari /INFN, Perugia /Perugia U. /Bari U. /INFN, Bari /Bari U. /INFN, Bari /Bologna Observ. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; /more authors..

    2012-08-16T23:59:59.000Z

    Numerical simulations based on the {Lambda}CDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the {gamma}-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard {gamma}-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We sought to identify LAT sources with these characteristics, focusing on {gamma}-ray spectra consistent with WIMP annihilation through the b{bar b} channel. We found no viable dark matter satellite candidates using one year of data, and we present a framework for interpreting this result in the context of numerical simulations to constrain the velocity-averaged annihilation cross section for a conventional 100 GeV WIMP annihilating through the b{bar b} channel.

  13. Dark Matter Searches with a Mono-Z' jet

    E-Print Network [OSTI]

    Yang Bai; James Bourbeau; Tongyan Lin

    2015-04-06T23:59:59.000Z

    We study collider signatures of a class of dark matter models with a GeV-scale dark Z'. At hadron colliders, the production of dark matter particles naturally leads to associated production of the Z', which can appear as a narrow jet after it decays hadronically. Contrary to the usual mono-jet signal from initial state radiation, the final state radiation of dark matter can generate the signature of a mono-Z' jet plus missing transverse energy. Performing a jet-substructure analysis to tag the Z' jet, we show that these Z' jets can be distinguished from QCD jets at high significance. Compared to mono-jets, a dedicated search for mono-Z' jet events can lead to over an order of magnitude stronger bounds on the interpreted dark matter-nucleon scattering cross sections.

  14. Light Dark Matter Detection Prospects at Neutrino Experiments

    E-Print Network [OSTI]

    Kumar, Jason; Smith, Stefanie

    2009-01-01T23:59:59.000Z

    We consider the prospects for the detection of relatively light dark matter through direct annihilation to neutrinos. We specifically focus on the detection possibilities of water Cherenkov and liquid scintillator neutrino detection devices. We find in particular that liquid scintillator detectors may potentially provide excellent detection prospects for dark matter in the 4-10 GeV mass range. These experiments can provide excellent corroborative checks of the DAMA/LIBRA annual modulation signal, but may yield results for low mass dark matter in any case. We identify important tests of the ratio of electron to muon neutrino events (and neutrino versus anti-neutrino events), which discriminate against background atmospheric neutrinos. In addition, the fraction of events which arise from muon neutrinos or anti-neutrinos ($R_{\\mu}$ and $R_{\\bar \\mu}$) can potentially yield information about the branching fractions of hypothetical dark matter annihilations into different neutrino flavors. These results apply to n...

  15. Turning off the lights: How dark is dark matter?

    SciTech Connect (OSTI)

    McDermott, Samuel D.; Yu Haibo; Zurek, Kathryn M. [Michigan Center for Theoretical Physics, Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2011-03-15T23:59:59.000Z

    We consider current observational constraints on the electromagnetic charge of dark matter. The velocity dependence of the scattering cross section through the photon gives rise to qualitatively different constraints than standard dark matter scattering through massive force carriers. In particular, recombination epoch observations of dark matter density perturbations require that {epsilon}, the ratio of the dark matter to electronic charge, is less than 10{sup -6} for m{sub X}=1 GeV, rising to {epsilon}<10{sup -4} for m{sub X}=10 TeV. Though naively one would expect that dark matter carrying a charge well below this constraint could still give rise to large scattering in current direct detection experiments, we show that charged dark matter particles that could be detected with upcoming experiments are expected to be evacuated from the Galactic disk by the Galactic magnetic fields and supernova shock waves and hence will not give rise to a signal. Thus dark matter with a small charge is likely not a source of a signal in current or upcoming dark matter direct detection experiments.

  16. Scaling of SiGe Heterojunction Bipolar Transistors

    E-Print Network [OSTI]

    Rieh, Jae-Sung

    Scaling of SiGe Heterojunction Bipolar Transistors JAE-SUNG RIEH, SENIOR MEMBER, IEEE, DAVID-century. This paper inves- tigates the impacts of scaling on SiGe heterojunction bipolar tran- sistors (HBTs), which), epitaxial-base Si BJTs (Epi Si BJT), SiGe HBTs (SiGe HBT), and SiGe HBTs with carbon-doped base (SiGeC HBT

  17. in Condensed Matter Physics

    E-Print Network [OSTI]

    van der Torre, Leon

    Master in Condensed Matter Physics ­ Master académique #12;2 #12;3 Students at the University. Condensed matter physics is about explaining and predicting the relationship between the atomic, and broad education in the field of condensed matter physics · introduce you to current research topics

  18. Exploring ? signals in dark matter detectors

    SciTech Connect (OSTI)

    Harnik, Roni; Kopp, Joachim; Machado, Pedro A.N., E-mail: roni@fnal.gov, E-mail: jkopp@fnal.gov, E-mail: accioly@fma.if.usp.br [Fermilab, P.O. Box 500, Batavia, IL 60510-0500 (United States)

    2012-07-01T23:59:59.000Z

    We investigate standard and non-standard solar neutrino signals in direct dark matter detection experiments. It is well known that even without new physics, scattering of solar neutrinos on nuclei or electrons is an irreducible background for direct dark matter searches, once these experiments reach the ton scale. Here, we entertain the possibility that neutrino interactions are enhanced by new physics, such as new light force carriers (for instance a ''dark photon'') or neutrino magnetic moments. We consider models with only the three standard neutrino flavors, as well as scenarios with extra sterile neutrinos. We find that low-energy neutrino-electron and neutrino-nucleus scattering rates can be enhanced by several orders of magnitude, potentially enough to explain the event excesses observed in CoGeNT and CRESST. We also investigate temporal modulation in these neutrino signals, which can arise from geometric effects, oscillation physics, non-standard neutrino energy loss, and direction-dependent detection efficiencies. We emphasize that, in addition to providing potential explanations for existing signals, models featuring new physics in the neutrino sector can also be very relevant to future dark matter searches, where, on the one hand, they can be probed and constrained, but on the other hand, their signatures could also be confused with dark matter signals.

  19. Enhancement of thermal stability and water resistance in yttrium-doped GeO{sub 2}/Ge gate stack

    SciTech Connect (OSTI)

    Lu, Cimang, E-mail: cimang@adam.t.u-tokyo.ac.jp; Hyun Lee, Choong; Zhang, Wenfeng; Nishimura, Tomonori; Nagashio, Kosuke; Toriumi, Akira [Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656 (Japan); JST, CREST, 7-3-1 Hongo, Tokyo 113-8656 (Japan)

    2014-03-03T23:59:59.000Z

    We have systematically investigated the material and electrical properties of yttrium-doped GeO{sub 2} (Y-GeO{sub 2}) on Germanium (Ge). A significant improvement of both thermal stability and water resistance were demonstrated by Y-GeO{sub 2}/Ge stack, compared to that of pure GeO{sub 2}/Ge stack. The excellent electrical properties of Y-GeO{sub 2}/Ge stacks with low D{sub it} were presented as well as enhancement of dielectric constant in Y-GeO{sub 2} layer, which is beneficial for further equivalent oxide thickness scaling of Ge gate stack. The improvement of thermal stability and water resistance are discussed both in terms of the Gibbs free energy lowering and network modification of Y-GeO{sub 2}.

  20. Engineer Receives UMass "Salute To Service" Award | GE Global...

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

    November 22, 2013 - GE Global Research, the technology development arm of the General Electric Company (NYSE: GE), is proud to announce that Dr. Marshall Jones, a world renowned...

  1. Crowdsourcing Wins Manufacturing Leadership 100 | GE Global Research

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

    NY, May 22, 2013 - GE Global Research, the technology development arm of the General Electric Co. (NYSE: GE) today announced that it has won a prestigious Manufacturing Leadership...

  2. Testimonials - Partnerships in Fuel Cells - GE Global Research...

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

    Fuel Cells - GE Global Research Testimonials - Partnerships in Fuel Cells - GE Global Research Addthis An error occurred. Unable to execute Javascript. Text Version The words...

  3. Butterfly-Inspired Thermal Imaging | GE Global Research

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

    primusenginefeaturedimage3 GE Innovation and Manufacturing in Europe 2-4-13-v-3d-printing-medical-devices Additive Manufacturing Demonstration at GE Global Research ...

  4. In situ nanotomography and operando transmission X-ray microscopy of micron-sized Ge

    E-Print Network [OSTI]

    Cui, Yi

    with transformation into a Li15Ge4-like phase. The high penetration power and large eld of view of nanometer graphite anodes. Yet large volume changes during operation severely limit their lifetime. To understand. Moreover, we show that the density changes due to lithiation are consistent with partial transformation

  5. GeV electron beams from a centimetre-scale accelerator

    E-Print Network [OSTI]

    to synchrotron radiation facilities and free-electron lasers, and as modules for high-energy particle physics. Radiofrequency-based accelerators are limited to relatively low accelerating fields (10-50 MV m-1 ), requiring tens to hundreds of metres to reach the multi-GeV beam energies needed to drive radiation sources

  6. Radio and gamma-ray constraints on dark matter annihilation in the Galactic center

    E-Print Network [OSTI]

    Roland M. Crocker; Nicole F. Bell; Csaba Balázs; David I. Jones

    2010-03-15T23:59:59.000Z

    We determine upper limits on the dark matter (DM) self-annihilation cross section for scenarios in which annihilation leads to the production of electron--positron pairs. In the Galactic centre (GC), relativistic electrons and positrons produce a radio flux via synchroton emission, and a gamma ray flux via bremsstrahlung and inverse Compton scattering. On the basis of archival, interferometric and single-dish radio data, we have determined the radio spectrum of an elliptical region around the Galactic centre of extent 3 degrees semi-major axis (along the Galactic plane) and 1 degree semi-minor axis and a second, rectangular region, also centered on the GC, of extent 1.6 degrees x 0.6 degrees. The radio spectra of both regions are non-thermal over the range of frequencies for which we have data: 74 MHz -- 10 GHz. We also consider gamma-ray data covering the same region from the EGRET instrument (about GeV) and from HESS (around TeV). We show how the combination of these data can be used to place robust constraints on DM annihilation scenarios, in a way which is relatively insensitive to assumptions about the magnetic field amplitude in this region. Our results are approximately an order of magnitude more constraining than existing Galactic centre radio and gamma ray limits. For a DM mass of m_\\chi =10 GeV, and an NFW profile, we find that the velocity-averaged cross-section must be less than a few times 10^-25 cm^3 s^-1.

  7. ME 227 CE 212 MATH 223 GE 210 CMPT 116 ABE 211CHE 210 GE 213# MATH 224

    E-Print Network [OSTI]

    Saskatchewan, University of

    GE 120 ME 227 CE 212 MATH 223 GE 210 CMPT 116 ABE 211CHE 210 GE 213# MATH 224 ABE 295 ABE 212Elective* Elective* AB E 311 ABE 313 ABE 312 GE 348#ABE 323 co-requisite ABE 327 HSS#@ HSS#@ ABE 324 GE 300# ABE 395 4TH YEAR ABE Elec* ABE Elec* ABE Elec*ABE 422 GE 449# Ag Elec* T.E.* T.E.* ABE Elec* Ag Elec

  8. Process Limits on Euclid

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

    Process Limits Process Limits Limit Hard Soft core file size (blocks) 0 unlimited data seg size (kbytes) unlimited unlimited scheduling priority 0 0 file size (blocks) unlimited...

  9. Thermal conductivity of sputtered amorphous Ge films

    SciTech Connect (OSTI)

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)] [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

    2014-02-15T23:59:59.000Z

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids.

  10. Energy band alignment of atomic layer deposited HfO{sub 2} oxide film on epitaxial (100)Ge, (110)Ge, and (111)Ge layers

    SciTech Connect (OSTI)

    Hudait, Mantu K.; Zhu Yan [Advanced Devices and Sustainable Energy Laboratory (ADSEL), Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2013-03-21T23:59:59.000Z

    Crystallographically oriented epitaxial Ge layers were grown on (100), (110), and (111)A GaAs substrates by in situ growth process using two separate molecular beam epitaxy chambers. The band alignment properties of atomic layer hafnium oxide (HfO{sub 2}) film deposited on crystallographically oriented epitaxial Ge were investigated using x-ray photoelectron spectroscopy (XPS). Valence band offset, {Delta}E{sub v} values of HfO{sub 2} relative to (100)Ge, (110)Ge, and (111)Ge orientations were 2.8 eV, 2.28 eV, and 2.5 eV, respectively. Using XPS data, variation in valence band offset, {Delta}E{sub V}(100)Ge>{Delta}E{sub V}(111)Ge>{Delta}E{sub V}(110)Ge, was obtained related to Ge orientation. Also, the conduction band offset, {Delta}E{sub c} relation, {Delta}E{sub c}(110)Ge>{Delta}E{sub c}(111)Ge>{Delta}E{sub c}(100)Ge related to Ge orientations was obtained using the measured bandgap of HfO{sub 2} on each orientation and with the Ge bandgap of 0.67 eV. These band offset parameters for carrier confinement would offer an important guidance to design Ge-based p- and n-channel metal-oxide field-effect transistor for low-power application.

  11. Of Matters Condensed

    E-Print Network [OSTI]

    Shulman, Michael

    2015-01-01T23:59:59.000Z

    The American Physical Society (APS) March Meeting of condensed matter physics has grown to nearly 10,000 participants, comprises 23 individual APS groups, and even warrants its own hashtag (#apsmarch). Here we analyze the text and data from March Meeting abstracts of the past nine years and discuss trends in condensed matter physics over this time period. We find that in comparison to atomic, molecular, and optical physics, condensed matter changes rapidly, and that condensed matter appears to be moving increasingly toward subject matter that is traditionally in materials science and engineering.

  12. Incompressibility of strange matter

    E-Print Network [OSTI]

    Monika Sinha; Manjari Bagchi; Jishnu Dey; Mira Dey; Subharthi Ray; Siddhartha Bhowmick

    2004-04-01T23:59:59.000Z

    Strange stars calculated from a realistic equation of state (EOS), that incorporate chiral symmetry restoration as well as deconfinement at high density show compact objects in the mass radius curve. We compare our calculations of incompressibility for this EOS with that of nuclear matter. One of the nuclear matter EOS has a continuous transition to ud-matter at about five times normal density. Another nuclear matter EOS incorporates density dependent coupling constants. From a look at the consequent velocity of sound, it is found that the transition to ud-matter seems necessary.

  13. Adsorbed Polymer and NOM Limits Adhesion and Toxicity of Nano

    E-Print Network [OSTI]

    Alvarez, Pedro J.

    Adsorbed Polymer and NOM Limits Adhesion and Toxicity of Nano Scale Zerovalent Iron to E. coli Z H. Here we assess the effect that adsorbed synthetic polymers and natural organic matter

  14. Hot and Cold Dark Matter Search with GENIUS

    E-Print Network [OSTI]

    Laura Baudis; Alexander Dietz; Gerd Heusser; Hans Volker Klapdor-Kleingrothaus; Bela Majorovits; Herbert Strecker

    2000-05-30T23:59:59.000Z

    GENIUS is a proposal for a large volume detector to search for rare events. An array of 40-400 'naked' HPGe detectors will be operated in a tank filled with ultra-pure liquid nitrogen. After a description of performed technical studies of detector operation in liquid nitrogen and of Monte Carlo simulations of expected background components, the potential of GENIUS for detecting WIMP dark matter, the neutrinoless double beta decay in 76-Ge and low-energy solar neutrinos is discussed.

  15. Bulk and surface half-metallicity: The case of D0{sub 3}-type Mn{sub 3}Ge

    SciTech Connect (OSTI)

    Liu, Hao; Gao, G. Y., E-mail: guoying-gao@mail.hust.edu.cn; Hu, Lei; Ni, Yun; Zu, Fengxia; Zhu, Sicong; Wang, Shuling; Yao, K. L. [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-01-21T23:59:59.000Z

    Motivated by the experimental realization of D0{sub 22}-type Mn{sub 3}Ge (001) films [Kurt et al. Appl. Phys. Lett. 101, 132410 (2012)] and the structural stability of D0{sub 3}-type Heusler alloy Mn{sub 3}Ge [Zhang et al. J. Phys.: Condens. Matter 25, 206006 (2013)], we use the first-principles calculations based on the full potential linearized augmented plane-wave method to investigate the electronic and magnetic properties of D0{sub 3}-type Heusler alloy Mn{sub 3}Ge and its (001) surface. We show that bulk D0{sub 3}-Mn{sub 3}Ge is a half-metallic ferromagnet with the minority-spin energy gap of 0.52?eV and the magnetic moment of 1.00??{sub B} per formula unit. The bulk half-metallicity is preserved at the pure Mn-terminated (001) surface due to the large exchange split, but the MnGe-terminated (001) surface destroys the bulk half-metallicity. We also reveal that the surface stabilities are comparable between the D0{sub 3}-Mn{sub 3}Ge (001) and the experimental D0{sub 22}-Mn{sub 3}Ge (001), which indicates the feasibility to grow the Mn{sub 3}Ge (001) films with D0{sub 3} phase other than D0{sub 22} one. The surface half-metallicity and stability make D0{sub 3}-Mn{sub 3}Ge a promising candidate for spintronic applications.

  16. Big Questions: Dark Matter

    ScienceCinema (OSTI)

    Lincoln, Don

    2014-08-07T23:59:59.000Z

    Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter idea is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.

  17. CONSTRAINTS ON COSMIC RAYS, MAGNETIC FIELDS, AND DARK MATTER FROM GAMMA-RAY OBSERVATIONS OF THE COMA CLUSTER OF GALAXIES WITH VERITAS AND FERMI

    SciTech Connect (OSTI)

    Arlen, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Aune, T.; Bouvier, A. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cannon, A.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A.; Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Cui, W.; Feng, Q.; Finley, J. P. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Dumm, J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Falcone, A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Federici, S., E-mail: pohlmadq@gmail.com, E-mail: christoph.pfrommer@h-its.org [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); and others

    2012-10-01T23:59:59.000Z

    Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may also be sources of very high energy (VHE; E > 100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cerenkov telescopes, with complementing Fermi Large Area Telescope observations at GeV energies. No significant gamma-ray emission from the Coma Cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order of (2-5) Multiplication-Sign 10{sup -8} photons m {sup -2} s {sup -1} (VERITAS, >220 GeV) and {approx}2 Multiplication-Sign 10{sup -6} photons m {sup -2} s {sup -1} (Fermi, 1-3 GeV), respectively. We use the gamma-ray upper limits to constrain cosmic rays (CRs) and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be <16% from VERITAS data and <1.7% from Fermi data (averaged within the virial radius). These upper limits are starting to constrain the CR physics in self-consistent cosmological cluster simulations and cap the maximum CR acceleration efficiency at structure formation shocks to be <50%. Alternatively, this may argue for non-negligible CR transport processes such as CR streaming and diffusion into the outer cluster regions. Assuming that the radio-emitting electrons of the Coma halo result from hadronic CR interactions, the observations imply a lower limit on the central magnetic field in Coma of {approx}(2-5.5) {mu}G, depending on the radial magnetic field profile and on the gamma-ray spectral index. Since these values are below those inferred by Faraday rotation measurements in Coma (for most of the parameter space), this renders the hadronic model a very plausible explanation of the Coma radio halo. Finally, since galaxy clusters are dark matter (DM) dominated, the VERITAS upper limits have been used to place constraints on the thermally averaged product of the total self-annihilation cross section and the relative velocity of the DM particles, ({sigma}v).

  18. Solar neutrino physics: Sensitivity to light dark matter particles

    E-Print Network [OSTI]

    Ilidio Lopes; Joseph Silk

    2013-09-29T23:59:59.000Z

    Neutrinos are produced in several neutrino nuclear reactions of the proton-proton chain and carbon-nitrogen-oxygen cycle that take place at different radius of the Sun's core. Hence, measurements of solar neutrino fluxes provide a precise determination of the local temperature. The accumulation of non-annihilating light dark matter particles (with masses between 5 GeV and 16 GeV in the Sun produces a change in the local solar structure, namely, a decrease in the central temperature of a few percent. This variation depends on the properties of the dark matter particles, such as the mass of the particle and its spin-independent scattering cross-section on baryon-nuclei, specifically, the scattering with helium, oxygen, and nitrogen among other heavy elements. This temperature effect can be measured in almost all solar neutrino fluxes. In particular, by comparing the neutrino fluxes generated by stellar models with current observations, namely 8B neutrino fluxes, we find that non-annihilating dark matter particles with a mass smaller than 10 GeV and a spin-independent scattering cross-section with heavy baryon-nuclei larger than 3 x 10^{-37} cm^-2 produce a variation in the 8B neutrino fluxes that would be in conflict with current measurements.

  19. GE Appliances: Order (2010-CE-2113)

    Broader source: Energy.gov [DOE]

    DOE issued an Order after entering into a Compromise Agreement with General Electric Appliances after finding GE Appliances had failed to certify that certain models of dehumidifiers comply with the applicable energy conservation standards.

  20. GE's Christine Furstoss Named to NACIE

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

    companies like GE will need workers with new and advanced skills in areas like 3D printing and virtual design. It's all about growing a new generation of workforce skills,...

  1. The CRESST Dark Matter Search

    E-Print Network [OSTI]

    B. Majorovits; G. Angloher; C. Bucci; P. Christ; C. Cozzini; F. von Feilitzsch; D. Hauff; S. Henry; Th. Jagemann; J. Jochum; H. Kraus; V. Mikhailik; J. Ninkovic; F. Petricca; W. Potzel; F. Proebst; Y. Ramachers; M. Razeti; W. Rau; W. Seidel; M. Stark; L. Stodolsky; A. J. B. Tolhurst; D. Wahl; W. Westphal; H. Wulandari

    2004-11-15T23:59:59.000Z

    We present first competitive results on WIMP dark matter using the phonon-light-detection technique. A particularly strong limit for WIMPs with coherent scattering results from selecting a region of the phonon-light plane corresponding to tungsten recoils. The observed count rate in the neutron band is compatible with the rate expected from neutron background. CRESST is presently being upgraded with a 66 channel SQUID readout system, a neutron shield and a muon veto system. This results in a significant improvement in sensitivity.

  2. Axion hot dark matter bounds

    E-Print Network [OSTI]

    G. Raffelt; S. Hannestad; A. Mirizzi; Y. Y. Y. Wong

    2008-08-06T23:59:59.000Z

    We derive cosmological limits on two-component hot dark matter consisting of neutrinos and axions. We restrict the large-scale structure data to the safely linear regime, excluding the Lyman-alpha forest. We derive Bayesian credible regions in the two-parameter space consisting of m_a and sum(m_nu). Marginalizing over sum(m_nu) provides m_aaxions the same data and methods give sum(m_nu)< 0.63 eV (95% CL).

  3. An Ultimate Target for Dark Matter Searches

    E-Print Network [OSTI]

    Kfir Blum; Yanou Cui; Marc Kamionkowski

    2014-12-10T23:59:59.000Z

    The combination of S-matrix unitarity and the dynamics of thermal freeze-out for massive relic particles (denoted here simply by WIMPs) implies a lower limit on the density of such particles, that provide a (potentially sub-dominant) contribution to dark matter. This then translates to lower limits to the signal rates for a variety of techniques for direct and indirect detection of dark matter. For illustration, we focus on models where annihilation is s-wave dominated. We derive lower limits to the flux of gamma-rays from WIMP annihilation at the Galactic center; direct detection of WIMPs; energetic neutrinos from WIMP annihilation in the Sun; and the effects of WIMPs on the angular power spectrum and frequency spectrum of the cosmic microwave background radiation. The results suggest that a variety of dark-matter-search techniques may provide interesting avenues to seek new physics, even if WIMPs do not constitute all the dark matter. While the limits are quantitatively some distance from the reach of current measurements, they may be interesting for long-range planning exercises.

  4. Status of Matter-Gravity Couplings in the SME

    E-Print Network [OSTI]

    Tasson, Jay D

    2013-01-01T23:59:59.000Z

    Constraints on Lorentz violation in matter-gravity couplings are summarized along with existing proposals to obtain sensitivities that exceed current limits by up to 11 orders of magnitude.

  5. Status of Matter-Gravity Couplings in the SME

    E-Print Network [OSTI]

    Jay D. Tasson

    2013-08-06T23:59:59.000Z

    Constraints on Lorentz violation in matter-gravity couplings are summarized along with existing proposals to obtain sensitivities that exceed current limits by up to 11 orders of magnitude.

  6. ORIGINAL CONTRIBUTION Association of White Matter Hyperintensity Volume

    E-Print Network [OSTI]

    California at Davis, University of

    ORIGINAL CONTRIBUTION Association of White Matter Hyperintensity Volume With Decreased Cognitive was restricted to the study of older in- dividuals, limiting our understanding of the full impact of WMH

  7. Modeling of Particulate Matter Emissions from Agricultural Operations

    E-Print Network [OSTI]

    Bairy, Jnana 1988-

    2013-01-02T23:59:59.000Z

    State Air Pollution Regulation Agencies (SAPRAs) issue and enforce permits that limit particulate matter emissions from all sources including layer and broiler facilities, cattle feedyards, dairies, cotton gins, and grain elevators...

  8. GE Unveils High-Tech Superhero GENIUS MAN | GE Global Research

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

    education Committed to inspiring the next generation of scientists and engineers Infused with an array of superpowers inspired by GE technologies Super Vision, ability to...

  9. Be a part of something bigger than yourself GE Healthcare

    E-Print Network [OSTI]

    Rimon, Elon

    Be a part of something bigger than yourself GE Healthcare Position: Mechanical Engineer as a contractor · Working at GE site at Tirat-Carmel. · Start: immediately · Duration 6-10 months, with optional elongation. ElgemsMoked@ge.com-CV www.gehealthcare.com We are GE Healthcare, a $17 billion division

  10. Matter: Space without Time

    E-Print Network [OSTI]

    Yousef Ghazi-Tabatabai

    2012-11-19T23:59:59.000Z

    While Quantum Gravity remains elusive and Quantum Field Theory retains the interpretational difficulties of Quantum Mechanics, we have introduced an alternate approach to the unification of particles, fields, space and time, suggesting that the concept of matter as space without time provides a framework which unifies matter with spacetime and in which we anticipate the development of complete theories (ideally a single unified theory) describing observed 'particles, charges, fields and forces' solely with the geometry of our matter-space-time universe.

  11. Energy Matters Mailbag

    Broader source: Energy.gov [DOE]

    This edition of the mailbag tackles follow-up questions from our Energy Matters discussion on breaking our reliance on foreign oil.

  12. UC IRVINE GENERAL EDUCATION (GE) REQUIREMENT AND APPROVED GE COURSES, 201213 Includes course titles and Schedule of Classes designations

    E-Print Network [OSTI]

    Loudon, Catherine

    UC IRVINE GENERAL EDUCATION (GE) REQUIREMENT AND APPROVED GE COURSES, 2012­13 Includes course titles and Schedule of Classes designations GENERAL EDUCATION (GE) REQUIREMENT UCI is committed undergraduates complete a set of general education (GE) requirements. General education courses introduce

  13. 2009-10 Princeton Global Scholar Ge Zhaoguang. Professor Ge is the founding director of the National Institute for Advanced

    E-Print Network [OSTI]

    2009-10 Princeton Global Scholar Ge Zhaoguang. Professor Ge is the founding director, and emendation of all sorts of newly discovered texts (mostly found at archaeological sites). Professor Ge University, Professor Ge taught at Tsinghua University for a number of years. He is known for many important

  14. Measurement of the direct energy gap of coherently strained SnxGe1x Ge,,001... heterostructures

    E-Print Network [OSTI]

    Atwater, Harry

    Measurement of the direct energy gap of coherently strained SnxGe1Ŕx ŐGe,,001... heterostructures The direct energy gap has been measured for coherently strained SnxGe1 x alloys on Ge 001 substrates with 0 for coherently strained SnxGe1 x alloys indicates a large alloy contribution and a small strain contribution

  15. GE Advising & Registration Students FT Faculty PT Faculty Admin Unit 4 Other Staff Students have access to quality GE advising

    E-Print Network [OSTI]

    de Lijser, Peter

    GE Advising & Registration Students FT Faculty PT Faculty Admin Unit 4 Other Staff Students have access to quality GE advising 9% 13% 11% 13% 10% 8% Faculty can easily advise students on GE requirements 10% 18% 9% 24% 33% 11% Staff academic advisors can easily advise students on GE requirements 8% 11

  16. High-germanium-content SiGe islands formed on compliant oxide by SiGe Haizhou Yina)

    E-Print Network [OSTI]

    High-germanium-content SiGe islands formed on compliant oxide by SiGe oxidation Haizhou Yina and the nonuniformity of the enhanced germanium content during the SiGe oxidation were improved by depositing a silicon was relaxed by lateral expansion of the SiGe islands, showing that dislocations were not required

  17. Extending the CRESST-II commissioning run limits to lower masses

    E-Print Network [OSTI]

    Andrew Brown; Sam Henry; Hans Kraus; Christopher McCabe

    2012-01-23T23:59:59.000Z

    Motivated by the recent interest in light WIMPs of mass ~O(10 GeV), an extension of the elastic, spin-independent WIMP-nucleon cross-section limits resulting from the CRESST-II commissioning run (2007) are presented. Previously, these data were used to set cross-section limits from 1000 GeV down to ~17 GeV, using tungsten recoils, in 47.9 kg-days of exposure of calcium tungstate. Here, the overlap of the oxygen and calcium bands with the acceptance region of the commissioning run data set is reconstructed using previously published quenching factors. The resulting elastic WIMP cross section limits, accounting for the additional exposure of oxygen and calcium, are presented down to 5 GeV.

  18. Relaxation and recombination processes in Ge/SiGe multiple quantum wells

    SciTech Connect (OSTI)

    Gatti, E., E-mail: gatti@mater.unimib.it; Giorgioni, A., E-mail: gatti@mater.unimib.it; Grilli, E., E-mail: gatti@mater.unimib.it; Guzzi, M., E-mail: gatti@mater.unimib.it [L-NESS and Universitŕ di Milano-Bicocca, Dip. di Scienza dei Materiali, via Cozzi 53, 20125 Milano (Italy); Chrastina, D.; Isella, G. [L-NESS and Politecnico di Milano, Dip. di Fisica, via Anzani 42, 22100 Como (Italy); Chernikov, A.; Kolata, K.; Bornwasser, V.; Köster, N. S.; Woscholski, R.; Chatterjee, S. [Faculty of Physics and Materials Sciences Center, Philipps-Universität, Renthof 5, 35032 Marburg (Germany)

    2013-12-04T23:59:59.000Z

    The carrier dynamics that occurs in Ge/SiGe QWs when electrons are excited to confined states at ? is studied by means of optical spectroscopy at different lattice temperatures. The typical times for the different relaxation and recombination processes are given and discussed.

  19. Maximally incompressible neutron star matter

    E-Print Network [OSTI]

    Timothy S. Olson

    2000-12-07T23:59:59.000Z

    Relativistic kinetic theory, based on the Grad method of moments as developed by Israel and Stewart, is used to model viscous and thermal dissipation in neutron star matter and determine an upper limit on the maximum mass of neutron stars. In the context of kinetic theory, the equation of state must satisfy a set of constraints in order for the equilibrium states of the fluid to be thermodynamically stable and for perturbations from equilibrium to propagate causally via hyperbolic equations. Application of these constraints to neutron star matter restricts the stiffness of the most incompressible equation of state compatible with causality to be softer than the maximally incompressible equation of state that results from requiring the adiabatic sound speed to not exceed the speed of light. Using three equations of state based on experimental nucleon-nucleon scattering data and properties of light nuclei up to twice normal nuclear energy density, and the kinetic theory maximally incompressible equation of state at higher density, an upper limit on the maximum mass of neutron stars averaging 2.64 solar masses is derived.

  20. Dynamical dark matter. I. Theoretical overview

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dienes, Keith R.; Thomas, Brooks

    2012-04-01T23:59:59.000Z

    In this paper, we propose a new framework for dark-matter physics. Rather than focus on one or more stable dark-matter particles, we instead consider a multicomponent framework in which the dark matter of the universe comprises a vast ensemble of interacting fields with a variety of different masses, mixings, and abundances. Moreover, rather than impose stability for each field individually, we ensure the phenomenological viability of such a scenario by requiring that those states with larger masses and standard-model decay widths have correspondingly smaller relic abundances, and vice versa. In other words, dark-matter stability is not an absolute requirement in such a framework, but is balanced against abundance. This leads to a highly dynamical scenario in which cosmological quantities such as ?CDM experience nontrivial time-dependences beyond those associated with the expansion of the universe. Although it may seem difficult to arrange an ensemble of states which have the required decay widths and relic abundances, we present one particular example in which this balancing act occurs naturally: an infinite tower of Kaluza-Klein (KK) states living in the bulk of large extra spacetime dimensions. Remarkably, this remains true even if the stability of the KK tower itself is entirely unprotected. Thus theories with large extra dimensions—and by extension, certain limits of string theory—naturally give rise to dynamical dark matter. Such scenarios also generically give rise to a rich set of collider and astrophysical phenomena which transcend those usually associated with dark matter.

  1. In Wino Veritas? Indirect Searches Shed Light on Neutralino Dark Matter

    E-Print Network [OSTI]

    JiJi Fan; Matthew Reece

    2013-07-16T23:59:59.000Z

    Indirect detection constraints on gamma rays (both continuum and lines) have set strong constraints on wino dark matter. By combining results from Fermi-LAT and HESS, we show that: light nonthermal wino dark matter is strongly excluded; thermal wino dark matter is allowed only if the Milky Way dark matter distribution has a significant (>~0.4 kpc) core; and for plausible NFW and Einasto distributions the entire range of wino masses from 100 GeV up to 3 TeV can be excluded. The case of light, nonthermal wino dark matter is particularly interesting in scenarios with decaying moduli that reheat the universe to a low temperature. Typically such models have been discussed for low reheating temperatures, not far above the BBN bound of a few MeV. We show that constraints on the allowed wino relic density push such models to higher reheating temperatures and hence heavier moduli. Even for a flattened halo model consisting of an NFW profile with constant-density core inside 1 kpc and a density near the sun of 0.3 GeV/cm^3, for 150 GeV winos current data constrains the reheat temperature to be above 1.4 GeV. As a result, for models in which the wino mass is a loop factor below the gravitino mass, the data favor moduli that are more than an order of magnitude heavier than the gravitino. We discuss some of the sobering implications of this result for the status of supersymmetry. We also comment on other neutralino dark matter scenarios, in particular the case of mixed bino/higgsino dark matter. We show that in this case, direct and indirect searches are complementary to each other and could potentially cover most of the parameter space.

  2. Dark matter and dark energy production in quantum model of the universe

    E-Print Network [OSTI]

    V. E. Kuzmichev; V. V. Kuzmichev

    2004-05-24T23:59:59.000Z

    The quantum model of the homogeneous, isotropic, and spatially closed universe predicts an existence of two types of collective quantum states in the universe. The states of one type characterize a gravitational field, the others describe a matter (uniform scalar) field. In the first stage of the evolution of the universe a primordial scalar field evolves slowly into its vacuum-like state. In the second stage the scalar field oscillates about an equilibrium due to the quantum fluctuations. The universe is being filled with matter in the form of elementary quantum excitations of the vibrations of the scalar field. The separate quantum excitations are characterized by non-zero values of their energies (masses). Under the action of gravitational forces mainly these excitations decay into ordinary particles (baryons and leptons) and dark matter. The elementary quantum excitations of the vibrations of the scalar field which have not decayed up to now form dark energy. The numerical estimations lead to realistic values of both the matter density \\Omega_{M} = 0.29 (with the contributions from dark matter, \\Omega_{DM} = 0.25, and optically bright baryons, \\Omega_{stars} = 0.0025) and the dark energy density \\Omega_{X} = 0.71 if one takes that the mean energy ~ 10 GeV is released in decay of dark energy quantum and fixes baryonic component \\Omega_{B} = 0.04 according to observational data. The energy (mass) of dark energy quantum is equal to ~ 17 GeV and the energy > 2 x 10^{10} GeV is needed in order to detect it. Dark matter particle has the mass ~ 6 GeV. The Jeans mass for dark matter which is considered as a gas of such massive particles is equal to M_{J} ~ 10^{5} M_{\\odot}.

  3. Isospin-Violating Dark Matter and Neutrinos From the Sun

    E-Print Network [OSTI]

    Shao-Long Chen; Yue Zhang

    2011-06-20T23:59:59.000Z

    We study the indirect detection of dark matter through neutrino flux from their annihilation in the center of the Sun, in a class of theories where the dark matter-nucleon spin-independent interactions break the isospin symmetry. We point out that, while the direct detection bounds with heavy targets like Xenon are weakened and reconciled with the positive signals in DAMA and CoGeNT experiments, the indirect detection using neutrino telescopes can impose a relatively stronger constraint and brings tension to such explanation, if the annihilation is dominated by heavy quark or $\\tau$-lepton final states. As a consequence, the qualified isospin violating dark matter candidate has to preferably annihilate into light flavors.

  4. Dipolar Dark Matter

    E-Print Network [OSTI]

    Blanchet, Luc

    2015-01-01T23:59:59.000Z

    Massive gravity theories have been developed as viable IR modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because the two types of dark matter interact through the vector field, a ghostly degree of fre...

  5. Measurement of the Crab Flux Above 60 GeV with the CELESTE Cherenkov Telescope

    E-Print Network [OSTI]

    M. De Naurois; J. Holder; R. Bazer-Bachi; H. Bergeret; P. Bruel; A. Cordier; G. Debiais; J-P. Dezalay; D. Dumora; E. Durand; P. Eschstruth; P. Espigat; B. Fabre; P. Fleury; N. Herault; M. Hrabovsky; S. Incerti; R. Le Gallou; F. Munz; A. Musquere; J-F. Olive; E. Pare; J. Quebert; R. C. Rannot; T. Reposeur; L. Rob; P. Roy; T. Sako; P. Schovanek; D. A. Smith; P. Snabre; A. Volte

    2001-12-05T23:59:59.000Z

    We have converted the former solar electrical plant THEMIS (French Pyrenees) into an atmospheric Cherenkov detector called CELESTE, which records gamma rays above 30 GeV (7E24 Hz). Here we present the first sub-100 GeV detection by a ground based telescope of a gamma ray source, the Crab nebula, in the energy region between satellite measurements and imaging atmospheric Cherenkov telescopes. At our analysis threshold energy of 60 +/- 20 GeV we measure a gamma ray rate of 6.1 +/- 0.8 per minute. Allowing for 30% systematic uncertainties and a 30% error on the energy scale yields an integral gamma ray flux of I(E>60 GeV) = 6.2^{+5.3}_{-2.3} E-6 photons m^-2 s^-1. The analysis methods used to obtain the gamma ray signal from the raw data are detailed. In addition, we determine the upper limit for pulsed emission to be <12% of the Crab flux at the 99% confidence level, in the same energy range. Our result indicates that if the power law observed by EGRET is attenuated by a cutoff of form e^{-E/E_0} then E_0 < 26 GeV. This is the lowest energy probed by a Cherenkov detector and leaves only a narrow range unexplored beyond the energy range studied by EGRET.

  6. A solution to the baryon-DM coincidence problem in the CMSSM with a 126-GeV Higgs boson

    E-Print Network [OSTI]

    Kamada, Ayuki; Yamada, Masaki

    2015-01-01T23:59:59.000Z

    We show that the baryon-dark matter coincidence problem is solved in the CMSSM. The baryons and dark matter are generated simultaneously through the late-time decay of non-topological solitons, Q-balls, which are formed after the Affleck-Dine baryogenesis. A certain relation between the universal scalar mass, $m_0$, and the universal gaugino mass, $M_{1/2}$, is required to solve the coincidence problem, marginally depending on the other CMSSM parameters, and the result is consistent with the observation of the 126-GeV Higgs boson.

  7. Search for R-parity violation with a $\\overline{U}\\overline{D}\\overlin e{D}$ coupling at $\\sqrt{s}$=189 GeV

    E-Print Network [OSTI]

    Abreu, P; Adye, T; Adzic, P; Ajinenko, I; Albrecht, Z; Alderweireld, T; Alekseev, G D; Alemany, R; Allmendinger, T; Allport, P P; Almehed, S; Amaldi, Ugo; Amapane, N; Amato, S; Anassontzis, E G; Andersson, P; Andreazza, A; Andringa, S; Antilogus, P; Apel, W D; Arnoud, Y; Augustin, J E; Augustinus, A; Baillon, Paul; Ballestrero, A; Bambade, P; Barbiellini, Guido; Barbier, R; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Barăo, F; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Beilličre, P; Belokopytov, Yu A; Benekos, N C; Benvenuti, Alberto C; Berggren, M; Bertrand, D; Besançon, M; Bilenky, S M; Bizouard, M A; Bloch, D; Blom, H M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Boyko, I; Bozovic, I; Bozzo, M; Bracko, M; Branchini, P; Brenner, R A; Brunet, J M; Brückman, P; Bugge, L; Buran, T; Buschbeck, Brigitte; Buschmann, P; Bérat, C; Cabrera, S; Caccia, M; Calvi, M; Camporesi, T; Canale, V; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Charpentier, P; Checchia, P; Chelkov, G A; Chierici, R; Chochula, P; Chorowicz, V; Chudoba, J; Cieslik, K; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Costa, M; Crawley, H B; Crennell, D J; Crosetti, G; Crépé, S; Cuevas-Maestro, J; Czellar, S; Da Silva, W; Davenport, M; De Angelis, A; De Clercq, C; De Lotto, B; De Min, A; De Paula, L S; Della Ricca, G; Delpierre, P A; Demaria, N; Di Ciaccio, Lucia; Dijkstra, H; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Dris, M; Duperrin, A; Durand, J D; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Ellert, M; Elsing, M; Engel, J P; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Fayot, J; Feindt, Michael; Fernández, J; Ferrer, A; Ferrer-Ribas, E; Ferro, F; Fichet, S; Firestone, A; Flagmeyer, U; Fokitis, E; Fontanelli, F; Franek, B J; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Föth, H; Galloni, A; Gamba, D; Gamblin, S; Gandelman, M; García, C; Gaspar, C; Gaspar, M; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Geralis, T; Gerdyukov, L N; Ghodbane, N; Gil, I; Glege, F; Gokieli, R; Golob, B; González-Caballero, I; Gonçalves, P; Gopal, Gian P; Gorn, L; Gracco, Valerio; Grahl, J; Graziani, E; Gris, P; Grosdidier, G; Grzelak, K; Guy, J; Guz, Yu; Gómez-Ceballos, G; Haag, C; Hahn, F; Hahn, S; Haider, S; Hallgren, A; Hamacher, K; Hansen, J; Harris, F J; Hauler, F; Hedberg, V; Heising, S; Hernández, J J; Herquet, P; Herr, H; Heuser, J M; Higón, E; Holmgren, Sven Olof; Holt, P J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huber, M; Hughes, G J; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Jeans, D; Johansson, E K; Joram, C; Juillot, P; Jungermann, L; Jönsson, P E; Kapusta, F; Karafasoulis, K; Katsanevas, S; Katsoufis, E C; Kernel, G; Kersevan, Borut P; Keränen, R; Khokhlov, Yu A; Khomenko, B A; Khovanskii, N N; Kiiskinen, A P; King, B J; Kinvig, A; Kjaer, N J; Klapp, O; Klein, H; Kluit, P M; Kokkinias, P; Kostyukhin, V; Kourkoumelis, C; Krammer, Manfred; Kriznic, E; Krumshtein, Z; Kubinec, P; Kurowska, J; Kurvinen, K L; Kuznetsov, O; Lamsa, J; Lane, D W; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Leinonen, L; Leisos, A; Leitner, R; Lenzen, Georg; Lepeltier, V; Lesiak, T; Lethuillier, M; Libby, J; Liebig, W; Liko, D; Lipniacka, A; Lippi, I; Loken, J G; Lopes, J H; Loukas, D; Lutz, P; Lyons, L; López, J M; López-Fernandez, R; Lörstad, B; MacNaughton, J N; Mahon, J R; Maio, A; Malek, A; Malmgren, T G M; Maltezos, S; Malychev, V; Mandl, F; Marco, J; Marco, R P; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martí i García, S; Martínez-Rivero, C; Maréchal, B; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, F; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; McPherson, G; Meroni, C; Meyer, W T; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Moch, M; Monge, M R; Moraes, D; Moreau, X; Morettini, P; Morton, G A; Mulders, M; Mulet-Marquis, C; Mundim, L M; Muresan, R; Murray, W J; Muryn, B; Myatt, Gerald; Myklebust, T; Mönig, K; Mřller, R; Müller, U; Münich, K; Naraghi, F; Nassiakou, M; Navarria, Francesco Luigi; Nawrocki, K; Negri, P; Neufeld, N; Nicolaidou, R; Nielsen, B S; Niezurawski, P; Nikolenko, M; Nomokonov, V P; Nygren, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Orazi, G; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Pain, R; Paiva, R; Palacios, J; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Pavel, T; Pegoraro, M; Peralta, L; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Pierre, F

    2001-01-01T23:59:59.000Z

    Searches for pair production of gauginos and squarks in $e^{+} e^{-}$ collisions at a centre-of-mass energy of 189 GeV have been performed on data corresponding to an integrated luminosity of 158 pb$^{-1}$ collected by the DELPHI detector at LEP. The data were analyzed under the assumption of non-conservation of \\mbox{$R$-parity} through a single dominant $\\bar{U} \\bar{D} \\bar{D}$~coupling between squarks and quarks. Typical final states contain between 4 and 10 jets with or without additional leptons. No excess of data above Standard Model expectations was observed. The results were used to constrain domains of the MSSM parameter space and derive limits on the masses of supersymmetric particles. The following mass limits at 95\\% CL were obtained from these searches: \\begin{itemize} \\item neutralino mass: $m_{\\tilde{\\chi^0_{1}}} \\ge 32$ GeV \\item chargino mass: $m_{\\tilde{\\chi^+_{1}}} \\ge 94 $ GeV \\item stop and sbottom mass (indirect decay) with $\\Delta M > 5$ GeV: $m_{\\tilde{t_{1}}} \\ge 74$ GeV, for $\\Phi_{...

  8. Search for GeV GRBs at Chacaltaya

    SciTech Connect (OSTI)

    Castellina, A.; Ghia, P. L.; Morello, C.; Trinchero, G.; Vallania, P.; Vernetto, S. [Istituto di Cosmogeofisica del C.N.R., Torino (Italy); Navarra, G.; Saavedra, O. [Dipartimento di Fisica Generale dell'Universita' di Torino (Italy); Yoshii, H. [Department of Physics, Ehime University, Ehime 790 (Japan); Kaneko, T. [Department of Physics, Okayama University, Okayama 700 (Japan); Kakimoto, K. [Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152 (Japan); Nishi, K. [Institute of Physical and Chemical Research, Wako, Saitama 351-01 (Japan); Cabrera, R.; Urzagasti, D.; Velarde, A. [Instituto de Investigaciones Fisicas, Universidad Mayor de San Andres, La Paz (Bolivia, Plurinational State of); Barthelmy, S. D.; Butterworth, P.; Cline, T. L.; Gehrels, N. [NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Fishman, G. J. [NASA Marshall Space Flight Center, Huntsville, Alabama 35812 (United States)] (and others)

    1998-05-16T23:59:59.000Z

    In this paper we present the results of a search for GeV Gamma Ray Bursts made by the INCA experiment during the first 9 months of operation. INCA, an air shower array located at Mount Chacaltaya (Bolivia) at 5200 m a.s.l., has been searching for GRBs since December 1996. Up to August, 1997, 34 GRBs detected by BATSE occurred in the field of view of the experiment. For any burst, the counting rate of the array in the 2 hours interval around the burst trigger time has been studied. No significant excess has been observed. Assuming for the bursts a power low energy spectrum extending up to 1 TeV with a slope {alpha}=-2 and a duration of 10 s, the obtained 1 GeV-1 TeV energy fluence upper limits range from 7.9 10{sup -5} erg cm{sup -2} to 3.5 10{sup -3} erg cm{sup -2} depending on the event zenith angles.

  9. Ge/SiGe quantum wells on Si(111): Growth, structural, and optical properties

    SciTech Connect (OSTI)

    Gatti, E., E-mail: eleonora.gatti@mater.unimib.it; Pezzoli, F.; Grilli, E. [L-NESS and Dipartimento di Scienza dei Materiali, Universitŕ di Milano Bicocca, via Cozzi 55, I-20125 Milano (Italy); Isa, F.; Chrastina, D.; Isella, G. [L-NESS and Dipartimento di Fisica, Politecnico di Milano, Polo di Como, via Anzani 42, I - 22100 Como (Italy); Müller Gubler, E. [Electron Microscopy Center of ETH Zürich (EMEZ), August-Piccard-Hof 1, CH-8093 Zürich (Switzerland)

    2014-07-28T23:59:59.000Z

    The epitaxial growth of Ge/Si{sub 0.15}Ge{sub 0.85} multiple quantum wells (MQWs) on Si(111) substrates is demonstrated. A 3??m thick reverse, double-step virtual substrate with a final composition of Si{sub 0.10}Ge{sub 0.90} has been employed. High resolution XRD, TEM, AFM and defect etching analysis has been used for the study of the structural properties of the buffer and of the QWs. The QW stack is characterized by a threading dislocation density of about 3?×?10{sup 7?}cm{sup ?2} and an interdiffusion layer at the well/barrier interface of 2.1?nm. The quantum confined energy levels of this system have been calculated using the k·p and effective mass approximation methods. The Ge/Si{sub 0.15}Ge{sub 0.85} MQWs have been characterized through absorption and photoluminescence measurements. The optical spectra have been compared with those of Ge/Si{sub 0.15}Ge{sub 0.85} QWs grown on Si(001) through a thick graded virtual substrate.

  10. Optical Link on Silicon Employing Ge/SiGe Quantum Well Structures Onur Fidaner, Ali K. Okyay, Jonathan E. Roth, Rebecca K. Scheavitz, Yu-Hsuan Kuo*

    E-Print Network [OSTI]

    Miller, David A. B.

    Optical Link on Silicon Employing Ge/SiGe Quantum Well Structures Onur Fidaner, Ali K. Okyay University, Taipei, Taiwan Abstract: We demonstrate an optical link on silicon employing Ge/SiGe quantum well of the quantum-confined Stark effect (QCSE) on silicon using Ge/SiGe quantum wells opened up the possibility

  11. The thermoelectric properties of Ge/SiGe modulation doped superlattices A. Samarelli, L. Ferre Llin, S. Cecchi, J. Frigerio, T. Etzelstorfer et al.

    E-Print Network [OSTI]

    Hague, Jim

    The thermoelectric properties of Ge/SiGe modulation doped superlattices A. Samarelli, L. Ferre Llin thermoelectric properties of Ge/SiGe modulation doped superlattices A. Samarelli,1 L. Ferre Llin,1 S. Cecchi,2 J in the thermoelectric figure of merit, ZT, and power factor at room temperature over bulk Ge, Si1ŔyGey, and Si/Ge

  12. Probing leptogenesis with GeV-scale sterile neutrinos at LHCb and BELLE II

    E-Print Network [OSTI]

    Laurent Canetti; Marco Drewes; Björn Garbrecht

    2015-05-22T23:59:59.000Z

    We show that existing laboratory experiments have the potential to unveil the origin of matter by probing leptogenesis in the type-I seesaw model with three right-handed neutrinos and Majorana masses in the GeV range. The baryon asymmetry is generated by CP-violating flavour oscillations during the production of the right-handed neutrinos. In contrast to the case with only two right-handed neutrinos, no degeneracy in the Majorana masses is required. The right-handed neutrinos can be found in meson decays at BELLE II and LHCb.

  13. Young Pulsars and the Galactic Center GeV Gamma-ray Excess

    E-Print Network [OSTI]

    O'Leary, Ryan M; Kerr, Matthew; Dexter, Jason

    2015-01-01T23:59:59.000Z

    Studies of Fermi data indicate an excess of GeV gamma rays around the Galactic center (GC), possibly due to dark matter. We show that young gamma-ray pulsars can yield a similar signal. First, a high concentration of GC supernovae naturally leads to a population of kicked pulsars symmetric about the GC. Second, while very-young pulsars with soft spectra reside near the Galactic plane, pulsars with spectra that have hardened with age accumulate at larger angles. This combination, including unresolved foreground pulsars, traces the morphology and spectrum of the Excess.

  14. Young Pulsars and the Galactic Center GeV Gamma-ray Excess

    E-Print Network [OSTI]

    Ryan M. O'Leary; Matthew D. Kistler; Matthew Kerr; Jason Dexter

    2015-04-09T23:59:59.000Z

    Studies of Fermi data indicate an excess of GeV gamma rays around the Galactic center (GC), possibly due to dark matter. We show that young gamma-ray pulsars can yield a similar signal. First, a high concentration of GC supernovae naturally leads to a population of kicked pulsars symmetric about the GC. Second, while very-young pulsars with soft spectra reside near the Galactic plane, pulsars with spectra that have hardened with age accumulate at larger angles. This combination, including unresolved foreground pulsars, traces the morphology and spectrum of the Excess.

  15. 23 6 12 8:00 III-V/Ge CMOS

    E-Print Network [OSTI]

    Katsumoto, Shingo

    23 6 12 8:00 - 1 - 1. : III-V/Ge CMOS ~ 200%~ 2. : III-V (Ge) III-V/Ge CMOS (Si) 200% III-V/Ge CMOS 200% III-V/Ge CMOS () () () () III-V III-V/Ge CMOS (1) III-V Ge III-V/Ge CMOS (2) III-V-OI MOSFET (3) III-V/Ge CMOS "2011 Symposia on VLSI

  16. Ice particle size matters | EMSL

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

    Ice particle size matters Ice particle size matters Released: May 04, 2014 Fine-tuning cloud models for improved climate predictions The Science Arctic clouds are widespread and...

  17. Photon and graviton mass limits

    SciTech Connect (OSTI)

    Nieto, Michael [Los Alamos National Laboratory; Goldhaber Scharff, Alfred [SUNY

    2008-01-01T23:59:59.000Z

    We review past and current studies of possible long-distance, low-frequency deviations from Maxwell electrodynamics and Einstein gravity. Both have passed through three phases: (1) Testing the inverse-square laws of Newton and Coulomb, (2) Seeking a nonzero value for the rest mass of photon or graviton, and (3) Considering more degrees of freedom, allowing mass while preserving gauge or general-coordinate invariance. For electrodynamics there continues to be no sign of any deviation. Since our previous review the lower limit on the photon Compton wavelength (associated with weakening of electromagnetic fields in vacuum over large distance scale) has improved by four orders of magnitude, to about one astronomical unit. Rapid current progress in astronomical observations makes it likely that there will be further advances. These ultimately could yield a bound exceeding galactic dimensions, as has long been contemplated. Meanwhile, for gravity there have been strong arguments about even the concept of a graviton rest mass. At the same time there are striking observations, commonly labeled 'dark matter' and 'dark energy' that some argue imply modified gravity. This makes the questions for gravity much more interesting. For dark matter, which involves increased attraction at large distances, any explanation by modified gravity would be qualitatively different from graviton mass. Because dark energy is associated with reduced attraction at large distances, it might be explained by a graviton-mass-like effect.

  18. Measurement of the neutron-capture cross section of ??Ge and ??Ge below 15 MeV and its relevance to 0??? decay searches of ??Ge

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bhike, Megha; Fallin, B.; Tornow, W.

    2015-02-01T23:59:59.000Z

    The neutron radiative-capture cross section of ??Ge was measured between 0.4 and 14.8 MeV using the activation technique. Germanium samples with the isotopic abundance of ~86% ??Ge and ~14% ??Ge used in the 0??? searches by the GERDA and Majorana Collaborations were irradiated with monoenergetic neutrons produced at eleven energies via the łH(p,n)łHe, ˛H(d,n)łHe and łH(d,n)?He reactions. Previously, data existed only at thermal energies and at 14 MeV. As a by-product, capture cross-section data were also obtained for ??Ge at neutron energies below 8 MeV. Indium and gold foils were irradiated simultaneously for neutron fluence determination. High-resolution ?-ray spectroscopy wasmore »used to determine the ?-ray activity of the daughter nuclei of interest. For the ??Ge total capture cross section the present data are in good agreement with the TENDL-2013 model calculations and the ENDF/B-VII.1 evaluations, while for the ??Ge(n,?)??Ge reaction, the present data are about a factor of two larger than predicted. It was found that the ??Ge(n,?)??Ge yield in the High-Purity Germanium (HPGe) detectors used by the GERDA and Majorana Collaborations is only about a factor of two smaller than the ??Ge(n,?)??Ge yield due to the larger cross section of the former reaction.« less

  19. Two-loop stability of singlet extensions of the SM with dark matter

    E-Print Network [OSTI]

    Costa, Raul; Sampaio, Marco O P; Santos, Rui

    2015-01-01T23:59:59.000Z

    We present a study of the high energy stability of a minimal complex singlet extension of the Standard Model with or without dark matter (CxSM). We start by obtaining the beta functions of the couplings of the theory from the effective potential and then perform the RGE evolution for the allowed parameter space of the model at the electroweak scale. We obtain the scale up to which the model survives and combine this information with all the LHC measurements as well as bounds from dark matter detection experiments as well as the relic density best measurement from Planck. We conclude that scenarios which solve both the dark matter and stability problems must contain a dark particle heavier than 50 GeV and a new visible state (mixing with the SM-like Higgs) heavier than 170 GeV.

  20. Two-loop stability of singlet extensions of the SM with dark matter

    E-Print Network [OSTI]

    Raul Costa; António P. Morais; Marco O. P. Sampaio; Rui Santos

    2015-04-24T23:59:59.000Z

    We present a study of the high energy stability of a minimal complex singlet extension of the Standard Model with or without dark matter (CxSM). We start by obtaining the beta functions of the couplings of the theory from the effective potential and then perform the RGE evolution for the allowed parameter space of the model at the electroweak scale. We obtain the scale up to which the model survives and combine this information with all the LHC measurements as well as bounds from dark matter detection experiments as well as the relic density best measurement from Planck. We conclude that scenarios which solve both the dark matter and stability problems must contain a dark particle heavier than 50 GeV and a new visible state (mixing with the SM-like Higgs) heavier than 170 GeV.

  1. Axion hot dark matter bounds after Planck

    SciTech Connect (OSTI)

    Archidiacono, Maria; Hannestad, Steen [Department of Physics and Astronomy, University of Aarhus DK-8000 Aarhus C (Denmark); Mirizzi, Alessandro [II. Institut für Theoretische Physik, Universität Hamburg Luruper Chaussee 149, D-22761 Hamburg (Germany); Raffelt, Georg [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6, D-80805 München (Germany); Wong, Yvonne Y.Y., E-mail: archi@phys.au.dk, E-mail: sth@phys.au.dk, E-mail: alessandro.mirizzi@desy.de, E-mail: raffelt@mpp.mpg.de, E-mail: yvonne.y.wong@unsw.edu.au [School of Physics, The University of New South Wales Sydney NSW 2052 (Australia)

    2013-10-01T23:59:59.000Z

    We use cosmological observations in the post-Planck era to derive limits on thermally produced cosmological axions. In the early universe such axions contribute to the radiation density and later to the hot dark matter fraction. We find an upper limit m{sub a} < 0.67 eV at 95% C.L. after marginalising over the unknown neutrino masses, using CMB temperature and polarisation data from Planck and WMAP respectively, the halo matter power spectrum extracted from SDSS-DR7, and the local Hubble expansion rate H{sub 0} released by the Carnegie Hubble Program based on a recalibration of the Hubble Space Telescope Key Project sample. Leaving out the local H{sub 0} measurement relaxes the limit somewhat to 0.86 eV, while Planck+WMAP alone constrain the axion mass to 1.01 eV, the first time an upper limit on m{sub a} has been obtained from CMB data alone. Our axion limit is therefore not very sensitive to the tension between the Planck-inferred H{sub 0} and the locally measured value. This is in contrast with the upper limit on the neutrino mass sum, which we find here to range from ? m{sub ?} < 0.27 eV at 95% C.L. combining all of the aforementioned observations, to 0.84 eV from CMB data alone.

  2. GE Lighting Solutions: Order (2013-SE-4901)

    Broader source: Energy.gov [DOE]

    DOE ordered General Electric Lighting Solutions, LLC to pay a $5,360 civil penalty after finding GE Lighting Solutions had manufactured and distributed in commerce in the U.S. 30 units of basic model DR4-RTFB-23B and 177 units (of which 85 units remain in inventory) of basic model DR4-RTFB-77A-002, noncompliant traffic signal modules.

  3. Viscosity Measurement G.E. Leblanc

    E-Print Network [OSTI]

    Kostic, Milivoje M.

    30 Viscosity Measurement G.E. Leblanc McMaster University R.A. Secco The University of Western Ontario 30.1 Shear Viscosity ............................................................. 30-l Newtonian and Non-Newtonian Fluids l Dimensions and Units of Viscosity l Viscometer Types l Capillary M. Kostic

  4. GE Teams with NY College to Pilot SOFC Technology |GE Global...

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

    Hudson Valley Community College to Pilot GE Solid Oxide Fuel Cell Technology Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to...

  5. GE partners with 'Girls Who Code' for summer program | GE Global...

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

    share on LinkedIn (Opens in new window) Click to share on Tumblr (Opens in new window) GE Partners with 'Girls Who Code' for Summer Immersion Program to Help Close the Gender Gap...

  6. GE, NASA Work to Relaunch Supersonic Air Travel | GE Global Research

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

    share on LinkedIn (Opens in new window) Click to share on Tumblr (Opens in new window) GE Supporting NASA's efforts to Relaunch Commercial Supersonic Air Travel Awarded 2- year...

  7. Metastability and relaxation in tensile SiGe on Ge(001) virtual substrates

    SciTech Connect (OSTI)

    Frigerio, Jacopo; Lodari, Mario; Chrastina, Daniel, E-mail: daniel.chrastina@polimi.it; Mondiali, Valeria; Isella, Giovanni [L-NESS, Dipartimento di Fisica, Politecnico di Milano, Polo di Como, via Anzani 42, 22100 Como (Italy); Bollani, Monica [IFN-CNR, L-NESS, via Anzani 42, 22100 Como (Italy)

    2014-09-21T23:59:59.000Z

    We systematically study the heteroepitaxy of SiGe alloys on Ge virtual substrates in order to understand strain relaxation processes and maximize the tensile strain in the SiGe layer. The degree of relaxation is measured by high-resolution x-ray diffraction, and surface morphology is characterized by atomic force microscopy. The results are analyzed in terms of a numerical model, which considers dislocation nucleation, multiplication, thermally activated glide, and strain-dependent blocking. Relaxation is found to be sensitive to growth rate and substrate temperature as well as epilayer misfit and thickness, and growth parameters are found which allow a SiGe film with over 4?GPa of tensile stress to be obtained.

  8. Hot and dark matter

    E-Print Network [OSTI]

    D'Eramo, Francesco

    2012-01-01T23:59:59.000Z

    In this thesis, we build new Effective Field Theory tools to describe the propagation of energetic partons in hot and dense media, and we propose two new reactions for dark matter in the early universe. In the first part, ...

  9. Programmable matter by folding

    E-Print Network [OSTI]

    Wood, R. J.

    Programmable matter is a material whose properties can be programmed to achieve specific shapes or stiffnesses upon command. This concept requires constituent elements to interact and rearrange intelligently in order to ...

  10. The Heart of Matter

    E-Print Network [OSTI]

    Rohini M. Godbole

    2010-06-30T23:59:59.000Z

    In this article I trace the development of the human understanding of the "Heart of Matter" from early concepts of "elements" (or alternatively "Panchmahabhootas") to the current status of "quarks" and "leptons" as the fundamental constituents of matter, interacting together via exchange of the various force carrier particles called "gauge bosons" such as the photon, W/Z-boson etc. I would like to show how our understanding of the fundamental constituents of matter has gone hand in hand with our understanding of the fundamental forces in nature. I will also outline how the knowledge of particle physics at the "micro" scale of less than a Fermi(one millionth of a nanometer), enables us to offer explanations of Cosmological observations at the "macro" scale. Consequently these observations, may in turn, help us address some very fundamental questions of the Physics at the "Heart of the Matter".

  11. Matter & Energy Electronics

    E-Print Network [OSTI]

    Suslick, Kenneth S.

    See also: Matter & Energy Electronics· Detectors· Technology· Construction· Sports Science Electronic Tongue Tastes Wine Variety, Vintage (Aug. 12, 2008) -- You don't need a wine expert to Advance

  12. Gaseous dark matter detectors

    E-Print Network [OSTI]

    Martoff, C. J.

    Dark matter (DM) detectors with directional sensitivity have the potential of yielding an unambiguous positive observation of WIMPs as well as discriminating between galactic DM halo models. In this paper, we introduce the ...

  13. The Majorana Ge-76 double-beta decay project

    SciTech Connect (OSTI)

    Avignone, Frank Titus [ORNL

    2010-01-01T23:59:59.000Z

    The MAJORANA Project is a research and development activity set up to establish the feasibility and cost of a doublebetadecay experiment comprising a one-ton array of Ge detectors fabricated from germanium enriched to about 86% in Ge-76.

  14. GE launches 'STEM empowers OK' initiative in Oklahoma City |...

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

    ok GE Foundation donates 400,000 to enhance STEM education initiatives across Oklahoma STEM Empowers OK to sponsor week-long, GE Summer Science Academy at OSSM for Oklahoma...

  15. Passionate Technologists Wanted at ASME Turbo Expo|GE Global...

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

    Meet & Greet GE Researchers at ASME Turbo 2014 Thomas Ripplinger 2014.06.10 Do you love gas turbine research as much as I do? Then I want to meet you next week Since joining GE...

  16. Driving Sensing Technology in Oil & Gas | GE Global Research

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

    a bit more about Bill's work. Bill joined GE Global Research in 2010. For the past four years his emphasis has been on developing advanced photonics technologies for multiple GE...

  17. Bounds on self-interacting fermion dark matter from observations of old neutron stars

    E-Print Network [OSTI]

    Joseph Bramante; Keita Fukushima; Jason Kumar; Elan Stopnitzky

    2014-05-28T23:59:59.000Z

    The existence of old neutron stars deeply constrains self-interacting fermion dark matter, which can form star-killing black holes. We quantify this constraint on dark matter-nucleon scattering, considering collapse scenarios that broaden bounds over intermediate masses. We then find the self- and co-annihilation rates necessary to lift these dark matter-nucleon scattering bounds. For Yukawa-coupled dark matter that fits dwarf galaxy halo profiles with a coupling $\\alpha = 10^{-1}-10^{-4}$, a scalar mediator mass $m_\\phi = 1-500$ MeV, and DM mass $m_X = 0.1-10^7$ GeV, we show that fermion dark matter is unconstrained if it self-annihilates at a rate greater than $10^{-40} ~ \\rm{cm^3/s}$ or co-annihilates with baryons at a rate greater than $10^{-50} ~ \\rm{cm^3/s}$.

  18. Tailoring the spin polarization in Ge/SiGe multiple quantum wells

    SciTech Connect (OSTI)

    Giorgioni, Anna; Pezzoli, Fabio; Gatti, Eleonora; Grilli, Emanuele; Guzzi, Mario [LNESS-Dipartimento di Scienza dei Materiali, Universitŕ degli Studi di Milano-Bicocca, I-20125 Milano (Italy); Bottegoni, Federico; Cecchi, Stefano; Ciccacci, Franco; Isella, Giovanni [LNESS-Dipartimento di Fisica, Politecnico di Milano, I-20133 Milano (Italy); Trivedi, Dhara; Song, Yang [Department of Physics and Astronomy, University of Rochester, Rochester (United States); Li, Pengki [Department of Electrical and Computer Engineering, University of Rochester, Rochester (United States); Dery, Hanan [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 and Department of Electrical and Computer Engineering, University of Rochester, Rochester (United States)

    2013-12-04T23:59:59.000Z

    We performed spin-resolved photoluminescence measurements on Ge/SiGe multiple quantum wells with different well thickness and using different exciting power densities. The polarization of the direct emission strongly depends on the relative weight of electrons photoexcited from the light and the heavy hole subbands. The study of the polarization as a function of the exciting power highlights the role of the carrier-carrier interactions in determining spin depolarization.

  19. High density matter

    E-Print Network [OSTI]

    J. R. Stone

    2013-02-11T23:59:59.000Z

    The microscopic composition and properties of matter at super-saturation densities have been the subject of intense investigation for decades. The scarcity of experimental and observational data has lead to the necessary reliance on theoretical models. However, there remains great uncertainty in these models, which, of necessity, have to go beyond the over-simple assumption that high density matter consists only of nucleons and leptons. Heavy strange baryons, mesons and quark matter in different forms and phases have to be included to fulfil basic requirements of fundamental laws of physics. In this review the latest developments in construction of the Equation of State (EoS) of high-density matter at zero and finite temperature assuming different composition of the matter are surveyed. Critical comparison of model EoS with available observational data on neutron stars, including gravitational masses, radii and cooling patterns is presented. The effect of changing rotational frequency on the composition of neutron stars during their lifetime is demonstrated. Compatibility of EoS of high-density, low temperature compact objects and low density, high temperature matter created in heavy-ion collisions is discussed.

  20. Strain and stability of ultrathin Ge layers in Si/Ge/Si axial heterojunction nanowires

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ross, Frances M.; Stach, Eric A.; Wen, Cheng -Yen; Reuter, Mark C.; Su, Dong

    2015-03-11T23:59:59.000Z

    The abrupt heterointerfaces in the Si/Ge materials system presents useful possibilities for electronic device engineering because the band structure can be affected by strain induced by the lattice mismatch. In planar layers, heterointerfaces with abrupt composition changes are difficult to realize without introducing misfit dislocations. However, in catalytically grown nanowires, abrupt heterointerfaces can be fabricated by appropriate choice of the catalyst. Here we grow nanowires containing Si/Ge and Si/Ge/Si structures respectively with sub-1nm thick Ge "quantum wells" and we measure the interfacial strain fields using geometric phase analysis. Narrow Ge layers show radial strains of several percent, with a correspondingmore »dilation in the axial direction. Si/Ge interfaces show lattice rotation and curvature of the lattice planes. We conclude that high strains can be achieved, compared to what is possible in planar layers. In addition, we study the stability of these heterostructures under heating and electron beam irradiation. The strain and composition gradients are supposed to the cause of the instability for interdiffusion.« less

  1. Thin SiGe virtual substrates for Ge heterostructures integration on silicon

    SciTech Connect (OSTI)

    Cecchi, S., E-mail: stefano.cecchi@mdm.imm.cnr.it; Chrastina, D.; Frigerio, J.; Isella, G. [L-NESS, Dipartimento di Fisica, Politecnico di Milano–Polo Territoriale di Como, Via Anzani 42, I-22100 Como (Italy); Gatti, E.; Guzzi, M. [L-NESS, Dipartimento di Scienza dei Materiali, Universitŕ di Milano Bicocca, via Cozzi 53, I-20126 Milano (Italy); Müller Gubler, E. [Electron Microscopy ETH Zurich, ETH Zurich, Auguste-Piccard-Hof 1, CH-8093 Zurich (Switzerland); Paul, D. J. [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT (United Kingdom)

    2014-03-07T23:59:59.000Z

    The possibility to reduce the thickness of the SiGe virtual substrate, required for the integration of Ge heterostructures on Si, without heavily affecting the crystal quality is becoming fundamental in several applications. In this work, we present 1??m thick Si{sub 1?x}Ge{sub x} buffers (with x?>?0.7) having different designs which could be suitable for applications requiring a thin virtual substrate. The rationale is to reduce the lattice mismatch at the interface with the Si substrate by introducing composition steps and/or partial grading. The relatively low growth temperature (475?°C) makes this approach appealing for complementary metal-oxide-semiconductor integration. For all the investigated designs, a reduction of the threading dislocation density compared to constant composition Si{sub 1?x}Ge{sub x} layers was observed. The best buffer in terms of defects reduction was used as a virtual substrate for the deposition of a Ge/SiGe multiple quantum well structure. Room temperature optical absorption and photoluminescence analysis performed on nominally identical quantum wells grown on both a thick graded virtual substrate and the selected thin buffer demonstrates a comparable optical quality, confirming the effectiveness of the proposed approach.

  2. Similarity of Stranski-Krastanow growth of Ge/Si and SiGe/Si (001)

    SciTech Connect (OSTI)

    Norris, D. J.; Qiu, Y.; Walther, T. [Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Building, Mappin Street, Sheffield S1 3JD (United Kingdom); Dobbie, A.; Myronov, M. [Department of Physics, University of Warwick, Coventry CV4 7A (United Kingdom)

    2014-01-07T23:59:59.000Z

    This study investigates the onset of islanding (Stranski-Krastanow transition) in strained pure germanium (Ge) and dilute silicon-germanium (SiGe) alloy layers grown by chemical vapour deposition on Si(001) substrates. Integration of compositional profiles is compared to a novel method for quantification of X-ray maps acquired in cross-sectional scanning transmission electron microscopy, together with simulations of surface segregation of Ge. We show that Si{sub 1?x}Ge{sub x} alloys for germanium concentrations x???0.27 grow two-dimensionally and stay flat up to considerable layer thicknesses, while layers with concentrations in the range 0.28?Ge is ±(0.2–0.3) ML. Modelling shows that of the amount of germanium deposited, 0.7 ML segregate towards the free surface so that only ?2.3/x ML are directly incorporated in the layer within a few nanometres, in good agreement with our measurements. For pure Ge (x?=?1), this thickness is smaller than most values quoted in the literature, which we attribute to the high sensitivity of our method to fractional monolayer changes in the effective chemical width of such thin layers.

  3. Erratum (astro-ph/0510172): Robust Limits on Lorentz Violation from Gamma-Ray Bursts

    E-Print Network [OSTI]

    John Ellis; N. E. Mavromatos; D. V. Nanopoulos; A. S. Sakharov; E. K. G. Sarkisyan

    2007-12-17T23:59:59.000Z

    We correct the fitting formula used in refs. [1,2] to obtain a robust limit on a violation of Lorentz invariance that depends linearly on the photon energy. The correction leads to a slight increase of the limit on the scale of the violation, to M > 1.4 x 10^{16} GeV.

  4. Upper limits for the photoproduction cross section for the ???(1860) pentaquark state off the deuteron

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Egiyan, H.; Langheinrich, J.; Gothe, R. W.; Graham, L.; Holtrop, M.; Lu, H.; Mattione, P.; Mutchler, G.; Park, K.; Smith, E. S.; Stepanyan, S.; Zhao, Z. W.; Adhikari, K. P.; Aghasyan, M.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Bennett, R. P.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Contalbrigo, M.; D’Angelo, A.; Daniel, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Dey, B.; Dickson, R.; Djalali, C.; Doughty, D.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fradi, A.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Heddle, D.; Hicks, K.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jo, H. S.; Joo, K.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kubarovsky, V.; Kuleshov, S. V.; Livingston, K.; MacGregor, I. J. D.; Mao, Y.; Mayer, M.; McKinnon, B.; Mokeev, V.; Munevar, E.; Nadel-Turonski, P.; Ni, A.; Niculescu, G.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L.; Paremuzyan, R.; Park, S.; Pasyuk, E.; Anefalos Pereira, S.; Phelps, E.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Raue, B. A.; Ricco, G.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Stepanyan, S. S.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tedeschi, D. J.; Ungaro, M.; Voutier, E.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhao, B.

    2012-01-01T23:59:59.000Z

    We searched for the ???(1860) pentaquark in the photoproduction process off the deuteron in the ????-decay channel using CLAS. The invariant-mass spectrum of the ???? system does not indicate any statistically significant enhancement near the reported mass M=1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90%-confidence-level upper limit of 0.7 nb for the photoproduction cross section of ???(1860) with a consecutive decay into???? in the photon-energy range 4.5GeV?<5.5GeV.

  5. Monolithic Ge/Si Avalanche Photodiodes Yimin Kanga*

    E-Print Network [OSTI]

    Bowers, John

    Monolithic Ge/Si Avalanche Photodiodes Yimin Kanga* , Mike Morsea , Mario J. Panicciaa , Moshe, Charlottesville, VA 22904, USA Abstract: We demonstrate mesa-type and waveguide-type Ge/Si avalanche photodiodes. Research on the Ge/Si photodiodes, one of the fundamental components needed for building integrated silicon

  6. MOTION OF ELECTRON-HOLE DROPS IN Ge

    E-Print Network [OSTI]

    Westervelt, R.M.

    2011-01-01T23:59:59.000Z

    MOTION OF ELECTRON-HOLE DROPS IN Ge R. M. Westervelt, J. C.MOTION OF ELECTRON-HOLE DROPS IN Ge R. M. Westervelt, J. C.OF ELECTRON-HOLE DROPS IN Ge R M Westervelt, J C Culbertson

  7. Ge.Meyer -MPL-27.11.002 Status Tunerentwicklung

    E-Print Network [OSTI]

    Ge.Meyer -MPL- 27.11.002 Status Tunerentwicklung 1) Geschichte: Alter franz. Tuner weich, hatte Hysterese. Federkonstante: Gerechnet 5,4 µ/kN, gemessen 26,7 µ/kN (Faktor 5), Ge.Meyer gerechnet 14,6 µ Felder. 2) Tuner 0 / H.Kaiser, Ge.Meyer -MPL- Deshalb wurde ein neues Konzept überlegt. Dieses Konzept

  8. Conduction band discontinuity and electron confinement at the Si[subscript x]Ge[subscript 1?x]/Ge interface

    E-Print Network [OSTI]

    Mazzeo, G.

    Germanium rich heterostructures can constitute a valid alternative to Silicon for the confinement of single electron spins. The conduction band discontinuity in SiGe/Ge heterostructures grown on pure germanium substrate ...

  9. Isocurvature constraints and anharmonic effects on QCD axion dark matter

    SciTech Connect (OSTI)

    Kobayashi, Takeshi [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 3H8 (Canada); Kurematsu, Ryosuke; Takahashi, Fuminobu, E-mail: takeshi@cita.utoronto.ca, E-mail: rkurematsu@tuhep.phys.tohoku.ac.jp, E-mail: fumi@tuhep.phys.tohoku.ac.jp [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

    2013-09-01T23:59:59.000Z

    We revisit the isocurvature density perturbations induced by quantum fluctuations of the axion field by extending a recently developed analytic method and approximations to a time-dependent scalar potential, which enables us to follow the evolution of the axion until it starts to oscillate. We find that, as the initial misalignment angle approaches the hilltop of the potential, the isocurvature perturbations become significantly enhanced, while the non-Gaussianity parameter increases slowly but surely. As a result, the isocurvature constraint on the inflation scale is tightened as H{sub inf}?GeV for the axion decay constant f{sub a}?<10{sup 10} GeV, near the smaller end of the axion dark matter window. We also derive useful formulae for the power spectrum and non-Gaussianity of the isocurvature perturbations.

  10. Pontecorvo neutrino-antineutrino oscillations: theory and experimental limits

    E-Print Network [OSTI]

    S. Esposito; N. Tancredi

    1997-05-19T23:59:59.000Z

    We study Pontecorvo neutrino-antineutrino oscillations both in vacuum and in matter within a field theoretic approach, showing that this phenomenon can occur only if neutrinos have a Dirac-Majorana mass term. We find that matter effects suppress these oscillations and cannot explain the solar neutrino problem. On the contrary, a vacuum neutrino-antineutrino oscillations solution to this problem exists. We analyze this solution and available data from laboratory experiments giving stringent limits on $\

  11. Pre-launch Estimates for GLAST Sensitivity to Dark Matter Annihilation Signals

    SciTech Connect (OSTI)

    Baltz, E.A.; Berenji, B.; /SLAC /KIPAC, Menlo Park; Bertone, G.; /Paris, Inst. Astrophys.; Bergstrom, L.; /Stockholm U.; Bloom, E.; /SLAC /KIPAC, Menlo Park; Bringmann, T.; /Stockholm U.; Chiang, J.; Cohen-Tanugi, J.; /SLAC /KIPAC, Menlo Park; Conrad, J.; /Stockholm U.; Edmonds, Y.; /SLAC /KIPAC, Menlo Park; Edsjo, J.; /Stockholm U.; Godfrey, G.; /SLAC /KIPAC, Menlo Park; Hughes, R.E.; /Ohio State U.; Johnson, R.P.; /UC, Santa Cruz; Lionetto, A.; /Rome U.,Tor Vergata /INFN, Rome2; Moiseev, A.A.; /CRESST; Morselli, A.; /Rome U.,Tor Vergata /INFN, Rome2; Moskalenko, I.V.; /Stanford U., HEPL /KIPAC, Menlo Park; Nuss, E.; /Montpellier U.; Ormes, J.F.; /Denver U.; Rando, R.; /INFN, Padua /Ohio State U. /Stockholm U. /Ohio State U. /Garching, Max Planck Inst., MPE /SLAC /KIPAC, Menlo Park /Ohio State U.

    2009-05-15T23:59:59.000Z

    We investigate the sensitivity of the Gamma-ray Large Area Space Telescope (GLAST) to indirectly detect weakly interacting massive particles (WIMPs) through the {gamma}-ray signal that their pair annihilation produces. WIMPs are among the favorite candidates to explain the compelling evidence that about 80% of the mass in the Universe is non-baryonic dark matter (DM). They are serendipitously motivated by various extensions of the standard model of particle physics such as Supersymmetry and Universal Extra Dimensions (UED). With its unprecedented sensitivity and its very large energy range (20 MeV to more than 300 GeV) the main instrument on board the GLAST satellite, the Large Area Telescope (LAT), will open a new window of discovery. As our estimates show, the LAT will be able to detect an indirect DM signature for a large class of WIMP models given a cuspy profile for the DM distribution. Using the current state of the art Monte Carlo and event reconstruction software developed within the LAT collaboration, we present preliminary sensitivity studies for several possible sources inside and outside the Galaxy. We also discuss the potential of the LAT to detect UED via the electron/positron channel. Diffuse background modeling and other background issues that will be important in setting limits or seeing a signal are presented.

  12. Dark Matter Searches in Jet plus Missing Energy in $\\rm ?p$ collision at CERN LHC

    E-Print Network [OSTI]

    Hao Sun

    2014-08-01T23:59:59.000Z

    In this paper, we investigate the $\\rm \\gamma p$ photoproduction of jet plus missing energy signal to set limits on the couplings of the fermionic dark matter to the quarks at the LHC via the main reaction $\\rm pp\\rightarrow p\\gamma p\\rightarrow p \\chi\\chi j$. We assume a typical LHC multipurpose forward detectors and work in a model independent Effective Field Theory framework. Typically, when we do the background analysis, we also include their corresponding Single Diffractive (SD) productions. Our result shows that by requiring a $5\\sigma$ ($\\rm S/\\sqrt{B} \\geq 5$) signal deviation, with an integrated luminosity of $\\rm {\\cal L} = 200 fb^{-1}$, the lower bounds of WIMP masses scale can be detected up to $\\rm \\Lambda$ equal 665.5, 808.9 and 564.0 GeV for the forward detector acceptances $\\xi_1$, $\\xi_2$, and $\\xi_3$, respectively, where $0.00150.5$, $0.10.5$ and $0.0015<\\xi_3<0.15$.

  13. Full jet reconstruction in 200 GeV p+p, d+Au and Au+Au collisions by STAR

    E-Print Network [OSTI]

    Jan Kapitan; for the STAR Collaboration

    2009-09-16T23:59:59.000Z

    Measurements of inclusive hadron suppression and di-hadron azimuthal correlations have provided important insights into jet quenching in hot QCD matter. However, they do not provide access to the energy of the hard scattering and are limited in their sensitivity since they can be affected by biases toward hard fragmentation and small energy loss. Full jet reconstruction in heavy-ion collisions enables a complete study of the modification of jet structure due to energy loss, but is challenging due to the high multiplicity environment. Study of jet production and properties in d+Au and p+p collisions provides important baseline measurement for jet studies in heavy-ion collisions. We report measurements of fully reconstructed jets in p+p, d+Au and Au+Au collisions at $\\sqrt{s_\\mathrm{NN}} = 200 \\mathrm{GeV}$ from the STAR experiment at RHIC. Measurement of initial state nuclear effects in d+Au collisions utilizing di-jet azimuthal correlations is presented together with similar measurement in p+p collisions. Inclusive jet $\\pt$ spectra and fragmentation functions in p+p and central Au+Au collisions are reported, with subsequent studies of jet nuclear modification factor, jet energy profile and modifications in the fragmentation function due to jet quenching.

  14. 33rd International Lie`ge Colloquium on Ocean Dynamics Lie`ge, Belgium, May 711, 2001

    E-Print Network [OSTI]

    Leonard, John J.

    Preface 33rd International Lie`ge Colloquium on Ocean Dynamics Lie`ge, Belgium, May 7­11, 2001 The International Lie`ge Colloquium on Ocean Dynamics is organized annually. The topic differs from year to year. Assembling a group of active and eminent scien- tists from various countries and often different disci

  15. Stealth Dark Matter: Dark scalar baryons through the Higgs portal

    E-Print Network [OSTI]

    Appelquist, Thomas; Buchoff, Michael I; Fleming, George T; Jin, Xiao-Yong; Kiskis, Joe; Kribs, Graham D; Neil, Ethan T; Osborn, James C; Rebbi, Claudio; Rinaldi, Enrico; Schaich, David; Schroeder, Chris; Syritsyn, Sergey; Vranas, Pavlos; Weinberg, Evan; Witzel, Oliver

    2015-01-01T23:59:59.000Z

    We present a new model of "Stealth Dark Matter": a composite baryonic scalar of an $SU(N_D)$ strongly-coupled theory with even $N_D \\geq 4$. All mass scales are technically natural, and dark matter stability is automatic without imposing an additional discrete or global symmetry. Constituent fermions transform in vector-like representations of the electroweak group that permit both electroweak-breaking and electroweak-preserving mass terms. This gives a tunable coupling of stealth dark matter to the Higgs boson independent of the dark matter mass itself. We specialize to $SU(4)$, and investigate the constraints on the model from dark meson decay, electroweak precision measurements, basic collider limits, and spin-independent direct detection scattering through Higgs exchange. We exploit our earlier lattice simulations that determined the composite spectrum as well as the effective Higgs coupling of stealth dark matter in order to place bounds from direct detection, excluding constituent fermions with dominant...

  16. Phenomenology of Dirac Neutralino Dark Matter

    SciTech Connect (OSTI)

    Buckley, Matthew R.; Hooper, Dan; Kumar, Jason

    2013-09-01T23:59:59.000Z

    In supersymmetric models with an unbroken R-symmetry (rather than only R-parity), the neutralinos are Dirac fermions rather than Majorana. In this article, we discuss the phenomenology of neutralino dark matter in such models, including the calculation of the thermal relic abundance, and constraints and prospects for direct and indirect searches. Due to the large elastic scattering cross sections with nuclei predicted in R-symmetric models, we are forced to consider a neutralino that is predominantly bino, with very little higgsino mixing. We find a large region of parameter space in which bino-like Dirac neutralinos with masses between 10 and 380 GeV can annihilate through slepton exchange to provide a thermal relic abundance in agreement with the observed cosmological density, without relying on coannihilations or resonant annihilations. The signatures for the indirect detection of Dirac neutralinos are very different than predicted in the Majorana case, with annihilations proceeding dominately to $\\tau^+ \\tau^-$, $\\mu^+ \\mu^-$ and $e^+ e^-$ final states, without the standard chirality suppression. And unlike Majorana dark matter candidates, Dirac neutralinos experience spin-independent scattering with nuclei through vector couplings (via $Z$ and squark exchange), leading to potentially large rates at direct detection experiments. These and other characteristics make Dirac neutralinos potentially interesting within the context of recent direct and indirect detection anomalies. We also discuss the case in which the introduction of a small Majorana mass term breaks the $R$-symmetry, splitting the Dirac neutralino into a pair of nearly degenerate Majorana states.

  17. Microstructure study of the rare-earth intermetallic compounds R5(SixGe1-x)4 and R5(SixGe1-x)3

    SciTech Connect (OSTI)

    Cao, Qing

    2012-07-26T23:59:59.000Z

    The unique combination of magnetic properties and structural transitions exhibited by many members of the R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} family (R = rare earths, 0 ? x ? 1) presents numerous opportunities for these materials in advanced energy transformation applications. Past research has proven that the crystal structure and magnetic ordering of the R{sub 5(Si{sub x}Ge{sub 1-x}){sub 4} compounds can be altered by temperature, magnetic field, pressure and the Si/Ge ratio. Results of this thesis study on the crystal structure of the Er{sub 5}Si{sub 4} compound have for the first time shown that the application of mechanical forces (i.e. shear stress introduced during the mechanical grinding) can also result in a structural transition from Gd{sub 5}Si{sub 4}-type orthorhombic to Gd{sub 5}Si{sub 2}Ge{sub 2}-type monoclinic. This structural transition is reversible, moving in the opposite direction when the material is subjected to low-temperature annealing at 500 ?C. Successful future utilization of the R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} family in novel devices depends on a fundamental understanding of the structure-property interplay on the nanoscale level, which makes a complete understanding of the microstructure of this family especially important. Past scanning electron microscopy (SEM) observation has shown that nanometer-thin plates exist in every R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} (“5:4”) phase studied, independent of initial parent crystal structure and composition. A comprehensive electron microscopy study including SEM, energy dispersive spectroscopy (EDS), selected area diffraction (SAD), and high resolution transmission electron microscopy (HRTEM) of a selected complex 5:4 compound based on Er rather than Gd, (Er{sub 0.9Lu{sub 0.1}){sub 5}Si{sub 4}, has produced data supporting the assumption that all the platelet-like features present in the R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} family are hexagonal R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 3} (“5:3”) phase and possess the same reported orientation relationship that exists for the Gd{sub 5}Ge{sub 4} and Gd{sub 5}Si{sub 2}Ge{sub 2} compounds, i.e. [010](102?){sub m} || [101?0](12?11){sub p}. Additionally, the phase identification in (Er{sub 0.9}Lu{sub 0.1}){sub 5}Si{sub 4} carried out using X-ray powder diffraction (XRD) techniques revealed that the low amount of 5:3 phase is undetectable in a conventional laboratory Cu K? diffractometer due to detection limitations, but that extremely low amounts of the 5:3 phase can be detected using high resolution powder diffraction (HRPD) employing a synchrotron source. These results suggest that use of synchrotron radiation for the study of R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} compounds should be favored over conventional XRD for future investigations. The phase stability of the thin 5:3 plates in a Gd{sub 5}Ge{sub 4} sample was examined by performing long-term annealing at very high temperature. The experimental results indicate the plates are thermally unstable above 1200?C. While phase transformation of 5:3 to 5:4 occurs during the annealing, the phase transition is still fairly sluggish, being incomplete even after 24 hours annealing at this elevated temperature. Additional experiments using laser surface melting performed on the surface of a Ho{sub 5}(Si{sub 0.8}Ge{sub 0.}2){sub 4} sample showed that rapid cooling will suppress the precipitation of 5:3 plates. Bulk microstructure studies of polycrystalline and monocrystalline Gd{sub 5}Ge{sub 3} compounds examined using optical microscopy, SEM and TEM also show a series of linear features present in the Gd{sub 5}Ge{sub 3} matrix, similar in appearance in many ways to the 5:3 plates observed in R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} compounds. A systematic microscopy analysis of these linear features revealed they also are thin plates with a stoichiometric composition of Gd{sub 5}Ge{sub 4} with an orthorhombic structure. The orientation relationship between the 5:3 matrix and the precipitate 5:4 thin plates was determined as [101?0] (12?11){s

  18. Phase transition from hadronic matter to quark matter

    E-Print Network [OSTI]

    P. Wang; A. W. Thomas; A. G. Williams

    2007-04-03T23:59:59.000Z

    We study the phase transition from nuclear matter to quark matter within the SU(3) quark mean field model and NJL model. The SU(3) quark mean field model is used to give the equation of state for nuclear matter, while the equation of state for color superconducting quark matter is calculated within the NJL model. It is found that at low temperature, the phase transition from nuclear to color superconducting quark matter will take place when the density is of order 2.5$\\rho_0$ - 5$\\rho_0$. At zero density, the quark phase will appear when the temperature is larger than about 148 MeV. The phase transition from nuclear matter to quark matter is always first order, whereas the transition between color superconducting quark matter and normal quark matter is second order.

  19. Properties of excited states in {sup 77}Ge.

    SciTech Connect (OSTI)

    Kay, B. P.; Chiara, C. J.; Schiffer, J. P.; Kondev, F. G.; Zhu, S.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; McCutchan, E. A.; Seweryniak, D.; Stefanescu, I.; Univ. of Maryland; Horia-Hulubei National Inst. for Physics and Nuclear Engineering

    2009-07-01T23:59:59.000Z

    The nucleus {sup 77}Ge was studied through the {sup 76}Ge({sup 13}C,{sup 12}C){sup 77}Ge reaction at a sub-Coulomb energy. The angular distributions of rays depopulating excited states in {sup 77}Ge were measured in order to constrain spin and parity assignments. Some of these assignments are of use in connection with neutrinoless double beta decay, where the population of states near the Fermi surface of {sup 76}Ge was recently explored using transfer reactions.

  20. Measurement of the Crab Flux Above 60 GeV with the CELESTE Cherenkov Telescope

    E-Print Network [OSTI]

    De Naurois, Mathieu; Bazer-Bachi, R; Bergeret, H; Bruel, P; Cordier, A; Debiais, G; Dezalay, J P; Dumora, D; Durand, E; Eschstruth, P T; Espigat, P; Fabre, B; Fleury, P; Herault, N; Hrabovsky, M; Incerti, S; Le Gallou, R; Munz, F; Musquere, A; Olive, J F; Paré, E; Quebert, J; Rannot, R C; Reposeur, T; Rob, L; Roy, P; Sako, T; Schovanek, P; Smith, D A; Snabre, P; Volte, A

    2002-01-01T23:59:59.000Z

    We have converted the former solar electrical plant THEMIS (French Pyrenees) into an atmospheric Cherenkov detector called CELESTE, which records gamma rays above 30 GeV (7E24 Hz). Here we present the first sub-100 GeV detection by a ground based telescope of a gamma ray source, the Crab nebula, in the energy region between satellite measurements and imaging atmospheric Cherenkov telescopes. At our analysis threshold energy of 60 +/- 20 GeV we measure a gamma ray rate of 6.1 +/- 0.8 per minute. Allowing for 30% systematic uncertainties and a 30% error on the energy scale yields an integral gamma ray flux of I(E>60 GeV) = 6.2^{+5.3}_{-2.3} E-6 photons m^-2 s^-1. The analysis methods used to obtain the gamma ray signal from the raw data are detailed. In addition, we determine the upper limit for pulsed emission to be <12% of the Crab flux at the 99% confidence level, in the same energy range. Our result indicates that if the power law observed by EGRET is attenuated by a cutoff of form e^{-E/E_0} then E_0 &l...

  1. Role of nucleation sites on the formation of nanoporous Ge

    SciTech Connect (OSTI)

    Yates, B. R.; Darby, B. L.; Jones, K. S. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611-6400 (United States); Elliman, R. G. [Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia)

    2012-09-24T23:59:59.000Z

    The role of nucleation sites on the formation of nanoporous Ge was investigated. Three Ge films with different spherical or columnar pore morphologies to act as inherent nucleation sites were sputtered on (001) Ge. Samples were implanted 90 Degree-Sign from incidence at 300 keV with fluences ranging from 3.0 Multiplication-Sign 10{sup 15} to 3.0 Multiplication-Sign 10{sup 16} Ge{sup +}/cm{sup 2}. Electron microscopy investigations revealed varying thresholds for nanoporous Ge formation and exhibited a stark difference in the evolution of the Ge layers based on the microstructure of the initial film. The results suggest that the presence of inherent nucleation sites significantly alters the onset and evolution of nanoporous Ge.

  2. Monolayer Passivation of Ge(100) Surface via Nitridation and Oxidation Joon Sung Leea,b

    E-Print Network [OSTI]

    Kummel, Andrew C.

    Monolayer Passivation of Ge(100) Surface via Nitridation and Oxidation Joon Sung Leea,b , Sarah R passivation of Ge(100) surface via formation of Ge-N and Ge-O surface species was studied using scanning cyclotron resonance (ECR) plasma source formed an ordered Ge-N structure on a Ge(100) surface at 500o C. DFT

  3. Prompt Gamma Rays in {sup 77}Ge after Neutron Capture on {sup 76}Ge

    SciTech Connect (OSTI)

    Meierhofer, Georg; Grabmayr, Peter; Jochum, Josef [Physikalisches Institut, Eberhard Karls Universitaet Tuebingen, Auf der Morgenstelle 14, 72076 Tuebingen (Germany); Canella, Lea [Institut fuer Radiochemie, Technische Universitaet Muenchen, Walther-Meissner-Str. 3, 85748 Garching (Germany); Jolie, Jan; Kudejova, Petra; Warr, Nigel [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Cologne (Germany)

    2009-01-28T23:59:59.000Z

    The observation of neutrinoless double beta decay would be proof of the Majorana nature of the neutrino. Half-lives for these decays are very long (for {sup 76}Ge:>10{sup 25} y), so background reduction and rejection is the major task for double beta experiments. The GERDA (GERmanium Detector Array) experiment at the Gran Sasso Laboratory of the INFN (LNGS) searches for neutrinoless double beta decay of {sup 76}Ge. The isotope {sup 76}Ge is an ideal candidate because it can be used as source and detector at the same time. A large remaining contribution to the background arises from the prompt gamma cascade after neutron capture by {sup 76}Ge followed by {beta}{sup -}-decay of {sup 77}Ge. Since the prompt gamma decay scheme is poorly known, measurements with isotopically enriched Germanium samples were carried out at the PGAA facility at the research reactor FRM II (Munich). With the known prompt gamma spectrum it will be possible to improve the overall veto efficiency of the GERDA experiment.

  4. Material properties in SiGe/Ge quantum wells Rebecca K. Schaevitz*, Jonathan E. Roth, Onur Fidaner, and David A. B. Miller

    E-Print Network [OSTI]

    Miller, David A. B.

    Material properties in SiGe/Ge quantum wells Rebecca K. Schaevitz*, Jonathan E. Roth, Onur Fidaner *Corresponding author: rschaevitz@stanford.edu Abstract: Photocurrent measurements in Ge quantum wells parameters for design of high-performance SiGe/Ge quantum well optoelectronics on silicon. Germanium

  5. Ge/SiGe Quantum Confined Stark Effect Modulators on Silicon James S. Harris, Yu-Hsuan Kuo, and David A. B. Miller

    E-Print Network [OSTI]

    Miller, David A. B.

    Ge/SiGe Quantum Confined Stark Effect Modulators on Silicon James S. Harris, Yu-Hsuan Kuo bandwidth have been demonstrated [4]. 2. Quantum well design Ge is an indirect band gap material, but it has. In order to have good quantum confinement, SiGe barriers are used since Si and Ge have a very high direct

  6. Central Limit Theorem for Branching Random Walks in Random Environment

    E-Print Network [OSTI]

    Nobuo Yoshida

    2007-12-05T23:59:59.000Z

    We consider branching random walks in $d$-dimensional integer lattice with time-space i.i.d. offspring distributions. When $d \\ge 3$ and the fluctuation of the environment is well moderated by the random walk, we prove a central limit theorem for the density of the population, together with upper bounds for the density of the most populated site and the replica overlap. We also discuss the phase transition of this model in connection with directed polymers in random environment.

  7. VEA-0016 - In the Matter of GE Appliances | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    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 current C3EDepartment ofPrivilegesUnauthorized Access |DarrylDepartment7 -

  8. TEE-0074 - In the Matter of GE Appliances & Lighting | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    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 April 23, 2014,ZaleskiThis Decision considers an AppealNORDYNE,Energy

  9. TEE-0077 - In the Matter of GE Appliances & Lighting | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    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 April 23, 2014,ZaleskiThis Decision considers an

  10. Accurately Analyzing Malaria Tests a Matter of Life and Death | GE Global

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

    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 for4,645U.S. DOE Office511041cloth DocumentationProducts (VAP) VAP7-0973 1 Introduction In

  11. Apply early! Limited enrollment.

    E-Print Network [OSTI]

    volcano. Experience the culture and history of Hawaii, and the impact of human activitiesApply early! Limited enrollment. Environmental Science in the Hawaiian Islands Observe, research

  12. Upgrade of CEBAF from 6-GeV To 12-GeV: Status

    SciTech Connect (OSTI)

    Harwood, Leigh H.

    2013-04-01T23:59:59.000Z

    The CEBAF accelerator is being upgraded from 6 GeV to 12 GeV by the US Department of Energy. The accelerator upgrade is being done within the existing tunnel footprint. The accelerator upgrade includes: 10 new srfbased high-performance cryomodules plus RF systems, doubling the 2K helium plants capability, upgrading the existing beamlines to operate at nearly double the original performance envelope, and adding a beamline to a new experimental area. Construction is over 75% complete with final completion projected for late FY13. Details of the upgrade and status of the work will be presented.

  13. Dark matter axions `96

    SciTech Connect (OSTI)

    Sikivie, P.

    1996-12-31T23:59:59.000Z

    This report discusses why axions have been postulated to exist, what cosmology implies about their presence as cold dark matter in the galactic halo, how axions might be detected in cavities wherein strong magnetic fields stimulate their conversion into photons, and relations between axions` energy spectra and galactic halos` properties.

  14. Matter & Energy Solar Energy

    E-Print Network [OSTI]

    Rogers, John A.

    See Also: Matter & Energy Solar Energy· Electronics· Materials Science· Earth & Climate Energy at the University of Illinois, the future of solar energy just got brighter. Although silicon is the industry Electronics Over 1.2 Million Electronics Parts, Components and Equipment. www.AlliedElec.com solar energy

  15. Matter & Energy Engineering

    E-Print Network [OSTI]

    Sóbester, András

    .com/products/seahawk/ Maryland Solar Panels-- Solar Installations from BGE HOME $0 Down For Big Energy Savings! www.bgehome.com/SolarLike 6 0 | More APA MLA See Also: Matter & Energy Petroleum Engineering Fossil Fuels Earth believe may be contributing to global warming. The UK government has just announced it is investing Ł1

  16. Interface and nanostructure evolution of cobalt germanides on Ge(001)

    SciTech Connect (OSTI)

    Grzela, T., E-mail: grzela@ihp-microelectronics.com; Schubert, M. A. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Koczorowski, W. [London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH,United Kingdom (United Kingdom); Institute of Physics, Poznan University of Technology, Nieszawska 13A, 60-965 Poznan (Poland); Capellini, G. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Dipartimento di Scienze, Universitŕ degli Studi Roma Tre, I-00146 Roma (Italy); Czajka, R. [Institute of Physics, Poznan University of Technology, Nieszawska 13A, 60-965 Poznan (Poland); Radny, M. W. [Institute of Physics, Poznan University of Technology, Nieszawska 13A, 60-965 Poznan (Poland); School of Mathematical and Physical Sciences, The University of Newcastle, University Drive, Callaghan NSW, 2308 (Australia); Curson, N.; Schofield, S. R. [London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH,United Kingdom (United Kingdom); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); BTU Cottbus, Konrad-Zuse Str. 1, 03046 Cottbus (Germany)

    2014-02-21T23:59:59.000Z

    Cobalt germanide (Co{sub x}Ge{sub y}) is a candidate system for low resistance contact modules in future Ge devices in Si-based micro and nanoelectronics. In this paper, we present a detailed structural, morphological, and compositional study on Co{sub x}Ge{sub y} formation on Ge(001) at room temperature metal deposition and subsequent annealing. Scanning tunneling microscopy and low energy electron diffraction clearly demonstrate that room temperature deposition of approximately four monolayers of Co on Ge(001) results in the Volmer Weber growth mode, while subsequent thermal annealing leads to the formation of a Co-germanide continuous wetting layer which evolves gradually towards the growth of elongated Co{sub x}Ge{sub y} nanostructures. Two types of Co{sub x}Ge{sub y} nanostructures, namely, flattop- and ridge-type, were observed and a systematic study on their evolution as a function of temperature is presented. Additional transmission electron microscopy and x-ray photoemission spectroscopy measurements allowed us to monitor the reaction between Co and Ge in the formation process of the Co{sub x}Ge{sub y} continuous wetting layer as well as the Co{sub x}Ge{sub y} nanostructures.

  17. SiGe thin-film structures for solar cells

    SciTech Connect (OSTI)

    Bremond, G.; Daami, A.; Laugier, A. [Inst. National des Sciences Appliquees de Lyon, Villeurbanne (France). Lab. de Physique de la Matiere] [and others

    1998-12-31T23:59:59.000Z

    In order to study their applicability as the active base material in Si thin crystalline film solar cell technology, SiGe relaxed layers grown by Liquid Phase Epitaxy (LPE) and Chemical Vapor Deposition (CVD) on Si substrates are investigated by optical and electrical measurements (TEM, EXD, PL, EBIC). The main results of this work is to point out the improvement of the SiGe active base layer by using smooth Ge graded SiGe buffer layer and remote plasma hydrogenation. TEM, EXD, PL experiments show the effect of the Ge graded buffer layer grown using LPE, by confining the threading dislocations in the SiGe buffer layer close to the Si/SiGe interface. EBIC measurements reveal low recombination activity of dislocations at 300 K providing the diffusion length exceeds the 15 {micro}m layer thickness. The enhanced luminescence of SiGe near bandgap indicates that remote plasma hydrogenation induces a decrease of the non-radiative recombination pathways due to dislocations on CVD layers where defect recombinations dominate as indicated by EBIC measurements. This study points out the importance of controlling relaxed SiGe layers with good minority carrier recombination quality as a key issue for the optimization of new SiGe/Si based solar cells.

  18. Energy Matters in Washington State Page 1 Energy Matters

    E-Print Network [OSTI]

    Collins, Gary S.

    Energy Matters in Washington State ­ Page 1 Energy Matters in Washington State June 2008 Updated November 2009 Updated and Revised October 2013 Grand Coulee Dam #12;Energy Matters in Washington State ­ Page 2 Copyright © 2013 Washington State University Energy Program. 905 Plum Street SE, P.O. Box 43169

  19. Self assembly in soft matter 

    E-Print Network [OSTI]

    Chremos, Alexandros

    2009-01-01T23:59:59.000Z

    The term “soft matter” applies to a variety of physical systems, such as liquids, colloids, polymers, foams, gels, and granular materials. The most fascinating aspect of soft matter lies in the fact that they are not ...

  20. Self Assembly in Soft Matter 

    E-Print Network [OSTI]

    Chremos, Alexandros

    2009-01-01T23:59:59.000Z

    The term “soft matter” applies to a variety of physical systems, such as liquids, colloids, polymers, foams, gels, and granular materials. The most fascinating aspect of soft matter lies in the fact that they are not ...

  1. The Search for Dark Matter

    ScienceCinema (OSTI)

    Orrell, John

    2014-07-24T23:59:59.000Z

    More than 25 years ago, PNNL scientists began the first underground measurements searching for dark matter using specialized radiation detector technology. Dark matter is yet to be discovered says Physicist John L. Orrell.

  2. The Search for Dark Matter

    SciTech Connect (OSTI)

    Orrell, John

    2013-11-20T23:59:59.000Z

    More than 25 years ago, PNNL scientists began the first underground measurements searching for dark matter using specialized radiation detector technology. Dark matter is yet to be discovered says Physicist John L. Orrell.

  3. The phase diagram of nuclear and quark matter at high baryon density

    E-Print Network [OSTI]

    Kenji Fukushima; Chihiro Sasaki

    2013-04-02T23:59:59.000Z

    We review theoretical approaches to explore the phase diagram of nuclear and quark matter at high baryon density. We first look over the basic properties of quantum chromodynamics (QCD) and address how to describe various states of QCD matter. In our discussions on nuclear matter we cover the relativistic mean-field model, the chiral perturbation theory, and the approximation based on the large-Nc limit where Nc is the number of colors. We then explain the liquid-gas phase transition and the inhomogeneous meson condensation in nuclear matter with emphasis put on the relevance to quark matter. We commence the next part focused on quark matter with the bootstrap model and the Hagedorn temperature. Then we turn to properties associated with chiral symmetry and exposit theoretical descriptions of the chiral phase transition. There emerge some quark-matter counterparts of phenomena seen in nuclear matter such as the liquid-gas phase transition and the inhomogeneous structure of the chiral condensate. The third regime that is being recognized recently is what is called quarkyonic matter, which has both aspects of nuclear and quark matter. We closely elucidate the basic idea of quarkyonic matter in the large-Nc limit and its physics implications. Finally, we discuss some experimental indications for the QCD phase diagram and close the review with outlooks.

  4. Patent Record Announcement | GE Global Research

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

    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:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPO WebsitePalms Village ResortEnergyL L 2PatentGE's E.

  5. Crowdsourcing Software Announcement | GE Global Research

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

    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 for4,645U.S. DOEThe Bonneville Power Administration would likeConstitution4 Department of EnergyCross-SectorDepartment ofGE, MIT

  6. Crowdsourcing Software Award | GE Global Research

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

    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 for4,645U.S. DOEThe Bonneville Power Administration would likeConstitution4 Department of EnergyCross-SectorDepartment ofGE,

  7. Brazil Technology Center | GE Global Research

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

    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 3,625govInstrumentstdmadapInactiveVisiting the TWPSuccess Stories Site MapSolarAboutTaubmanBiofuels Research at GE's

  8. Limits to the muon flux from neutralino annihilations in the Sun with the AMANDA detector

    E-Print Network [OSTI]

    The AMANDA collaboration; M. Ackermann

    2005-08-24T23:59:59.000Z

    A search for an excess of muon-neutrinos from neutralino annihilations in the Sun has been performed with the AMANDA-II neutrino detector using data collected in 143.7 days of live-time in 2001. No excess over the expected atmospheric neutrino background has been observed. An upper limit at 90% confidence level has been obtained on the annihilation rate of captured neutralinos in the Sun, as well as the corresponding muon flux limit at the Earth, both as functions of the neutralino mass in the range 100 GeV-5000 GeV.

  9. Flavored Dark Matter and the Galactic Center Gamma-Ray Excess

    SciTech Connect (OSTI)

    Agrawal, Prateek; Batell, Brian; Hooper, Dan; Lin, Tongyan

    2014-09-01T23:59:59.000Z

    Thermal relic dark matter particles with a mass of 31-40 GeV and that dominantly annihilate to bottom quarks have been shown to provide an excellent description of the excess gamma rays observed from the center of the Milky Way. Flavored dark matter provides a well-motivated framework in which the dark matter can dominantly couple to bottom quarks in a flavor-safe manner. We propose a phenomenologically viable model of bottom flavored dark matter that can account for the spectral shape and normalization of the gamma-ray excess while naturally suppressing the elastic scattering cross sections probed by direct detection experiments. This model will be definitively tested with increased exposure at LUX and with data from the upcoming high-energy run of the Large Hadron Collider (LHC).

  10. Matter Bounce Loop Quantum Cosmology from $F(R)$ Gravity

    E-Print Network [OSTI]

    S. D. Odintsov; V. K. Oikonomou

    2014-12-04T23:59:59.000Z

    Using the reconstruction method, we investigate which $F(R)$ theories, with or without the presence of matter fluids, can produce the matter bounce scenario of holonomy corrected Loop Quantum Cosmology. We focus our study in two limits of the cosmic time, the large cosmic time limit and the small cosmic time limit. For the former, we found that, in the presence of non-interacting and non-relativistic matter, the $F(R)$ gravity that reproduces the late time limit of the matter bounce solution is actually the Einstein-Hilbert gravity plus a power law term. In the early time limit, since it corresponds to large spacetime curvatures, assuming that the Jordan frame is described by a general metric that when it is conformally transformed to the Einstein frame, produces an accelerating Friedmann-Robertson-Walker metric, we found explicitly the scalar field dependence on time. After demonstrating that the solution in the Einstein frame is indeed accelerating, we calculate the spectral index derived from the Einstein frame scalar-tensor counterpart theory of the $F(R)$ theory and compare it with the Planck experiment data. In order to implement the resulting picture, we embed the $F(R)$ gravity explicitly in a Loop Quantum Cosmology framework by introducing holonomy corrections to the $F(R)$ gravity. In this way, the resulting inflation picture corresponding to the $F(R)$ gravity can be corrected in order it coincides to some extent with the current experimental data.

  11. Study of the low-lying states of Ge2 and Ge2 using negative ion zero electron kinetic energy spectroscopy

    E-Print Network [OSTI]

    Neumark, Daniel M.

    Study of the low-lying states of Ge2 and Ge2 using negative ion zero electron kinetic energy The low-lying states of Ge2 and Ge2 are probed using negative ion zero electron kinetic energy ZEKE spectroscopy. The ZEKE spectrum of Ge2 yields an electron affinity of 2.035 0.001 eV for Ge2, as well as term

  12. Normal matter storage of antiprotons

    SciTech Connect (OSTI)

    Campbell, L.J.

    1987-01-01T23:59:59.000Z

    Various simple issues connected with the possible storage of anti p in relative proximity to normal matter are discussed. Although equilibrium storage looks to be impossible, condensed matter systems are sufficiently rich and controllable that nonequilibrium storage is well worth pursuing. Experiments to elucidate the anti p interactions with normal matter are suggested. 32 refs.

  13. dark matter dark energy inflation

    E-Print Network [OSTI]

    Hu, Wayne

    theory dark matter dark energy inflation The National Science Foundation The Kavli Foundation NSF Site Review November 28-29, 2005 #12;dark matter dark energy inflation NSF Site Visit ­ November 28 Gravitation initial conditions beyond single-field slow roll #12;dark matter dark energy inflation NSF Site

  14. Dark Energy and Dark Matter

    E-Print Network [OSTI]

    Keith A. Olive

    2010-01-27T23:59:59.000Z

    A brief overview of our current understanding of abundance and properties of dark energy and dark matter is presented. A more focused discussion of supersymmetric dark matter follows. Included is a frequentist approach to the supersymmetric parameter space and consequences for the direct detection of dark matter.

  15. Universal Parametrization of Thermal Photon Rates in Hadronic Matter

    E-Print Network [OSTI]

    Matthew Heffernan; Paul Hohler; Ralf Rapp

    2014-11-25T23:59:59.000Z

    Electromagnetic (EM) radiation off strongly interacting matter created in high-energy heavy-ion collisions (HICs) encodes information on the high-temperature phases of nuclear matter. Microscopic calculations of thermal EM emission rates are usually rather involved and not readily accessible to broad applications in models of the fireball evolution which are required to compare to experimental data. An accurate and universal parametrization of the microscopic calculations is thus key to honing the theory behind the EM spectra. Here we provide such a parametrization for photon emission rates from hadronic matter, including the contributions from in-medium rho mesons (which incorporate effects from anti-/baryons), as well as Bremsstrahlung from pi-pi scattering. Individual parametrizations for each contribution are numerically determined through nested fitting functions for photon energies from 0.2 to 5 GeV in chemically equilibrated matter of temperatures 100-180 MeV and baryon chemical potentials 0-400 MeV. Special care is taken to extent the parameterizations to chemical off-equilibrium as encountered in HICs after chemical freezeout. This provides a functional description of thermal photon rates within a 20% variation of the microscopically calculated values.

  16. The Isotropic Radio Background and Annihilating Dark Matter

    SciTech Connect (OSTI)

    Hooper, Dan [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Belikov, Alexander V. [Institut d'Astrophysique (France); Jeltema, Tesla E. [Univ. of California, Santa Cruz, CA (United States); Linden, Tim [Univ. of California, Santa Cruz, CA (United States); Profumo, Stefano [Univ. of California, Santa Cruz, CA (United States); Slatyer, Tracy R. [Princeton Univ., Princeton, NJ (United States)

    2012-11-01T23:59:59.000Z

    Observations by ARCADE-2 and other telescopes sensitive to low frequency radiation have revealed the presence of an isotropic radio background with a hard spectral index. The intensity of this observed background is found to exceed the flux predicted from astrophysical sources by a factor of approximately 5-6. In this article, we consider the possibility that annihilating dark matter particles provide the primary contribution to the observed isotropic radio background through the emission of synchrotron radiation from electron and positron annihilation products. For reasonable estimates of the magnetic fields present in clusters and galaxies, we find that dark matter could potentially account for the observed radio excess, but only if it annihilates mostly to electrons and/or muons, and only if it possesses a mass in the range of approximately 5-50 GeV. For such models, the annihilation cross section required to normalize the synchrotron signal to the observed excess is sigma v ~ (0.4-30) x 10^-26 cm^3/s, similar to the value predicted for a simple thermal relic (sigma v ~ 3 x 10^-26 cm^3/s). We find that in any scenario in which dark matter annihilations are responsible for the observed excess radio emission, a significant fraction of the isotropic gamma ray background observed by Fermi must result from dark matter as well.

  17. Light Dark Matter Detection Prospects at Neutrino Experiments

    E-Print Network [OSTI]

    Jason Kumar; John G. Learned; Stefanie Smith

    2010-04-13T23:59:59.000Z

    We consider the prospects for the detection of relatively light dark matter through direct annihilation to neutrinos. We specifically focus on the detection possibilities of water Cherenkov and liquid scintillator neutrino detection devices. We find in particular that liquid scintillator detectors may potentially provide excellent detection prospects for dark matter in the 4-10 GeV mass range. These experiments can provide excellent corroborative checks of the DAMA/LIBRA annual modulation signal, but may yield results for low mass dark matter in any case. We identify important tests of the ratio of electron to muon neutrino events (and neutrino versus anti-neutrino events), which discriminate against background atmospheric neutrinos. In addition, the fraction of events which arise from muon neutrinos or anti-neutrinos ($R_{\\mu}$ and $R_{\\bar \\mu}$) can potentially yield information about the branching fractions of hypothetical dark matter annihilations into different neutrino flavors. These results apply to neutrinos from secondary and tertiary decays as well, but will suffer from decreased detectability.

  18. Symmetry energy coefficients for asymmetric nuclear matter

    E-Print Network [OSTI]

    Fábio L. Braghin

    2003-12-16T23:59:59.000Z

    Symmetry energy coefficients of asymmetric nuclear matter are investigated as the inverse of nuclear matter polarizabilities with two different approaches. Firstly a general calculation shows they may depend on the neutron-proton asymmetry itself. The choice of particular prescriptions for the density fluctuations lead to certain isospin (n-p asymmetry) dependences of the polarizabilities. Secondly, with Skyrme type interactions, the static limit of the dynamical polarizability is investigated corresponding to the inverse symmetry energy coefficient which assumes different values at different asymmetries (and densities and temperatures). The symmetry energy coefficient (in the isovector channel) is found to increase as n-p asymmetries increase. The spin symmetry energy coefficient is also briefly investigated.

  19. A New Look at the Galactic Diffuse GeV

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    ;Gamma-ray Detectors from 10s MeV to 100s GeV Gamma-rays' trajectories cannot be directly detected #12;Gamma-ray Detectors from 10s MeV to 100s GeV Gamma-rays' trajectories cannot be directly detected Physics 1 #12;Overview Diffuse gamma-ray emission The Galactic diffuse gamma-ray GeV excess Discussion

  20. Structure and vibrations of different charge Ge impurity in ?-quartz

    SciTech Connect (OSTI)

    Kislov, A. N., E-mail: a.n.kislov@urfu.ru; Mikhailovich, A. P., E-mail: a.n.kislov@urfu.ru; Zatsepin, A. F., E-mail: a.n.kislov@urfu.ru [Ural Federal University, 19 Mira St., Yekaterinburg, 620002 (Russian Federation)

    2014-10-21T23:59:59.000Z

    Atomic structure and localized vibrations of ??SiO{sub 2}:Ge are studied using computer modeling techniques. The simulation was carried out by the lattice dynamics calculation of the local density of vibrational states. Local structures parameters are calculated, localized symmetrized vibrations frequency caused by Ge impurity in different charge states are defined. The movements of atoms located near Ge impurity are analyzed and their contribution into localized vibrations of different type is evaluated.

  1. Supersymmetry and dark matter post LHC8: Why we may expect both axion and WIMP detection

    SciTech Connect (OSTI)

    Baer, Howard [Dep't of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

    2014-01-01T23:59:59.000Z

    In the post-LHC8 era, it is perceived that what is left of SUSY model parameter space is highly finetuned in the EW sector (EWFT). We discuss how conventional measures overestimate EWFT in SUSY theory. Radiatively-driven natural SUSY (RNS) models maintain the SUSY GUT paradigm with low EWFT at 10% level, but are characterized by light higgsinos ~100–300 GeV and a thermal underabundance of WIMP dark matter. Implementing the SUSY DFSZ solution to the strong CP problem explains the small ? parameter but indicates dark matter should be comprised mainly of axions with a small admixture of higgsino-like WIMPs. While RNS might escape LHC14 searches, we would expect ultimately direct detection of both WIMPs and axions. An e?e? collider with ?(s)~500–600 GeV should provide a thorough search for the predicted light higgsinos.

  2. Axion Bose-Einstein Condensation: a model beyond Cold Dark Matter

    SciTech Connect (OSTI)

    Yang, Q. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States)

    2010-08-30T23:59:59.000Z

    Cold dark matter axions form a Bose-Einstein condensate if the axions thermalize. Recently, it was found [1] that they do thermalize when the photon temperature reaches T{approx}100 eV(f/10{sup 12} GeV){sup 1/2} and that they continue to do so thereafter. We discuss the differences between axion BEC and CDM in the linear regime and the non-linear regime of evolution of density perturbations. We find that axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multi-poles.

  3. Optical limiting materials

    DOE Patents [OSTI]

    McBranch, Duncan W. (Santa Fe, NM); Mattes, Benjamin R. (Santa Fe, NM); Koskelo, Aaron C. (Los Alamos, NM); Heeger, Alan J. (Santa Barbara, CA); Robinson, Jeanne M. (Los Alamos, NM); Smilowitz, Laura B. (Los Alamos, NM); Klimov, Victor I. (Los Alamos, NM); Cha, Myoungsik (Goleta, CA); Sariciftci, N. Serdar (Santa Barbara, CA); Hummelen, Jan C. (Groningen, NL)

    1998-01-01T23:59:59.000Z

    Optical limiting materials. Methanofullerenes, fulleroids and/or other fullerenes chemically altered for enhanced solubility, in liquid solution, and in solid blends with transparent glass (SiO.sub.2) gels or polymers, or semiconducting (conjugated) polymers, are shown to be useful as optical limiters (optical surge protectors). The nonlinear absorption is tunable such that the energy transmitted through such blends saturates at high input energy per pulse over a wide range of wavelengths from 400-1100 nm by selecting the host material for its absorption wavelength and ability to transfer the absorbed energy into the optical limiting composition dissolved therein. This phenomenon should be generalizable to other compositions than substituted fullerenes.

  4. Kinetic limits of dynamical systems

    E-Print Network [OSTI]

    Jens Marklof

    2014-08-06T23:59:59.000Z

    Since the pioneering work of Maxwell and Boltzmann in the 1860s and 1870s, a major challenge in mathematical physics has been the derivation of macroscopic evolution equations from the fundamental microscopic laws of classical or quantum mechanics. Macroscopic transport equations lie at the heart of many important physical theories, including fluid dynamics, condensed matter theory and nuclear physics. The rigorous derivation of macroscopic transport equations is thus not only a conceptual exercise that establishes their consistency with the fundamental laws of physics: the possibility of finding deviations and corrections to classical evolution equations makes this subject both intellectually exciting and relevant in practical applications. The plan of these lectures is to develop a renormalisation technique that will allow us to derive transport equations for the kinetic limits of two classes of simple dynamical systems, the Lorentz gas and kicked Hamiltonians (or linked twist maps). The technique uses the ergodic theory of flows on homogeneous spaces (homogeneous flows for short), and is based on joint work with Andreas Str\\"ombergsson.

  5. Scaling Properties of Hyperon Production in Au + Au Collisions at sqrt sNN = 200 GeV

    SciTech Connect (OSTI)

    Adams, J.

    2006-06-08T23:59:59.000Z

    We present the scaling properties of Lambda, Xi, and their anti-particles produced at mid-rapidity in Au+Au collisions at RHIC at psNN = 200 GeV. The yield of multi-strange baryons per participant nucleon increases from peripheral to central collisions more rapidly than the Lambda yield, which appears to correspond to an increasing strange quark density of matter produced. The value of the strange phase space occupancy factor gamma s, obtained from a thermal model fit to the data, approaches unity for the most central collisions. We also show that the nuclear modification factors, RCP, of Lambda and Xi are consistent with each other and with that of protons in the transverse momentum range2.0< pT< 5.0 GeV/c. This scaling behaviour is consistent with a scenario of hadron formation from constituent quark degrees of freedom through quark recombination or coalescence.

  6. GE Technology to Help Canada Province Meet Growing Energy Needs

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

    funding and collaboration models at its European Global Research Center near Munich, Germany. Mark Little, GE's Senior Vice President and Chief Technology Officer, and thought...

  7. Limitless Hot Gas Path Cooling Design | GE Global Research

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

    Organization at GE Global Research, one such potent combination already taking shape is Additive Manufacturing and High Pressure Turbine Blade Cooling. Additive Manufacturing...

  8. GE researchers perform simulations in pursuit of more efficient...

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

    GE researchers perform simulations in pursuit of more efficient jet engines and wind turbines Author: John Spizzirri . July 1, 2014 Printer-friendly version The recent addition of...

  9. How Will We Explore Earth's Final Frontier? | GE Global Research

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

    see how technology is helping us understand, utilize and protect the last frontier on earth. At GE Global Research's Rio de Janiero location, researchers are developing...

  10. Media Advisory - Jefferson Lab 12 GeV Upgrade Groundbreaking...

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

    for its 310 million 12 GeV Upgrade project. When: Tuesday, April 14, 2009. Where: CEBAF Center, Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue,...

  11. GE's Arnie Lund Discusses User Experience at an Industrial Scale...

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

    at an Industrial Scale Arnie Lund, manager of the UX Industrial Innovation Lab at GE Global Research in San Ramon, Calif, recently spoke to the Farstuff Podcast about...

  12. Titan propels GE wind turbine research into new territory | ornl...

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

    Titan propels GE wind turbine research into new territory January 17, 2014 The amount of global electricity supplied by wind, the world's fastest growing energy source, is expected...

  13. Particulate matter dynamics

    E-Print Network [OSTI]

    Cionco, Rodolfo G; Caligaris, Marta G

    2012-01-01T23:59:59.000Z

    A substantial fraction of the particulate matter released into the atmosphere by industrial or natural processes corresponds to particles whose aerodynamic diameters are greater than 50 mm. It has been shown that, for these particles, the classical description of Gaussian plume diffusion processes, is inadequate to describe the transport and deposition. In this paper we present new results concerning the dispersion of coarse particulate matter. The simulations are done with our own code that uses the Bulirsch Stoer numerical integrator to calculate threedimensional trajectories of particles released into the environment under very general conditions. Turbulent processes are simulated by the Langevin equation and weather conditions are modeled after stable (Monin-Obukhov length L> 0) and unstable conditions (L <0). We present several case studies based on Monte Carlo simulations and discusses the effect of weather on the final deposition of these particles.

  14. Constraining Decaying Dark Matter

    E-Print Network [OSTI]

    Ran Huo

    2011-07-13T23:59:59.000Z

    We revisited the decaying dark matter (DDM) model, in which one collisionless particle decays early into two collisionless particles, that are potentially dark matter particles today. The effect of DDM will be manifested in the cosmic microwave background (CMB) and structure formation. With a systematic modification of CMB calculation tool \\texttt{camb}, we can numerically calculated this effect, and compare it to observations. Further Markov Chain Monte Carlo \\texttt{cosmomc} runnings update the constraints in that model: the free streaming length $\\lambda_{FS}\\lesssim0.5$Mpc for nonrelativistic decay, and $((M_{DDM}/keV) Y)^2 (T_d/yr)\\lesssim5\\times10^{-5}$ for relativistic decay.

  15. Synchronization of Limit Sets

    E-Print Network [OSTI]

    Changpin Li; Weihua Deng

    2005-10-10T23:59:59.000Z

    In this Letter, we derive a sufficient condition of synchronizing limit sets (attractors and repellers) by using the linear feedback control technique proposed here. There examples are included. The numerical simulations and computer graphics show that our method work well.

  16. Luminous Dark Matter

    E-Print Network [OSTI]

    Brian Feldstein; Peter W. Graham; Surjeet Rajendran

    2011-01-13T23:59:59.000Z

    We propose a dark matter model in which the signal in direct detection experiments arises from electromagnetic, not nuclear, energy deposition. This can provide a novel explanation for DAMA while avoiding many direct detection constraints. The dark matter state is taken nearly degenerate with another state. These states are naturally connected by a dipole moment operator, which can give both the dominant scattering and decay modes between the two states. The signal at DAMA then arises from dark matter scattering in the Earth into the excited state and decaying back to the ground state through emission of a single photon in the detector. This model has unique signatures in direct detection experiments. The density and chemical composition of the detector is irrelevant, only the total volume affects the event rate. In addition, the spectrum is a monoenergetic line, which can fit the DAMA signal well. This model is readily testable at experiments such as CDMS and XENON100 if they analyze their low-energy, electronic recoil events.

  17. Dark matter axions revisited

    SciTech Connect (OSTI)

    Visinelli, Luca; Gondolo, Paolo [Department of Physics, University of Utah, 115 S 1400 E 201, Salt Lake City, Utah 84102 (United States)

    2009-08-01T23:59:59.000Z

    We study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae, and assume an inflationary scenario and standard cosmology. We also upgrade the treatment of anharmonicities in the axion potential, which we find important in certain cases. If the Peccei-Quinn symmetry is restored after inflation, we recover the usual relation between axion mass and density, so that an axion mass m{sub a}=(85{+-}3) {mu}eV makes the axion 100% of the cold dark matter. If the Peccei-Quinn symmetry is broken during inflation, the axion can instead be 100% of the cold dark matter for m{sub a}<15 meV provided a specific value of the initial misalignment angle {theta}{sub i} is chosen in correspondence to a given value of its mass m{sub a}. Large values of the Peccei-Quinn symmetry breaking scale correspond to small, perhaps uncomfortably small, values of the initial misalignment angle {theta}{sub i}.

  18. Hidden vector dark matter

    E-Print Network [OSTI]

    Thomas Hambye

    2010-03-16T23:59:59.000Z

    We show that dark matter could be made of massive gauge bosons whose stability doesn't require to impose by hand any discrete or global symmetry. Stability of gauge bosons can be guaranteed by the custodial symmetry associated to the gauge symmetry and particle content of the model. The particle content we consider to this end is based on a hidden sector made of a vector multiplet associated to a non-abelian gauge group and of a scalar multiplet charged under this gauge group. The hidden sector interacts with the Standard Model particles through the Higgs portal quartic scalar interaction in such a way that the gauge bosons behave as thermal WIMPS. This can lead easily to the observed dark matter relic density in agreement with the other various constraints, and can be tested experimentally in a large fraction of the parameter space. In this model the dark matter direct detection rate and the annihilation cross section can decouple if the Higgs portal interaction is weak.

  19. Two Loop Radiative Seesaw and X-ray line Dark Matter with Global U(1) Symmetry

    E-Print Network [OSTI]

    Okada, Hiroshi

    2015-01-01T23:59:59.000Z

    We study a two loop induced radiative neutrino model with global $U(1)$ symmetry at 0.1 GeV scale, in which we consider a keV scale of dark matter candidate recently reported by XMN-Newton X-ray observatory using data of various galaxy clusters and Andromeda galaxy. We also discuss the vacuum stability of singly charged bosons, lepton flavor violation processes, and a role of Goldstone boson.

  20. Probing Extra Matter in Gauge Mediation Through the Lightest Higgs Boson Mass

    E-Print Network [OSTI]

    Jason L. Evans; Masahiro Ibe; Tsutomu T. Yanagida

    2011-08-17T23:59:59.000Z

    We discuss the implications of the excesses in LHC Higgs boson searches on the gauge mediated supersymmetric standard model, for the mass range 120-140\\,GeV. We find that a relatively heavy lightest Higgs boson mass in this range can be reconciled with light SUSY particles, $m_{\\rm gluino}Higgs boson. We also find that the mass of this extra matter can be predicted rather precisely in gauge mediation for a given Higgs boson and gluino mass.

  1. Quantum Limits of Thermometry

    E-Print Network [OSTI]

    Thomas M. Stace

    2010-06-08T23:59:59.000Z

    The precision of typical thermometers consisting of $N$ particles is shot noise limited, improving as $\\sim1/\\sqrt{N}$. For high precision thermometry and thermometric standards this presents an important theoretical noise floor. Here it is demonstrated that thermometry may be mapped onto the problem of phase estimation, and using techniques from optimal phase estimation, it follows that the scaling of the precision of a thermometer may in principle be improved to $\\sim1/N$, representing a Heisenberg limit to thermometry.

  2. Unruh effect for neutrinos interacting with accelerated matter

    E-Print Network [OSTI]

    Dvornikov, Maxim

    2015-01-01T23:59:59.000Z

    We study the evolution of neutrinos in a background matter moving with a linear acceleration. The Dirac equation for a massive neutrino electroweakly interacting with background fermions is obtained in a comoving frame where matter is at rest. We solve this Dirac equation for ultrarelativistic neutrinos. The neutrino quantum states in matter moving with a linear acceleration are obtained. We demonstrate that the neutrino electroweak interaction with an accelerated matter leads to the vacuum instability which results in the neutrino-antineutrino pairs creation. We rederive the temperature of the Unruh radiation and find the correction to the Unruh effect due to the specific neutrino interaction with background fermions. As a possible application of the obtained results we discuss the neutrino pairs creation in a core collapsing supernova. The astrophysical upper limit on the neutrino masses is obtained.

  3. Structural and optical properties of GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells

    SciTech Connect (OSTI)

    Aleshkin, V. Ya.; Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Drozdov, M. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Zvonkov, B. N. [Nizhni Novgorod State University, Research Physical Technical Institute (Russian Federation); Kudryavtsev, K. E.; Tonkikh, A. A.; Yablonskiy, A. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Werner, P. [Max Planck Institute of Microstructure Physics (Germany)

    2013-05-15T23:59:59.000Z

    GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells are grown by laser-assisted sputtering. Structural and optical studies of the heterostructures are carried out. A broad photoluminescence line is observed in the wavelength range from 1300 to 1650 nm. The line corresponds to indirect transitions in the momentum space of the Ge quantum wells and to transitions between the In{sub 0.28}Ga{sub 0.72}As and Ge layers, indirect in coordinate space, but direct in momentum space.

  4. Serial and parallel Si, Ge, and SiGe direct-write with scanning probes and conducting stamps

    SciTech Connect (OSTI)

    Vasko, Stephanie E.; Kapetanovic, Adnan; Talla, Vamsi; Brasino, Michael D.; Zhu, Zihua; Scholl, Andreas; Torrey, Jessica D.; Rolandi, Marco

    2011-05-16T23:59:59.000Z

    Precise materials integration in nanostructures is fundamental for future electronic and photonic devices. We demonstrate Si, Ge, and SiGe nanostructure direct-write with deterministic size, geometry, and placement control. The biased probe of an atomic force microscope (AFM) reacts diphenylsilane or diphenylgermane to direct-write carbon-free Si, Ge, and SiGe nano and heterostructures. Parallel directwrite is available on large areas by substituting the AFM probe with conducting microstructured stamps. This facile strategy can be easily expanded to a broad variety of semiconductor materials through precursor selection.

  5. Disorder resistivity of solid neutron-star matter

    E-Print Network [OSTI]

    P. B. Jones

    2004-11-01T23:59:59.000Z

    Lower limits are found for the disorder resistivity of solid neutron-star matter in the neutron-drip region which is amorphous and heterogeneous in nuclear charge. This temperature-independent resistivity, large compared with that produced by phonon scattering, has direct consequences for theories of neutron-star magnetic field generation and evolution.

  6. Axisymmmetric empty space: light propagation, orbits and dark matter

    E-Print Network [OSTI]

    Sergio Giardino

    2014-09-18T23:59:59.000Z

    This study presents a axisymmetric solution of the Einstein equations for empty space. The geometry is studied by determining its Petrov classification and Killing vectors. Light propagation, orbital motion and asymptotic and Newtonian limits are also studied. Additionally, cosmological applications of the geometry as an alternative model for the inflationary universe and as a substitute for dark matter and quintessence are also outlined.

  7. Cold + Hot Dark Matter After Super-Kamiokande

    E-Print Network [OSTI]

    Joel R. Primack; Michael A. K. Gross

    1998-12-15T23:59:59.000Z

    The recent atmospheric neutrino data from Super-Kamiokande provide strong evidence of neutrino oscillations and therefore of non-zero neutrino mass. These data imply a lower limit on the hot dark matter (i.e., light neutrino) contribution to the cosmological density $\\Omega_\

  8. Shell model description of Ge isotopes

    E-Print Network [OSTI]

    J. G. Hirsch; P. C. Srivastava

    2012-04-12T23:59:59.000Z

    A shell model study of the low energy region of the spectra in Ge isotopes for $38\\leq N\\leq 50$ is presented, analyzing the excitation energies, quadrupole moments, $B(E2)$ values and occupation numbers. The theoretical results have been compared with the available experimental data. The shell model calculations have been performed employing three different effective interactions and valence spaces.We have used two effective shell model interactions, JUN45 and jj44b, for the valence space $f_{5/2} \\, p \\,g_{9/2}$ without truncation. To include the proton subshell $f_{7/2}$ in valence space we have employed the $fpg$ effective interaction due to Sorlin {\\it et al.}, with $^{48}$Ca as a core and a truncation in the number of excited particles.

  9. 3 GeV Injector Design Handbook

    SciTech Connect (OSTI)

    Wiedemann, H.; /SLAC, SSRL

    2009-12-16T23:59:59.000Z

    This Design Handbook is intended to be the main reference book for the specifications of the 3 GeV SPEAR booster synchrotron project. It is intended to be a consistent description of the project including design criteria, key technical specifications as well as current design approaches. Since a project is not complete till it's complete changes and modifications of early conceptual designs must be expected during the duration of the construction. Therefore, this Design Handbook is issued as a loose leaf binder so that individual sections can be replaced as needed. Each page will be dated to ease identification with respect to latest revisions. At the end of the project this Design Handbook will have become the 'as built' reference book of the injector for operations and maintenance personnel.

  10. Nanostructure and infrared photoluminescence of nanocrystalline Ge formed by reduction of Si0.75Ge0.25O2 Si0.75Ge0.25 using various H2 pressures

    E-Print Network [OSTI]

    Nanostructure and infrared photoluminescence of nanocrystalline Ge formed by reduction of Si0.75Ge0.25O2 ŐSi0.75Ge0.25 using various H2 pressures Gianni Taraschi,a) Sajan Saini, Wendy W. Fan, Lionel C Ge in SiO2 was synthesized by the reduction of Si0.75Ge0.25O2 with H2 , at various annealing

  11. High Capacity Li Ion Battery Anodes Using Ge Nanowires

    E-Print Network [OSTI]

    Cui, Yi

    High Capacity Li Ion Battery Anodes Using Ge Nanowires Candace K. Chan, Xiao Feng Zhang, and Yi Cui efficiency > 99%. Structural characterization revealed that the Ge nanowires remain intact and connected nanowire anodes are promising candidates for the development of high-energy-density lithium batteries

  12. Project-X Workshop 120 GeV Target

    E-Print Network [OSTI]

    McDonald, Kirk

    Project-X Workshop 120 GeV Target Summary ­ Workshop # 1 N. Simos, M. Martens #12;Project-X Workshop Challenges OVERVIEW Driven by 120 GeV/170 TP-per-spill · Short Term: 170 TPs/2us-spill (materials an existing 400 kW facility ­ Constraints #12;Project-X Workshop Presentations - Discussions · Engineering

  13. Band-engineered Ge-on-Si lasers

    E-Print Network [OSTI]

    Liu, Jifeng

    We report optically-pumped Ge-on-Si lasers with direct gap emission near 1600 nm at room temperature. The Ge-on-Si material was band-engineered by tensile strain and n-type doping to compensate the energy difference between ...

  14. Excess vacancies in high energy ion implanted SiGe

    SciTech Connect (OSTI)

    Koegler, R.; Muecklich, A.; Skorupa, W.; Peeva, A.; Kuznetsov, A. Yu.; Christensen, J. S.; Svensson, B. G. [Forschungszentrum Rossendorf, PF 510119, D-01314 Dresden (Germany); Institute of Solid State Physics BAS, Boulevard Tzarigradsko Chaussee 72, 1784 Sofia (Bulgaria); Deparment of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Center for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway)

    2007-02-01T23:59:59.000Z

    Excess vacancies generated by high energy implantation with 1.2 MeV Si{sup +} and 2 MeV Ge{sup +} ions in SiGe were investigated after rapid thermal annealing at 900 degree sign C. Excess vacancies were probed by decoration with Cu and measuring the Cu profile by secondary ion mass spectrometry. Cross section transmission electron microscopy of cleaved specimen enabled to visualize nanocavities resulting from agglomeration of excess vacancies. The ion-induced damage in SiGe increases with increasing Ge fraction of the alloy. The amorphization threshold decreases and the extension of a buried amorphous layer increases for given implantation and annealing conditions. In contrast to ballistic simulations of excess defect generation where perfect local self-annihilation is assumed the concentrations of excess vacancies and excess interstitials in SiGe increase with increasing Ge fraction. The main contribution to the high excess vacancy concentration in SiGe results from the inefficient recombination of vacancies and interstitials. The widely used +1 model describing the ion-induced damage in Si is not valid for SiGe.

  15. Volcanic rifting at Martian grabens Daniel Me`ge,1

    E-Print Network [OSTI]

    Mege, Daniel

    Volcanic rifting at Martian grabens Daniel Me`ge,1 Anthony C. Cook,2,3 Erwan Garel,4 Yves: Solar System Objects: Mars; 8121 Tectonophysics: Dynamics, convection currents and mantle plumes; 8010: Me`ge, D., A. C. Cook, E. Garel, Y. Lagabrielle, and M.-H. Cormier, Volcanic rifting at Martian

  16. Optical limiting materials

    DOE Patents [OSTI]

    McBranch, D.W.; Mattes, B.R.; Koskelo, A.C.; Heeger, A.J.; Robinson, J.M.; Smilowitz, L.B.; Klimov, V.I.; Cha, M.; Sariciftci, N.S.; Hummelen, J.C.

    1998-04-21T23:59:59.000Z

    Methanofullerenes, fulleroids and/or other fullerenes chemically altered for enhanced solubility, in liquid solution, and in solid blends with transparent glass (SiO{sub 2}) gels or polymers, or semiconducting (conjugated) polymers, are shown to be useful as optical limiters (optical surge protectors). The nonlinear absorption is tunable such that the energy transmitted through such blends saturates at high input energy per pulse over a wide range of wavelengths from 400--1,100 nm by selecting the host material for its absorption wavelength and ability to transfer the absorbed energy into the optical limiting composition dissolved therein. This phenomenon should be generalizable to other compositions than substituted fullerenes. 5 figs.

  17. Superconnections and Matter

    E-Print Network [OSTI]

    Roepstorff, G

    1998-01-01T23:59:59.000Z

    In a previous paper, the superconnection formalism was used to naturally fit the Higgs field into a U(n) gauge theory where we aimed at the reconstruction of the standard model. The approach provides an alternative to non-commutative geometry. This work is now continued by including matter field (leptons). The essentially new ingredient is the right-handed neutrino field and a new kind of interaction that goes with it. All interactions follow from one Dirac operator associated to a superconnection.

  18. Superconnections and Matter

    E-Print Network [OSTI]

    G. Roepstorff

    2000-08-17T23:59:59.000Z

    In a previous paper (hep-th/9801040), the superconnection formalism was used to fit the Higgs field into a U(n) gauge theory with particular emphasis on the n=2 case, aiming at the reconstruction of certain parts of the Standard Model. The approach provides an alternative to the one bases on non-commutative geometry. This work is continued by including matter fields (leptons only). We extend the Standard Model by including the right-handed neutrino field. The possibility of a finite neutrino mass is thus accounted for.

  19. Thermodynamics of electroweak matter

    E-Print Network [OSTI]

    A. Gynther

    2006-09-21T23:59:59.000Z

    This paper is a slightly modified version of the introductory part of a PhD thesis, also containing the articles hep-ph/0303019, hep-ph/0510375 and hep-ph/0512177. We provide a short history of the research of electroweak thermodynamics and a brief introduction to the theory as well as to the necessary theoretical tools needed to work at finite temperatures. We then review computations regarding the pressure of electroweak matter at high temperatures (the full expression of the perturbative expansion of the pressure is given in the appendix) and the electroweak phase diagram at finite chemical potentials. Finally, we compare electroweak and QCD thermodynamics.

  20. Discrete dark matter

    SciTech Connect (OSTI)

    Hirsch, M.; Morisi, S.; Peinado, E.; Valle, J. W. F. [AHEP Group, Institut de Fisica Corpuscular--C.S.I.C./Universitat de Valencia, Edificio Institutos de Paterna, Apartado 22085, E-46071 Valencia (Spain)

    2010-12-01T23:59:59.000Z

    We propose a new motivation for the stability of dark matter (DM). We suggest that the same non-Abelian discrete flavor symmetry which accounts for the observed pattern of neutrino oscillations, spontaneously breaks to a Z{sub 2} subgroup which renders DM stable. The simplest scheme leads to a scalar doublet DM potentially detectable in nuclear recoil experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta decay rate accessible to upcoming searches, while {theta}{sub 13}=0 gives no CP violation in neutrino oscillations.

  1. Particulate Matter Aerosols

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

    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 742EnergyOnItemResearch > TheNuclear Astrophysics OneOutreach EffortsSearchParticulate Matter

  2. Dark Matter Theory

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

    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 for4,645U.S. DOEThe Bonneville Power Administration wouldDECOMPOSITION OFSupplemental TechnologySummaryDariuszDark Matter Theory

  3. Excess carrier lifetimes in Ge layers on Si

    SciTech Connect (OSTI)

    Geiger, R., E-mail: richard.geiger@psi.ch, E-mail: hans.sigg@psi.ch; Sigg, H., E-mail: richard.geiger@psi.ch, E-mail: hans.sigg@psi.ch [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Frigerio, J.; Chrastina, D.; Isella, G. [L-NESS, Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100 Como (Italy); Süess, M. J. [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Laboratory for Nanometallurgy, Department of Materials Science, ETH Zurich, 8093 Zurich (Switzerland); Scientific Center for Optical and Electron Microscopy (SCOPEM), ETH Zurich, 8093 Zurich (Switzerland); Spolenak, R. [Laboratory for Nanometallurgy, Department of Materials Science, ETH Zurich, 8093 Zurich (Switzerland); Faist, J. [Institute for Quantum Electronics, ETH Zurich, 8093 Zurich (Switzerland)

    2014-02-10T23:59:59.000Z

    The excess charge carrier lifetimes in Ge layers grown on Si or germanium-on-insulator are measured by synchrotron based pump-probe transmission spectroscopy. We observe that the lifetimes do not strongly depend on growth parameters and annealing procedure, but on the doping profile. The defect layer at the Ge/Si interface is found to be the main non-radiative recombination channel. Therefore, the longest lifetimes in Ge/Si (2.6?ns) are achieved in sufficiently thick Ge layers with a built-in field, which repels electrons from the Ge/Si interface. Longer lifetimes (5.3?ns) are obtained in overgrown germanium-on-insulator due to the absence of the defective interface.

  4. Recent results in relativistic heavy ion collisions: from ``a new state of matter'' to "the perfect fluid"

    E-Print Network [OSTI]

    M. J. Tannenbaum

    2006-07-28T23:59:59.000Z

    Experimental Physics with Relativistic Heavy Ions dates from 1992 when a beam of 197Au of energy greater than 10A GeV/c first became available at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL) soon followed in 1994 by a 208Pb beam of 158A GeV/c at the Super Proton Synchrotron (SPS) at CERN (European Center for Nuclear Research). Previous pioneering measurements at the Berkeley Bevalac in the late 1970's and early 1980's were at much lower bombarding energies (~ 1 A GeV/c) where nuclear breakup rather than particle production is the dominant inelastic process in A+A collisions. More recently, starting in 2000, the Relativistic Heavy Ion Collider (RHIC) at BNL has produced head-on collisions of two 100A GeV beams of fully stripped Au ions, corresponding to nucleon-nucleon center-of-mass energy, sqrt(sNN)=200 GeV, total c.m. energy 200A GeV. The objective of this research program is to produce nuclear matter with extreme density and temperature, possibly resulting in a state of matter where the quarks and gluons normally confined inside individual nucleons (r < 1 fm) are free to act over distances an order of magnitude larger. Progress from the period 1992 to the present will be reviewed, with reference to previous results from light ion and proton-proton collisions where appropriate. Emphasis will be placed on the measurements which formed the basis for the announcements by the two major laboratories: "A new state of matter", by CERN on Feb 10, 2000 and "The perfect fluid", by BNL on April 19, 2005.

  5. Structural phase transitions on the nanoscale: The crucial pattern in the phase-change materials Ge2Sb2Te5 and GeTe

    E-Print Network [OSTI]

    Structural phase transitions on the nanoscale: The crucial pattern in the phase-change materials Ge2Sb2Te5 and GeTe J. Akola1,2 and R. O. Jones1 1Institut für Festkörperforschung, Forschungszentrum to characterize the amorphous structure of the prototype materials Ge2Sb2Te5 and GeTe. In both, there is long

  6. III International Conference on SiGe(C) Epitaxy and Heterostructures, NM, Mar. 2003 SiGe Single-Hole Transistor Fabricated by AFM Oxidation and Epitaxial Regrowth

    E-Print Network [OSTI]

    III International Conference on SiGe(C) Epitaxy and Heterostructures, NM, Mar. 2003 110 SiGe Single, West Lafayette, IN 47907, U.S.A. Nanodevices on Si/SiGe heterostructures are of growing interest [1 the performance of the devices. In this paper, we demonstrate a reproducible single-hole transistor SiGe device

  7. The role of straining and morphology in thermal conductivity of a set of SiGe superlattices and biomimetic SiGe nanocomposites

    E-Print Network [OSTI]

    Tomar, Vikas

    The role of straining and morphology in thermal conductivity of a set of Si­Ge superlattices and biomimetic Si­Ge nanocomposites This article has been downloaded from IOPscience. Please scroll down to see and morphology in thermal conductivity of a set of Si­Ge superlattices and biomimetic Si­Ge nanocomposites Vikas

  8. The influence of a Si cap on self-organized SiGe islands and the underlying wetting layer

    SciTech Connect (OSTI)

    Brehm, M.; Grydlik, M.; Groiss, H.; Hackl, F.; Schaeffler, F.; Fromherz, T.; Bauer, G. [Institut fuer Halbleiter -u. Festkoerperphysik, Universitaet Linz, A-4040 Linz (Austria)

    2011-06-15T23:59:59.000Z

    For the prototypical SiGe/Si(001) Stranski-Krastanow (SK) growth system, the influence of intermixing caused by the deposition of a Si cap layer at temperatures T{sub cap} between 300 deg. C and 700 deg. C is studied both for the SiGe wetting layer (WL) and the SiGe islands. Systematic growth experiments were carried out with an ultrahigh resolution of down to 0.005 monolayers (ML) of deposited Ge. The properties of the samples were investigated via photoluminescence (PL) spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy. We studied in detail the influence of T{sub cap} in the three main coverage regions of SiGe SK growth, which are (i) the WL build-up regime, (ii) the island nucleation regime, where most of the Ge is supplied via material transfer from the WL, and (iii) the saturation regime, where the WL thickness remains initially stable. At T{sub cap} = 300 deg. C, we found that both the WL and the island are essentially preserved in composition and shape, whereas at 500 deg. C the WL becomes heavily alloyed during capping, and at 700 deg. C the islands also become alloyed. At T{sub cap} = 500 deg. C we found enhanced WL intermixing in the presence of dome-shaped islands, whereas at T{sub cap} 700 deg. C the WL properties become dominated by the dissolution of pyramid-shaped islands upon capping. At Ge coverages above {approx_equal}6 ML, we found an unexpected thickening of the WL, almost independently of T{sub cap}. This finding suggests that the density and the volume of the dome-shaped islands have an upper limit, beyond which excess Ge from the external source again becomes incorporated into the WL. Finally, we compared PL spectra with AFM-based evaluations of the integral island volumes in order to determine in a straightforward manner the average composition of the SiGe islands.

  9. On atomic structure of Ge huts growing on the Ge/Si(001) wetting layer

    SciTech Connect (OSTI)

    Arapkina, Larisa V.; Yuryev, Vladimir A. [A. M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Street, Moscow, 119991 (Russian Federation)] [A. M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov Street, Moscow, 119991 (Russian Federation)

    2013-09-14T23:59:59.000Z

    Structural models of growing Ge hut clusters—pyramids and wedges—are proposed on the basis of data of recent STM investigations of nucleation and growth of Ge huts on the Si(001) surface in the process of molecular beam epitaxy. It is shown that extension of a hut base along <110> directions goes non-uniformly during the cluster growth regardless of its shape. Growing pyramids, starting from the second monolayer, pass through cyclic formation of slightly asymmetrical and symmetrical clusters, with symmetrical ones appearing after addition of every fourth monolayer. We suppose that pyramids of symmetrical configurations composed by 2, 6, 10, etc., monolayers over the wetting layer are more stable than asymmetrical ones. This might explain less stability of pyramids in comparison with wedges in dense arrays forming at low temperatures of Ge deposition. Possible nucleation processes of pyramids and wedges on wetting layer patches from identical embryos composed by 8 dimers through formation of 1 monolayer high 16-dimer nuclei different only in their symmetry is discussed. Schematics of these processes are presented. It is concluded from precise STM measurements that top layers of wetting layer patches are relaxed when huts nucleate on them.

  10. Exploring Jet Properties in p-p Collisions at 200 GeV with STAR

    E-Print Network [OSTI]

    Helen Caines

    2009-10-06T23:59:59.000Z

    The mechanisms underlying hadronization are not well understood, both in vacuum and in hot QCD matter. Precise characterization of jet fragmentation to hadrons in p-p collisions will help elucidate the fundamental process of hadronization, and will serve as essential reference to measure the modification of hadronization in heavy ion collisions. We present measurements of fragmentation functions for unidentified particles in jets produced in p-p collisions at 200 GeV using the STAR detector at RHIC. The results from different jet reconstruction algorithms are compared, including variations of the resolution parameter. It is found that the results are largely insensitive to details of the jet-finding algorithm at RHIC energies. Particle production inside and outside of these reconstructed jets will be compared to improve our understanding of the hadronization mechanisms for soft and hard particles in p-p events at RHIC energies.

  11. Perturbative exponential expansion and matter neutrino oscillations

    E-Print Network [OSTI]

    A. D. Supanitsky; J. C. D'Olivo; G. Medina-Tanco

    2008-10-13T23:59:59.000Z

    We derive an analytical description of neutrino oscillations in matter based on the Magnus exponential representation of the time evolution operator. Our approach is valid in a wide range of the neutrino energies and properly accounts for the modifications that the respective probability transitions suffer when neutrinos originated in different sources traverse the Earth. The present approximation considerably improves over other perturbative treatments existing in the current literature. Furthermore, the analytical expressions derived inside the Magnus framework are remarkably simple, which facilitates their practical use. When applied to the calculation of the day-night asymmetry in the solar neutrino flux our result reproduces the numerical calculation with an accuracy better than 1% for the first order approximation. When the approximation is extended to the second order, the accuracy of the method is further improved by almost one order of magnitude, and it is still better than 5% even for neutrino energies as large as 100 MeV. In the GeV regime characteristic of atmospheric and accelerator neutrinos this accuracy is complemented by a good reproduction of the position of the maxima in the flavor transition probabilities.

  12. Anti-helium from Dark Matter annihilations

    E-Print Network [OSTI]

    Marco Cirelli; Nicolao Fornengo; Marco Taoso; Andrea Vittino

    2014-10-21T23:59:59.000Z

    Galactic Dark Matter (DM) annihilations can produce cosmic-ray anti-nuclei via the nuclear coalescence of the anti-protons and anti-neutrons originated directly from the annihilation process. Since anti-deuterons have been shown to offer a distinctive DM signal, with potentially good prospects of detection in large portions of the DM-particle parameter space, we explore here the production of heavier anti-nuclei, specifically anti-helium. Even more than for anti-deuterons, the DM-produced anti-He flux can be mostly prominent over the astrophysical anti-He background at low kinetic energies, typically below 3-5 GeV/n. However, the larger number of anti-nucleons involved in the formation process makes the anti-He flux extremely small. We therefore explore, for a few DM benchmark cases, whether the yield is sufficient to allow for anti-He detection in current-generation experiments, such as AMS-02. We account for the uncertainties due to the propagation in the Galaxy and to the uncertain details of the coalescence process, and we consider the constraints already imposed by anti-proton searches. We find that only for very optimistic configurations it might be possible to achieve detection with current generation detectors. We estimate that, in more realistic configurations, an increase in experimental sensitivity at low-kinetic energies of about a factor of 500-1000 would allow to start probing DM through the rare cosmic anti-He production.

  13. Multiverse Dark Matter: SUSY or Axions

    E-Print Network [OSTI]

    Francesco D'Eramo; Lawrence J. Hall; Duccio Pappadopulo

    2015-03-11T23:59:59.000Z

    The observed values of the cosmological constant {\\it and} the abundance of Dark Matter (DM) can be successfully understood, using certain measures, by imposing the anthropic requirement that density perturbations go non-linear and virialize to form halos. This requires a probability distribution favoring low amounts of DM, i.e. low values of the PQ scale $f$ for the QCD axion and low values of the superpartner mass scale $\\tilde{m}$ for LSP thermal relics. In theories with independent scanning of multiple DM components, there is a high probability for DM to be dominated by a single component. For example, with independent scanning of $f$ and $\\tilde{m}$, TeV-scale LSP DM and an axion solution to the strong CP problem are unlikely to coexist. With thermal LSP DM, the scheme allows an understanding of a Little SUSY Hierarchy with multi-TeV superpartners. Alternatively, with axion DM, PQ breaking before (after) inflation leads to $f$ typically below (below) the projected range of the current ADMX experiment of $f = (3 - 30) \\times 10^{11}$ GeV, providing strong motivation to develop experimental techniques for probing lower $f$.

  14. Test of the equivalence principle for ordinary matter falling toward dark matter

    SciTech Connect (OSTI)

    Smith, G.; Adelberger, E.G.; Heckel, B.R.; Su, Y. (Department of Physics FM-15, University of Washington, Seattle, Washington 98195 (United States))

    1993-01-11T23:59:59.000Z

    We tested the equivalence principle (EP) for Be, Cu, and Al falling toward the galactic center, and found [Delta][ital a](Be,Cu)=[minus](0.1 [plus minus]5.8)[times]10[sup [minus]12] cm/[ital s][sup 2] and [Delta][ital a](Be,Al)=(3.6[plus minus]6.9)[times]10[sup [minus]12] cm/[ital s][sup 2]. As dark matter is thought to account for (25--30)% of our galacticentric acceleration, the EP parameters for Be/Cu, or Be/Al, falling toward dark matter, are [eta](Be,Cu)=(0.0[plus minus]1.2)[times]10[sup [minus]3] and [eta](Be,Al)=(0.7[plus minus]1.4)[times]10[sup [minus]3] (1[sigma] errors). This limits any EP-violating component of our acceleration toward dark matter and provides laboratory evidence that gravitation is the only significant long-range interaction between dark and ordinary matter.

  15. Ratio of jet cross sections at root s=630 GeV and 1800 GeV

    E-Print Network [OSTI]

    Baringer, Philip S.; Bean, Alice; Coppage, Don; Hebert, C.

    2001-03-01T23:59:59.000Z

    The DO Collaboration has measured the inclusive jet cross section in (p) over barp collisions at roots = 630 GeV. The results for pseudorapidities \\ eta \\ < 0.5 are combined with our previous results at roots = 1800 GeV ...

  16. The PICASSO Direct Dark Matter Search Experiment

    SciTech Connect (OSTI)

    Aubin, F.; Barnabe-Heider, M.; Doane, P.; Genest, M.-H.; Gornea, R.; Guenette, R.; Lessard, L.; Martin, J.-P.; Wichoski, U.; Zacek, V. [Departement de physique, Universite de Montreal, Montreal, H3C 3J7 (Canada); Behnke, E.; Levine, I. [Department of physics and astronomy, Indiana University South Bend, South Bend, Indiana, 46634 (United States); Clark, K.; Di Marco, M.; Krauss, C. B.; Noble, A. J. [Department of physics, Queens University, Kingston, K7L 3NG (Canada); Feighery, W.; Muthusi, C. [Department of Chemistry, Indiana University South Bend, South Bend, Indiana, 46634 (United States); Kanagalingam, S.; Noulty, R. [Bubble Technology Industries, Chalk River K0J 1J0 (Canada)] (and others)

    2006-04-11T23:59:59.000Z

    The PICASSO experiment is searching for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs), in particular neutralinos ({chi}) via their spin-dependent interactions with nuclei. The experiment is installed in the Sudbury Neutrino Observatory Laboratory at a depth of 2070 m (6000 mwe). PICASSO makes use of the superheated droplet technique with C4F10 as the active material, and searches for {chi} interactions on 19F. The results of these measurements are presented in terms of limits on the spin-dependent {chi}-proton and {chi}-neutron cross sections. Limits on the effective {chi}-proton and {chi}-neutron coupling strengths ap and an are also reported. The results exclude new regions of the spin-dependent {chi}-nucleon interaction parameter space. The next phase of PICASSO is briefly discussed.

  17. Compressively strained Ge trigate p-MOSFETs

    E-Print Network [OSTI]

    Chern, Winston

    2012-01-01T23:59:59.000Z

    State of the art MOSFET performance is limited by the electronic properties of the material that is being used, silicon (Si). In order to continue performance enhancements, different materials are being studied for the ...

  18. CDF Note 9674 Combined Upper Limit on Standard Model Higgs Boson Production for Winter 2009

    E-Print Network [OSTI]

    Fermilab

    CDF Note 9674 Combined Upper Limit on Standard Model Higgs Boson Production for Winter 2009 The CDF of searches for the Standard Model Higgs boson at CDF. The six major analyses combined are the WH bV/c2 in steps of 5 GeV/c2 , assuming Standard Model decay branching fractions of the Higgs boson

  19. Ion Implanted Ge:B Far Infrard Blocked Impurity Band Detectors

    E-Print Network [OSTI]

    Beeman, J.W.; Goyal, S.; Reichertz, L.A.; Haller, E.E.

    2008-01-01T23:59:59.000Z

    +16 1.E+15 1.E+14 Depth into Ge Crystal Surface (Ĺ) Figure 5devices does not match that of Ge:Ga photoconductors, whichimplants or stacking devices) Ge IBIB detectors will reach

  20. ALFVEN-WAVE OSCILLATIONS IN A SPHERE, WITH APPLICATIONS TO ELECTRON-HOLE DROPS IN Ge

    E-Print Network [OSTI]

    Markiewicz, R.S.

    2011-01-01T23:59:59.000Z

    Rev. B 13,4626 (1976). For Ge(4:2) m is the average of thediscussed for EHD in unstressed Ge (B II )TO ELECI'RON-OOLE DROPS IN Ge R. S. Markiewicz January 1978

  1. NUCLEATION PHENOMENA IN THE FORMATION OF ELECTRON-HOLE DROPS IN Ge

    E-Print Network [OSTI]

    Westervelt, R.M.

    2010-01-01T23:59:59.000Z

    lO cjl(K) Symbol erg cm ) Ge - 0.064 T2 Ref. x x Si Ref. T2constructed the ultra-sensitive Ge photodetector which wasand method of mounting. The Ge sample is electrically and

  2. Photo-oxidation of Ge Nanocrystals: Kinetic Measurements by In Situ Raman Spectroscopy

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    Photo-oxidation of Ge Nanocrystals: Kinetic Measurements byBerkeley, CA, 94720 ABSTRACT Ge nanocrystals are formed inthe Raman spectra of the Ge nanocrystals in-situ. The

  3. 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

  4. The Majorana Demonstrator: A Search for Neutrinoless Double-beta Decay of 76Ge

    E-Print Network [OSTI]

    Majorana Collaboration; W. Xu; N. Abgrall; F. T. Avignone III; A. S. Barabash; F. E. Bertrand; V. Brudanin; M. Busch; M. Buuck; D. Byram; A. S. Caldwell; Y-D. Chan; C. D. Christofferson; C. Cuesta; J. A. Detwiler; Yu. Efremenko; H. Ejiri; S. R. Elliott; A. Galindo-Uribarri; G. K. Giovanetti; J. Goett; M. P. Green; J. Gruszko; I. Guinn; V. E. Guiseppe; R. Henning; E. W. Hoppe; S. Howard; M. A. Howe; B. R. Jasinski; K. J. Keeter; M. F. Kidd; S. I. Konovalov; R. T. Kouzes; B. D. LaFerriere; J. Leon; J. MacMullin; R. D. Martin; S. J. Meijer; S. Mertens; J. L. Orrell; C. O'Shaughnessy; N. R. Overman; A. W. P. Poon; D. C. Radford; J. Rager; K. Rielage; R. G. H. Robertson; E. Romero-Romero; M. C. Ronquest; B. Shanks; M. Shirchenko; N. Snyder; A. M. Suriano; D. Tedeschi; J. E. Trimble; R. L. Varner; S. Vasilyev; K. Vetter; K. Vorren; B. R. White; J. F. Wilkerson; C. Wiseman; E. Yakushev; C-H. Yu; V. Yumatov

    2015-05-09T23:59:59.000Z

    Neutrinoless double-beta decay is a hypothesized process where in some even-even nuclei it might be possible for two neutrons to simultaneously decay into two protons and two electrons without emitting neutrinos. This is possible only if neutrinos are Majorana particles, i.e. fermions that are their own antiparticles. Neutrinos being Majorana particles would explicitly violate lepton number conservation, and might play a role in the matter-antimatter asymmetry in the universe. The observation of neutrinoless double-beta decay would also provide complementary information related to neutrino masses. The Majorana Collaboration is constructing the Majorana Demonstrator, a 40-kg modular germanium detector array, to search for the Neutrinoless double-beta decay of 76Ge and to demonstrate a background rate at or below 3 counts/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039 keV Q-value for 76Ge Neutrinoless double-beta decay. In this paper, we discuss the physics of neutrinoless double beta decay and then focus on the Majorana Demonstrator, including its design and approach to achieve ultra-low backgrounds and the status of the experiment.

  5. The Majorana Demonstrator: A Search for Neutrinoless Double-beta Decay of 76Ge

    E-Print Network [OSTI]

    Majorana Collaboration; W. Xu; N. Abgrall; F. T. Avignone III; A. S. Barabash; F. E. Bertrand; V. Brudanin; M. Busch; M. Buuck; D. Byram; A. S. Caldwell; Y-D. Chan; C. D. Christofferson; C. Cuesta; J. A. Detwiler; Yu. Efremenko; H. Ejiri; S. R. Elliott; A. Galindo-Uribarri; G. K. Giovanetti; J. Goett; M. P. Green; J. Gruszko; I. Guinn; V. E. Guiseppe; R. Henning; E. W. Hoppe; S. Howard; M. A. Howe; B. R. Jasinski; K. J. Keeter; M. F. Kidd; S. I. Konovalov; R. T. Kouzes; B. D. LaFerriere; J. Leon; J. MacMullin; R. D. Martin; S. J. Meijer; S. Mertens; J. L. Orrell; C. O'Shaughnessy; N. R. Overman; A. W. P. Poon; D. C. Radford; J. Rager; K. Rielage; R. G. H. Robertson; E. Romero-Romero; M. C. Ronquest; B. Shanks; M. Shirchenko; N. Snyder; A. M. Suriano; D. Tedeschi; J. E. Trimble; R. L. Varner; S. Vasilyev; K. Vetter; K. Vorren; B. R. White; J. F. Wilkerson; C. Wiseman; E. Yakushev; C-H. Yu; V. Yumatov

    2015-01-13T23:59:59.000Z

    Neutrinoless double-beta decay is a hypothesized process where in some even-even nuclei it might be possible for two neutrons to simultaneously decay into two protons and two electrons without emitting neutrinos. This is possible only if neutrinos are Majorana particles, i.e. fermions that are their own antiparticles. Neutrinos being Majorana particles would explicitly violate lepton number conservation, and might play a role in the matter-antimatter asymmetry in the universe. The observation of neutrinoless double-beta decay would also provide complementary information related to neutrino masses. The Majorana Collaboration is constructing the Majorana Demonstrator, a 40-kg modular germanium detector array, to search for the Neutrinoless double-beta decay of 76Ge and to demonstrate a background rate at or below 3 counts/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039 keV Q-value for 76Ge Neutrinoless double-beta decay. In this paper, we discuss the physics of neutrinoless double beta decay and then focus on the Majorana Demonstrator, including its design and approach to achieve ultra-low backgrounds and the status of the experiment.

  6. The Majorana Demonstrator: A Search for Neutrinoless Double-beta Decay of 76Ge

    E-Print Network [OSTI]

    Xu, W; Avignone, F T; Barabash, A S; Bertrand, F E; Brudanin, V; Busch, M; Buuck, M; Byram, D; Caldwell, A S; Chan, Y-D; Christofferson, C D; Cuesta, C; Detwiler, J A; Efremenko, Yu; Ejiri, H; Elliott, S R; Galindo-Uribarri, A; Giovanetti, G K; Goett, J; Green, M P; Gruszko, J; Guinn, I; Guiseppe, V E; Henning, R; Hoppe, E W; Howard, S; Howe, M A; Jasinski, B R; Keeter, K J; Kidd, M F; Konovalov, S I; Kouzes, R T; LaFerriere, B D; Leon, J; MacMullin, J; Martin, R D; Meijer, S J; Mertens, S; Orrell, J L; O'Shaughnessy, C; Overman, N R; Poon, A W P; Radford, D C; Rager, J; Rielage, K; Robertson, R G H; Romero-Romero, E; Ronquest, M C; Shanks, B; Shirchenko, M; Snyder, N; Suriano, A M; Tedeschi, D; Trimble, J E; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Wiseman, C; Yakushev, E; Yu, C-H; Yumatov, V

    2015-01-01T23:59:59.000Z

    Neutrinoless double-beta decay is a hypothesized process where in some even-even nuclei it might be possible for two neutrons to simultaneously decay into two protons and two electrons without emitting neutrinos. This is possible only if neutrinos are Majorana particles, i.e. fermions that are their own antiparticles. Neutrinos being Majorana particles would explicitly violate lepton number conservation, and might play a role in the matter-antimatter asymmetry in the universe. The observation of neutrinoless double-beta decay would also provide complementary information related to neutrino masses. The Majorana Collaboration is constructing the Majorana Demonstrator, a 40-kg modular germanium detector array, to search for the Neutrinoless double-beta decay of 76Ge and to demonstrate a background rate at or below 3 counts/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039 keV Q-value for 76Ge Neutrinoless double-beta decay. In this paper, we discuss the physics of neutrinoless double beta decay and...

  7. Origins of low resistivity and Ge donor level in Ge ion-implanted ZnO bulk single crystals

    SciTech Connect (OSTI)

    Kamioka, K.; Oga, T.; Izawa, Y.; Kuriyama, K. [College of Engineering and Research Center of Ion Beam Technology, Hosei University Koganei, Tokyo 184-8584 (Japan); Kushida, K. [Departments of Arts and Sciences, Osaka Kyoiku University Kashiwara, Osaka 582-8582 (Japan)

    2013-12-04T23:59:59.000Z

    The energy level of Ge in Ge-ion implanted ZnO single crystals is studied by Hall-effect and photoluminescence (PL) methods. The variations in resistivity from ?10{sup 3} ?cm for un-implanted samples to ?10{sup ?2} ?cm for as-implanted ones are observed. The resistivity is further decreased to ?10{sup ?3} ?cm by annealing. The origins of the low resistivity are attributed to both the zinc interstitial (Zn{sub i}) related defects and the electrical activated Ge donor. An activation energy of Ge donors estimated from the temperature dependence of carrier concentration is 102 meV. In PL studies, the new peak at 372 nm (3.33 eV) related to the Ge donor is observed in 1000 °C annealed samples.

  8. GeO{sub 2}/Ge structure submitted to annealing in deuterium: Incorporation pathways and associated oxide modifications

    SciTech Connect (OSTI)

    Bom, N. M., E-mail: nicolau.bom@ufrgs.br [PGMICRO, UFRGS, 91509-900 Porto Alegre, Rio Grande do Sul (Brazil); Soares, G. V.; Hartmann, S.; Bordin, A. [Instituto de Física, UFRGS, 91509-900 Porto Alegre, Rio Grande do Sul (Brazil); Radtke, C. [Instituto de Química, UFRGS, 91509-900 Porto Alegre, Rio Grande do Sul (Brazil)

    2014-10-06T23:59:59.000Z

    Deuterium (D) incorporation in GeO{sub 2}/Ge structures following D{sub 2} annealing was investigated. Higher D concentrations were obtained for GeO{sub 2}/Ge samples in comparison to their SiO{sub 2}/Si counterparts annealed in the same conditions. Oxygen vacancies produced during the annealing step in D{sub 2} constitute defect sites for D incorporation, analogous to defects at the SiO{sub 2}/Si interfacial region. Besides D incorporation, volatilization of the oxide layer is also observed as a consequence of D{sub 2} annealing, especially in the high temperature regime of the present study (>450?°C). In parallel to this volatilization, the stoichiometry and chemical structure of remnant oxide are modified as well. These results evidence the broader impact of forming gas annealing in dielectric/Ge structures with respect to SiO{sub 2}/Si counterparts.

  9. Nuclear Matter and Nuclear Dynamics

    E-Print Network [OSTI]

    M Colonna

    2009-02-26T23:59:59.000Z

    Highlights on the recent research activity, carried out by the Italian Community involved in the "Nuclear Matter and Nuclear Dynamics" field, will be presented.

  10. Atomic geometry of mixed Ge-Si dimers in the initial-stage growth of Ge on Si,,001...2 1 X. Chen* and D. K. Saldin

    E-Print Network [OSTI]

    Saldin, Dilano

    Atomic geometry of mixed Ge-Si dimers in the initial-stage growth of Ge on Si,,001...2 1 X. Chen quantitatively the geometry of mixed Ge-Si dimers on a single domain Si 001 2 1 surface by azimuthal scanning core-level photoelectron diffraction. By analyzing Ge 3d diffraction patterns from Ge/Si 001 at 0.1 ML

  11. Explaining Low Energy ?-ray Excess from the Galactic Centre using a Two Component Dark Matter Model

    E-Print Network [OSTI]

    Anirban Biswas

    2014-12-04T23:59:59.000Z

    Over the past few years, there has been a hint of the $\\gamma$-ray excess observed by the Fermi-LAT satellite borne telescope from the region surrounding the Galactic Centre at an energy range $\\sim 1$-$3$ GeV. The nature of this excess $\\gamma$-ray spectrum is found to be consistent with the $\\gamma$-ray emission expected from dark matter annihilation at the Galactic Centre while disfavouring other known astrophysical sources as the possible origin of this phenomena. It is also reported that the spectrum and morphology of this excess $\\gamma$-rays can well be explained by the dark matter particles having mass in the range $30\\sim 40$ GeV annihilating into ${\\rm b}$ $\\bar{\\rm b}$ final state with an annihilation cross section ${\\sigma {\\rm v}} \\sim 1.4 - 2.0\\times10^{-26}$ cm$^3/$s at the Galactic centre. In this work, we propose a two component dark matter model where two different types of dark matter particles namely a complex scalar and a Dirac fermion are considered. The stability of both the dark sector particles are maintained by virtue of an additional local U$(1)_{\\rm X}$ gauge symmetry. We find that our proposed scenario can provide a viable explanation besides satisfying all the existing relevant theoretical, experimental and observational bounds.

  12. XENON dark matter searches: Results and the future

    SciTech Connect (OSTI)

    Brown, Andrew [Physics Department, Purdue University - 525 Northwestern Ave., West Lafayette, IN 47907 (United States); Collaboration: XENON Collaboration

    2014-06-24T23:59:59.000Z

    XENON100 is a dark matter search experiment looking for elastic WIMP scattering using a 62 kg liquid target. WIMP search data from XENON100 published in 2012 has set the world's strongest limits on WIMP-nucleus spinindependent, elastic scattering. It has also set the strongest limits on WIMP-nucleus spin-dependent scattering considering neutron scattering only, and competitive limits considering proton scattering only. The successor experiment to XENON100, XENON1T, is currently under construction, with commissioning scheduled to begin in 2014. XENON1T's design goal is a 100 fold increase in sensitivity for elastic WIMP searches over XENON100.

  13. Wino Dark Matter in the light of AMS-02 2015

    E-Print Network [OSTI]

    Ibe, Masahiro; Shirai, Satoshi; Yanagida, Tsutomu T

    2015-01-01T23:59:59.000Z

    The AMS-02 collaboration has recently reported the antiproton to proton ratio with improved accuracy. In view of uncertainties of the production and the propagation of the cosmic rays, the observed ratio is still consistent with the secondary astrophysical antiproton to proton ratio. However, it is nonetheless enticing to examine whether the observed spectrum can be explained by a strongly motivated dark matter, the wino dark matter. As we will show, we find that the antiproton flux from the wino annihilation can explain the observed spectrum well for its mass range 2.5-3 TeV. The fit to data becomes particularly well compared to the case without the annihilation for the thermal wino dark matter case with a mass about 3 TeV. The ratio is predicted to be quickly decreased at the energy several hundreds of GeV, if this possibility is true, and it will be confirmed or ruled out in near future when the AMS-02 experiment accumulates enough data at this higher energy region.

  14. The Cryogenic Dark Matter Search: First 5-Tower Data and Improved Understanding of Ionization Collection

    SciTech Connect (OSTI)

    Bailey, Catherine N.; /Case Western Reserve U.

    2010-01-01T23:59:59.000Z

    The Cryogenic Dark Matter Search (CDMS) is searching for Weakly Interacting Massive Particles (WIMPs) with cryogenic particle detectors. These detectors have the ability to discriminate between nuclear recoil candidate and electron recoil background events by collecting both phonon and ionization energy from recoils in the detector crystals. The CDMS-II experiment has completed analysis of the first data runs with 30 semiconductor detectors at the Soudan Underground Laboratory, resulting in a world leading WIMP-nucleon spin-independent cross section limit for WIMP masses above 44 GeV/c{sup 2}. As CDMS aims to achieve greater WIMP sensitivity, it is necessary to increase the detector mass and discrimination between signal and background events. Incomplete ionization collection results in the largest background in the CDMS detectors as this causes electron recoil background interactions to appear as false candidate events. Two primary causes of incomplete ionization collection are surface and bulk trapping. Recent work has been focused on reducing surface trapping through the modification of fabrication methods for future detectors. Analyzing data taken with test devices has shown that hydrogen passivation of the amorphous silicon blocking layer worsens surface trapping. Additional data has shown that the iron-ion implantation used to lower the critical temperature of the tungsten transition-edge sensors causes a degradation of the ionization collection. Using selective implantation on future detectors may improve ionization collection for events near the phonon side detector surface. Bulk trapping is minimized by neutralizing ionized lattice impurities. Detector investigations at testing facilities and in situ at the experimental site have provided methods to optimize the neutralization process and monitor running conditions to maintain full ionization collection. This work details my contribution to the 5-tower data taking, monitoring, and analysis effort as well as the SuperCDMS detector development with the focus on monitoring and improving ionization collection in the detectors.

  15. Measurements of the Electron-Helicity Dependent Cross Sections of Deeply Virtual Compton Scattering with CEBAF at 12 GeV

    E-Print Network [OSTI]

    J. Roche; C. E. Hyde-Wright; B. Michel; C. Munoz Camacho

    2006-09-11T23:59:59.000Z

    We propose precision measurements of the helicity-dependent and helicity independent cross sections for the ep->epg reaction in Deeply Virtual Compton Scattering (DVCS) kinematics. DVCS scaling is obtained in the limits Q^2>>Lambda_{QCD}^2, x_Bj fixed, and -\\Delta^2=-(q-q')^22 GeV^2, W>2 GeV, and -\\Delta^21 GeV^2. We will use our successful technique from the 5.75 GeV Hall A DVCS experiment (E00-110). With polarized 6.6, 8.8, and 11 GeV beams incident on the liquid hydrogen target, we will detect the scattered electron in the Hall A HRS-L spectrometer (maximum central momentum 4.3 GeV/c) and the emitted photon in a slightly expanded PbF_2 calorimeter. In general, we will not detect the recoil proton. The H(e,e'g)X missing mass resolution is sufficient to isolate the exclusive channel with 3% systematic precision.

  16. Measurements of the Electron-Helicity Dependent Cross Sections of Deeply Virtual Compton Scattering with CEBAF at 12 GeV

    SciTech Connect (OSTI)

    J. Roche; C. E. Hyde-Wright; B. Michel; C. Munoz Camacho; et al. (The Jefferson Lab Hall A Collaboration)

    2006-09-11T23:59:59.000Z

    We propose precision measurements of the helicity-dependent and helicity independent cross sections for the ep {yields} ep{gamma} reaction in Deeply Virtual Compton Scattering (DVCS) kinematics. DVCS scaling is obtained in the limits Q{sup 2} >> {Lambda}{sub QCD}{sup 2}, x{sub Bj} fixed, and -{Delta}{sup 2} = -(q-q{prime}){sup 2} << Q{sup 2}. We consider the specific kinematic range Q{sup 2} > 2 GeV{sup 2}, W > 2 GeV, and -{Delta}{sup 2} {le} 1 GeV{sup 2}. We will use our successful technique from the 5.75 GeV Hall A DVCS experiment (E00-110). With polarized 6.6, 8.8, and 11 GeV beams incident on the liquid hydrogen target, we will detect the scattered electron in the Hall A HRS-L spectrometer (maximum central momentum 4.3 GeV/c) and the emitted photon in a slightly expanded PbF{sub 2} calorimeter. In general, we will not detect the recoil proton. The H(e,e{prime}{gamma})X missing mass resolution is sufficient to isolate the exclusive channel with 3% systematic precision.

  17. GeV Emission from Collisional Magnetized Gamma Ray Bursts

    E-Print Network [OSTI]

    P. Mészáros; M. J. Rees

    2011-04-26T23:59:59.000Z

    Magnetic fields may play a dominant role in gamma-ray bursts, and recent observations by the Fermi satellite indicate that GeV radiation, when detected, arrives delayed by seconds from the onset of the MeV component. Motivated by this, we discuss a magnetically dominated jet model where both magnetic dissipation and nuclear collisions are important. We show that, for parameters typical of the observed bursts, such a model involving a realistic jet structure can reproduce the general features of the MeV and a separate GeV radiation component, including the time delay between the two. The model also predicts a multi-GeV neutrino component.

  18. Efficient tunable luminescence of SiGe alloy sheet polymers

    SciTech Connect (OSTI)

    Vogg, G.; Meyer, A. J.-P.; Miesner, C.; Brandt, M. S.; Stutzmann, M.

    2001-06-18T23:59:59.000Z

    Crystalline SiGe alloy sheet polymers were topotactically prepared from epitaxially grown calcium germanosilicide Ca(Si{sub 1{minus}x}Ge{sub x}){sub 2} precursor films in the whole composition range. These polygermanosilynes are found to be a well-defined mixture of the known siloxene and polygermyne sheet polymers with the OH groups exclusively bonded to silicon. The optical properties determined by photoluminescence and optical reflection measurements identify the mixed SiGe sheet polymers as direct semiconductors with efficient luminescence tunable in the energy range between 2.4 and 1.3 eV. {copyright} 2001 American Institute of Physics.

  19. Spin-polarized photoemission from SiGe heterostructures

    SciTech Connect (OSTI)

    Ferrari, A.; Bottegoni, F.; Isella, G.; Cecchi, S.; Chrastina, D.; Finazzi, M.; Ciccacci, F. [LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2013-12-04T23:59:59.000Z

    We apply the principles of Optical Orientation to measure by Mott polarimetry the spin polarization of electrons photoemitted from different group-IV heterostructures. The maximum measured spin polarization, obtained from a Ge/Si{sub 0.31}Ge{sub 0.69} strained film, undoubtedly exceeds the maximum value of 50% attainable in bulk structures. The explanation we give for this result lies in the enhanced band orbital mixing between light hole and split-off valence bands as a consequence of the compressive strain experienced by the thin Ge layer.

  20. Charmonium mass in nuclear matter

    E-Print Network [OSTI]

    Lee, S. H.; Ko, Che Ming.

    2003-01-01T23:59:59.000Z

    The mass shift of charmonium states in nuclear matter is studied in the perturbative QCD approach. The leading-order effect due to the change of gluon condensate in nuclear matter is evaluated using the leading-order QCD formula, while the higher...

  1. Astronomical Evidence for Dark Matter

    E-Print Network [OSTI]

    Golwala, Sunil

    weapon in "Quake 4" is the Dark Matter Gun. In Futurama they use dark matter fuel, where "one pound is 10 and neutrons, can compute relative ratio. Using nuclear reaction rates, can compute relative abundances oscillations). Peak is from maximal compression of photon-baryon fluid. Peak sensitive to curvature

  2. Energy Matters in Washington State

    E-Print Network [OSTI]

    Collins, Gary S.

    Energy Matters in Washington State Energy Matters in Washington State www.energy.wsu.edu/library/ November 2009 #12;905 Plum Street SE, Building 3 P.O. Box 43169 Olympia, Washington 98504-3169 Energy University Extension Energy Program. 905 Plum Street SE, Building 3, P.O. Box 43169, Olympia, Washington

  3. Optical absorption in highly-strained Ge/SiGe quantum wells: the role of ?-to-? scattering

    E-Print Network [OSTI]

    L. Lever; Z. Ikoni?; A. Valavanis; R. W. Kelsall; M. Myronov; D. R. Leadley; Y. Hu; N. Owens; F. Y. Gardes; G. T. Reed

    2013-02-28T23:59:59.000Z

    We report the observation of the quantum-confined Stark effect in Ge/SiGe multiple quantum well heterostructures grown on Si(0.22)Ge(0.78) virtual substrates. The large compressive strain in the Ge quantum well layers caused by the lattice mismatch with the virtual substrate results in a blue shift of the direct absorption edge, as well as a reduction in the \\Gamma-valley scattering lifetime because of strain-induced splittings of the conduction band valleys. We investigate theoretically the \\Gamma-valley carrier lifetimes by evaluating the \\Gamma-to-L and \\Gamma-to-\\Delta{} scattering rates in strained Ge/SiGe semiconductor heterostructures. These scattering rates are used to determine the lifetime broadening of excitonic peaks and the indirect absorption in simulated absorption spectra, which are compared with measured absorption spectra for quantum well structures with systematically-varied dimensions. We find that \\Gamma-to-\\Delta{} scattering is significant in compressively strained Ge quantum wells and that the \\Gamma-valley electron lifetime is less than 50 fs in the highly-strained structures reported here, where \\Gamma-to-\\Delta{} scattering accounted for approximately half of the total scattering rate.

  4. Identified high-pT spectra in Cu+Cu collisions at sqrt sNN=200 GeV

    SciTech Connect (OSTI)

    STAR Collaboration; Abelev, Betty

    2010-07-05T23:59:59.000Z

    We report new results on identified (anti)proton and charged pion spectra at large transverse momenta (3 < p{sub T} < 10 GeV/c) from Cu+Cu collisions at {radical}s{sub NN} = 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). This study explores the system size dependence of two novel features observed at RHIC with heavy ions: the hadron suppression at high-p{sub T} and the anomalous baryon to meson enhancement at intermediate transverse momenta. Both phenomena could be attributed to the creation of a new form of QCD matter. The results presented here bridge the system size gap between the available pp and Au+Au data, and allow the detailed exploration for the on-set of the novel features. Comparative analysis of all available 200 GeV data indicates that the system size is a major factor determining both the magnitude of the hadron spectra suppression at large transverse momenta and the relative baryon to meson enhancement.

  5. Quantum vacuum and dark matter

    E-Print Network [OSTI]

    Dragan Slavkov Hajdukovic

    2011-11-21T23:59:59.000Z

    Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.

  6. Flavor evolution of supernova neutrinos in turbulent matter

    SciTech Connect (OSTI)

    Lund, Tina; Kneller, James P. [Department of Physics, North Carolina State University, 2401 Stinson Drive, Raleigh, NC 27695 (United States)

    2014-01-01T23:59:59.000Z

    The neutrino signal from the next galactic supernova carries with it an enormous amount of information on the explosion mechanism of a core-collapse supernova, as well as on the stellar progenitor and on the neutrinos themselves. In order to extract this information we need to know how the neutrino flavor evolves over time due to the interplay of neutrino self-interactions and matter effects. Additional turbulence in the supernova matter may impart its own signatures on the neutrino spectrum, and could partly obscure the imprints of collective and matter effects. We investigate the neutrino flavor evolution due to neutrino self-interactions, matter effects due to the shock wave propagation, and turbulence in three progenitors with masses of 8.8 M?, 10.8 M? and 18.0 M?. In the lightest progenitor we find that the impact of moderate turbulence of the order 10% is limited and occurs only briefly early on. This makes the signatures of collective and matter interactions relatively straightforward to interpret. Similarly, with moderate turbulence the two heavier progenitors exhibit only minor changes in the neutrino spectrum, and collective and matter signatures persists. However, when the turbulence is increased to 30% and 50% the high density matter resonance features in the neutrino spectrum get obscured, while new features arise in the low density resonance channel and in the non-resonant channels. We conclude that with moderate amounts of turbulence spectral features of collective and matter interactions survive in all three progenitors. For the larger amounts of turbulence in the 10.8 M? and 18.0 M? progenitor new features arise, as others disappear.

  7. GE Store for Technology is Open for Business | GE Global Research

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

    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 for4,645U.S. DOE Office of Science (SC) Environmental AssessmentsGeoffrey Campbell isOklahoma City, USAGE BBQ Center isThe GE

  8. Greatly improved interfacial passivation of in-situ high ? dielectric deposition on freshly grown molecule beam epitaxy Ge epitaxial layer on Ge(100)

    SciTech Connect (OSTI)

    Chu, R. L. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liu, Y. C.; Lee, W. C.; Huang, M. L.; Kwo, J., E-mail: raynien@phys.nthu.edu.tw, E-mail: mhong@phys.ntu.edu.tw [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Lin, T. D.; Hong, M., E-mail: raynien@phys.nthu.edu.tw, E-mail: mhong@phys.ntu.edu.tw [Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Pi, T. W. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China)

    2014-05-19T23:59:59.000Z

    A high-quality high-?/Ge interface has been achieved by combining molecule beam epitaxy grown Ge epitaxial layer and in-situ deposited high ? dielectric. The employment of Ge epitaxial layer has sucessfully buried and/or removed the residue of unfavorable carbon and native oxides on the chemically cleaned and ultra-high vacuum annealed Ge(100) wafer surface, as studied using angle-resolved x-ray photoelectron spectroscopy. Moreover, the scanning tunneling microscopy analyses showed the significant improvements in Ge surface roughness from 3.5?Ĺ to 1?Ĺ with the epi-layer growth. Thus, chemically cleaner, atomically more ordered, and morphologically smoother Ge surfaces were obtained for the subsquent deposition of high ? dielectrics, comparing with those substrates without Ge epi-layer. The capacitance-voltage (C-V) characteristics and low extracted interfacial trap density (D{sub it}) reveal the improved high-?/Ge interface using the Ge epi-layer approach.

  9. Atomic layer-by-layer oxidation of Ge (100) and (111) surfaces by plasma post oxidation of Al{sub 2}O{sub 3}/Ge structures

    SciTech Connect (OSTI)

    Zhang, Rui [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan) [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); School of Electronic Science and Engineering, Nanjing University, 22 Hankou Road, Nanjing 210093 (China); Huang, Po-Chin; Lin, Ju-Chin; Takenaka, Mitsuru; Takagi, Shinichi [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)] [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2013-02-25T23:59:59.000Z

    The ultrathin GeO{sub x}/Ge interfaces formed on Ge (100) and (111) surfaces by applying plasma post oxidation to thin Al{sub 2}O{sub 3}/Ge structures are characterized in detail using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy. It is found that the XPS signals assigned to Ge 1+ and the 2+ states in the GeO{sub x} layers by post plasma oxidation have oscillating behaviors on Ge (100) surfaces in a period of {approx}0.3 nm with an increase in the GeO{sub x} thickness. Additionally, the oscillations of the signals assigned to Ge 1+ and 2+ states show opposite phase to each other. The similar oscillation behaviors are also confirmed on Ge (111) surfaces for Ge 1+ and 3+ states in a period of {approx}0.5 nm. These phenomena can be strongly regarded as an evidence of the atomic layer-by-layer oxidation of GeO{sub x}/Ge interfaces on Ge (100) and (111) surfaces.

  10. Investigations of segregation phenomena in highly strained Mn-doped Ge wetting layers and Ge quantum dots embedded in silicon

    SciTech Connect (OSTI)

    Prestat, E., E-mail: eric.prestat@gmail.com; Porret, C.; Favre-Nicolin, V.; Tainoff, D.; Boukhari, M.; Bayle-Guillemaud, P.; Jamet, M.; Barski, A., E-mail: andre.barski@cea.com [INAC, SP2M, CEA and Université Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

    2014-03-10T23:59:59.000Z

    In this Letter, we investigate manganese diffusion and the formation of Mn precipitates in highly strained, few monolayer thick, Mn-doped Ge wetting layers and nanometric size Ge quantum dot heterostructures embedded in silicon. We show that in this Ge(Mn)/Si system manganese always precipitates and that the size and the position of Mn clusters (precipitates) depend on the growth temperature. At high growth temperature, manganese strongly diffuses from germanium to silicon, whereas decreasing the growth temperature reduces the manganese diffusion. In the germanium quantum dots layers, Mn precipitates are detected, not only in partially relaxed quantum dots but also in fully strained germanium wetting layers between the dots.

  11. Fault current limiter

    DOE Patents [OSTI]

    Darmann, Francis Anthony

    2013-10-08T23:59:59.000Z

    A fault current limiter (FCL) includes a series of high permeability posts for collectively define a core for the FCL. A DC coil, for the purposes of saturating a portion of the high permeability posts, surrounds the complete structure outside of an enclosure in the form of a vessel. The vessel contains a dielectric insulation medium. AC coils, for transporting AC current, are wound on insulating formers and electrically interconnected to each other in a manner such that the senses of the magnetic field produced by each AC coil in the corresponding high permeability core are opposing. There are insulation barriers between phases to improve dielectric withstand properties of the dielectric medium.

  12. Axial SiGe Heteronanowire Tunneling Field-Effect Transistors...

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

    tunneling field-effect transistors (TFETs), where on-state tunneling occurs in the Ge drain section, while off-state leakage is dominated by the Si junction in the source. Our...

  13. Technology makes reds "pop" in LED displays | GE Global Research

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

    Reveal and Energy Smart consumer brands, and Evolve(tm), GTx(tm), Immersion(tm), Infusion(tm), Lumination(tm), Albeo(tm) and Tetra commercial brands, all trademarks of GE....

  14. Taking on the World's Toughest Problems | GE Global Research

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

    direct write2square The GE Store for Technology is Open for Business 2-4-13-v-3d-printing-medical-devices Invention Factory: How Will The World Get Smaller? ...

  15. Carrier Density Modulation in Ge Heterostructure by Ferroelectric Switching

    SciTech Connect (OSTI)

    Ponath, Patrick [University of Texas at Austin; Fredrickson, Kurt [University of Texas at Austin; Posadas, Agham B. [University of Texas at Austin; Ren, Yuan [University of Texas at Austin; Vasudevan, Rama K [ORNL; Okatan, Mahmut Baris [ORNL; Jesse, Stephen [ORNL; Aoki, Toshihiro [Arizona State University; McCartney, Martha [Arizona State University; Smith, David J [Arizona State University; Kalinin, Sergei V [ORNL; Lai, Keji [University of Texas at Austin; Demkov, Alexander A. [University of Texas at Austin

    2015-01-01T23:59:59.000Z

    The development of nonvolatile logic through direct coupling of spontaneous ferroelectric polarization with semiconductor charge carriers is nontrivial, with many issues, including epitaxial ferroelectric growth, demonstration of ferroelectric switching, and measurable semiconductor modulation. Here we report a true ferroelectric field effect carrier density modulation in an underlying Ge(001) substrate by switching of the ferroelectric polarization in the epitaxial c-axis-oriented BaTiO3 (BTO) grown by molecular beam epitaxy (MBE) on Ge. Using density functional theory, we demonstrate that switching of BTO polarization results in a large electric potential change in Ge. Aberration-corrected electron microscopy confirms the interface sharpness, and BTO tetragonality. Electron-energy-loss spectroscopy (EELS) indicates the absence of any low permittivity interlayer at the interface with Ge. Using piezoelectric force microscopy (PFM), we confirm the presence of fully switchable, stable ferroelectric polarization in BTO that appears to be single domain. Using microwave impedance microscopy (MIM), we clearly demonstrate a ferroelectric field effect.

  16. Direct band gap narrowing in highly doped Ge

    E-Print Network [OSTI]

    Han, Zhaohong

    Direct band gap narrowing in highly doped n-type Ge is observed through photoluminescence measurements by determining the spectrum peak shift. A linear relationship between the direct band gap emission and carrier concentration ...

  17. Growth strategies to control tapering in Ge nanowires

    SciTech Connect (OSTI)

    Periwal, P.; Baron, T., E-mail: thierry.baron@cea.fr; Salem, B.; Bassani, F. [Laboratoire des Technologies de la Microelectronique (LTM), UMR 5129 CNRS-UJF, CEA Grenoble, 17 Rue des Martyrs, 38054 Grenoble (France); Gentile, P. [SiNaPs Laboratory SP2M, UMR-E, CEA/UJF-Grenoble 1, INAC, 38054 Grenoble (France)

    2014-04-01T23:59:59.000Z

    We report the effect of PH{sub 3} on the morphology of Au catalyzed Ge nanowires (NWs). Ge NWs were grown on Si (111) substrate at 400?°C in the presence of PH{sub 3}, using vapor-liquid-solid method by chemical vapor deposition. We show that high PH{sub 3}/GeH{sub 4} ratio causes passivation at NW surface. At high PH{sub 3} concentration phosphorous atoms attach itself on NW surface and form a self-protection coating that prevents conformal growth and leads to taper free nanostructures. However, in case of low PH{sub 3} flux the combination of axial and radial growth mechanism occurs resulting in conical structure. We have also investigated axial PH{sub 3}-intrinsic junctions in Ge NWs. The unusual NW shape is attributed to a combination of catalyzed, uncatalyzed and diffusion induced growth.

  18. Nanocrystalline Ge Flash Memories: Electrical Characterization and Trap Engineering

    E-Print Network [OSTI]

    Kan, Eric Win Hong

    Conventional floating gate non-volatile memories (NVMs) present critical issues for device scalability beyond the sub-90 nm node, such as gate length and tunnel oxide thickness reduction. Nanocrystalline germanium (nc-Ge) ...

  19. Discovery of Isotopes of Elements with Z $\\ge$ 100

    E-Print Network [OSTI]

    M. Thoennessen

    2012-03-09T23:59:59.000Z

    Currently, 163 isotopes of elements with Z $\\ge$ 100 have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  20. Ge-on-Si laser operating at room temperature

    E-Print Network [OSTI]

    Liu, Jifeng

    Monolithic lasers on Si are ideal for high-volume and large-scale electronic–photonic integration. Ge is an interesting candidate owing to its pseudodirect gap properties and compatibility with Si complementary metal oxide ...

  1. High-Speed Network Enables Industrial Internet | GE Global Research

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

    share on LinkedIn (Opens in new window) Click to share on Tumblr (Opens in new window) GE Unveils High-Speed Network Infrastructure to Connect Machines, Data and People at Light...

  2. GE Software Expert Julian Keith Loren Discusses Innovation and...

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

    GE Software Expert Julian Keith Loren Discusses Innovation and the Industrial Internet Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window)...

  3. Technology "Relay Race" Against Cancer | GE Global Research

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

    GE Scientists in Technology "Relay Race" Against Cancer Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new...

  4. An Update on the Brazil Tech Center | GE Global Research

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

    desde meu ultimo update a voces sobre o Centro de Pesquisas da GE no Rio de Janeiro, Brasil e tambm minha terra natal 2011 foi um timo ano para mim. Depois de viver na...

  5. Construction progresses at GE's Oil & Gas Technology Center ...

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

    progressing at GE's newest research center, the Oil & Gas Technology Center in Oklahoma City Click to email this to a friend (Opens in new window) Share on Facebook (Opens...

  6. ECS Transactions 3, (7), 1211-1222 (2006) Characterization of Strained Si/SiGe with Raman, Pulsed MOS Capacitor

    E-Print Network [OSTI]

    Schroder, Dieter K.

    2006-01-01T23:59:59.000Z

    ECS Transactions 3, (7), 1211-1222 (2006) 1211 Characterization of Strained Si/SiGe with Raman silicon/relaxed SiGe/graded SiGe/Si samples. The effective generation lifetime depends on the defect defective SiGe. GOI statistical analysis shows worsening oxide breakdown as the Ge concentration in the SiGe

  7. (Limiting the greenhouse effect)

    SciTech Connect (OSTI)

    Rayner, S.

    1991-01-07T23:59:59.000Z

    Traveler attended the Dahlem Research Conference organized by the Freien Universitat, Berlin. The subject of the conference was Limiting the Greenhouse Effect: Options for Controlling Atmospheric CO{sub 2} Accumulation. Like all Dahlem workshops, this was a meeting of scientific experts, although the disciplines represented were broader than usual, ranging across anthropology, economics, international relations, forestry, engineering, and atmospheric chemistry. Participation by scientists from developing countries was limited. The conference was divided into four multidisciplinary working groups. Traveler acted as moderator for Group 3 which examined the question What knowledge is required to tackle the principal social and institutional barriers to reducing CO{sub 2} emissions'' The working rapporteur was Jesse Ausubel of Rockefeller University. Other working groups examined the economic costs, benefits, and technical feasibility of options to reduce emissions per unit of energy service; the options for reducing energy use per unit of GNP; and the significant of linkage between strategies to reduce CO{sub 2} emissions and other goals. Draft reports of the working groups are appended. Overall, the conference identified a number of important research needs in all four areas. It may prove particularly important in bringing the social and institutional research needs relevant to climate change closer to the forefront of the scientific and policy communities than hitherto.

  8. The Jefferson Lab 12 GeV Upgrade

    E-Print Network [OSTI]

    McKeown, R D

    2010-01-01T23:59:59.000Z

    Construction of the 12 GeV upgrade to the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility is presently underway. This upgrade includes doubling the energy of the electron beam to 12 GeV, the addition of a new fourth experimental hall, and the construction of upgraded detector hardware. An overview of this upgrade project is presented, along with highlights of the anticipated experimental program.

  9. The Jefferson Lab 12 GeV Upgrade

    E-Print Network [OSTI]

    R. D. McKeown

    2010-09-22T23:59:59.000Z

    Construction of the 12 GeV upgrade to the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility is presently underway. This upgrade includes doubling the energy of the electron beam to 12 GeV, the addition of a new fourth experimental hall, and the construction of upgraded detector hardware. An overview of this upgrade project is presented, along with highlights of the anticipated experimental program.

  10. AC transport in p-Ge/GeSi quantum well in high magnetic fields

    SciTech Connect (OSTI)

    Drichko, I. L.; Malysh, V. A.; Smirnov, I. Yu.; Golub, L. E.; Tarasenko, S. A. [A.F. Ioffe Physical Technical Institute of Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Suslov, A. V. [National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Mironov, O. A. [Warwick SEMINANO R and D Center, University of Warwick Science Park, Coventry CV4 7EZ (United Kingdom); Kummer, M.; Känel, H. von [Laboratorium für Festkörperphysik ETH Zürich, CH-8093 Zürich (Switzerland)

    2014-08-20T23:59:59.000Z

    The contactless surface acoustic wave technique is implemented to probe the high-frequency conductivity of a high-mobility p-Ge/GeSi quantum well structure in the regime of integer quantum Hall effect (IQHE) at temperatures 0.3–5.8 K and magnetic fields up to 18 T. It is shown that, in the IQHE regime at the minima of conductivity, holes are localized and ac conductivity is of hopping nature and can be described within the “two-site” model. The analysis of the temperature and magnetic-field-orientation dependence of the ac conductivity at odd filing factors enables us to determine the effective hole g-factor, |g{sub zz}|?4.5. It is shown that the in-plane component of the magnetic field leads to a decrease in the g-factor as well as increase in the cyclotron mass, which is explained by orbital effects in the complex valence band of germanium.

  11. Laser Driven Dynamic Loading of Condensed Matter

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

    Laser Driven Dynamic Loading of Condensed Matter Laser Driven Dynamic Loading of Condensed Matter Advanced diagnostics of experiments covering many orders of magnitude in strain...

  12. Developments in Chiral effective Field Theory for Nuclear Matter

    E-Print Network [OSTI]

    J. A. Oller

    2012-06-12T23:59:59.000Z

    We review on a chiral power counting scheme for in-medium chiral perturbation theory with nucleons and pions as degrees of freedom \\cite{ref}. It allows for a systematic expansion taking into account local as well as pion-mediated inter-nucleon interactions. Based on this power counting, one can identify classes of non-perturbative diagrams that require a resummation. We then calculate the nuclear matter energy density for the symmetric and purely neutron matter cases up-to-and-including next-to-leading order (NLO), in good agreement with sophisticated many-body calculations. Next, the neutron matter equation of state is applied to calculate the upper limit for neutron stars, with an upper bound around 2.3 solar masses, large enough to accommodate the most massive neutron star observed until now. We also apply our equation state to constraint $G_N$ in exceptionally large gravitational fields.

  13. Directional Dark Matter Detection Beyond the Neutrino Bound

    E-Print Network [OSTI]

    Philipp Grothaus; Malcolm Fairbairn; Jocelyn Monroe

    2014-09-30T23:59:59.000Z

    Coherent scattering of solar, atmospheric and diffuse supernovae neutrinos creates an irreducible background for direct dark matter experiments with sensitivities to WIMP-nucleon spin-independent scattering cross-sections of 10^(-46)-10^(-48) cm^2, depending on the WIMP mass. Even if one could eliminate all other backgrounds, this "neutrino floor" will limit future experiments with projected sensitivities to cross-sections as small as 10^(-48) cm^2. Direction-sensitive detectors have the potential to study dark matter beyond the neutrino bound by fitting event distributions in multiple dimensions: recoil kinetic energy, recoil track angle with respect to the sun, and event time. This work quantitatively explores the impact of direction-sensitivity on the neutrino bound in dark matter direct detection.

  14. A Radio for Hidden-Photon Dark Matter Detection

    E-Print Network [OSTI]

    Saptarshi Chaudhuri; Peter W. Graham; Kent Irwin; Jeremy Mardon; Surjeet Rajendran; Yue Zhao

    2014-11-26T23:59:59.000Z

    We propose a resonant electromagnetic detector to search for hidden-photon dark matter over an extensive range of masses. Hidden-photon dark matter can be described as a weakly coupled "hidden electric field," oscillating at a frequency fixed by the mass, and able to penetrate any shielding. At low frequencies (compared to the inverse size of the shielding), we find that observable effect of the hidden photon inside any shielding is a real, oscillating magnetic field. We outline experimental setups designed to search for hidden-photon dark matter, using a tunable, resonant LC circuit designed to couple to this magnetic field. Our "straw man" setups take into consideration resonator design, readout architecture and noise estimates. At high frequencies,there is an upper limit to the useful size of a single resonator set by $1/\

  15. Members of a workshop at the tenth IAYC Conference, July 7, 2006 1. ge -hak -te le -ber, ge -fil -te -fish: sha-bes iz a far -ge -ni -gn

    E-Print Network [OSTI]

    Finkel, Raphael

    A SUDE Members of a workshop at the tenth IAYC Conference, July 7, 2006 = 90 4 4 1. ge - hak - te le - ber, ge - fil - te - fish: sha- bes iz a far - ge - ni - gn 2. kha - le gri - vn, ku - gl yoykh: ku - men on di ma - khe - to - nem. 3. shtru - dl, tsi - mes, zi - se kalte: a su - de vos men vet ge

  16. Co silicide formation on SiGeC/Si and SiGe/Si layers R. A. Donatona)

    E-Print Network [OSTI]

    on the total strain energy in the layer and restricts the applications where high Ge concentrations are needed spectrometry, secondary ion mass spectroscopy SIMS , and four point probe for sheet resistance measure- ments

  17. Light Dark Matter in the light of CRESST-II

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kopp, Joachim; Schwetz, Thomas; Zupan, Jure

    2012-03-01T23:59:59.000Z

    Recently the CRESST collaboration has published the long anticipated results of their direct Dark Matter (DM) detection experiment with a CaWO4 target. The number of observed events exceeds known backgrounds at more than 4? significance, and this excess could potentially be due to DM scattering. We confront this interpretation with null results from other direct detection experiments for a number of theoretical models, and find that consistency is achieved in non-minimal models such as inelastic DM and isospin-violating DM. In both cases mild tension with constraints remain. The CRESST data can, however, not be reconciled with the null results andmore »with the positive signals from DAMA and CoGeNT simultaneously in any of the models we study.« less

  18. Light Dark Matter in the light of CRESST-II

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kopp, Joachim; Schwetz, Thomas; Zupan, Jure

    2012-03-01T23:59:59.000Z

    Recently the CRESST collaboration has published the long anticipated results of their direct Dark Matter (DM) detection experiment with a CaWO4 target. The number of observed events exceeds known backgrounds at more than 4? significance, and this excess could potentially be due to DM scattering. We confront this interpretation with null results from other direct detection experiments for a number of theoretical models, and find that consistency is achieved in non-minimal models such as inelastic DM and isospin-violating DM. In both cases mild tension with constraints remain. The CRESST data can, however, not be reconciled with the null results and with the positive signals from DAMA and CoGeNT simultaneously in any of the models we study.

  19. A Superheated Droplet Detector for Dark Matter Search

    E-Print Network [OSTI]

    Hamel, L A; Rainville, L; Sur, B; Zacek, V

    1997-01-01T23:59:59.000Z

    We discuss the operation principle of a detector based on superheated droplets of Freon-12 and its feasibility for the search of weakly interacting cold dark matter particles. In particular we are interested in a neutralino search experiment in the mass range from 10 to 10^4 GeV/c^2 and with a sensitivity of better than 10^-2 events/kg/d. We show that our new proposed detector can be operated at ambient pressure and room temperature in a mode where it is exclusively sensitive to nuclear recoils like those following neutralino interactions, which allows a powerful background discrimination. An additional advantage of this technique is due to the fact that the detection material, Freon-12, is cheap and readily available in large quantities. Moreover we were able to show that piezoelectric transducers allow efficient event localization in large volumes.

  20. A Superheated Droplet Detector for Dark Matter Search

    E-Print Network [OSTI]

    L. A. Hamel; L. Lessard; L. Rainville; B. Sur; V. Zacek

    1996-12-15T23:59:59.000Z

    We discuss the operation principle of a detector based on superheated droplets of Freon-12 and its feasibility for the search of weakly interacting cold dark matter particles. In particular we are interested in a neutralino search experiment in the mass range from 10 to 10^4 GeV/c^2 and with a sensitivity of better than 10^-2 events/kg/d. We show that our new proposed detector can be operated at ambient pressure and room temperature in a mode where it is exclusively sensitive to nuclear recoils like those following neutralino interactions, which allows a powerful background discrimination. An additional advantage of this technique is due to the fact that the detection material, Freon-12, is cheap and readily available in large quantities. Moreover we were able to show that piezoelectric transducers allow efficient event localization in large volumes.

  1. The Energy of Charged Matter

    E-Print Network [OSTI]

    Jan Philip Solovej

    2004-06-07T23:59:59.000Z

    In this talk I will discuss some of the techniques that have been developed over the past 35 years to estimate the energy of charged matter. These techniques have been used to solve stability of (fermionic) matter in different contexts, and to control the instability of charged bosonic matter. The final goal will be to indicate how these techniques with certain improvements can be used to prove Dyson's 1967 conjecture for the energy of a charged Bose gas--the sharp $N^{7/5}$ law.

  2. The Unification and Cogeneration of Dark Matter and Baryonic Matter

    E-Print Network [OSTI]

    S. M. Barr

    2011-09-18T23:59:59.000Z

    In grand unified theories with gauge groups larger than SU(5), the multiplets that contain the known quarks and leptons also contain fermions that are singlets under the Standard Model gauge group. Some of these could be the dark matter of the universe. Grand unified theories can also have accidental U(1) global symmetries (analogous to B-L in minimal SU(5)) that can stabilize dark matter. These ideas are illustrated in an SU(6) model.

  3. The Unification and Cogeneration of Dark Matter and Baryonic Matter

    E-Print Network [OSTI]

    Barr, S M

    2011-01-01T23:59:59.000Z

    In grand unified theories with gauge groups larger than SU(5), the multiplets that contain the known quarks and leptons also contain fermions that are singlets under the Standard Model gauge group. Some of these could be the dark matter of the universe. Grand unified theories can also have accidental U(1) global symmetries (analogous to B-L in minimal SU(5)) that can stabilize dark matter. These ideas are illustrated in an SU(6) model.

  4. The Limits of Quintessence

    SciTech Connect (OSTI)

    Caldwell, R.R.; Linder, Eric V.

    2005-05-24T23:59:59.000Z

    We present evidence that the simplest particle-physics scalar-field models of dynamical dark energy can be separated into distinct behaviors based on the acceleration or deceleration of the field as it evolves down its potential towards a zero minimum. We show that these models occupy narrow regions in the phase-plane of w and w', the dark energy equation-of-state and its time-derivative in units of the Hubble time. Restricting an energy scale of the dark energy microphysics limits how closely a scalar field can resemble a cosmological constant. These results, indicating a desired measurement resolution of order \\sigma(w')\\approx (1+w), define firm targets for observational tests of the physics of dark energy.

  5. GE & AE Extension Request Form, Version 7, Feb 2013, JC Program Change

    E-Print Network [OSTI]

    Escher, Christine

    GE & AE Extension Request Form, Version 7, Feb 2013, JC Program Change Pathway Today's Date to General English. How many sessions of GE do you wish to request? 1 2 3 4 (GE sessions are 5 weeks) How many GE hours do you wish to take? 21 hours 27 hours OR ____ I am a Pathway student, and I would like

  6. CTu2J.1.pdf CLEO Technical Digest OSA 2012 Light Emission in Ge Quantum Wells

    E-Print Network [OSTI]

    Miller, David A. B.

    CTu2J.1.pdf CLEO Technical Digest © OSA 2012 Light Emission in Ge Quantum Wells Edward T. Fei1 Engineering, Stanford University, Stanford, CA 94305, USA edfei@stanford.edu Abstract: We present the Ge/SiGe and electroluminescence show enhanced optical properties over bulk Ge. Further optical enhancement is observed in disk

  7. College of Engineering Partner Schools Australia Melbourne University, Melbourne GE3*

    E-Print Network [OSTI]

    Lee, Tonghun

    College of Engineering Partner Schools Australia Melbourne University, Melbourne ­ GE3* University of New South Wales, New South Wales ­ GE3* Austria Technical University of Vienna, Vienna - GE3* Chile Universidad del Bio Bio, Concepcion China Xiamen University, Xiamen ­ GE3* Denmark Aalborg University, Aalborg

  8. On the Comparison of Fisher Information of the Weibull and GE Distributions

    E-Print Network [OSTI]

    Kundu, Debasis

    On the Comparison of Fisher Information of the Weibull and GE Distributions Rameshwar D. Gupta exponen- tial (GE) and Weibull distributions for complete and Type-I censored observations. Fisher is much more than the GE distribution. We compute the total information of the Weibull and GE

  9. C-band side-entry Ge quantum-well electroabsorption modulator on SOI

    E-Print Network [OSTI]

    Miller, David A. B.

    C-band side-entry Ge quantum-well electroabsorption modulator on SOI operating at 1 V swing J. Modulation was due to the quantum-confined Stark effect from ten Ge/SiGe quantum wells epitaxially grown the totally internally reflecting air-SiGe interface and a frustrated total internal reflection from

  10. University of California and HRL Laboratories, LLC. All rights reserved. SiGe/Si SUPERLATTICE COOLERS

    E-Print Network [OSTI]

    © University of California and HRL Laboratories, LLC. All rights reserved. SiGe/Si SUPERLATTICE and characterization of SiGe/Si superlattice coolers are described. Superlattice structures were used to enhance for SiGe/Si superlattice coolers. SiGe is a good thermoelectric material for high temperature

  11. Strain Relaxation of SiGe on Compliant BPSG and Its Applications

    E-Print Network [OSTI]

    Strain Relaxation of SiGe on Compliant BPSG and Its Applications Haizhou Yin A DISSERTATION of SiGe on compliant borophosphosilicate glass (BPSG). Through modeling and experiments it has been shown that strain relaxation in the SiGe film can be induced by lateral expansion and buckling of the SiGe

  12. OPTIMIZATION OF a-SiGe BASED TRIPLE, TANDEM AND SINGLE-JUNCTION SOLAR Xunming Deng

    E-Print Network [OSTI]

    Deng, Xunming

    OPTIMIZATION OF a-SiGe BASED TRIPLE, TANDEM AND SINGLE-JUNCTION SOLAR CELLS Xunming Deng Department cells, all employing high- quality a-SiGe cells, are reviewed in this paper. Incorporating various improvements in device fabrication, the UT group fabricated 1) triple-junction a-Si/a-SiGe/a- SiGe solar cells

  13. SiGe virtual substrate HMOS transistor for analogue applications K. Michelakisa,*

    E-Print Network [OSTI]

    Papavassiliou, Christos

    SiGe virtual substrate HMOS transistor for analogue applications K. Michelakisa,* , S Abstract Silicon­germanium (SiGe) heterojunction metal-oxide-semiconductor field-effect transistors (SiGe design. The results suggest that the realisation of buried-channel SiGe n-HMOSFETs is feasible in MOS

  14. SiGe-On-Insulator (SGOI): Two Structures for CMOS Application

    E-Print Network [OSTI]

    SiGe-On-Insulator (SGOI): Two Structures for CMOS Application Zhiyuan Cheng,a) Jongwan Jung, b Massachusetts Avenue, Cambridge, MA 02141 a) E-mail: cheng@alum.MIT.EDU Abstract ­ Two SiGe-on-insulator (SGOI enhancement on both electron and hole mobilities. Keywords ­ strained-Si, SiGe, SiGe-on-Insulator, SGOI

  15. The Conformal Universe III: Basic Mechanisms of Matter Generation

    E-Print Network [OSTI]

    Renato Nobili

    2014-12-22T23:59:59.000Z

    This is the last of three papers on Conformal General Relativity (CGR), which describes inflation as a process primed by the spontaneous breakdown of a conformal-symmetric instable vacuum and the big bang as a sudden transfer of energy from geometry to matter. This process is driven by the interaction of a ghost scalar field $\\sigma$, called the {\\em dilation field}, with a scalar field $\\varphi$ behaving as a Higgs field of varying mass. Inflation ends when the interaction potential vanishes and $\\sigma,\\varphi$ amplitudes converge to their expectation values in a stable vacuum. Explicit solutions of $\\sigma, \\varphi$ dynamics in the semiclassical approximation are exemplified by numerical simulations. In order that the theory may survive quantization, the perfect vanishing of the total zero-point energy density of all involved fields must be postulated, which is equivalent to extending the correspondence principle of Bohr to quantum field theory. Since inflation actually is an adiabatic thermodynamic process, the temperature $T_B\\simeq 142$\\,GeV and the effective degeneracy $g_{*s}(T_B)\\simeq 0.887$ of Higgs-boson entropy at big bang are easily found. The application of entropy-conservation property then results in striking predictions. In particular, given the Higg-boson mass $\\mu_H\\simeq 126.5$ GeV and self-coupling constant $\\lambda\\simeq 0.132$, and the temperature $T_{BK}= 2.35\\times 10^{-13}$ and effective entropy degeneracy $g_{*s}(T_{BK})\\simeq 3.91$ of the current cosmic-background radiation, the cosmological constant $\\rho_{\\hbox{vac}}\\simeq 6.91\\times 10^{-47}$GeV$^4$ and expansion factor across inflation $F\\simeq 1.32\\times 10^{27}$ are predicted.

  16. Upper limits for the photoproduction cross section for the Phi--(1860) pentaquark state off the deuteron

    SciTech Connect (OSTI)

    Hovanes Egiyan

    2012-01-01T23:59:59.000Z

    We searched for the {Phi}{sup --}(1860) pentaquark in the photoproduction process off the deuteron in the {Xi}{sup -} {pi}{sup -} decay channel using CLAS. The invariant mass spectrum of the {Xi}{sup -} {pi}{sup -} system does not indicate any statistically significant enhancement near the reported mass M = 1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90% confidence level upper limit of 0.7 nb for the photoproduction cross section of {Phi}{sup --}(1860) with a consecutive decay into {Xi}{sup -} {pi}{sup -} in the photon energy range 4.5 GeV < E{sub {gamma}} < 5.5 GeV.

  17. Constraints on dark matter annihilation from CMB observations before Planck

    SciTech Connect (OSTI)

    Lopez-Honorez, Laura [Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes, Pleinlaan 2, B-1050 Brussels (Belgium); Mena, Olga; Palomares-Ruiz, Sergio; Vincent, Aaron C., E-mail: llopezho@vub.ac.be, E-mail: omena@ific.uv.es, E-mail: sergio.palomares.ruiz@ist.utl.pt, E-mail: vincent@ific.uv.es [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de Valčncia, Apartado de Correos 22085, E-46071 Valencia (Spain)

    2013-07-01T23:59:59.000Z

    We compute the bounds on the dark matter (DM) annihilation cross section using the most recent Cosmic Microwave Background measurements from WMAP9, SPT'11 and ACT'10. We consider DM with mass in the MeV–TeV range annihilating 100% into either an e{sup +}e{sup ?} or a ?{sup +}?{sup ?} pair. We consider a realistic energy deposition model, which includes the dependence on the redshift, DM mass and annihilation channel. We exclude the canonical thermal relic abundance cross section ((?v) = 3 × 10{sup ?26}cm{sup 3}s{sup ?1}) for DM masses below 30 GeV and 15 GeV for the e{sup +}e{sup ?} and ?{sup +}?{sup ?} channels, respectively. A priori, DM annihilating in halos could also modify the reionization history of the Universe at late times. We implement a realistic halo model taken from results of state-of-the-art N-body simulations and consider a mixed reionization mechanism, consisting on reionization from DM as well as from first stars. We find that the constraints on DM annihilation remain unchanged, even when large uncertainties on the halo model parameters are considered.

  18. Strain-induced self-assembly of Ge nanodashes, nanodumbbells, and dot chains on Si(001)

    SciTech Connect (OSTI)

    Zhang, J. J. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany) [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany); Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Schmidt, O. G. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany) [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden (Germany); Center for Advancing Electronics Dresden, TU Dresden (Germany)

    2013-09-30T23:59:59.000Z

    We investigate the growth of self-assembled Ge nanostructures on top of embedded Ge nanowires on Si(001) substrates. Ge nanostructures, such as nanodashes, nanodumbbells, and dot chains are observed simply by tuning the growth temperature and thickness of the Si spacer between the Ge layers. The self-assembly process is governed by the surface strain fields generated by the embedded Ge nanowires and is well-described by our theoretical calculations. The catalyst-free and horizontal growth of such Ge nanostructures directly on Si(001) is attractive for investigating exotic transport properties through Si/Ge-based quantum devices.

  19. Background p(450 GeV/c)-p,d (NA51)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    #12;#12;Background ' Open charm J / Drell-Yan #12;* p(450 GeV/c)-p,d (NA51) 208 16 p(200 Ge) 32 p(450 GeV/c)-A (A=C,Al,Cu,W) (NA38) 10101 10101010 652 3 4 B targetprojectile B(J/)/(AB)(nb) 5 4 3 Pb(208x158 GeV/c)-Pb (NA50) S(32x200 GeV/c)-U (NA38) p(200 GeV/c)-W (NA38) p(450 GeV/c)-A (A=p,d) (NA

  20. Hypothetical Dark Matter/Axion rockets: What can be said about Dark Matter in terms of space physics propulsion

    SciTech Connect (OSTI)

    Beckwith, Andrew [APS/Fermi contractor Aurora, Illinois 60502 630-840-2201 (United States)

    2009-03-16T23:59:59.000Z

    This paper discusses dark matter (DM) particle candidates from non-supersymmetry (SUSY) processes and explores how a DM candidate particle in the 100-400 GeV range could be created. Thrust from DM particles is also proposed for Photon rocket and Axion rockets. It would use a magnetic field to convert DM particles to near photonlike particles in a chamber to create thrust from the discharge of the near-photon-like particles. The presence of DM particles would suggest that thrust from the emerging near-photon-like particle would be greater than with conventional photon rockets. This amplifies and improves on an 'axion rocket ramjet' for interstellar travel. It is assumed that the same methodology used in an axion ramjet could be used with DM, with perhaps greater thrust/power conversion efficiencies.

  1. Photoluminescence and positron annihilation spectroscopy investigation of (Ge, Er) codoped Si oxides deposited by magnetron sputtering

    SciTech Connect (OSTI)

    Heng, C. L.; Chelomentsev, E.; Peng, Z. L.; Mascher, P. [Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4K1 (Canada); Simpson, P. J. [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

    2009-01-01T23:59:59.000Z

    We have investigated the nature of violet-blue emission from (Ge, Er) codoped Si oxides (Ge+Er+SiO{sub 2}) using photoluminescence (PL) and positron annihilation spectroscopy (PAS) measurements. The PL spectra and PAS analysis for a control Ge-doped SiO{sub 2} (Ge+SiO{sub 2}) indicate that Ge-associated neutral oxygen vacancies (Ge-NOV) are likely responsible for the major emission in the violet-blue band. For Ge+Er+SiO{sub 2}, both Ge-NOV and GeO color centers are believed to be responsible for the emission band. The addition of Er has a significant influence on the emission, which is discussed in terms of Er-concentration-related structural change in the Ge+Er+SiO{sub 2}.

  2. Physical Protection of Classified Matter

    Broader source: Directives, Delegations, and Requirements [Office of Management (MA)]

    1988-02-03T23:59:59.000Z

    The order establishes policy and objectives for physical protection of classified matter. This directive does not cancel another directive. Chg 1, 7-30-93. Canceled by 5632.1C.

  3. Radio observations of the Galactic Centre and the Coma cluster as a probe of light dark matter self-annihilations and decay

    E-Print Network [OSTI]

    Celine Boehm; Joseph Silk; Torsten Ensslin

    2010-09-30T23:59:59.000Z

    We update our earlier calculations of gamma ray and radio observational constraints on annihilations of dark matter particles lighter than 10 GeV. We predict the synchrotron spectrum as well as the morphology of the radio emission associated with light decaying and annihilating dark matter candidates in both the Coma cluster and the Galactic Centre. Our new results basically confirm our previous findings: synchrotron emission in the very inner part of the Milky Way constrains or even excludes dark matter candidates if the magnetic field is larger than 50 micro Gauss. In fact, our results suggest that light annihilating candidates must have a S-wave suppressed pair annihilation cross section into electrons (or the branching ratio into electron positron must be small). If dark matter is decaying, it must have a life time that is larger than t = 3. 10^{25} s. Therefore, radio emission should always be considered when one proposes a "light" dark matter candidate.

  4. ?CDM cosmology from matter only

    E-Print Network [OSTI]

    Herman Telkamp

    2015-04-08T23:59:59.000Z

    I discuss a matter-only interpretation of {\\Lambda}CDM cosmology, based on conservation of energy and assuming a Machian definition of inertia. {\\Lambda}CDM cosmology can be linked to a Newtonian cosmic potential, subject to a propagating gravitational horizon. In a matter-only universe where total energy is conserved, Machian inertia related to the evolving potential may cause both deceleration and acceleration of recession.

  5. Shear viscosity of nuclear matter

    E-Print Network [OSTI]

    Jun Xu

    2013-02-01T23:59:59.000Z

    In this talk I report my recent study on the shear viscosity of neutron-rich nuclear matter from a relaxation time approach. An isospin- and momentum-dependent interaction is used in the study. Effects of density, temperature, and isospin asymmetry of nuclear matter on its shear viscosity have been discussed. Similar to the symmetry energy, the symmetry shear viscosity is defined and its density and temperature dependence are studied.

  6. Dark Matter Triggers of Supernovae

    E-Print Network [OSTI]

    Peter W. Graham; Surjeet Rajendran; Jaime Varela

    2015-05-17T23:59:59.000Z

    The transit of primordial black holes through a white dwarf causes localized heating around the trajectory of the black hole through dynamical friction. For sufficiently massive black holes, this heat can initiate runaway thermonuclear fusion causing the white dwarf to explode as a supernova. The shape of the observed distribution of white dwarfs with masses up to $1.25 M_{\\odot}$ rules out primordial black holes with masses $\\sim 10^{19}$ gm - $10^{20}$ gm as a dominant constituent of the local dark matter density. Black holes with masses as large as $10^{24}$ gm will be excluded if recent observations by the NuStar collaboration of a population of white dwarfs near the galactic center are confirmed. Black holes in the mass range $10^{20}$ gm - $10^{22}$ gm are also constrained by the observed supernova rate, though these bounds are subject to astrophysical uncertainties. These bounds can be further strengthened through measurements of white dwarf binaries in gravitational wave observatories. The mechanism proposed in this paper can constrain a variety of other dark matter scenarios such as Q balls, annihilation/collision of large composite states of dark matter and models of dark matter where the accretion of dark matter leads to the formation of compact cores within the star. White dwarfs, with their astronomical lifetimes and sizes, can thus act as large space-time volume detectors enabling a unique probe of the properties of dark matter, especially of dark matter candidates that have low number density. This mechanism also raises the intriguing possibility that a class of supernova may be triggered through rare events induced by dark matter rather than the conventional mechanism of accreting white dwarfs that explode upon reaching the Chandrasekhar mass.

  7. Valley splitting in Si quantum dots embedded in SiGe S. Srinivasan,1,2

    E-Print Network [OSTI]

    Rokhinson, Leonid

    Valley splitting in Si quantum dots embedded in SiGe S. Srinivasan,1,2 G. Klimeck,1,2 and L. P subband.4 Recently, calculations predicted that valley splitting in nar- row few nanometers SiGe/Si/SiGe that prediction, which has been explained12 by the disorders of the Si/SiGe interface and in the SiGe buffer

  8. Gamma-ray probes of dark matter substructure

    SciTech Connect (OSTI)

    Campbell, Sheldon [Department of Physics and Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210 (United States)

    2014-06-24T23:59:59.000Z

    The substructure content of dark matter halos is interesting because it can be affected by complex galaxy physics and dark matter particle physics. However, observing the small scale structure of dark matter is a challenge. The subhalo abundance (mass function, minimum mass) and morphology (density profile, subhalo shape, subsubstructure) contain information about complex astrophysics (halo formation processes) and new exotic fundamental physics (dark matter interactions). Indirect detection of dark matter annihilation radiation (DMAR) in gamma rays may be the most direct method for observing small scale structure. I outline the ways in which gamma rays may probe halo substructure. If substructure is bountiful, it may be responsible for the eventual discovery of DMAR, for instance in galaxy clusters or the diffuse gamma-ray background. Otherwise, the observation of DMAR in places without much substructure, such as the Galactic center, would lead to strict limits on the properties of small scale structure. Properties of the gamma-ray angular power spectrum will also provide information or constraints on Milky Way halo substructure.

  9. Two field matter bounce cosmology

    SciTech Connect (OSTI)

    Cai, Yi-Fu; McDonough, Evan; Duplessis, Francis; Brandenberger, Robert H., E-mail: yifucai@physics.mcgill.ca, E-mail: evanmc@physics.mcgill.ca, E-mail: francis.duplessis@mail.mcgill.ca, E-mail: rhb@hep.physics.mcgill.ca [Department of Physics, McGill University, Montréal, QC H3A 2T8 (Canada)

    2013-10-01T23:59:59.000Z

    We re-examine the non-singular Matter Bounce scenario first developed in [20], which starts with a matter-dominated period of contraction and transitions into an Ekpyrotic phase of contraction. We consider both matter fields, the first of which plays the role of regular matter, and the second of which is responsible for the non-singular bounce. Since the dominant matter field is massive, the induced curvature fluctuations are initially not scale-invariant, whereas the fluctuations of the second scalar field (which are initially entropy fluctuations) are scale-invariant. We study the transfer of the initial entropy perturbations into curvature fluctuations in the matter-dominated phase of contraction and show that the latter become nearly scale invariant on large scales but are blue tilted on small scales. We study the evolution of both curvature and entropy fluctuations through the bounce, and show that both have a scale-invariant spectrum which is blue-tilted on small scales. However, we find that the entropy fluctuations have an amplitude that is much smaller than that of the curvature perturbations, due to gravitational amplification of curvature perturbations during the bounce phase.

  10. Comparison of luminescent efficiency of InGaAs quantum well structures grown on Si, GaAs, Ge, and SiGe virtual substrate

    E-Print Network [OSTI]

    , and SiGe virtual substrate V. K. Yang, S. M. Ting, M. E. Groenert, M. T. Bulsara, M. T. Currie, C. W efficiency of InGaAs quantum wells on Si via SiGe interlayers, identical In0.2Ga0.8As quantum well structures metalorganic vapor deposition system. The substrates used include GaAs, Si, Ge, and SiGe virtual substrates

  11. Quark Matter, Massive Stars and Strange Planets

    E-Print Network [OSTI]

    F. Weber; Ch. Schaab; M. K. Weigel; N. K. Glendenning

    1996-04-09T23:59:59.000Z

    This paper gives an overview of the properties of all possible equilibrium sequences of compact strange-matter stars with nuclear crusts, which range from strange stars to strange dwarfs. In contrast to their non-strange counterparts, --neutron stars and white dwarfs--, their properties are determined by two (rather than one) parameters, the central star density and the density at the base of the nuclear crust. This leads to stellar strange-matter configurations whose properties are much more complex than those of the conventional sequence. As an example, two generically different categories of stable strange dwarfs are found, which could be the observed white dwarfs. Furthermore we find very low-mass strange stellar objects, with masses as small as those of Jupiter or even lighter planets. Such objects, if abundant enough in our Galaxy, should be seen by the presently performed gravitational microlensing searches. Further aspects studied in this paper concern the limiting rotational periods and the cooling behavior of neutron stars and their strange counterparts.

  12. Mrk 421, Mrk 501, and 1ES 1426+428 at 100 GeV with the CELESTE Cherenkov Telescope

    E-Print Network [OSTI]

    Smith, D A; Britto, R; Bruel, P; Gordo, J B; Dumora, D; Durand, E; Eschstruth, P; Espigat, P; Holder, J; Jacholkowska, A; Lavalle, J; Le Gallou, R; Lott, B; Manseri, H; Munz, F; Nuss, E; Piron, Frédéric; Reposeur, T; Sako, T

    2006-01-01T23:59:59.000Z

    We have measured the gamma-ray fluxes of the blazars Mrk 421 and Mrk 501 in the energy range between 50 and 350 GeV (1.2 to 8.3 x 10^25 Hz). The detector, called CELESTE, used first 40, then 53 heliostats of the former solar facility "Themis" in the French Pyrenees to collect Cherenkov light generated in atmospheric particle cascades. The signal from Mrk 421 is often strong. We compare its flux with previously published multi-wavelength studies and infer that we are straddling the high energy peak of the spectral energy distribution. The signal from Mrk 501 in 2000 was weak (3.4 sigma). We obtain an upper limit on the flux from 1ES 1426+428 of less than half that of the Crab flux near 100 GeV. The data analysis and understanding of systematic biases have improved compared to previous work, increasing the detector's sensitivity.

  13. Mrk 421, Mrk 501, and 1ES 1426+428 at 100 GeV with the CELESTE Cherenkov Telescope

    E-Print Network [OSTI]

    D. A. Smith; E. Brion; R. Britto; P. Bruel; J. Bussons Gordo; D. Dumora; E. Durand; P. Eschstruth; P. Espigat; J. Holder; A. Jacholkowska; J. Lavalle; R. Le Gallou; B. Lott; H. Manseri; F. Munz; E. Nuss; F. Piron; R. C. Rannot; T. Reposeur; T. Sako

    2006-08-19T23:59:59.000Z

    We have measured the gamma-ray fluxes of the blazars Mrk 421 and Mrk 501 in the energy range between 50 and 350 GeV (1.2 to 8.3 x 10^25 Hz). The detector, called CELESTE, used first 40, then 53 heliostats of the former solar facility "Themis" in the French Pyrenees to collect Cherenkov light generated in atmospheric particle cascades. The signal from Mrk 421 is often strong. We compare its flux with previously published multi-wavelength studies and infer that we are straddling the high energy peak of the spectral energy distribution. The signal from Mrk 501 in 2000 was weak (3.4 sigma). We obtain an upper limit on the flux from 1ES 1426+428 of less than half that of the Crab flux near 100 GeV. The data analysis and understanding of systematic biases have improved compared to previous work, increasing the detector's sensitivity.

  14. Magnetotransport in low-density p-Si/SiGe heterostructures : from metal through hopping insulator to Wigner glass.

    SciTech Connect (OSTI)

    Drichko, I. L.; Dyakonov, A. M.; Smirnov, I. Yu.; Suslov, A. V.; Galperin, Y. M.; Vinokur , V.; Myronov, M.; Mironov, O. A.; Leadley, D. R.; Materials Science Division; Russian Acadademy of Science; National High Magnetic Field Lab.; Univ. of Oslo; Musashi Inst. of Tech.; Univ.of Warwick

    2008-02-01T23:59:59.000Z

    We study dc and ac transport in low-density p-Si/SiGe heterostructures at low temperatures and in a broad domain of magnetic fields up to 18 T. Complex ac conductance is determined from simultaneous measurement of velocity and attenuation of a surface acoustic wave propagating in close vicinity of the two-dimensional hole layer. The observed behavior of dc and ac conductances is interpreted as an evolution from metallic conductance at B=0 through hopping between localized states in intermediate magnetic fields (close to the plateau of the integer quantum Hall effect corresponding to the Landau-level filling factor {nu}=1) to formation of the Wigner glass in the extreme quantum limit (B {ge} 14, T {le} 0.8 K).

  15. Constraints on GRB TeV Emission from the GeV Extragalactic Diffuse Gamma-Ray Flux

    E-Print Network [OSTI]

    Casanova, S; Zhang, B; Zhang, Bing

    2006-01-01T23:59:59.000Z

    TeV gamma rays emitted by GRBs are converted into electron-positron pairs via interactions with the extragalactic infrared radiation fields. In turn the pairs produced, whose trajectories are randomized by magnetic fields, will inverse Compton scatter off the cosmic microwave background photons. The beamed TeV gamma ray flux from GRBs is thus transformed into a GeV isotropic gamma ray flux, which contributes to the total extragalactic gamma-ray background emission. Assuming a model for the extragalactic radiation fields, for the GRB redshift distribution and for the GRB luminosity function, we use the measured GeV extragalactic gamma-ray flux to set upper limits on the GRB emission in TeV gamma rays that is predicted in several models.

  16. Searching for dark matter with helium atom

    E-Print Network [OSTI]

    Imre Ferenc Barna

    2006-08-10T23:59:59.000Z

    With the help of the boost operator we can model the interaction between a weakly interacting particle(WIMP) of dark matter(DAMA) and an atomic nuclei. Via this "kick" we calculate the total electronic excitation cross section of the helium atom. The bound spectrum of He is calculated through a diagonalization process with a configuration interaction (CI) wavefunction built up from Slater orbitals. All together 19 singly- and doubly-excited atomic sates were taken with total angular momenta of L=0,1 and 2. Our calculation may give a rude estimation about the magnitude of the total excitation cross section which could be measured in later scintillator experiments. The upper limit of the excitation cross section is $9.7\\cdot 10^{-8}$ barn.

  17. From massive gravity to dark matter density II

    E-Print Network [OSTI]

    G. Scharf

    2009-02-18T23:59:59.000Z

    As previously observed the massless limit of massive gravity leads to a modification of general relativity. Here we study spherically symmetric solutions of the modified field equations which contain normal matter together with a dark energy density. If the dark density profile is assumed to be known, the whole problem is reduced to a linear first order differential equation which can be solved by quadratures.

  18. el /SUB T/ -change in the KEK 12 GeV-PS

    SciTech Connect (OSTI)

    Ando, A.

    1985-10-01T23:59:59.000Z

    The beam intensity of the KEK 12 GeV-PS is presently about 4 x 10 S ppp and its deviation is about 7% in short time. But the stability of the spill of the extracted beam is not so good. The origin of this problem is unstable acceleration due to transition crossing at el approx. = 6.5. For the intensity, the increase by ten times is investigated, but the space charge limit is estimated about 2 x 10 T ppp (500 MeV injection) and 6.5 x 10 T ppp (1 GeV injection) where the horizontal and vertical emittances are 80 and 20 mm-mrad., the tune spread is 0.25 and the bunching factor is 0.3. The Keil-Schnell criteria give the limits as, for the transversal stability with zero-chromaticity: N /SUB i/ < 1.4 x 10 V US //eta// p/p, for the longitudinal stability: N /SUB ii/ < 8.8 x 10 Z BETASUPSILON//eta// ( p/p)S, where US and el are the Lorentz kinematical factors, /eta/ = el S - el S, and p/p is the FWHM of the momentum spread of the beam. In the above the impedances are roughly estimated from the transversal head-tail instability at 500 MeV, Z /SUB i/ ( ) approx. = 2 x 10V ( /m), Z /SUB ii/ ( )/n approx. = 30 ( ). At present, the injection energy is 500 MeV and typically p/p = 0.15%, then N /SUB i/ < 10 . To overcome this limit, the non-zero chromaticity scheme and the Landau damping by the octupole magnets are adopted.

  19. TEM Study on the Evolution of Ge Nanocrystals in Si Oxide Matrix as a Function of Ge Concentration and the Si Reduction Process

    E-Print Network [OSTI]

    Chew, Han Guan

    Growth and evolution of germanium (Ge) nanocrystals embedded into a silicon oxide (SiO?) system have been studied based on the Ge content of co-sputtered Ge-SiO? films using transmission electron microscopy (TEM) and X-ray ...

  20. Constraints on Resonant Dark Matter Annihilation

    E-Print Network [OSTI]

    Backovic, Mihailo

    2011-07-04T23:59:59.000Z

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.1 Thermally averaged cross section for a pole below threshold (blue line on the bottom) and above threshold (red line on the top). Parameters used for the purpose of the graphics are mX = 300GeV , gXXY = 0.1, ?Y = 3GeV . The resonance below... threshold lies 30GeV below the threshold 2mX , while the above threshold case is just 30GeV above the threshold. Notice that in both cases ??v? ? a + b/x + ... is not a good approximation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3.2 Thermal...