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Sample records for limits matter ge

  1. Window in the dark matter exclusion limits

    SciTech Connect (OSTI)

    Zaharijas, Gabrijela; Farrar, Glennys R. [Center for Cosmology and Particle Physics, New York University, New York, New York 10003 (United States)

    2005-10-15

    We consider the cross section limits for light dark matter cadnidates (m=0.4 to 10 GeV). We calculate the interaction of dark matter in the crust above underground dark matter detectors and find that in the intermediate cross section range, the energy loss of dark matter is sufficient to fall below the energy threshold of current underground experiments. This implies the existence of a window in the dark matter exclusion limits in the micro-barn range.

  2. A Window in the Dark Matter Exclusion Limits

    E-Print Network [OSTI]

    Gabrijela Zaharijas; Glennys R. Farrar

    2005-06-28

    We consider the cross section limits for light dark matter candidates ($m=0.4$ to 10 GeV). We calculate the interaction of dark matter in the crust above underground dark matter detectors and find that in the intermediate cross section range, the energy loss of dark matter is sufficient to fall below the energy threshold of current underground experiments. This implies the existence of a window in the dark matter exclusion limits in the micro-barn range.

  3. Direct Detection of sub-GeV Dark Matter with Semiconductor Targets

    E-Print Network [OSTI]

    Rouven Essig; Marivi Fernandez-Serra; Jeremy Mardon; Adrian Soto; Tomer Volansky; Tien-Tien Yu

    2015-09-04

    Dark matter in the sub-GeV mass range is a theoretically motivated but largely unexplored paradigm. Such light masses are out of reach for conventional nuclear recoil direct detection experiments, but may be detected through the small ionization signals caused by dark matter-electron scattering. Semiconductors are well-studied and are particularly promising target materials because their ${\\cal O}(1~\\rm{eV})$ band gaps allow for ionization signals from dark matter as light as a few hundred keV. Current direct detection technologies are being adapted for dark matter-electron scattering. In this paper, we provide the theoretical calculations for dark matter-electron scattering rate in semiconductors, overcoming several complications that stem from the many-body nature of the problem. We use density functional theory to numerically calculate the rates for dark matter-electron scattering in silicon and germanium, and estimate the sensitivity for upcoming experiments such as DAMIC and SuperCDMS. We find that the reach for these upcoming experiments has the potential to be orders of magnitude beyond current direct detection constraints and that sub-GeV dark matter has a sizable modulation signal. We also give the first direct detection limits on sub-GeV dark matter from its scattering off electrons in a semiconductor target (silicon) based on published results from DAMIC. We make available publicly our code, QEdark, with which we calculate our results. Our results can be used by experimental collaborations to calculate their own sensitivities based on their specific setup. The searches we propose will probe vast new regions of unexplored dark matter model and parameter space.

  4. A 750 GeV Portal: LHC Phenomenology and Dark Matter Candidates

    E-Print Network [OSTI]

    D'Eramo, Francesco; Panci, Paolo

    2016-01-01

    We study the effective field theory obtained by extending the Standard Model field content with two singlets: a 750 GeV (pseudo-)scalar and a stable fermion. Accounting for collider productions initiated by both gluon and photon fusion, we investigate where the theory is consistent with both the LHC diphoton excess and bounds from Run 1. We analyze dark matter phenomenology in such regions, including relic density constraints as well as collider, direct, and indirect bounds. Scalar portal dark matter models are very close to limits from direct detection if gluon fusion dominates, and not constrained at all otherwise. Pseudo-scalar models are challenged by photon line limits in most of the parameter space.

  5. A 750 GeV Portal: LHC Phenomenology and Dark Matter Candidates

    E-Print Network [OSTI]

    Francesco D'Eramo; Jordy de Vries; Paolo Panci

    2016-01-07

    We study the effective field theory obtained by extending the Standard Model field content with two singlets: a 750 GeV (pseudo-)scalar and a stable fermion. Accounting for collider productions initiated by both gluon and photon fusion, we investigate where the theory is consistent with both the LHC diphoton excess and bounds from Run 1. We analyze dark matter phenomenology in such regions, including relic density constraints as well as collider, direct, and indirect bounds. Scalar portal dark matter models are very close to limits from direct detection if gluon fusion dominates, and not constrained at all otherwise. Pseudo-scalar models are challenged by photon line limits in most of the parameter space.

  6. CONSTRAINING THE DISTRIBUTION OF DARK MATTER IN THE INNER GALAXY WITH AN INDIRECT DETECTION SIGNAL: THE CASE OF A TENTATIVE 130 GeV {gamma}-RAY LINE

    SciTech Connect (OSTI)

    Yang Ruizhi; Feng Lei; Li Xiang; Fan Yizhong

    2013-06-20

    Dark matter distribution in the very inner region of our Galaxy is still debated. In N-body simulations, a cuspy dark matter halo density profile is favored. Several dissipative baryonic processes, however, are found to be able to significantly flatten dark matter distribution, and a cored dark matter halo density profile is possible. Baryons dominate the gravitational potential in the inner Galaxy, hence a direct constraint on the abundance of dark matter particles is rather challenging. Recently, a few groups have identified a tentative 130 GeV line signal in the Galactic center, which could be interpreted as the signal of dark matter annihilation. Using current 130 GeV line data and adopting the generalized Navarro-Frenk-White profile of the dark matter halo-local dark matter density {rho}{sub 0} = 0.4 GeV cm{sup -3} and r{sub s} = 20 kpc-we obtain a 95% confidence level lower (upper) limit on the inner slope of dark matter density distribution, {alpha} = 1.06 (the cross section of dark matter annihilation into {gamma}-rays ({sigma}v){sub {chi}{chi}{sub {yields}{sub {gamma}{gamma}}}} = 1.3 Multiplication-Sign 10{sup -27} cm{sup 3} s{sup -1}). Such a slope is consistent with the results of some N-body simulations and, if the signal is due to dark matter, suggests that baryonic processes may be unimportant.

  7. GeV-scale dark matter: Production at the Main Injector

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

    Dobrescu, Bogdan A.; Frugiuele, Claudia

    2015-02-03

    Assuming that dark matter particles interact with quarks via a GeV-scale mediator, we study dark matter production in fixed target collisions. The ensuing signal in a neutrino near detector consists of neutral-current events with an energy distribution peaked at higher values than the neutrino background. We find that for a Z' boson of mass around a few GeV that decays to dark matter particles, the dark matter beam produced by the Main Injector at Fermilab allows the exploration of a range of values for the gauge coupling that currently satisfy all experimental constraints. The NO?A near detector is well positionedmore »for probing the presence of a dark matter beam, and future LBNF near detectors would provide more sensitive probes.« less

  8. GeV-scale dark matter: Production at the Main Injector

    SciTech Connect (OSTI)

    Dobrescu, Bogdan A.; Frugiuele, Claudia

    2015-02-03

    Assuming that dark matter particles interact with quarks via a GeV-scale mediator, we study dark matter production in fixed target collisions. The ensuing signal in a neutrino near detector consists of neutral-current events with an energy distribution peaked at higher values than the neutrino background. We find that for a Z' boson of mass around a few GeV that decays to dark matter particles, the dark matter beam produced by the Main Injector at Fermilab allows the exploration of a range of values for the gauge coupling that currently satisfy all experimental constraints. The NO?A near detector is well positioned for probing the presence of a dark matter beam, and future LBNF near detectors would provide more sensitive probes.

  9. Higgs-Portal Dark Matter for GeV Gamma-Ray Excess

    E-Print Network [OSTI]

    P. Ko; Wan-Il Park; Yong Tang

    2015-04-27

    We present Higgs-Portal dark matter (DM) models to explain the reported Galactic Center GeV gamma-ray excess. Naive effective theories are inconsistent with direct detection constraint for the relevant parameter range. Simple extended models with dark gauge symmetries can easily accommodate the gamma-ray excess through the Higgs-Portal coupling while satisfying various constraints.

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

    E-Print Network [OSTI]

    Dan Hooper; Brenda Dingus

    2002-10-29

    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.

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

    E-Print Network [OSTI]

    Hooper, D; Hooper, Dan; Dingus, Brenda

    2002-01-01

    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.

  12. Higgs portal, fermionic dark matter, and a Standard Model like Higgs at 125 GeV

    E-Print Network [OSTI]

    Laura Lopez-Honorez; Thomas Schwetz; Jure Zupan

    2012-07-09

    We show that fermionic dark matter (DM) which communicates with the Standard Model (SM) via the Higgs portal is a viable scenario, even if a SM-like Higgs is found at around 125 GeV. Using effective field theory we show that for DM with a mass in the range from about 60 GeV to 2 TeV the Higgs portal needs to be parity violating in order to be in agreement with direct detection searches. For parity conserving interactions we identify two distinct options that remain viable: a resonant Higgs portal, and an indirect Higgs portal. We illustrate both possibilities using a simple renormalizable toy model.

  13. Higgs portal vector dark matter for GeV scale ?-ray excess from galactic center

    SciTech Connect (OSTI)

    Ko, P.; Park, Wan-Il; Tang, Yong E-mail: wipark@kias.re.kr

    2014-09-01

    We show that the GeV scale ?-ray excess from the direction of the Galactic Center can be naturally explained by the pair annihilation of Abelian vector dark matter (VDM) into a pair of dark Higgs bosons (VV? ? ?), followed by the subsequent decay of ? into b b-bar or ? ?-bar  . All the processes are described by a renormalizable VDM model with the Higgs portal, which is naturally flavor-dependent. Some parameter space of this scenario can be tested at the near future direct dark matter search experiments such as LUX and XENON1T.

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

    E-Print Network [OSTI]

    CDMS Collaboration

    2002-08-16

    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.

  15. A tale of tails. Dark matter interpretations of the Fermi GeV excess in light of background model systematics

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

    Calore, Francesca; Cholis, Ilias; McCabe, Christopher; Weniger, Christoph

    2015-03-10

    Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. This excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular:more »(1) In the case of DM annihilation into bŻb, we find that even large DM masses up to m??74 GeV are allowed at p-value >0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from ?+?– with m? ~ 60–70 GeV can also account for the excess at higher latitudes, |b|>2°, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. In conclusion, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.« less

  16. Dark matter limits froma 15 kg windowless bubble chamber

    SciTech Connect (OSTI)

    Szydagis, Matthew Mark; /Chicago U.

    2010-12-01

    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.

  17. Low Mass Neutralino Dark Matter in the MSSM with Constraints from $B_s\\to ?^+?^-$ and Higgs Search Limits

    E-Print Network [OSTI]

    Daniel Feldman; Zuowei Liu; Pran Nath

    2010-05-21

    The region of low neutralino masses as low as (5-10) GeV has attracted attention recently due to the possibility of excess events above background in dark matter detectors. An analysis of spin independent neutralino-proton cross sections $\\SI$ which includes this low mass region is given. The analysis is done in MSSM with radiative electroweak symmetry breaking (REWSB). It is found that cross sections as large as $10^{-40}$ cm$^2$ can be accommodated in MSSM within the REWSB framework. However, inclusion of sparticle mass limits from current experiments, as well as lower limits on the Higgs searches from the Tevatron, and the current experimental upper limit on $B_s\\to \\mu^+\\mu^-$ significantly limit the allowed parameter space reducing $\\SI$ to lie below $\\sim 10^{-41}$cm$^2$ or even lower for neutralino masses around 10 GeV. These cross sections are an order of magnitude lower than the cross sections needed to explain the reported data in the recent dark matter experiments in the low neutralino mass region.

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

    SciTech Connect (OSTI)

    IceCube Collaboration; Abbasi, R.; al., et

    2009-10-23

    A search for muon neutrinos from Kaluza-Klein dark matter annihilations in the Sun has been performed with the 22-string configuration of the IceCube neutrino detector using data collected in 104.3 days of live-time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured lightest Kaluza-Klein particle (LKP) WIMPs in the Sun and converted to limits on the LKP-proton cross-sections for LKP masses in the range 250 - 3000 GeV. These results are the most stringent limits to date on LKP annihilation in the Sun.

  19. Electronic and nuclear contributions in sub-GeV dark matter scattering: A case study with hydrogen

    E-Print Network [OSTI]

    Jiunn-Wei Chen; Hsin-Chang Chi; C. -P. Liu; Chih-Liang Wu; Chih-Pan Wu

    2015-08-14

    Scattering of sub-GeV dark matter (DM) particles with hydrogen atoms is studied in this paper. The interactions of DM with electrons and nucleons are both included and formulated in a general framework based on nonrelativistic effective field theory. On the assumption of same dark matter coupling strengths, it is found that DM-electron interactions dominate the inelastic atomic transitions to discrete excited states and ionization continuum around the threshold regions, and DM-nucleon interactions become more important with increasing energy and dominate in elastic scattering. The conclusion should apply, qualitatively, to practical detector species so that electronic and nuclear contributions in DM scattering processes can be disentangled, while issues including binding effects and recoil mechanism in many-body systems will require further detailed calculations.

  20. Electronic and nuclear contributions in sub-GeV dark matter scattering: A case study with hydrogen

    E-Print Network [OSTI]

    Chen, Jiunn-Wei; Liu, C -P; Wu, Chih-Liang; Wu, Chih-Pan

    2015-01-01

    Scattering of sub-GeV dark matter (DM) particles with hydrogen atoms is studied in this paper. The interactions of DM with electrons and nucleons are both included and formulated in a general framework based on nonrelativistic effective field theory. On the assumption of same dark matter coupling strengths, it is found that DM-electron interactions dominate the inelastic atomic transitions to discrete excited states and ionization continuum around the threshold regions, and DM-nucleon interactions become more important with increasing energy and dominate in elastic scattering. The conclusion should apply, qualitatively, to practical detector species so that electronic and nuclear contributions in DM scattering processes can be disentangled, while issues including binding effects and recoil mechanism in many-body systems will require further detailed calculations.

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

    E-Print Network [OSTI]

    V. A. Bednyakov; F. Simkovic

    2006-08-09

    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.

  2. Investigating dark matter substructure with pulsar timing: II. Improved limits on small-scale cosmology

    E-Print Network [OSTI]

    Hamish A. Clark; Geraint F. Lewis; Pat Scott

    2015-11-19

    Ultracompact Minihalos (UCMHs) have been proposed as a type of dark matter sub-structure seeded by large-amplitude primordial perturbations and topological defects. UCMHs are expected to survive to the present era, allowing constraints to be placed on their cosmic abundance using observations within our own Galaxy. Constraints on their number density can be linked to conditions in the early universe that impact structure formation, such as increased primordial power on small scales, generic weak non-Gaussianity, and the presence of cosmic strings. We use new constraints on the abundance of UCMHs from pulsar timing to place generalised limits on the parameters of each of these cosmological scenarios. At some scales, the limits are the strongest to date, exceeding those from dark matter annihilation. Our new limits have the added advantage of being independent of the particle nature of dark matter, as they are based only on gravitational effects.

  3. 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.

    2014-12-18

    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

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

    E-Print Network [OSTI]

    Kozaczuk, Jonathan

    2013-01-01

    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-...

  5. First limit from a surface run of a 10 liter Dark Matter Time Projection Chamber

    E-Print Network [OSTI]

    Caldwell, Thomas S., Jr

    2009-01-01

    A 10 liter prototype Dark Matter Time Projection Chamber (DMTPC) is operated on the surface of the earth at 75 Torr using carbon-tetrafluoride (CF4) as a target material to obtain a 24.57 gram-day exposure. A limit is set ...

  6. Degenerate limit thermodynamics beyond leading order for models of dense matter

    E-Print Network [OSTI]

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

    2015-01-01

    Analytical formulas for next-to-leading order temperature corrections to the thermal state variables of interacting nucleons in bulk matter are derived in the degenerate limit. The formalism developed is applicable to a wide class of non-relativistic and relativistic models of hot and dense matter currently used in nuclear physics and astrophysics (supernovae, proto-neutron stars and neutron star mergers) as well as in condensed matter physics. We consider the general case of arbitrary dimensionality of momentum space and an arbitrary degree of relativity (for relativistic mean-field theoretical models). For non-relativistic zero-range interactions, knowledge of the Landau effective mass suffices to compute next-to-leading order effects, but in the case of finite-range interactions, momentum derivatives of the Landau effective mass function up to second order are required. Numerical computations are performed to compare results from our analytical formulas with the exact results for zero- and finite-range pot...

  7. The 130 GeV gamma-ray line and generic dark matter model building constraints from continuum gamma rays, radio and antiproton data

    E-Print Network [OSTI]

    Masaki Asano; Torsten Bringmann; Gunter Sigl; Martin Vollmann

    2013-05-16

    An analysis of the Fermi gamma ray space telescope data has recently revealed a resolved gamma-ray feature close to the galactic center which is consistent with monochromatic photons at an energy of about 130 GeV. If interpreted in terms of dark matter (DM) annihilating into \\gamma\\gamma (\\gamma Z, \\gamma h), this would correspond to a DM particle mass of roughly 130 GeV (145 GeV, 155 GeV). The rate for these loop-suppressed processes, however, is larger than typically expected for thermally produced DM. Correspondingly, one would generically expect even larger tree level production rates of standard model fermions or gauge bosons. Here, we quantify this expectation in a rather model-independent way by relating the tree level and loop amplitudes with the help of the optical theorem. As an application, we consider bounds from continuum gamma rays, radio and antiproton data on the tree level amplitudes and translate them into constraints on the loop amplitudes. We find that, independently of the DM production mechanism, any DM model aiming at explaining the line signal in terms of charged standard model particles running in the loop is in rather strong tension with at least one of these constraints, with the exception of loops dominated by top quarks. We stress that attempts to explain the 130 GeV feature with internal bremsstrahlung do not suffer from such difficulties.

  8. Low-momentum ring diagrams of neutron matter at and near the unitary limit

    E-Print Network [OSTI]

    L. -W. Siu; T. T. S. Kuo; R. Machleidt

    2007-10-30

    We study neutron matter at and near the unitary limit using a low-momentum ring diagram approach. By slightly tuning the meson-exchange CD-Bonn potential, neutron-neutron potentials with various $^1S_0$ scattering lengths such as $a_s=-12070fm$ and $+21fm$ are constructed. Such potentials are renormalized with rigorous procedures to give the corresponding $a_s$-equivalent low-momentum potentials $V_{low-k}$, with which the low-momentum particle-particle hole-hole ring diagrams are summed up to all orders, giving the ground state energy $E_0$ of neutron matter for various scattering lengths. At the limit of $a_s\\to \\pm \\infty$, our calculated ratio of $E_0$ to that of the non-interacting case is found remarkably close to a constant of 0.44 over a wide range of Fermi-momenta. This result reveals an universality that is well consistent with the recent experimental and Monte-Carlo computational study on low-density cold Fermi gas at the unitary limit. The overall behavior of this ratio obtained with various scattering lengths is presented and discussed. Ring-diagram results obtained with $V_{low-k}$ and those with $G$-matrix interactions are compared.

  9. 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.

  10. Fits to the Fermi-LAT GeV excess with RH sneutrino dark matter: implications for direct and indirect dark matter searches and the LHC

    E-Print Network [OSTI]

    Cerdeno, D G; Robles, S

    2015-01-01

    We show that the right-handed (RH) sneutrino in the NMSSM can account for the observed excess in the Fermi-LAT spectrum of gamma rays from the Galactic Centre, while fulfilling all the current experimental constraints from the LHC as well as from direct and indirect dark matter searches. We have explored the parameter space of this scenario, computed the gamma ray spectrum for each phenomenologically viable solution and then performed a chi^2 fit to the excess. Unlike previous studies based on model independent interpretations, we have taken into account the full annihilation spectrum, without assuming pure annihilation channels. Furthermore, we have incorporated limits from direct detection experiments, LHC bounds and also the constraints from Fermi-LAT on dwarf spheroidal galaxies (dSphs) and gamma ray spectral lines. In addition, we have estimated the effect of the most recent Fermi-LAT reprocessed data (Pass~8). In general, we obtain good fits to the GCE when the RH sneutrino annihilates mainly into pairs...

  11. A new look at microlensing limits on dark matter in the Galactic halo

    E-Print Network [OSTI]

    Hawkins, M R S

    2015-01-01

    The motivation for this paper is to review the limits set on the MACHO content of the Galactic halo by microlensing experiments in the direction of the Large Magellanic Cloud. This has been prompted by recent measurements of the Galactic rotation curve, which suggest that the limits have been biassed by the assumption of an over-massive halo. The paper first discusses the security of the detection efficiency calculations which are central to deriving the MACHO content of the Galactic halo. It then sets out to compare the rotation curves from various halo models with recent observations, with a view to establishing what limits can be put on an all-MACHO halo. The main thrust of the paper is to investigate whether lighter halo models which are consistent with microlensing by an all-MACHO halo are also consistent with recent measures of the Galactic rotation curve. In this case the population of bodies discovered by the MACHO collaboration would make up the entire dark matter content of the Galactic halo. The ma...

  12. Preliminary Limits on the WIMP-Nucleon Cross Section from the Cryogenic Dark Matter Search (CDMS)

    E-Print Network [OSTI]

    DS Akerib; PD Barnes Jr; DA Bauer; PL Brink; B Cabrera; DO Caldwell; RM Clarke; A Da Silva; AK Davies; BL Dougherty; KD Irwin; RJ Gaitskell; SR Golwala; EE Haller; J Jochum; WB Knowlton; V Kuzminov; SW Nam; V Novikov; MJ Penn; TA Perera; RR Ross; B Sadoulet; RW Schnee; T Shutt; A Smith; AH Sonnenschein; AL Spadafora; WK Stockwell; S Yellin; BA Young

    1997-12-30

    We are conducting an experiment to search for WIMPs, or weakly-interacting massive particles, in the galactic halo using terrestrial detectors. This generic class of hypothetical particles, whose properties are similar to those predicted by extensions of the standard model of particle physics, could comprise the cold component of non-baryonic dark matter. We describe our experiment, which is based on cooled germanium and silicon detectors in a shielded low-background cryostat. The detectors achieve a high degree of background rejection through the simultaneous measurement of the energy in phonons and ionization. Using exposures on the order of one kilogram-day from initial runs of our experiment, we have achieved (preliminary) upper limits on the WIMP-nucleon cross section that are comparable to much longer runs of other experiments.

  13. Cold Nuclear Matter Effects on J/Psi as Constrained by Deuteron-Gold Measurements at sqrt(s_NN) = 200 GeV

    E-Print Network [OSTI]

    PHENIX Collaboration; A. Adare

    2007-11-25

    We present a new analysis of J/psi production yields in deuteron-gold collisions at sqrt(s_NN) = 200 GeV using data taken by the PHENIX experiment in 2003 and previously published in [S.S. Adler et al., Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/psi data taken in 2005 is used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors R_dAu. A suppression of J/psi in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/psi (or precursor) break-up cross-section is added. Breakup cross sections of sigma_breakup = 2.8^[+1.7_-1.4] (2.2^[+1.6_-1.5]) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross section values are consistent within large uncertainties with the 4.2 +/- 0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.

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

    SciTech Connect (OSTI)

    Adare, A. [Univ. of Colorado, Boulder, CO (United States)

    2014-12-18

    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 the 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.

  15. Nuclear matter effects on J/? production in asymmetric Cu + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV

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

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Aramaki, Y.; et al

    2014-12-18

    We report on J/? production from asymmetric Cu+Au heavy-ion collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 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 inmore »the larger Au nucleus. Thus, 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

  16. Nuclear matter effects on J/? production in asymmetric Cu + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 200\\) GeV

    SciTech Connect (OSTI)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Aramaki, Y.; Asano, H.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bai, X.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bathe, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Bing, X.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Chen, C. -H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Christiansen, P.; Chujo, T.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Cronin, N.; Crossette, N.; Csanád, M.; Csörg?, T.; Datta, A.; Daugherity, M. S.; David, G.; DeBlasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Ding, L.; Dion, A.; Do, J. H.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Gainey, K.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, A.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Hashimoto, K.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Huang, J.; Huang, S.; Ichihara, T.; Ikeda, Y.; Imai, K.; Imazu, Y.; Inaba, M.; Iordanova, A.; Isenhower, D.; Isinhue, A.; Ivanishchev, D.; Jacak, B. V.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, E.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kanda, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Kawall, D.; Kazantsev, A. V.; Key, J. A.; Khachatryan, V.; Khandai, P. K.; Khanzadeev, A.; Kihara, K.; Kijima, K. M.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E. -J.; Kim, H. -J.; Kim, M.; Kim, Y. -J.; Kim, Y. K.; Kistenev, E.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kofarago, M.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Krizek, F.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, G. H.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Leitch, M. J.; Leitgab, M.; Lewis, B.; Li, X.; Lim, S. H.; Liu, M. X.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Maruyama, T.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Montuenga, P.; Moon, T.; Morrison, D. P.; Moskowitz, M.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nouicer, R.; Novak, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Oide, H.; Okada, K.; Orjuela Koop, J. D.; Oskarsson, A.; Ozaki, H.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Peng, J. -C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Riveli, N.; Roach, D.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Ryu, M. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sekiguchi, Y.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shaver, A.; Shein, I.; Shibata, T. -A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Skolnik, M.; Slune?ka, M.; Solano, S.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Soumya, M.; Sourikova, I. V.; Stankus, P. W.; Steinberg, P.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Stone, M. R.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takahara, A.; Taketani, A.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vrba, V.

    2014-12-18

    We report on J/? production from asymmetric Cu+Au heavy-ion collisions at \\(\\sqrt{s_{\\mathrm{NN}}} = 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 the larger Au nucleus. Thus, 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.

  17. 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

    2002-12-20

    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.

  18. 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

    2002-01-01

    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.

  19. Limiter

    DOE Patents [OSTI]

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  20. Upper Limit on the Central Density of Dark Matter in the Eddington inspired Born-Infield (EiBI) Gravity

    E-Print Network [OSTI]

    Ramil Izmailov; Alexander A. Potapov; Alexander I. Filippov; Mithun Ghosh; Kamal K. Nandi

    2015-06-11

    We investigate the stability of circular material orbits in the analytic galactic metric recently derived by Harko \\textit{et al.} (2014). It turnsout that stability depends more strongly on the dark matter central density $%\\rho_{0}$ than on other parameters of the solution. This property then yields an upper limit on $\\rho _{0}$ for each individual galaxy, which we call here $\\rho _{0}^{\\text{upper}}$, such that stable circular orbits are possible \\textit{only} when the constraint $\\rho _{0}\\leq \\rho _{0}^{\\text{upper}}$ is satisfied. This is our new result. To approximately quantify the upper limit, we consider as a familiar example our Milky Way galaxy that has a projected dark matter radius $R_{\\text{DM}}\\sim 180$ kpc and find that $\\rho _{0}^{\\text{upper}}\\sim 2.37\\times 10^{11}$ $M_{\\odot }$kpc$^{-3}$. This limit turns out to be about four orders of magnitude larger than the latest data on central density $\\rho _{0}$ arising from the fit to the Navarro-Frenk-White (NFW) and Burkert density profiles. Such consistency indicates that the EiBI solution could qualify as yet another viable alternative model for dark matter.

  1. On the capture of dark matter by neutron stars

    SciTech Connect (OSTI)

    Güver, Tolga; Erkoca, Arif Emre; Sarcevic, Ina; Reno, Mary Hall E-mail: aeerkoca@gmail.com E-mail: ina@physics.arizona.edu

    2014-05-01

    We calculate the number of dark matter particles that a neutron star accumulates over its lifetime as it rotates around the center of a galaxy, when the dark matter particle is a self-interacting boson but does not self-annihilate. We take into account dark matter interactions with baryonic matter and the time evolution of the dark matter sphere as it collapses within the neutron star. We show that dark matter self-interactions play an important role in the rapid accumulation of dark matter in the core of the neutron star. We consider the possibility of determining an exclusion region of the parameter space for dark matter mass and dark matter interaction cross section with the nucleons as well as dark matter self-interaction cross section, based on the observation of old neutron stars. We show that for a dark matter density of 10{sup 3} GeV/cm{sup 3}and dark matter mass m{sub ?} ?< 10 GeV, there is a potential exclusion region for dark matter interactions with nucleons that is three orders of magnitude more stringent than without self-interactions. The potential exclusion region for dark matter self-interaction cross sections is many orders of magnitude stronger than the current Bullet Cluster limit. For example, for high dark matter density regions, we find that for m{sub ?} ? 10 GeV when the dark matter interaction cross section with the nucleons ranges from ?{sub ?n} ? 10{sup ?52} cm{sup 2} to ?{sub ?n} ? 10{sup ?57} cm{sup 2}, the dark matter self-interaction cross section limit is ?{sub ??} ?< 10{sup ?33} cm{sup 2}, which is about ten orders of magnitude stronger than the Bullet Cluster limit.

  2. Limiter

    DOE Patents [OSTI]

    Cohen, Samuel A. (Hopewell, NJ); Hosea, Joel C. (Princeton, NJ); Timberlake, John R. (Allentown, NJ)

    1986-01-01

    A limiter with a specially contoured front face accommodates the various power scrape-off distances .lambda..sub.p, which depend on the parallel velocity, V.sub..parallel., of the impacting particles. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution.

  3. 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

    2008-10-20

    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.

  4. Dark matter capture in the first stars: a power source and limit on stellar mass

    SciTech Connect (OSTI)

    Freese, Katherine; Spolyar, Douglas; Aguirre, Anthony E-mail: dspolyar@physics.ucsc.edu

    2008-11-15

    The annihilation of weakly interacting massive particles can provide an important heat source for the first (Pop III, 'Pop' standing for 'population') stars, potentially leading to a new phase of stellar evolution known as a 'dark star'. When dark matter (DM) capture via scattering off baryons is included, the luminosity from DM annihilation may dominate over the luminosity due to fusion, depending on the DM density and scattering cross section. The influx of DM due to capture may thus prolong the dark star phase of stellar evolution as long as the ambient DM density is high enough. Comparison of DM luminosity with the Eddington luminosity for the star may constrain the stellar mass of zero-metallicity stars. Alternatively, if sufficiently massive Pop III stars are found, they might be used to bound dark matter properties.

  5. Upper Limit on the Central Density of Dark Matter in the Eddington inspired Born-Infield (EiBI) Gravity

    E-Print Network [OSTI]

    Izmailov, Ramil; Filippov, Alexander I; Ghosh, Mithun; Nandi, Kamal K

    2015-01-01

    We investigate the stability of circular material orbits in the analytic galactic metric recently derived by Harko \\textit{et al.} (2014). It turnsout that stability depends more strongly on the dark matter central density $%\\rho_{0}$ than on other parameters of the solution. This property then yields an upper limit on $\\rho _{0}$ for each individual galaxy, which we call here $\\rho _{0}^{\\text{upper}}$, such that stable circular orbits are possible \\textit{only} when the constraint $\\rho _{0}\\leq \\rho _{0}^{\\text{upper}}$ is satisfied. This is our new result. To approximately quantify the upper limit, we consider as a familiar example our Milky Way galaxy that has a projected dark matter radius $R_{\\text{DM}}\\sim 180$ kpc and find that $\\rho _{0}^{\\text{upper}}\\sim 2.37\\times 10^{11}$ $M_{\\odot }$kpc$^{-3}$. This limit turns out to be about four orders of magnitude larger than the latest data on central density $\\rho _{0}$ arising from the fit to the Navarro-Frenk-White (NFW) and Burkert density profiles. Su...

  6. Toward the Limits of Matter: Ultra-relativistic nuclear collisions at CERN

    E-Print Network [OSTI]

    Jurgen Schukraft; Reinhard Stock

    2015-05-26

    Strongly interacting matter as described by the thermodynamics of QCD undergoes a phase transition, from a low temperature hadronic medium to a high temperature quark-gluon plasma state. In the early universe this transition occurred during the early microsecond era. It can be investigated in the laboratory, in collisions of nuclei at relativistic energy, which create "fireballs" of sufficient energy density to cross the QCD Phase boundary. We describe 3 decades of work at CERN, devoted to the study of the QCD plasma and the phase transition. From modest beginnings at the SPS, ultra-relativistic heavy ion physics has evolved today into a central pillar of contemporary nuclear physics and forms a significant part of the LHC program.

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

    E-Print Network [OSTI]

    David S. Graff; Katherine Freese

    1996-06-18

    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.

  8. Dark Matter with Topological Defects in the Inert Doublet Model

    E-Print Network [OSTI]

    Mark Hindmarsh; Russell Kirk; Jose Miguel No; Stephen M. West

    2015-07-29

    We examine the production of dark matter by decaying topological defects in the high mass region $m_{\\mathrm{DM}} \\gg m_W$ of the Inert Doublet Model, extended with an extra U(1) gauge symmetry. The density of dark matter states (the neutral Higgs states of the inert doublet) is determined by the interplay of the freeze-out mechanism and the additional production of dark matter states from the decays of topological defects, in this case cosmic strings. These decays increase the predicted relic abundance compared to the standard freeze-out only case, and as a consequence the viable parameter space of the Inert Doublet Model can be widened substantially. In particular, for a given dark matter annihilation rate lower dark matter masses become viable. We investigate the allowed mass range taking into account constraints on the energy injection rate from the diffuse $\\gamma$-ray background and Big Bang Nucleosynthesis, together with constraints on the dark matter properties coming from direct and indirect detection limits. For the Inert Doublet Model high-mass region, an inert Higgs mass as low as $\\sim 200$ GeV is permitted. There is also an upper limit on string mass per unit length, and hence the symmetry breaking scale, from the relic abundance in this scenario. Depending on assumptions made about the string decays, the limits are in the range $10^{12}$ GeV to $10^{13}$ GeV.

  9. Study of Interaction of the Heavy Quarks with Nuclear Matter in Cu+Cu at sqrt(s_NN)=200 GeV

    E-Print Network [OSTI]

    Miroslav Krus; for the STAR Collaboration

    2009-01-29

    In this paper we present the study of the azimuthal correlation function of non-photonic electrons with low-pT hadrons produced in Cu+Cu collision at sqrt(s_NN) = 200 GeV measured by STAR experiment at RHIC. Possible modification of the awayside peak is observed.

  10. 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)

    2014-10-13

    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.

  11. 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

    2008-08-05

    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.

  12. Cold-nuclear-matter effects on heavy-quark production at forward and backward rapidity in d+Au collisions at sqrt(s_NN)=200 GeV

    E-Print Network [OSTI]

    A. Adare; C. Aidala; N. N. Ajitanand; Y. Akiba; R. Akimoto; H. Al-Bataineh; H. Al-Ta'ani; J. Alexander; K. R. Andrews; A. Angerami; K. Aoki; N. Apadula; E. Appelt; Y. Aramaki; R. Armendariz; E. C. Aschenauer; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; B. Bannier; K. N. Barish; B. Bassalleck; A. T. Basye; S. Bathe; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; J. Ben-Benjamin; R. Bennett; J. H. Bhom; D. S. Blau; J. S. Bok; K. Boyle; M. L. Brooks; D. Broxmeyer; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; S. Campbell; A. Caringi; P. Castera; C. -H. Chen; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; Z. Conesa del Valle; M. Connors; M. Csanád; T. Csörg?; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; M. K. Dayananda; A. Denisov; A. Deshpande; E. J. Desmond; K. V. Dharmawardane; O. Dietzsch; A. Dion; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; J. M. Durham; A. Durum; D. Dutta; L. D'Orazio; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; B. Fadem; D. E. Fields; M. Finger; M. Finger; \\, Jr.; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; C. Gal; I. Garishvili; A. Glenn; H. Gong; X. Gong; M. Gonin; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; G. Grim; M. Grosse Perdekamp; T. Gunji; L. Guo; H. -Ĺ. Gustafsson; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; R. Han; J. Hanks; C. Harper; K. Hashimoto; E. Haslum; R. Hayano; X. He; M. Heffner; T. K. Hemmick; T. Hester; J. C. Hill; M. Hohlmann; R. S. Hollis; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; Y. Hori; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; H. Iinuma; Y. Ikeda; K. Imai; M. Inaba; A. Iordanova; D. Isenhower; M. Ishihara; M. Issah; D. Ivanischev; Y. Iwanaga; B. V. Jacak; J. Jia; X. Jiang; J. Jin; D. John; B. M. Johnson; T. Jones; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; J. Kamin; S. Kaneti; B. H. Kang; J. H. Kang; J. S. Kang; J. Kapustinsky; K. Karatsu; M. Kasai; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; J. Kikuchi; A. Kim; B. I. Kim; D. J. Kim; E. -J. Kim; Y. -J. Kim; Y. K. Kim; E. Kinney; Á. Kiss; E. Kistenev; D. Kleinjan; P. Kline; L. Kochenda; B. Komkov; M. Konno; J. Koster; D. Kotov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; A. Lebedev; D. M. Lee; J. Lee; K. B. Lee; K. S. Lee; S. H. Lee; S. R. Lee; M. J. Leitch; M. A. L. Leite; X. Li; P. Lichtenwalner; P. Liebing; S. H. Lim; L. A. Linden Levy; T. Liška; H. Liu; M. X. Liu; B. Love; D. Lynch; C. F. Maguire; Y. I. Makdisi; M. D. Malik; A. Manion; V. I. Manko; E. Mannel; Y. Mao; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; D. McGlinchey; C. McKinney; N. Means; M. Mendoza; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; K. Miki; A. Milov; J. T. Mitchell; Y. Miyachi; A. K. Mohanty; H. J. Moon; Y. Morino; A. Morreale; D. P. Morrison; S. Motschwiller; T. V. Moukhanova; T. Murakami; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; S. Nam; J. Newby; M. Nguyen; M. Nihashi; R. Nouicer; A. S. Nyanin; C. Oakley; E. O'Brien; S. X. Oda; C. A. Ogilvie; M. Oka; K. Okada; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; V. Pantuev; V. Papavassiliou; B. H. Park; I. H. Park; S. K. Park; W. J. Park; S. F. Pate; L. Patel; H. Pei; J. -C. Peng; H. Pereira; D. Yu. Peressounko; R. Petti; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; H. Qu; J. Rak; I. Ravinovich; K. F. Read; S. Rembeczki; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Ruži?ka; B. Sahlmueller; N. Saito; T. Sakaguchi; K. Sakashita; V. Samsonov; S. Sano; M. Sarsour; T. Sato; M. Savastio; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; R. Seto; D. Sharma; I. Shein; T. -A. Shibata; K. Shigaki; H. H. Shim; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slune?ka; T. Sodre; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; P. W. Stankus; E. Stenlund; S. P. Stoll; T. Sugitate; A. Sukhanov; J. Sun; J. Sziklai; E. M. Takagui; A. Takahara; A. Taketani; R. Tanabe; Y. Tanaka; S. Taneja; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko; E. Tennant; H. Themann; D. Thomas; T. L. Thomas; M. Togawa; A. Toia; L. Tomášek; M. Tomášek; H. Torii; R. S. Towell; I. Tserruya; Y. Tsuchimoto; K. Utsunomiya; C. Vale; H. Valle; H. W. van Hecke; E. Vazquez-Zambrano; A. Veicht; J. Velkovska; R. Vértesi; M. Virius; A. Vossen; V. Vrba; E. Vznuzdaev

    2013-10-03

    The PHENIX experiment has measured open heavy-flavor production via semileptonic decay muons over the transverse momentum range 1 < pT < 6 GeV/c at forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p+p collisions at ?sNN = 200 GeV. In central d+Au collisions an enhancement (suppression) of heavy-flavor muon production is observed at backward (forward) rapidity relative to the yield in p+p collisions scaled by the number of binary collisions. Modification of the gluon density distribution in the Au nucleus contributes in terms of anti-shadowing enhancement and shadowing suppression; however, the enhancement seen at backward rapidity exceeds expectations from this effect alone. These results, implying an important role for additional cold nuclear matter effects, serves as a key baseline for heavy-quark measurements in A+A collisions and in constraining the magnitude of charmonia breakup effects at the Relativistic Heavy Ion Collider and the Large Hadron Collider.

  13. Diffusion in SiGe and Ge

    E-Print Network [OSTI]

    Liao, Christopher Yuan Ting

    2010-01-01

    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

  14. 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: andrea.desimone@sissa.it

    2013-07-01

    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.

  15. 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

    2013-02-19

    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{\

  16. 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)

    2013-08-19

    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.

  17. Excluding the light dark matter window of a 331 model using LHC and direct dark matter detection data

    SciTech Connect (OSTI)

    Cogollo, D.; Gonzalez-Morales, Alma X.; Queiroz, Farinaldo S.; Teles, P. Rebello E-mail: alxogonz@ucsc.edu E-mail: patricia.rebello.teles@cern.ch

    2014-11-01

    We sift the impact of the recent Higgs precise measurements, and recent dark matter direct detection results, on the dark sector of an electroweak extension of the Standard Model that has a complex scalar as dark matter. We find that in this model the Higgs decays with a large branching ratio into dark matter particles, and charged scalars when these are kinematically available, for any coupling strength differently from the so called Higgs portal. Moreover, we compute the abundance and spin-independent WIMP-nucleon scattering cross section, which are driven by the Higgs and Z{sup '} boson processes. We decisively exclude the 1–500 GeV dark matter window and find the most stringent lower bound in the literature on the scale of symmetry breaking of the model namely 10 TeV, after applying the LUX-2013 limit. Interestingly, the projected XENON1T constraint will be able to rule out the entire 1 GeV–1000 GeV dark matter mass range. Lastly, for completeness, we compute the charged scalar production cross section at the LHC and comment on the possibility of detection at current and future LHC runnings.

  18. GE's Digital Marketplace to Revolutionize Manufacturing | GE...

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

    an open online space for companies to collaborate and transform how they design and manufacture their products in the future NISKAYUNA, NY, June 2, 2015 - GE (NYSE:GE), a leading...

  19. Properties of galactic dark matter: Constraints from astronomical observations

    SciTech Connect (OSTI)

    Burch, B.; Cowsik, R.

    2013-12-10

    The distributions of normal matter and of dark matter in the Galaxy are coupled to each other as they both move in the common gravitational potential. In order to fully exploit this interplay and to derive the various properties of dark matter relevant to their direct and indirect detection, we have comprehensively reviewed the astronomical observations of the spatial and velocity distributions of the components of normal matter. We then postulate that the phase-space distribution of dark matter follows a lowered-isothermal form and self-consistently solve Poisson's equation to construct several models for the spatial and velocity distributions of dark matter. In this paper, we compute the total gravitational potential of the normal and dark matter components and investigate their consistency with current observations of the rotation curve of the Galaxy and of the spatial and velocity distributions of blue horizontal-branch and blue straggler stars. Even with this demand of consistency, a large number of models with a range of parameters characterizing the dark matter distribution remain. We find that the best choice of parameters, within the range of allowed values for the surface density of the disk 55 M {sub ?} pc{sup –2}, are the following: the dark matter density at the Galactic center ?{sub DM,} {sub c} ? 100-250 GeV cm{sup –3}, the local dark matter density ?{sub DM}(R {sub 0}) ? 0.56-0.72 GeV cm{sup –3}, and the rms speed of dark matter particles ?v{sub DM}{sup 2}(R{sub 0})?{sup 1/2}?490??550 km s{sup –1}. We also discuss possible astronomical observations that may further limit the range of the allowed models. The predictions of the allowed models for direct and indirect detection will be discussed separately in a companion paper.

  20. Equation of state of isospin-asymmetric nuclear matter in relativistic mean-field models with chiral limits

    E-Print Network [OSTI]

    Wei-Zhou Jiang; Bao-An Li; Lie-Wen Chen

    2007-05-12

    Using in-medium hadron properties according to the Brown-Rho scaling due to the chiral symmetry restoration at high densities and considering naturalness of the coupling constants, we have newly constructed several relativistic mean-field Lagrangians with chiral limits. The model parameters are adjusted such that the symmetric part of the resulting equation of state at supra-normal densities is consistent with that required by the collective flow data from high energy heavy-ion reactions, while the resulting density dependence of the symmetry energy at sub-saturation densities agrees with that extracted from the recent isospin diffusion data from intermediate energy heavy-ion reactions. The resulting equations of state have the special feature of being soft at intermediate densities but stiff at high densities naturally. With these constrained equations of state, it is found that the radius of a 1.4$M_\\odot$ canonical neutron star is in the range of 11.9 km$\\leq$R$\\leq$13.1 km, and the maximum neutron star mass is around 2.0$M_\\odot$ close to the recent observations.

  1. Transverse momentum and centrality dependence of dihadron correlations in Au plus Au collisions at root s(NN)=200 GeV: Jet quenching and the response of partonic matter 

    E-Print Network [OSTI]

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Al-Jamel, A.; Aoki, K.; Aphecetche, L.; Armendariz, R.; Aronson, S. H.; Asai, J.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Baksay, G.; Baksay, L.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Bathe, S.; Batsouli, S.; Baublis, V.; Bauer, F.; Bazilevsky, A.; Belikov, S.; Bennett, R.; Berdnikov, Y.; Bickley, A. A.; Bjorndal, M. T.; Boissevain, J. G.; Borel, H.; Boyle, K.; Brooks, M. L.; Brown, D. S.; Bucher, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Burward-Hoy, J. M.; Butsyk, S.; Campbell, S.; Chai, J. -S; Chang, B. S.; Charvet, J. -L; Chernichenko, S.; Chiba, J.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Chujo, T.; Chung, P.; Churyn, A.; Cianciolo, V.; Cleven, C. R.; Cobigo, Y.; Cole, B. A.; Comets, M. P.; Constantin, P.; Csanad, M.; Csoergo, T.; Dahms, T.; Das, K.; David, G.; Deaton, M. B.; Dehmelt, K.; Delagrange, H.; Denisov, A.; d'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drachenberg, J. L.; Drapier, O.; Drees, A.; Dubey, A. K.; Durum, A.; Dzhordzhadze, V.; Efremenko, Y. V.; Egdemir, J.; Ellinghaus, F.; Emam, W. S.; Enokizono, A.; En'yo, H.; Espagnon, B.; Esumi, S.; Eyser, K. O.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Forestier, B.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fung, S. -Y; Fusayasu, T.; Gadrat, S.; Garishvili, I.; Gastineau, F.; Germain, M.; Glenn, A.; Gong, H.; Gonin, M.; Gosset, J.; Goto, Y.; de Cassagnac, R. Granier; Grau, N.; Greene, S. V.; Perdekamp, M. Grosse; Gunji, T.; Gustafsson, H. -A; Hachiya, T.; Hadj Henni, A.; Haegemann, C.; Haggerty, J. S.; Hagiwara, M. N.; Hamagaki, H.; Han, R.; Harada, H.; Hartouni, E. P.; Haruna, K.; Harvey, M.; Haslum, E.; Hasuko, K.; Hayano, R.; Heffner, M.; Hemmick, T. K.; Hester, T.; Heuser, J. M.; He, X.; Hiejima, H.; Hill, J. C.; Hobbs, R.; Hohlmann, M.; Holmes, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Hur, M. G.; Ichihara, T.; Imai, K.; Inaba, M.; Inoue, Y.; Isenhower, D.; Isenhower, L.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Jacak, B. V.; Jia, J.; Jin, J.; Jinnouchi, O.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kaneta, M.; Kang, J. H.; Kanou, H.; Kawagishi, T.; Kawall, D.; Kazantsev, A. V.; Kelly, S.; Khanzadeev, A.; Kikuchi, J.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, Y. -S; Kinney, E.; Kiss, A.; Kistenev, E.; Kiyomichi, A.; Klay, J.; Klein-Boesing, C.; Kochenda, L.; Kochetkov, V.; Komkov, B.; Konno, M.; Kotchetkov, D.; Kozlov, A.; Kral, A.; Kravitz, A.; Kroon, P. J.; Kubart, J.; Kunde, G. J.; Kurihara, N.; Kurita, K.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. -S; Lajoie, J. G.; Lebedev, A.; Le Bornec, Y.; Leckey, S.; Lee, D. M.; Lee, M. K.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Lenzi, B.; Lim, H.; Liska, T.; Litvinenko, A.; Liu, M. X.; Li, X.; Li, X. H.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mao, Y.; Masek, L.; Masui, H.; Matathias, F.; McCain, M. C.; McCumber, M.; McGaughey, P. L.; Miake, Y.; Mikes, P.; Miki, K.; Miller, T. E.; Milov, A.; Mioduszewski, Saskia; Mishra, G. C.; Mishra, M.; Mitchell, J. T.; Mitrovski, M.; Morreale, A.; Morrison, D. P.; Moss, J. M.; Moukhanova, T. V.; Mukhopadhyay, D.; Murata, J.; Nagamiya, S.; Nagata, Y.; Nagle, J. L.; Naglis, M.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Norman, B. E.; Nyanin, A. S.; Nystrand, J.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Ohnishi, H.; Ojha, I. D.; Okada, H.; Okada, K.; Oka, M.; Omiwade, O. O.; Oskarsson, A.; Otterlund, I.; Ouchida, M.; Ozawa, K.; Pak, R.; Pal, D.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, J.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J. -C; Pereira, H.; Peresedov, V.; Peressounko, D. Yu; Pinkenburg, C.; Pisani, R. P.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reuter, M.; Reygers, K.; Riabov, V.; Riabov, Y.; Roche, G.; Romana, A.; Rosati, M.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Rykov, V. L.; Ryu, S. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakata, H.; Samsonov, V.; Sato, H. D.; Sato, S.; Sawada, S.; Seele, J.; Seidl, R.; Semenov, V.; Seto, R.; Sharma, D.; Shea, T. K.; Shein, I.; Shevel, A.; Shibata, T. -A; Shigaki, K.; Shimomura, M.; Shohjoh, T.; Shoji, K.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, C. P.; Singh, V.; Skutnik, S.; Slunecka, M.; Smith, W. C.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.

    2008-01-01

    The results of midrapidity (0 < y < 0.8) neutral pion spectra over an extended transverse momentum range (1 < p(T) < 12 GeV/c) in root s(NN) = 200 GeV Au + Au collisions, measured by the STAR experiment, are presented. The ...

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

    SciTech Connect (OSTI)

    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.

    2012-05-01

    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˛.

  3. 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

    2012-05-23

    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

  4. 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

  5. Developing the Theory of Flux Limits from $?$-Ray Cascades

    E-Print Network [OSTI]

    John A. Cairns

    2007-05-18

    Dark matter annihilation and other processes may precipitate a flux of diffuse ultra-high energy $\\gamma$-rays. These $\\gamma$-rays may be observable in present day experiments which observe diffuse fluxes at the GeV scale. Yet the universe is presently opaque to $\\gamma$-rays above 10 TeV. It is generally assumed that cascade radiation is observable at all high energies, however the disparity in energy from production to observation has important consequences for theoretical flux limits. We detail the physics of cascade radiation development and consider the influence of energy and redshift scale on arbitrary flux limits that result from electromagnetic cascade.

  6. Probing Light Dark Matter via Evaporation from the Sun

    E-Print Network [OSTI]

    Chris Kouvaris

    2015-06-13

    Dark matter particles can be captured by the sun with rates that depend on the dark matter mass and the DM-nucleon cross section. However, for masses below $\\sim 3.3$ GeV, the captured dark matter particles evaporate, leading to an equilibrium where the rate of captured particles is equal to the rate of evaporating ones. Unlike dark matter particles from the halo, the evaporating dark matter particles have velocities that are not limited to values below the escape velocity of the galaxy. Despite the fact that high velocities are exponentially suppressed, I demonstrate here that current underground detectors have the possibility to probe/constrain low dark matter parameter space by (not)-observing the high energy tail of the evaporating dark matter particles from the sun. I also show that the functional form of the differential rate of counts with respect to the recoil energy in earth based detectors can identify precisely the mass and the cross section of the dark matter particle in this case.

  7. Strangelet search in Pb-Pb interactions at 158 GeV/{ital c} per nucleon

    SciTech Connect (OSTI)

    Appelquist, G.; Baglin, C.; Beringer, J.; Bohm, C.; Borer, K.; Bussiere, A.; Dittus, F.; Elsener, K.; Frei, D.; Gorodetzky, P.; Guillaud, J.P.; Hugentobler, E.; Klingenberg, R.; Linden, T.; Lohmann, K.D.; Moser, U.; Pal, T.; Pretzl, K.; Schacher, J.; Sellden, B.; Stoffel, F.; Tuominiemi, J.; Zhang, Q.P.

    1996-05-01

    The NA52 experiment searches for long-lived massive strange quark matter particles, so-called {ital strangelets}, produced in Pb-Pb collisions at a beam momentum of {ital p}{sub lab}=158 AGeV/{ital c}. Upper limits for the production of strangelets at zero degree production angle covering a mass to charge ratio up to 120 GeV/{ital c}{sup 2} and lifetimes {ital t}{sub lab}{approx_gt}1.2 {mu}s are given. The data presented here were taken during the 1994 lead beam running period at CERN. {copyright} {ital 1996 The American Physical Society.}

  8. Phase transitions in Ge-Sb phase change materials

    SciTech Connect (OSTI)

    Raoux, Simone; Virwani, Kumar; Hitzbleck, Martina; Salinga, Martin; Madan, Anita; Pinto, Teresa L.

    2009-03-15

    Thin films of the phase change material Ge-Sb with Ge concentrations between 7.3 and 81.1 at. % were deposited by cosputtering from elemental targets. Their crystallization behavior was studied using time-resolved x-ray diffraction, Auger electron spectroscopy, differential scanning calorimetry, x-ray reflectivity, profilometry, optical reflectivity, and resistivity versus temperature measurements. It was found that the crystallization temperature increases with Ge content. Calculations of the glass transition temperature (which is a lower limit for the crystallization temperature T{sub x}) also show an increase with Ge concentration closely tracking the measured values of T{sub x}. For low Ge content samples, Sb x-ray diffraction peaks occurred during a heating ramp at lower temperature than Ge diffraction peaks. The appearance of Ge peaks is related to Ge precipitation and agglomeration. For Ge concentrations of 59.3 at. % and higher, Sb and Ge peaks occurred at the same temperature. Upon crystallization, film mass density and optical reflectivity increase as well as electrical contrast (ratio of resistivity in amorphous phase to crystalline phase) all showed a maximum for the eutectic alloy (14.5 at. % Ge). For the alloy with 59.3 at. % Ge there was very little change in any of these parameters, while the alloy with 81.1 at. % Ge behaved opposite to a typical phase change alloy and showed reduced mass density and reflectivity and increased resistivity.

  9. 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

  10. 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.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2012-03-01

    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}.

  11. Update on light WIMP limits: LUX, lite and light

    SciTech Connect (OSTI)

    Nobile, Eugenio Del; Gelmini, Graciela B.; Huh, Ji-Haeng [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Gondolo, Paolo, E-mail: delnobile@physics.ucla.edu, E-mail: gelmini@physics.ucla.edu, E-mail: paolo@physics.utah.edu, E-mail: jhhuh@physics.ucla.edu [Department of Physics and Astronomy, University of Utah, 115 South 1400 East #201, Salt Lake City, UT 84112 (United States)

    2014-03-01

    We reexamine the current direct dark matter data including the recent CDMSlite and LUX data, assuming that the dark matter consists of light WIMPs, with mass close to 10 GeV/c{sup 2} with spin-independent and isospin-conserving or isospin-violating interactions. We compare the data with a standard model for the dark halo of our galaxy and also in a halo-independent manner. In our standard-halo analysis, we find that for isospin-conserving couplings, CDMSlite and LUX together exclude the DAMA, CoGeNT, CDMS-II-Si, and CRESST-II possible WIMP signal regions. For isospin-violating couplings instead, we find that a substantial portion of the CDMS-II-Si region is compatible with all exclusion limits. In our halo-independent analysis, we find that for isospin-conserving couplings, the situation is of strong tension between the positive and negative results, as it was before the LUX and CDMSlite bounds, which turn out to exclude the same possible WIMP signals as previous limits. For isospin-violating couplings, we find that LUX and CDMS-II-Si bounds together exclude or severely constrain the DAMA, CoGeNT and CRESST-II possible WIMP signals.

  12. 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.

    2010-01-01

    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

  13. GE ?????????????????4G?????...

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

    A die containing 400 ohmic MEMS switches, as viewed under a microscope, atop a U.S. dime. This device, made with GE's...

  14. 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 CHE

  15. 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

  16. Solving the Dark Matter Problem

    ScienceCinema (OSTI)

    Baltz, Ted

    2009-09-01

    Cosmological observations have firmly established that the majority of matter in the universe is of an unknown type, called 'dark matter'. A compelling hypothesis is that the dark matter consists of weakly interacting massive particles (WIMPs) in the mass range around 100 GeV. If the WIMP hypothesis is correct, such particles could be created and studied at accelerators. Furthermore they could be directly detected as the primary component of our galaxy. Solving the dark matter problem requires that the connection be made between the two. We describe some theoretical and experimental avenues that might lead to this connection.

  17. 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

    2015-05-28

    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.

  18. Probing the Small Scale Matter Power Spectrum through Dark Matter Annihilation in the Early Universe

    E-Print Network [OSTI]

    Aravind Natarajan; Nick Zhu; Naoki Yoshida

    2015-03-11

    Recent observations of the cosmic microwave background (CMB) anisotropies and the distribution of galaxies, galaxy clusters, and the Lyman Alpha forest have constrained the shape of the power spectrum of matter fluctuations on large scales k Energy released by dark matter annihilation can modify the spectrum of CMB temperature fluctuations and thus CMB experiments such as Planck have been able to constrain the quantity f /m energy absorbed by gas, is the annihilation rate assumed constant, and m is the particle mass. We assume the standard scale-invariant primordial matter power spectrum of P_prim(k) ~ k^{n_s} at large scales k n_s, the excess small-scale power results in a much larger number of nonlinear small mass halos, particularly at high redshifts. Dark matter annihilation in these halos releases sufficient energy to partially ionize the gas, and consequently modify the spectrum of CMB fluctuations. We show that the recent Planck data can already be used to constrain the power spectrum on small scales. For a simple model with an NFW profile with halo concentration parameter c_200 = 5 and f / m = 1/100 picobarn c / GeV, we can limit the mass variance sigma_{max} < 100 at the 95% confidence level, corresponding to a power law index m_s < 1.43 (1.63) for k_p = 100 (1000) h/Mpc. Our results are also relevant to theories that feature a running spectral index.

  19. 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

    2014-12-09

    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.

  20. NEW LIMITS ON GAMMA-RAY EMISSION FROM GALAXY CLUSTERS

    SciTech Connect (OSTI)

    Griffin, Rhiannon D.; Dai, Xinyu; Kochanek, Christopher S. E-mail: xdai@ou.edu

    2014-11-01

    Galaxy clusters are predicted to produce ?-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z < 0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3 × 10{sup –11} photons cm{sup –2} s{sup –1} (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5 × 10{sup 44} photons s{sup –1}. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and ?-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.

  1. Anisotropic dark matter distribution functions and impact on WIMP direct detection

    SciTech Connect (OSTI)

    Bozorgnia, Nassim; Schwetz, Thomas; Catena, Riccardo E-mail: riccardo.catena@theorie.physik.uni-goettingen.de

    2013-12-01

    Dark matter N-body simulations suggest that the velocity distribution of dark matter is anisotropic. In this work we employ a mass model for the Milky Way whose parameters are determined from a fit to kinematical data. Then we adopt an ansatz for the dark matter phase space distribution which allows to construct self-consistent halo models which feature a degree of anisotropy as a function of the radius such as suggested by the simulations. The resulting velocity distributions are then used for an analysis of current data from dark matter direct detection experiments. We find that velocity distributions which are radially biased at large galactocentric distances (up to the virial radius) lead to an increased high velocity tail of the local dark matter distribution. This affects the interpretation of data from direct detection experiments, especially for dark matter masses around 10 GeV, since in this region the high velocity tail is sampled. We find that the allowed regions in the dark matter mass-cross section plane as indicated by possible hints for a dark matter signal reported by several experiments as well as conflicting exclusion limits from other experiments shift in a similar way when the halo model is varied. Hence, it is not possible to improve the consistency of the data by referring to anisotropic halo models of the type considered in this work.

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

    SciTech Connect (OSTI)

    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.

    2012-05-01

    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˛.

  3. 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

    2012-05-01

    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

  4. GE Research and Development | GE Global Research

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of rare Kaonforsupernovae model (Journal About DOE ButtonFSO HomefeatureGE

  5. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation Current HABFESOpportunities Nuclear Physics (NP)about aMunich, GermanyAbout GE

  6. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation Current HABFESOpportunities Nuclear Physics (NP)aboutRio de Janeiro,theIsGE

  7. Optimized dark matter searches in deep observations of Segue 1 with MAGIC

    SciTech Connect (OSTI)

    Aleksi?, J.; Blanch, O.; Ansoldi, S.; Antonelli, L.A.; Bonnoli, G.; Antoranz, P.; Babic, A.; Bangale, P.; De Almeida, U. Barres; Bock, R.K.; Borracci, F.; Barrio, J.A.; Bonnefoy, S.; González, J. Becerra; Berger, K.; Bednarek, W.; Bernardini, E.; Biland, A.; Bretz, T.; Carmona, E. E-mail: jrico@ifae; and others

    2014-02-01

    We present the results of stereoscopic observations of the satellite galaxy Segue 1 with the MAGIC Telescopes, carried out between 2011 and 2013. With almost 160 hours of good-quality data, this is the deepest observational campaign on any dwarf galaxy performed so far in the very high energy range of the electromagnetic spectrum. We search this large data sample for signals of dark matter particles in the mass range between 100 GeV and 20 TeV. For this we use the full likelihood analysis method, which provides optimal sensitivity to characteristic gamma-ray spectral features, like those expected from dark matter annihilation or decay. In particular, we focus our search on gamma-rays produced from different final state Standard Model particles, annihilation with internal bremsstrahlung, monochromatic lines and box-shaped signals. Our results represent the most stringent constraints to the annihilation cross-section or decay lifetime obtained from observations of satellite galaxies, for masses above few hundred GeV. In particular, our strongest limit (95% confidence level) corresponds to a ? 500 GeV dark matter particle annihilating into ?{sup +}?{sup ?}, and is of order (?{sub ann}v) ?  1.2 × 10{sup ?24} cm{sup 3} s{sup ?1} — a factor ? 40 above the (?{sub ann}v) ?  thermal value.

  8. Diffusion of dark matter in a hot and dense nuclear environment

    E-Print Network [OSTI]

    Cermeńo, Marina; Silk, Joseph

    2015-01-01

    We calculate the mean free path in a hot and dense nuclear environment for a fermionic dark matter particle candidate interacting with nucleons via scalar and vector couplings. We determine the effects of density and temperature in the medium by using nuclear distribution functions to size the importance of the final state blocking. Our results show that stellar nuclear scenarios, where dark matter may be accreted, provide opacities several orders of magnitude larger than those for Standard Model neutrinos in the context of cooling of proto-neutron stars. We also show that in a diffusive approximation with couplings of Fermi's constant strength the obtained dark matter-nucleon crosss sections display the same sensitivity that upper limits constrained with collider searches in the mass region $m_\\chi \\lesssim$ 5 GeV.

  9. Upsilon (1S+2S+3S) production in d+Au and p+p collisions at sqrt(s_NN)=200 GeV and cold-nuclear matter effects

    E-Print Network [OSTI]

    A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; R. Akimoto; H. Al-Bataineh; H. Al-Ta'ani; J. Alexander; K. R. Andrews; A. Angerami; K. Aoki; N. Apadula; L. Aphecetche; E. Appelt; Y. Aramaki; R. Armendariz; J. Asai; E. C. Aschenauer; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; A. Baldisseri; B. Bannier; K. N. Barish; P. D. Barnes; B. Bassalleck; A. T. Basye; S. Bathe; S. Batsouli; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; J. Ben-Benjamin; R. Bennett; A. Berdnikov; Y. Berdnikov; J. H. Bhom; A. A. Bickley; D. S. Blau; J. G. Boissevain; J. S. Bok; H. Borel; K. Boyle; M. L. Brooks; D. Broxmeyer; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; A. Caringi; P. Castera; B. S. Chang; W. C. Chang; J. -L. Charvet; C. -H. Chen; S. Chernichenko; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; A. Churyn; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; Z. Conesa del Valle; M. Connors; P. Constantin; M. Csanád; T. Csörg?; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; M. K. Dayananda; A. Denisov; D. d'Enterria; A. Deshpande; E. J. Desmond; K. V. Dharmawardane; O. Dietzsch; A. Dion; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; A. K. Dubey; J. M. Durham; A. Durum; D. Dutta; V. Dzhordzhadze; L. D'Orazio; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; K. O. Eyser; B. Fadem; D. E. Fields; M. Finger; M. Finger Jr; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; X. Gong; M. Gonin; J. Gosset; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; G. Grim; M. Grosse Perdekamp; T. Gunji; L. Guo; H. -Ĺ. Gustafsson; A. Hadj Henni; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; R. Han; J. Hanks; C. Harper; E. P. Hartouni; K. Haruna; K. Hashimoto; E. Haslum; R. Hayano; X. He; M. Heffner; T. K. Hemmick; T. Hester; J. C. Hill; M. Hohlmann; R. S. Hollis; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; Y. Hori; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; H. Iinuma; Y. Ikeda; K. Imai; J. Imrek; M. Inaba; A. Iordanova; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; Y. Iwanaga; B. V. Jacak; J. Jia; X. Jiang; J. Jin; D. John; B. M. Johnson; T. Jones; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; S. Kaneti; B. H. Kang; J. H. Kang; J. S. Kang; J. Kapustinsky; K. Karatsu; M. Kasai; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; J. Kikuchi; A. Kim; B. I. Kim; D. H. Kim; D. J. Kim; E. Kim; E. -J. Kim; S. H. Kim; Y. -J. Kim; Y. K. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; J. Klay; C. Klein-Boesing; D. Kleinjan; P. Kline; L. Kochenda; B. Komkov; M. Konno; J. Koster; D. Kotov; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; M. J. Kweon; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; D. Layton; A. Lebedev; D. M. Lee; J. Lee; K. B. Lee; K. S. Lee; S. H. Lee; S. R. Lee; T. Lee; M. J. Leitch; M. A. L. Leite; B. Lenzi; X. Li; P. Lichtenwalner; P. Liebing; S. H. Lim; L. A. Linden Levy; T. Liška; A. Litvinenko; H. Liu; M. X. Liu; B. Love; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; A. Manion; V. I. Manko; E. Mannel; Y. Mao; L. Mašek; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; D. McGlinchey; C. McKinney; N. Means; M. Mendoza; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; P. Mikeš; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; Y. Miyachi; A. K. Mohanty; H. J. Moon; Y. Morino; A. Morreale; D. P. Morrison; S. Motschwiller; T. V. Moukhanova; D. Mukhopadhyay; T. Murakami; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; S. Nam; J. Newby; M. Nguyen; M. Nihashi; T. Niita; R. Nouicer; A. S. Nyanin; C. Oakley; E. O'Brien; S. X. Oda; C. A. Ogilvie; M. Oka; K. Okada; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; A. P. T. Palounek; V. Pantuev; V. Papavassiliou; B. H. Park; I. H. Park; J. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J. -C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; R. Petti; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; S. Rembeczki; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruži?ka; V. L. Rykov; B. Sahlmueller; N. Saito; T. Sakaguchi; S. Sakai; K. Sakashita; V. Samsonov; S. Sano; M. Sarsour; T. Sato; M. Savastio; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; V. Semenov; R. Seto; D. Sharma; I. Shein; T. -A. Shibata

    2012-11-16

    The three Upsilon states, Upsilon(1S+2S+3S), are measured in d+Au and p+p collisions at sqrt(s_NN)=200 GeV and rapidities 1.2<|y|<2.2 by the PHENIX experiment at the Relativistic Heavy-Ion Collider. Cross sections for the inclusive Upsilon(1S+2S+3S) production are obtained. The inclusive yields per binary collision for d+Au collisions relative to those in p+p collisions (R_dAu) are found to be 0.62 +/- 0.26 (stat) +/- 0.13 (syst) in the gold-going direction and 0.91 +/- 0.33 (stat) +/- 0.16 (syst) in the deuteron-going direction. The measured results are compared to a nuclear-shadowing model, EPS09 [JHEP 04, 065 (2009)], combined with a final-state breakup cross section, sigma_br, and compared to lower energy p+A results. We also compare the results to the PHENIX J/psi results [Phys. Rev. Lett. 107, 142301 (2011)]. The rapidity dependence of the observed Upsilon suppression is consistent with lower energy p+A measurements.

  10. 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 ...

  11. Too massive neutron stars: The role of dark matter?

    E-Print Network [OSTI]

    Ang Li; Feng Huang; Ren-Xin Xu

    2012-08-18

    The maximum mass of a neutron star is generally determined by the equation of state of the star material. In this study, we take into account dark matter particles, assumed to behave like fermions with a free parameter to account for the interaction strength among the particles, as a possible constituent of neutron stars. We find dark matter inside the star would soften the equation of state more strongly than that of hyperons, and reduce largely the maximum mass of the star. However, the neutron star maximum mass is sensitive to the particle mass of dark matter, and a very high neutron star mass larger than 2 times solar mass could be achieved when the particle mass is small enough. Such kind of dark-matter- admixed neutron stars could explain the recent measurement of the Shapiro delay in the radio pulsar PSR J1614-2230, which yielded a neutron star mass of 2 times solar mass that may be hardly reached when hyperons are considered only, as in the case of the microscopic Brueckner theory. Furthermore, in this particular case, we point out that the dark matter around a neutron star should also contribute to the mass measurement due to its pure gravitational effect. However, our numerically calculation illustrates that such contribution could be safely ignored because of the usual diluted dark matter environment assumed. We conclude that a very high mass measurement of about 2 times solar mass requires a really stiff equation of state in neutron stars, and find a strong upper limit (<= 0.64 GeV) for the particle mass of non-self- annihilating dark matter based on the present model.

  12. 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

    2015-11-19

    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.

  13. Dark matter directionality revisited with a high pressure xenon gas detector

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

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

    2015-07-20

    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 inmore »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.« less

  14. Photonic dark matter portal revisited

    E-Print Network [OSTI]

    S. A. Alavi; F S Kazemian

    2015-11-18

    In our previous paper [1], we studied a model of dark matter (DM) in which the hidden sector interacts with standard model particles via a hidden photonic portal (HP). We investigated the effects of this new interaction on the hydrogen atom and obtained an upper bound for the coupling of the model. In this work, we study the effects of HP on two interesting exotic atoms namely muonium and positronium. We obtain a tighter upper limit on the coupling. We also calculate the change (shift) in the Aharonov-Bohm phase due to HP and find that the phase shift is negligibly small (for DM particles mass in the GeV range). Recently a 3.5 keV X ray line signal observed in the spectrum of 73 galaxy clusters, reported by the XXM-Newton X ray observatory. Since in HP model the DM particles can decay directly into photons, so we finally calculate the value of the coupling constant f using the condition Delta E=3.5 keV.

  15. 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)

    2013-05-10

    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.

  16. 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

  17. Dipolar Dark Matter

    E-Print Network [OSTI]

    Luc Blanchet; Lavinia Heisenberg

    2015-05-19

    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 freedom in the decoupling limit is reintroduced in the dark matter sector. Crucial questions to address in future work is whether the polarisation mechanism can be realized in absence of ghosts, and what are the cosmological implications of the model.

  18. 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

    2006-08-22

    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.

  19. Global fits of the dark matter-nucleon effective interactions

    SciTech Connect (OSTI)

    Catena, Riccardo; Gondolo, Paolo E-mail: paolo.gondolo@utah.edu

    2014-09-01

    The effective theory of isoscalar dark matter-nucleon interactions mediated by heavy spin-one or spin-zero particles depends on 10 coupling constants besides the dark matter particle mass. Here we compare this 11-dimensional effective theory to current observations in a comprehensive statistical analysis of several direct detection experiments, including the recent LUX, SuperCDMS and CDMSlite results. From a multidimensional scan with about 3 million likelihood evaluations, we extract the marginalized posterior probability density functions (a Bayesian approach) and the profile likelihoods (a frequentist approach), as well as the associated credible regions and confidence levels, for each coupling constant vs dark matter mass and for each pair of coupling constants. We compare the Bayesian and frequentist approach in the light of the currently limited amount of data. We find that current direct detection data contain sufficient information to simultaneously constrain not only the familiar spin-independent and spin-dependent interactions, but also the remaining velocity and momentum dependent couplings predicted by the dark matter-nucleon effective theory. For current experiments associated with a null result, we find strong correlations between some pairs of coupling constants. For experiments that claim a signal (i.e., CoGeNT and DAMA), we find that pairs of coupling constants produce degenerate results.

  20. Search for a dark matter candidate produced in association with a single top quark in $p\\bar{p}$ collisions at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect (OSTI)

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Anza, F.; Apollinari, G.; Appel, J.A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2012-02-01

    We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb{sup -1} of Tevatron p{bar p} collisions at {radical}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 p{bar p} {yields} 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{sup 2}.

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

    E-Print Network [OSTI]

    Henry T. Wong

    2008-03-01

    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.

  2. On The Origin of Light Dark Matter Species

    SciTech Connect (OSTI)

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

    2010-06-04

    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.

  3. 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..

    2012-09-14

    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.

  4. 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

  5. GE Partners on Microgrid Project | GE Global Research

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

    control platform which can be used to host intelligent grid management software for microgrids. A typical GE control platform which can be used to host intelligent grid management...

  6. GE Develops High Water Recovery Technology in China | GE Global...

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

    purification industry SHANGHAI, September. 17, 2015 - A team of scientists led by the Coating and Membrane Technology Laboratory at GE's China Technology Center have successfully...

  7. Indirect search for dark matter with AMS in positrons, gamma and antiprotons channels

    E-Print Network [OSTI]

    Diego Casadei

    2006-09-04

    The Alpha Magnetic Spectrometer (AMS), to be installed on the International Space Station, will provide data on cosmic radiations in a large energy range. The main physics goals in the astroparticle domain are the antimatter and the dark matter searches. Dark matter should be composed of non baryonic weakly interacting massive particles, a good candidate being the lightest SUSY particle in R-parity conserving models. As a prototype for the AMS-02 experiment, the AMS-01 particle spectrometer was flown on the Space Shuttle Discovery in near earth orbit for a ten day mission in June 1998. The direct identification of positrons in AMS-01 was limited to energies below 3 GeV due to the vast proton background and the characteristics of the subdetectors, but the sensitivity towards higher energies (up to 40 GeV) was extended by identifying positrons through the conversion of bremsstrahlung photons. AMS-02 will greatly improve the accuracy on the positron spectrum, which will be measured up to 300 GeV, together with the antiproton and $\\gamma$-ray flux, thus providing a unique chance to measure all relevant neutralino decay channels with the same experiment.

  8. Indirect search for dark matter with AMS in positrons, gamma and antiprotons channels

    E-Print Network [OSTI]

    Casadei, D

    2007-01-01

    The Alpha Magnetic Spectrometer (AMS), to be installed on the International Space Station, will provide data on cosmic radiations in a large energy range. The main physics goals in the astroparticle domain are the antimatter and the dark matter searches. Dark matter should be composed of non baryonic weakly interacting massive particles, a good candidate being the lightest SUSY particle in R-parity conserving models. As a prototype for the AMS-02 experiment, the AMS-01 particle spectrometer was flown on the Space Shuttle Discovery in near earth orbit for a ten day mission in June 1998. The direct identification of positrons in AMS-01 was limited to energies below 3 GeV due to the vast proton background and the characteristics of the subdetectors, but the sensitivity towards higher energies (up to 40 GeV) was extended by identifying positrons through the conversion of bremsstrahlung photons. AMS-02 will greatly improve the accuracy on the positron spectrum, which will be measured up to 300 GeV, together with t...

  9. 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.

    1995-07-01

    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.

  10. 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

  11. Magnetic Refrigeration | GE Global Research

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

    and it will become hotter. Move it away (demagnetization) and the food cools down. GE researchers predict the cooling refrigerators could reduce energy consumption by 20%, in...

  12. Flexible Energy | GE Global Research

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

    (Opens in new window) Flexible Fuel Solutions Offer Efficient, Reliable Energy The world of power generation is evolving at lightning speed. GE is focused on staying one step...

  13. GE Energy Management Ancillary Services

    E-Print Network [OSTI]

    GE Energy Management Ancillary Services Definitions and Capability Study Part 2, Tasks 3-4, Final Online Wind Plants & Frequency Responsive Load Reserves

  14. Scalar Dark Matter From Theory Space

    SciTech Connect (OSTI)

    Birkedal-Hansen, Andreas; Wacker, Jay G.

    2003-12-26

    The scalar dark matter candidate in a prototypical theory space little Higgs model is investigated. We review all details of the model pertinent to a relic density calculation. We perform a thermal relic density calculation including couplings to the gauge and Higgs sectors of the model. We find two regions of parameter space that give acceptable dark matter abundances. The first region has a dark matter candidate with a mass {Omicron}(100 GeV), the second region has a candidate with a mass greater than {Omicron}(500 GeV). The dark matter candidate in either region is an admixture of an SU(2) triplet and an SU(2) singlet, thereby constituting a possible WIMP (weakly interacting massive particle).

  15. Warm Dark Matter via Ultra-Violet Freeze-In: Reheating Temperature and Non-Thermal Distribution for Fermionic Higgs Portal Dark Matter

    E-Print Network [OSTI]

    John McDonald

    2015-12-20

    Warm dark matter (WDM) of order keV mass may be able to resolve the disagreement between structure formation in cold dark matter simulations and observations. The detailed properties of WDM will depend upon its energy distribution, in particular how it deviates from the thermal distribution usually assumed in WDM simulations. Here we focus on WDM production via the Ultra-Violet (UV) freeze-in mechanism, for the case of fermionic Higgs portal dark matter $\\psi$ produced the portal interaction $\\overline{\\psi}\\psi H^{\\dagger}H/\\Lambda$. We show that the reheating temperature must satisfy $T_{R} \\gtrsim 0.3 $ TeV in order to account for the observed dark matter density when $m_{\\psi} \\approx 2 $ keV, where the lower bound on $T_{R}$ corresponds to the limit where the fermion mass is entirely due to electroweak symmetry breaking via the portal interaction. The corresponding bound on the interaction scale is $\\Lambda \\gtrsim 1.5 \\times 10^{10}$ GeV. We introduce a new method to simplify the computation of the non-thermal energy distribution of dark matter from freeze-in. We show that the non-thermal energy distribution from UV freeze-in is much broader and flatter than the corresponding thermal distribution.

  16. The C-4 Dark Matter Experiment

    SciTech Connect (OSTI)

    Bonicalzi, Ricco; Collar, J. I.; Colaresi, J.; Fast, James E.; Fields, N.; Fuller, Erin S.; Hai, M.; Hossbach, Todd W.; Kos, Marek S.; Orrell, John L.; Overman, Cory T.; Reid, Douglas J.; VanDevender, Brent A.; Wiseman, Clinton G.; Yocum, K. M.

    2013-06-01

    Abstract We describe the experimental design of C-4, an expansion of the CoGeNT dark matter search to four identical detectors each approximately three times the mass of the p-type point contact (PPC) germanium diode presently taking data at the Soudan Underground Laboratory. Expected reductions of radioactive backgrounds and energy threshold are discussed, including an estimate of the additional sensitivity to low-mass dark matter candidates to be obtained with this search.

  17. Axion Dark Matter Searches

    E-Print Network [OSTI]

    I. Stern

    2014-03-21

    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.

  18. Axion Dark Matter Searches

    E-Print Network [OSTI]

    Stern, I

    2014-01-01

    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.

  19. Axion Dark Matter Searches

    E-Print Network [OSTI]

    I. Stern

    2015-11-17

    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.

  20. Assessing Exposures to Particulate Matter and Manganese in Welding Fumes

    E-Print Network [OSTI]

    LIU, SA

    2010-01-01

    limit PM: particulate matter PTFE: polytetrafluoroethylenepolytetrafluoroethylene (PTFE) with polymethylpentenethrough the OPC and a 47 mm PTFE filter (Grimm Technologies,

  1. H.E.S.S. constraints on Dark Matter annihilations towards the Sculptor and Carina Dwarf Galaxies

    E-Print Network [OSTI]

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Barnacka, A; de Almeida, U Barres; Bazer-Bachi, A R; Becherini, Y; Becker, J; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Borrel, V; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L -M; Clapson, A C; Coignet, G; Conrad, J; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataď, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fiasson, A; Frster, A; Fontaine, G; Füßling, M; Gallant, Y A; Gast, H; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Hague, J D; Hampf, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzy?ski, K; Katz, U; Kaufmann, S; Keogh, D; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Klochkov, D; Klu?niak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Laffon, H; Lamanna, G; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, D; Maxted, N; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; Wilhelmi, E de Ońa; Opitz, B; Ostrowski, M; Panter, M; Arribas, M Paz; Pedaletti1, G; Pelletier, G; Petrucci, P -O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Ryde, F; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schönwald, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Spengler, G; Stawarz, ?; Steenkamp, R; Stegmann, C; Stinzing, F; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tibolla, O; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Viana, A; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; Wierzcholska, A; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S; 10.1016/j.astropartphys.2010.12.006

    2010-01-01

    The Sculptor and Carina Dwarf spheroidal galaxies were observed with the H.E.S.S. Cherenkov telescope array between January 2008 and December 2009. The data sets consist of a total of 11.8 and 14.8 hours of high quality data, respectively. No gamma-ray signal was detected at the nominal positions of these galaxies above 220 GeV and 320 GeV, respectively. Upper limits on the gamma-ray fluxes at 95% C.L. assuming two forms for the spectral energy distribution (a power law shape and one derived from dark matter annihilation) are obtained at the level of 10^-13 to 10^-12 cm^-2s^-1 in the TeV range. Constraints on the velocity weighted dark matter particle annihilation cross section for both Sculptor and Carina dwarf galaxies range from ~ 10^-21 cm^3s^-1 down to ~ 10^-22 cm^3s^-1 depending on the dark matter halo model used. Possible enhancements of the gamma-ray flux are studied: the Sommerfeld effect, which is found to exclude some dark matter particle masses, the internal Bremsstrahlung and clumps in the dark...

  2. 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

  3. Generalised form factor dark matter in the Sun

    E-Print Network [OSTI]

    Aaron C. Vincent; Aldo Serenelli; Pat Scott

    2015-04-16

    We study the effects of energy transport in the Sun by asymmetric dark matter with momentum and velocity-dependent interactions, with an eye to solving the decade-old Solar Abundance Problem. We study effective theories where the dark matter-nucleon scattering cross-section goes as $v_{\\rm rel}^{2n}$ and $q^{2n}$ with $n = -1, 0, 1 $ or $2$, where $v_{\\rm rel}$ is the dark matter-nucleon relative velocity and $q$ is the momentum exchanged in the collision. Such cross-sections can arise generically as leading terms from the most basic nonstandard DM-quark operators. We employ a high-precision solar simulation code to study the impact on solar neutrino rates, the sound speed profile, convective zone depth, surface helium abundance and small frequency separations. We find that the majority of models that improve agreement with the observed sound speed profile and depth of the convection zone also reduce neutrino fluxes beyond the level that can be reasonably accommodated by measurement and theory errors. However, a few specific points in parameter space yield a significant overall improvement. A 3-5 GeV DM particle with $\\sigma_{SI} \\propto q^2$ is particularly appealing, yielding more than a $6\\sigma$ improvement with respect to standard solar models, while being allowed by direct detection and collider limits. We provide full analytical capture expressions for $q$- and $v_{\\rm rel}$-dependent scattering, as well as complete likelihood tables for all models.

  4. 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

  5. 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

    GE 449# GE 110 Geological Engineering CE 271 GEOE 378 4TH YEAR 3RD YEAR 2ND YEAR 1ST YEAR or PHYS 128

  6. Dark Matters

    ScienceCinema (OSTI)

    Joseph Silk

    2010-01-08

    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.

  7. Miniaturized Turbine Offers Desalination Solution | GE Global...

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

    salt from ice New solution draws from the GE Store, integrating GE's experience with steam turbine, oil & gas compressors, 3D printing and water processing NISKAYUNA, NY,...

  8. Energy Frontier Research Center | GE Global Research

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

    include GE Global Research, Yale University-Crabtree Group, Yale University-Batista Group, Stanford University and Lawrence Berkeley National Laboratory. GE Global...

  9. The DAMIC dark matter experiment

    E-Print Network [OSTI]

    Aguilar-Arevalo, A; Bertou, X; Bole, D; Butner, M; Cancelo, G; Vázquez, A Castańeda; Chavarria, A E; Neto, J R T de Mello; Dixon, S; D'Olivo, J C; Estrada, J; Moroni, G Fernandez; Torres, K P Hernández; Izraelevitch, F; Kavner, A; Kilminster, B; Lawson, I; Liao, J; López, M; Molina, J; Moreno-Granados, G; Pena, J; Privitera, P; Sarkis, Y; Scarpine, V; Schwarz, T; Haro, M Sofo; Tiffenberg, J; Machado, D Torres; Trillaud, F; You, X; Zhou, J

    2015-01-01

    The DAMIC (Dark Matter in CCDs) experiment uses high resistivity, scientific grade CCDs to search for dark matter. The CCD's low electronic noise allows an unprecedently low energy threshold of a few tens of eV that make it possible to detect silicon recoils resulting from interactions of low mass WIMPs. In addition the CCD's high spatial resolution and the excellent energy response results in very effective background identification techniques. The experiment has a unique sensitivity to dark matter particles with masses below 10 GeV/c$^2$. Previous results have demonstrated the potential of this technology, motivating the construction of DAMIC100, a 100 grams silicon target detector currently being installed at SNOLAB. In this contribution, the mode of operation and unique imaging capabilities of the CCDs, and how they may be exploited to characterize and suppress backgrounds will be discussed, as well as physics results after one year of data taking.

  10. Understanding Phase Transformation in Crystalline Ge Anodes for Li-Ion Batteries

    E-Print Network [OSTI]

    Cui, Yi

    studies. 1. INTRODUCTION One of the most important renewable energy storage technologies is lithium to silicon. Despite recent studies on Ge electrode reactions, there is still limited understanding elements, such as silicon (Si) and germanium (Ge), are very attractive candidates for high- capacity

  11. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation of Fe(II) by Carbon-RichProton Delivery and Removal Purchasing In

  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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation CurrentHenry Bellamy, Ph.D.Food Drive HolidayHours UsedFireAmberMind Overcome

  13. Edison Summit Brings GE Leaders Together | GE Global Research

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

    We are ONE Edison Aisha Yousuf 2014.03.21 "We are ONE Edison" was the theme of the first GE Global Edison Summit held February 16-18, 2014 at Coronado Springs Resort in Orlando,...

  14. 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...

  15. H.E.S.S. upper limits for Kepler's supernova remnant

    E-Print Network [OSTI]

    Aharonian, F; Barresde Almeida, U; Bazer-Bachi, A R; Behera, B; Beilicke, M; Benbow, W; Berge, D; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Brion, E; Brucker, J; Buhler, R; Bulik, T; Büsching, I; Boutelier, T; Carrigan, S; Chadwick, P M; Chounet, L M; Clapson, A C; Coignet, G; Cornils, R; Costamante, L; Dalton, M; Degrange, B; Dickinson, H J; Djannati-Ata, A; Domainko, i W; O'Connor-Drury, L; Dubois, F; Dubus, G; Dyks, J; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Fuling, M; Gallant, Y A; Giebels, B; Glück, B; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, J F Glicenstein G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; De Jager, O C; Jung, I; Katarzynski, K; Kendziorra, E; Kerschhaggl, M; Khelifi, B; Keogh, D; Komin, Nu; Kosack, K; Lamanna, G; Latham, I J; Lemoine-Goumard, M; Lenain, J P; Lohse, T; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masterson, C; Maurin, D; McComb, T J L; Moderski, R; Moulin, E; Naumann-Godo, M; De Naurois, Mathieu; Nedbal, D; Nekrassov, D; Nolan, S J; Ohm, S; Olive, J P; de Ona Wilhelmi, E; Orford, K J; Osborne, J L; Ostrowski, M; Panter, M; Pedaletti, G; Pelletier, G; Petrucci, P O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, Andreas G; Raubenheimer, B C; Raue, M; Rayner, S M; Renaud, M; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Ruppel, J; Sahakian, V V; Santangelo, A; Schlickeiser, R; Schock, F M; Schroder, R; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sol, H; Spangler, D; Stawarz, L; Steenkamp, R; Stegmann, C; Superina, G; Tam, P H; Tavernet, J P; Terrier, R; Van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Ward, M; Zdziarski, A A; Wagner, A; Zech, J

    2008-01-01

    Observations of Kepler's supernova remnant (G4.5+6.8) with the H.E.S.S. telescope array in 2004 and 2005 with a total live time of 13 h are presented. Stereoscopic imaging of Cherenkov radiation from extensive air showers is used to reconstruct the energy and direction of the incident gamma rays. No evidence for a very high energy (VHE: >100 GeV) gamma-ray signal from the direction of the remnant is found. An upper limit (99% confidence level) on the energy flux in the range 230 GeV - 12.8 TeV of 8.6 x 10^{-13} erg cm^{-2} s^{-1} is obtained. In the context of an existing theoretical model for the remnant, the lack of a detectable gamma-ray flux implies a distance of at least 6.4 kpc. A corresponding upper limit for the density of the ambient matter of 0.7 cm^{-3} is derived. With this distance limit, and assuming a spectral index Gamma = 2, the total energy in accelerated protons is limited to E_p law measured by RX...

  16. Conformal Complex Singlet Extension of the Standard Model: Scenario for Dark Matter and a Second Higgs Boson

    E-Print Network [OSTI]

    Wang, Zhi-Wei; Hanif, T; Mann, R B

    2015-01-01

    We consider a conformal complex singlet extension of the Standard Model with a Higgs portal interaction. Two different scenarios depending on whether the global $U(1)$ symmetry of the complex singlet is broken or unbroken have been studied. In the unbroken case, the decay of the complex singlet is protected by the global $U(1)$ symmetry which leads to an ideal cold dark matter candidate with approximately $100\\,\\rm{GeV}$ mass along with a significant proportion of thermal relic dark matter abundance. In the broken case, we generalize our method to incorporate a renormalization-scale optimization technique and are able to provide unique predictions for all the model's couplings and masses. We have found there exists a second Higgs boson with a mass of approximately $550\\,\\rm{GeV}$ that mixes with the known $125\\,\\rm{GeV}$ Higgs with a large mixing angle $\\sin\\theta\\approx 0.47$ consistent with current experimental limits. Furthermore, the imaginary part of the complex singlet in the broken case could provide a...

  17. 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

  18. 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

  19. Advanced Analytics | GE Global Research

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

    GE Predictivity(tm) Industrial Internet Solutions Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new window)...

  20. Impact of Minority Carrier Lifetime on the Performance of Strained Ge Light Sources

    E-Print Network [OSTI]

    Sukhdeo, David S; Birendra,; Dutt,; Nam, Donguk

    2015-01-01

    We theoretically investigate the impact of the defect-limited carrier lifetime on the performance of germanium (Ge) light sources, specifically LEDs and lasers. For Ge LEDs, we show that improving the material quality can offer even greater enhancements than techniques such as tensile strain, the leading approach for enhancing Ge light emission. Even for Ge that is so heavily strained that it becomes a direct bandgap semiconductor, the ~1 ns defect-limited carrier lifetime of typical epitaxial Ge limits the LED internal quantum efficiency to less than 10%. In contrast, if the epitaxial Ge carrier lifetime can be increased to its bulk value, internal quantum efficiencies exceeding 90% become possible. For Ge lasers, we show that the defect-limited lifetime becomes increasing important as tensile strain is introduced, and that this defect-limited lifetime must be improved if the full benefits of strain are to be realized. We conversely show that improving the material quality supersedes much of the utility of n...

  1. Thermodynamics of clusterized matter

    E-Print Network [OSTI]

    Ad. R. Raduta; F. Gulminelli

    2009-08-26

    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.

  2. Cold nuclear matter

    E-Print Network [OSTI]

    C. O. Dorso; P. A. Giménez Molinelli; J. I. Nichols; J. A. López

    2013-05-09

    The behavior of nuclear matter is studied at low densities and temperatures using classical molecular dynamics with three different sets of potentials with different compressibility. Nuclear matter is found to arrange in crystalline structures around the saturation density and in non-homogeneous (i.e. pasta-like) structures at lower densities. Similar results were obtained with a simple Lennard-Jones potential. Finite size effects are analysed and the existence of the non-homogeneous structures is shown to be inherent to the use of periodic boundary conditions and the finitude of the system. For large enough systems the non-homogeneous structures are limited to one sphere, one rod or one slab per simulation cell, which are shown to be minimal surface structures under cubic periodic boundary conditions at the corresponding volume fraction. The relevance of these findings to the simulations of neutron star and supernovae matter is discussed.

  3. 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

  4. 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 the contamination of non-specific large vessel signals. Animal studies have used non- conventional functional minimizing the contributions of extravascular BOLD signals around large vessels due to the refocusing pulse

  5. Dark Matter Searche with GLAST

    E-Print Network [OSTI]

    E. Nuss

    2007-04-20

    The Gamma-Ray Large Area Space Telescope (GLAST), scheduled to be launched in fall 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT), GLAST main instrument, with a wide field of view (> 2 sr), a large effective area (> 8000 cm^2 at 1 GeV) and 20 MeV - 300 GeV energy range, will provide excellent high energy gamma-ray observations for Dark Matter searches. In this paper we examine the potential of the LAT to detect gamma-rays coming from WIMPS annihilation in the context of supersymmetry. As an example, two search regions are investigated: the galactic center and the galactic satellites.

  6. Two-portal Dark Matter

    E-Print Network [OSTI]

    Karim Ghorbani; Hossein Ghorbani

    2015-06-14

    We propose a renormalizable dark matter model in which a fermionic dark matter (DM) candidate communicates with the standard model particles through two distinct portals: Higgs and vector portals. The dark sector is charged under a $U(1)'$ gauge symmetry while the standard model has a leptophobic interaction with the dark vector boson. The leading contribution of DM-nucleon elastic scattering cross section begins at one-loop level. The model meets all the constraints imposed by direct detection experiments provided by LUX and XENON100, observed relic abundance according to WMAP and Planck, and the invisible Higgs decay width measured at the LHC. It turns out that the dark matter mass in the viable parameter space can take values from a few GeV up to 1 TeV. This is a new feature which is absent in the models with only one portal. In addition, we can find in the constrained regions of the parameter space a DM mass of $\\sim 34$ GeV annihilating into $b$ quark pair, which explains the Fermi-LAT gamma-ray excess.

  7. 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-insulator include SIMOX, Ge condensation and wafer bonding. In this paper, a brief introduction of each method

  8. 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

  9. 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

  10. First dark matter search results from the PandaX-I experiment

    E-Print Network [OSTI]

    Xiao, Mengjiao; Zhao, Li; Cao, Xiguang; Chen, Xun; Chen, Yunhua; Cui, Xiangyi; Fang, Deqing; Fu, Changbo; Giboni, Karl L; Gong, Haowei; Guo, Guodong; Hu, Jie; Huang, Xingtao; Ji, Xiangdong; Ju, Yonglin; Lei, Siao; Li, Shaoli; Lin, Qing; Liu, Huaxuan; Liu, Jianglai; Liu, Xiang; Lorenzon, Wolfgang; Ma, Yugang; Mao, Yajun; Ni, Kaixuan; Pushkin, Kirill; Ren, Xiangxiang; Schubnell, Michael; Shen, Manbing; Stephenson, Scott; Tan, Andi; Tarle, Greg; Wang, Hongwei; Wang, Jimin; Wang, Meng; Wang, Xuming; Wang, Zhou; Wei, Yuehuan; Wu, Shiyong; Xie, Pengwei; You, Yinghui; Zeng, Xionghui; Zhang, Hua; Zhang, Tao; Zhu, Zhonghua

    2014-01-01

    We report on the first dark-matter (DM) search results from PandaX-I, a low threshold dual-phase xenon experiment operating at the China Jinping Underground Laboratory. In the 37-kg liquid xenon target with 17.4 live-days of exposure, no DM particle candidate event was found. This result sets a stringent limit for low-mass DM particles and disfavors the interpretation of previously-reported positive experimental results. The minimum upper limit, $3.7\\times10^{-44}$\\,cm$^2$, for the spin-independent isoscalar DM-particle-nucleon scattering cross section is obtained at a DM-particle mass of 49\\,GeV/c$^2$ at 90\\% confidence level.

  11. First dark matter search results from the PandaX-I experiment

    E-Print Network [OSTI]

    PandaX Collaboration; Mengjiao Xiao; Xiang Xiao; Li Zhao; Xiguang Cao; Xun Chen; Yunhua Chen; Xiangyi Cui; Deqing Fang; Changbo Fu; Karl L. Giboni; Haowei Gong; Guodong Guo; Jie Hu; Xingtao Huang; Xiangdong Ji; Yonglin Ju; Siao Lei; Shaoli Li; Qing Lin; Huaxuan Liu; Jianglai Liu; Xiang Liu; Wolfgang Lorenzon; Yugang Ma; Yajun Mao; Kaixuan Ni; Kirill Pushkin; Xiangxiang Ren; Michael Schubnell; Manbing Shen; Scott Stephenson; Andi Tan; Greg Tarle; Hongwei Wang; Jimin Wang; Meng Wang; Xuming Wang; Zhou Wang; Yuehuan Wei; Shiyong Wu; Pengwei Xie; Yinghui You; Xionghui Zeng; Hua Zhang; Tao Zhang; Zhonghua Zhu

    2014-09-04

    We report on the first dark-matter (DM) search results from PandaX-I, a low threshold dual-phase xenon experiment operating at the China Jinping Underground Laboratory. In the 37-kg liquid xenon target with 17.4 live-days of exposure, no DM particle candidate event was found. This result sets a stringent limit for low-mass DM particles and disfavors the interpretation of previously-reported positive experimental results. The minimum upper limit, $3.7\\times10^{-44}$\\,cm$^2$, for the spin-independent isoscalar DM-particle-nucleon scattering cross section is obtained at a DM-particle mass of 49\\,GeV/c$^2$ at 90\\% confidence level.

  12. 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

    2014-09-15

    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.

  13. 7-GeV Advanced Photon Source Conceptual Design Report

    SciTech Connect (OSTI)

    Not Available

    1987-04-01

    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.

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

    E-Print Network [OSTI]

    ENGINEERING USING STRAINED SI, SIGE, AND GE CHANNELS E.A. Fitzgerald,1 M.L. Lee,1 C.W. Leitz,1 and D 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

  15. Cosmology, Thermodynamics and Matter Creation

    E-Print Network [OSTI]

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

    2007-08-24

    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.

  16. Contamination of Dark Matter Experiments from Atmospheric Magnetic Dipoles

    E-Print Network [OSTI]

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

    2013-10-14

    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.

  17. Double-Disk Dark Matter

    E-Print Network [OSTI]

    JiJi Fan; Andrey Katz; Lisa Randall; Matthew Reece

    2013-07-31

    Based on observational constraints on large scale structure and halo structure, dark matter is generally taken to be cold and essentially collisionless. On the other hand, given the large number of particles and forces in the visible world, a more complex dark sector could be a reasonable or even likely possibility. This hypothesis leads to testable consequences, perhaps portending the discovery of a rich hidden world neighboring our own. We consider a scenario that readily satisfies current bounds that we call Partially Interacting Dark Matter (PIDM). This scenario contains self-interacting dark matter, but it is not the dominant component. Even if PIDM contains only a fraction of the net dark matter density, comparable to the baryonic fraction, the subdominant component's interactions can lead to interesting and potentially observable consequences. Our primary focus will be the special case of Double-Disk Dark Matter (DDDM), in which self-interactions allow the dark matter to lose enough energy to lead to dynamics similar to those in the baryonic sector. We explore a simple model in which DDDM can cool efficiently and form a disk within galaxies, and we evaluate some of the possible observational signatures. The most prominent signal of such a scenario could be an enhanced indirect detection signature with a distinctive spatial distribution. Even though subdominant, the enhanced density at the center of the galaxy and possibly throughout the plane of the galaxy can lead to large boost factors, and could even explain a signature as large as the 130 GeV Fermi line. Such scenarios also predict additional dark radiation degrees of freedom that could soon be detectable and would influence the interpretation of future data, such as that from Planck and from the Gaia satellite. We consider this to be the first step toward exploring a rich array of new possibilities for dark matter dynamics.

  18. Strongly Interacting Matter at High Energy Density

    E-Print Network [OSTI]

    Larry McLerran

    2008-12-08

    This lecture concerns the properties of strongly interacting matter (which is described by Quantum Chromodynamics) at very high energy density. I review the properties of matter at high temperature, discussing the deconfinement phase transition . At high baryon density and low temperature, large $N_c$ arguments are developed which suggest that high baryonic density matter is a third form of matter, Quarkyonic Matter, that is distinct from confined hadronic matter and deconfined matter. I finally discuss the Color Glass Condensate which controls the high energy limit of QCD, and forms the low x part of a hadron wavefunction. The Glasma is introduced as matter formed by the Color Glass Condensate which eventually thermalizes into a Quark Gluon Plasma.

  19. Superconducting Detectors for Super Light Dark Matter

    E-Print Network [OSTI]

    Yonit Hochberg; Yue Zhao; Kathryn M. Zurek

    2015-04-27

    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.

  20. Superconducting Detectors for Super Light Dark Matter

    E-Print Network [OSTI]

    Hochberg, Yonit; Zurek, Kathryn M

    2015-01-01

    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.

  1. Superconducting Detectors for Super Light Dark Matter

    E-Print Network [OSTI]

    Yonit Hochberg; Yue Zhao; Kathryn M. Zurek

    2015-11-11

    We propose and study a new class 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 of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological/astrophysical constraints could be detected by such detectors with a moderate size exposure.

  2. 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)

    1995-01-01

    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.

  3. Constraints on Light Dark Matter from Big Bang Nucleosynthesis

    E-Print Network [OSTI]

    Brian Henning; Hitoshi Murayama

    2012-05-29

    We examine the effects of relic dark matter annihilations on big bang nucleosynthesis (BBN). The magnitude of these effects have scale simply with the dark matter mass and annihilation cross-section, which we derive. Estimates based on these scaling behaviors indicate that BBN severely constrains hadronic and radiative dark matter annihilation channels in the previously unconsidered dark matter mass region MeV $\\lesssim m_{\\chi} \\lesssim 10$ GeV. Interestingly, we find that BBN constraints on hadronic annihilation channels are competitive with similar bounds derived from the cosmic microwave background.

  4. 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

    ND YEAR 1ST YEAR 3RD YEAR # These courses can be taken in either term.*must meet specific Hum/SocSci@# Bus Sci/HSS#Design Elec.#* T.E.*# T.E.*#GE 449# ME 314 or PHYS 128 or GEOL 121 4TH YEAR 2

  5. GE Energy Management Ancillary Services

    E-Print Network [OSTI]

    GE Energy Management Ancillary Services Definitions and Capability Study Part 1, Tasks 1-2, FinalRose Michael O'Connor Sundar Venkataraman Revision 1 Date: 12/19/2012 #12;Ancillary Services Definitions.................................................................................................................... 7 3.1 Task 1: Identify and define ancillary services needed for integration of new generation

  6. Microgravity and Vision in Astronauts | 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shines light on dark matterEnergyPublicatonsSubstancesproteinGE Researchers Study

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

    E-Print Network [OSTI]

    N. Fornengo; L. Maccione; A. Vittino

    2015-01-30

    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.

  8. Indirect dark matter search with AMS-02

    E-Print Network [OSTI]

    S. Di Falco

    2006-07-06

    The Alpha Magnetic Spectrometer (AMS), to be installed on the International Space Station, will provide data on cosmic radiations in the energy range from 0.5 GeV to 3 TeV. The main physics goals are the anti-matter and the dark matter searches. Observations and cosmology indicate that the Universe may include a large amount of unknown Dark Matter. It should be composed of non baryonic Weakly Interacting Massive Particles (WIMP). In R-parity conserving models a good WIMP candidate is the lightest SUSY particle. AMS offers a unique opportunity to study simultaneously SUSY dark matter in three decay channels resulting from the neutralino annihilation: e+, antiproton and gamma. Either in the SUSY frame and in alternative scenarios (like extra-dimensions) the expected flux sensitivities as a function of energy in 3 year exposure for the e+/e- ratio, gamma and antiproton yields are presented.

  9. Scalar Dark Matter: Direct vs. Indirect Detection

    E-Print Network [OSTI]

    Michael Duerr; Pavel Fileviez Perez; Juri Smirnov

    2015-09-14

    We revisit the simplest model for dark matter. In this context the dark matter candidate is a real scalar field which interacts with the Standard Model particles through the Higgs portal. We discuss the relic density constraints as well as the predictions for direct and indirect detection. The final state radiation processes are investigated in order to understand the visibility of the gamma lines from dark matter annihilation. We find two regions where one could observe the gamma lines at gamma-ray telescopes. We point out that the region where the dark matter mass is between 100 and 300 GeV can be tested in the near future at direct and indirect detection experiments.

  10. Scalar Dark Matter: Direct vs. Indirect Detection

    E-Print Network [OSTI]

    Duerr, Michael; Smirnov, Juri

    2015-01-01

    We revisit the simplest model for dark matter. In this context the dark matter candidate is a real scalar field which interacts with the Standard Model particles through the Higgs portal. We discuss the relic density constraints as well as the predictions for direct and indirect detection. The final state radiation processes are investigated in order to understand the visibility of the gamma lines from dark matter annihilation. We find two regions where one could observe the gamma lines at gamma-ray telescopes. We point out that the region where the dark matter mass is between 100 and 300 GeV can be tested in the near future at direct and indirect detection experiments.

  11. Asymmetric condensed dark matter

    E-Print Network [OSTI]

    Aguirre, Anthony

    2015-01-01

    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. Anticipating Patentable Subject Matter

    E-Print Network [OSTI]

    Burk, DL

    2015-01-01

    February 2013] PATENTABLE SUBJECT MATTER patentability—imports into patent law’s subject matter provisions theunder either novelty or subject matter. The proper question

  13. Dark Matter Signals In Cosmic Rays?

    E-Print Network [OSTI]

    Shlomo Dado; Arnon Dar

    2009-03-10

    The flux of the diffuse gamma-ray background radiation (GBR) does not confirm that the excess in the flux of cosmic ray electrons between 300-800 GeV, which was measured locally with the ATIC instrument in balloon flights over Antartica, is universal as expected from dark matter annihilation. Neither does the increase with energy of the fraction of positrons in the cosmic ray flux of electrons in the 10-100 GeV range that was measured by PAMELA imply a dark matter origin: It is consistent with that expected from the sum of the two major sources of Galactic cosmic rays, non relativistic spherical ejecta and highly relativistic jets from supernova explosions.

  14. Hidden photons in connection to dark matter

    SciTech Connect (OSTI)

    Andreas, Sarah; Ringwald, Andreas [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Goodsell, Mark D. [CPhT, Ecole Polytechnique, Palaiseau (France)

    2013-11-07

    Light extra U(1) gauge bosons, so called hidden photons, which reside in a hidden sector have attracted much attention since they are a well motivated feature of many scenarios beyond the Standard Model and furthermore could mediate the interaction with hidden sector dark matter. We review limits on hidden photons from past electron beam dump experiments including two new limits from such experiments at KEK and Orsay. In addition, we study the possibility of having dark matter in the hidden sector. A simple toy model and different supersymmetric realisations are shown to provide viable dark matter candidates in the hidden sector that are in agreement with recent direct detection limits.

  15. Axions as hot and cold dark matter

    SciTech Connect (OSTI)

    Jeong, Kwang Sik; Kawasaki, Masahiro; Takahashi, Fuminobu E-mail: kawasaki@icrr.u-tokyo.ac.jp

    2014-02-01

    The presence of a hot dark matter component has been hinted at 3? by a combination of the results from different cosmological observations. We examine a possibility that pseudo Nambu-Goldstone bosons account for both hot and cold dark matter components. We show that the QCD axions can do the job for the axion decay constant f{sub a}?GeV, if they are produced by the saxion decay and the domain wall annihilation. We also investigate the cases of thermal QCD axions, pseudo Nambu-Goldstone bosons coupled to the standard model sector through the Higgs portal, and axions produced by modulus decay.

  16. Asymmetric dark matter and the Sun

    E-Print Network [OSTI]

    Mads T. Frandsen; Subir Sarkar

    2010-06-01

    Cold dark matter particles with an intrinsic matter-antimatter asymmetry do not annihilate after gravitational capture by the Sun and can affect its interior structure. The rate of capture is exponentially enhanced when such particles have self-interactions of the right order to explain structure formation on galactic scales. A `dark baryon' of mass 5 GeV is a natural candidate and has the required relic abundance if its asymmetry is similar to that of ordinary baryons. We show that such particles can solve the `solar composition problem'. The predicted small decrease in the low energy neutrino fluxes may be measurable by the Borexino and SNO+ experiments.

  17. Matter Field, Dark Matter and Dark Energy

    E-Print Network [OSTI]

    Masayasu Tsuge

    2009-03-24

    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.

  18. 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

  19. Modulation Effects in Dark Matter-Electron Scattering Experiments

    E-Print Network [OSTI]

    Lee, Samuel K; Mishra-Sharma, Siddharth; Safdi, Benjamin R

    2015-01-01

    One of the next frontiers in dark-matter direct-detection experiments is to explore the MeV to GeV mass regime. Such light dark matter does not carry enough kinetic energy to produce an observable nuclear recoil, but it can scatter off electrons, leading to a measurable signal. We introduce a semi-analytic approach to characterize the resulting electron-scattering events in atomic and semiconductor targets, improving on previous analytic proposals that underestimate the signal at high recoil energies. We then use this procedure to study the time-dependent properties of the electron-scattering signal, including the modulation fraction, higher-harmonic modes and modulation phase. The time dependence can be distinct in a non-trivial way from the nuclear scattering case. Additionally, we show that dark-matter interactions inside the Earth can significantly distort the lab-frame phase-space distribution of sub-GeV dark matter.

  20. Discovering Inelastic Thermal-Relic Dark Matter at Colliders

    E-Print Network [OSTI]

    Izaguirre, Eder; Shuve, Brian

    2015-01-01

    Dark Matter particles with inelastic interactions are ubiquitous in extensions of the Standard Model, yet remain challenging to fully probe with existing strategies. We propose a series of powerful searches at hadron and lepton colliders that are sensitive to inelastic dark matter dynamics. In representative models, we find that the LHC and BaBar could offer strong sensitivity to the thermal-relic dark matter parameter space for dark matter masses between ~100 MeV-100 GeV and fractional mass-splittings above the percent level; future searches at Belle II with a dedicated monophoton trigger could also offer sensitivity to thermal-relic scenarios with masses below a few GeV. Thermal scenarios with either larger masses or splittings are largely ruled out; lower masses remain viable yet may be accessible with other search strategies.

  1. 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)

    2014-08-11

    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.

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

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

    Barreto, J.; Cease, H.; Diehl, H. T.; Estrada, J.; Flaugher, B.; Harrison, N.; Jones, J.; Kilminster, B.; Molina, J.; Smith, J.; et al

    2012-05-15

    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. 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

    Engineering * must meet specific requirements # These courses can be taken in either term. 2ND YEAR 3RD YEAR 4 431 Last editted Apr 4, 2006 ^offered in alternate years; take in either 3rd or 4th year CHEM 242TH YEAR 1ST YEAR CHE 422 CHE 232 HSS@# 2005-2006 or PHYS 128 or GEOL 121 or AB E 312 GE 300# CHE 332

  4. Dark matter from decaying topological defects

    SciTech Connect (OSTI)

    Hindmarsh, Mark [Helsinki Institute of Physics, Gustaf Hällströmin katu, P.O. Box 64, 00014 Helsinki University (Finland); Kirk, Russell; West, Stephen M., E-mail: m.b.hindmarsh@sussex.ac.uk, E-mail: russell.kirk.2008@live.rhul.ac.uk, E-mail: stephen.west@rhul.ac.uk [Dept. of Physics, Royal Holloway University of London, Egham Hill, Egham, Surrey, TW20 0EX (United Kingdom)

    2014-03-01

    We study dark matter production by decaying topological defects, in particular cosmic strings. In topological defect or ''top-down'' (TD) scenarios, the dark matter injection rate varies as a power law with time with exponent p?4. We find a formula in closed form for the yield for all p < 3/2, which accurately reproduces the solution of the Boltzmann equation. We investigate two scenarios (p = 1, p = 7/6) motivated by cosmic strings which decay into TeV-scale states with a high branching fraction into dark matter particles. For dark matter models annihilating either by s-wave or p-wave, we find the regions of parameter space where the TD model can account for the dark matter relic density as measured by Planck. We find that topological defects can be the principal source of dark matter, even when the standard freeze-out calculation under-predicts the relic density and hence can lead to potentially large ''boost factor'' enhancements in the dark matter annihilation rate. We examine dark matter model-independent limits on this scenario arising from unitarity and discuss example model-dependent limits coming from indirect dark matter search experiments. In the four cases studied, the upper bound on G? for strings with an appreciable channel into TeV-scale states is significantly more stringent than the current Cosmic Microwave Background limits.

  5. Strangelet search in S-W collisions at 200[ital A] GeV/[ital c

    SciTech Connect (OSTI)

    Borer, K.; Dittus, F.; Frei, D.; Hugentobler, E.; Klingenberg, R.; Moser, U.; Pretzl, K.; Schacher, J.; Stoffel, F.; Volken, W. ); Elsener, K.; Lohmann, K.D. ); Baglin, C.; Bussiere, A.; Guillaud, J.P. ); Appelquist, G.; Bohm, C.; Hovander, B.; Sellden, B.; Zhang, Q.P. )

    1994-03-07

    A search for new massive particles with a low charge to mass ratio in S-W collisions at a beam momentum of 200 GeV/[ital c] per nucleon is presented. Upper limits for the production of strangelets with a mass to charge ratio of up to 60 GeV/[ital c][sup 2] at rigidities of [plus minus]150 GV are reported.

  6. How cold is cold dark matter?

    SciTech Connect (OSTI)

    Armendariz-Picon, Cristian; Neelakanta, Jayanth T., E-mail: armen@phy.syr.edu, E-mail: jtneelak@syr.edu [Department of Physics, Syracuse University, Syracuse, NY 13244-1130 (United States)

    2014-03-01

    If cold dark matter consists of particles, these must be non-interacting and non-relativistic by definition. In most cold dark matter models however, dark matter particles inherit a non-vanishing velocity dispersion from interactions in the early universe, a velocity that redshifts with cosmic expansion but certainly remains non-zero. In this article, we place model-independent constraints on the dark matter temperature to mass ratio, whose square root determines the dark matter velocity dispersion. We only assume that dark matter particles decoupled kinetically while non-relativistic, when galactic scales had not entered the horizon yet, and that their momentum distribution has been Maxwellian since that time. Under these assumptions, using cosmic microwave background and matter power spectrum observations, we place upper limits on the temperature to mass ratio of cold dark matter today (away from collapsed structures). These limits imply that the present cold dark matter velocity dispersion has to be smaller than 54 m/s. Cold dark matter has to be quite cold, indeed.

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

    E-Print Network [OSTI]

    H. T. Wong

    2007-11-08

    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.

  8. 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 212 can be taken in either term. GE 124 MATH 110 MATH 124CHEM 115 PHYS 155 3RD YEAR GE 125 GE 110 COMM 102

  9. Purdue, GE Collaborate On Advanced Manufacturing | 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass mapSpeedingProgramExemptionsProteinTotal natural gasPurchase, Delivery,Purdue, GE to

  10. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of raregovAboutRecovery Act Recovery ActARM OverviewAbout GE Global Research

  11. GE Scientists Experiment With Texas BBQ | 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverse (Journal Article)Forthcoming UpgradesArea:Benefits ofofStackOn thePower ofGE

  12. Search for muon signal from dark matter annihilations in the Sun with the Baksan Underground Scintillator Telescope for 24.12 years

    SciTech Connect (OSTI)

    Boliev, M.M.; Demidov, S.V.; Mikheyev, S.P.; Suvorova, O.V. E-mail: demidov@ms2.inr.ac.ru E-mail: suvorova@cpc.inr.ac.ru

    2013-09-01

    We present a new dataset analysis of the neutrino experiment at the Baksan Underground Scintillator Telescope with muon energy threshold about 1 GeV for the longest exposure time toward the Sun. In search for a signal from self-annihilations of dark matter particles in the center of the Sun we use an updated sample of upward through-going muons for 24.12 years of live time. No observable excess has been found in measured muons relative to expected background from neutrinos of atmospheric origin. We present an improved data analysis procedure and describe it in detail. We set the 90% C.L. new upper limits on expected neutrino and muon fluxes from dark matter annihilations in the Sun, on the corresponding annihilation rates and cross sections of their elastic scattering off proton.

  13. 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)

    2011-07-15

    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.

  14. Chevron, GE form Technology Alliance

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsiclouddenDVA N C E D BGene NetworkNuclear SecurityChattanChemistry ofNanChevron, GE form

  15. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room News Publications Traditional Knowledge KiosksAboutHelp & Reference Users AdvAncedGE

  16. Characterising dark matter searches at colliders and direct detection experiments: Vector mediators

    SciTech Connect (OSTI)

    Buchmueller, Oliver; Dolan, Matthew J.; Malik, Sarah A.; McCabe, Christopher

    2015-01-09

    We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: mDM, Mmed , gDM and gq, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (?5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. In conclusion, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.

  17. Characterising dark matter searches at colliders and direct detection experiments: Vector mediators

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

    Buchmueller, Oliver; Dolan, Matthew J.; Malik, Sarah A.; McCabe, Christopher

    2015-01-09

    We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: mDM, Mmed , gDM and gq, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establishmore »an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (?5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. In conclusion, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.« less

  18. Characterising Dark Matter Searches at Collider and Direct Detection Experiments: Vector Mediators

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

    Buchmueller, Oliver; Dolan, Matthew J.; Malik, Sarah A.; McCabe, Christopher

    2015-01-09

    We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: m DM , M med , g DM and g q, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this frameworkmore »can be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (?5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. Finally, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.« less

  19. Gravitational-wave spin-down and stalling lower limits on the electrical resistivity of the accreted mountain in a millisecond pulsar

    E-Print Network [OSTI]

    Matthias Vigelius; Andrew Melatos

    2010-05-13

    The electrical resistivity of the accreted mountain in a millisecond pulsar is limited by the observed spin-down rate of binary radio millisecond pulsars (BRMSPs) and the spins and X-ray fluxes of accreting millisecond pulsars (AMSPs). We find $\\eta \\ge 10^{-28}\\,\\mathrm{s}\\, (\\tau_\\mathrm{SD}/1\\,\\mathrm{Gyr})^{-0.8}$ (where $\\tau_\\mathrm{SD}$ is the spin-down age) for BRMSPs and $\\eta \\ge 10^{-25}\\,\\mathrm{s}\\,(\\dot{M}_\\mathrm{a}/\\dot{M}_\\mathrm{E})^{0.6}$ (where $\\dot{M}_\\mathrm{a}$ and $\\dot{M}_\\mathrm{E}$ are the actual and Eddington accretion rates) for AMSPs. These limits are inferred assuming that the mountain attains a steady state, where matter diffuses resistively across magnetic flux surfaces but is replenished at an equal rate by infalling material. The mountain then relaxes further resistively after accretion ceases. The BRMSP spin-down limit approaches the theoretical electron-impurity resistivity at temperatures $\\ga 10^5$ K for an impurity concentration of $\\sim 0.1$, while the AMSP stalling limit falls two orders of magnitude below the theoretical electron-phonon resistivity for temperatures above $10^8$ K. Hence BRMSP observations are already challenging theoretical resistivity calculations in a useful way. Next-generation gravitational-wave interferometers will constrain $\\eta$ at a level that will be competitive with electromagnetic observations.

  20. GE Global Research in San Ramon, California

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

    Careers Leadership Programs What's new in San Ramon Ars Technica: Analyzing the Internet of Things GE Unveils High-Speed Network Infrastructure to Connect Machines, Data...

  1. Matter Wave Radiation Leading to Matter Teleportation

    E-Print Network [OSTI]

    Yong-Yi Huang

    2015-02-12

    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.

  2. 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 ...

  3. 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)

    2013-09-30

    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.

  4. ? meson production in d+Au collisions at ?sNN = 200 GeV

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

    Adare, A.

    2015-10-19

    The PHENIX Collaboration has measured ? meson production in d+Au collisions at ?sNN=200 GeV using the dimuon and dielectron decay channels. The ? meson is measured in the forward (backward) d-going (Au-going) direction, 1.2 T) range from 1–7 GeV/c and at midrapidity |y|T range below 7 GeV/c. The ? meson invariant yields and nuclear-modification factors as a function of pT, rapidity, and centrality are reported. An enhancement of ? meson production is observed in the Au-going direction, while suppression is seen in the d-going direction,more »and no modification is observed at midrapidity relative to the yield in p+p collisions scaled by the number of binary collisions. As a result, similar behavior was previously observed for inclusive charged hadrons and open heavy flavor, indicating similar cold-nuclear-matter effects.« less

  5. 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)

    2013-07-01

    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.

  6. Baryonic matter and beyond

    E-Print Network [OSTI]

    Kenji Fukushima

    2014-10-01

    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.

  7. LIGHT PHOTINOS AS DARK MATTER

    E-Print Network [OSTI]

    Glennys R. Farrar; Edward W. Kolb

    1995-04-24

    There are good reasons to consider models of low-energy supersymmetry with very light photinos and gluinos. In a wide class of models the lightest $R$-odd, color-singlet state containing a gluino, the $\\r0$, has a mass in the 1-2 GeV range and the slightly lighter photino, $\\pho$, would survive as the relic $R$-odd species. For the light photino masses considered here, previous calculations resulted in an unacceptable photino relic abundance. But we point out that processes other than photino self-annihilation determine the relic abundance when the photino and $R^0$ are close in mass. Including $\\r0\\longleftrightarrow\\pho$ processes, we find that the photino relic abundance is most sensitive to the $\\r0$-to-$\\pho$ mass ratio, and within model uncertainties, a critical density in photinos may be obtained for an $\\r0$-to-$\\pho$ mass ratio in the range 1.2 to 2.2. We propose photinos in the mass range of 500 MeV to 1.6 GeV as a dark matter candidate, and discuss a strategy to test the hypothesis.

  8. Lepton-flavored dark matter

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

    Kile, Jennifer; Kobach, Andrew; Soni, Amarjit

    2015-05-01

    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

  9. Lepton-flavored dark matter

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

    Kile, Jennifer; Kobach, Andrew; Soni, Amarjit

    2015-05-01

    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)

  10. Chiral condensate in neutron matter

    E-Print Network [OSTI]

    N. Kaiser; W. Weise

    2008-08-06

    A recent chiral perturbation theory calculation of the in-medium quark condensate $$ is extended to the isospin-asymmetric case of pure neutron matter. In contrast to the behavior in isospin-symmetric nuclear matter we find only small deviations from the linear density approximation. This feature originates primarily from the reduced weight factors (e.g. 1/6 for the dominant contributions) of the $2\\pi$-exchange mechanisms in pure neutron matter. Our result suggests therefore that the tendencies for chiral symmetry restoration are actually favored in systems with large neutron excess (e.g. neutron stars). We also analyze the behavior of the density-dependent quark condensate $(\\rho_n)$ in the chiral limit $m_\\pi\\to 0$.

  11. Modeling of GE Appliances: Final Presentation

    SciTech Connect (OSTI)

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

    2013-01-31

    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.

  12. GE Turbine Parts www.edisonmachine.com

    E-Print Network [OSTI]

    Chiao, Jung-Chih

    GE Turbine Parts www.edisonmachine.com New authentic GE and Westinghouse Turbine Parts Muscle cars vehicle: Has the code for a hydrogen car been cracked? World-first working eukaryotic cell mad from's smallest windmills to power cell phones 1/17/2014http://www.gizmag.com/worlds-smallest-windmill-energy

  13. Dark Matter Antibaryons from a Supersymmetric Hidden Sector

    E-Print Network [OSTI]

    Nikita Blinov; David E. Morrissey; Kris Sigurdson; Sean Tulin

    2012-12-03

    The cosmological origin of both dark and baryonic matter can be explained through a unified mechanism called hylogenesis where baryon and antibaryon number are divided between the visible sector and a GeV-scale hidden sector, while the Universe remains net baryon symmetric. The "missing" antibaryons, in the form of exotic hidden states, are the dark matter. We study model-building, cosmological, and phenomenological aspects of this scenario within the framework of supersymmetry, which naturally stabilizes the light hidden sector and electroweak mass scales. Inelastic dark matter scattering on visible matter destroys nucleons, and nucleon decay searches offer a novel avenue for the direct detection of the hidden antibaryonic dark matter sea.

  14. Dark Matter Antibaryons from a Supersymmetric Hidden Sector

    E-Print Network [OSTI]

    Blinov, Nikita; Sigurdson, Kris; Tulin, Sean

    2012-01-01

    The cosmological origin of both dark and baryonic matter can be explained through a unified mechanism called hylogenesis where baryon and antibaryon number are divided between the visible sector and a GeV-scale hidden sector, while the Universe remains net baryon symmetric. The "missing" antibaryons, in the form of exotic hidden states, are the dark matter. We study model-building, cosmological, and phenomenological aspects of this scenario within the framework of supersymmetry, which naturally stabilizes the light hidden sector and electroweak mass scales. Inelastic dark matter scattering on visible matter destroys nucleons, and nucleon decay searches offer a novel avenue for the direct detection of the hidden antibaryonic dark matter sea.

  15. Effect of low mass dark matter particles on the Sun

    E-Print Network [OSTI]

    Marco Taoso; Fabio Iocco; Georges Meynet; Gianfranco Bertone; Patrick Eggenberger

    2010-09-07

    We study the effect of dark matter (DM) particles in the Sun, focusing in particular on the possible reduction of the solar neutrinos flux due to the energy carried away by DM particles from the innermost regions of the Sun, and to the consequent reduction of the temperature of the solar core. We find that in the very low-mass range between 4 and 10 GeV, recently advocated to explain the findings of the DAMA and CoGent experiments, the effects on neutrino fluxes are detectable only for DM models with very small, or vanishing, self-annihilation cross section, such as the so-called asymmetric DM models, and we study the combination of DM masses and Spin Dependent cross sections which can be excluded with current solar neutrino data. Finally, we revisit the recent claim that DM models with large self-interacting cross sections can lead to a modification of the position of the convective zone, alleviating or solving the solar composition problem. We show that when the `geometric' upper limit on the capture rate is correctly taken into account, the effects of DM are reduced by orders of magnitude, and the position of the convective zone remains unchanged.

  16. Growth and characterization of isotopically enriched [sup 70]Ge and [sup 74]Ge single crystals

    SciTech Connect (OSTI)

    Itoh, K.

    1992-10-01

    Isotopically enriched [sup 70]Ge and [sup 74]Ge single crystals were successfully gown by a newly developed vertical Bridgman method. The system allows us to reliably grow high purity Ge single crystals of approximately 1 cm[sup 3] volume. To our knowledge, we have grown the first [sup 70]Ge single crystal. The electrically active chemical impurity concentration for both crystals was found to be [approximately]2 [times] cm[sup [minus]3] which is two order of magnitude better that of [sup 74]Ge crystals previously grown by two different groups. Isotopic enrichment of the [sup 70]Ge and the [sup 74]Ge crystals is 96.3% and 96.8%, respectively. The residual chemical impurities present in both crystals were identified as phosphorus, copper, aluminum, and indium. A wide variety of experiments which take advantage of the isotopic purity of our crystals are discussed.

  17. Growth and characterization of isotopically enriched {sup 70}Ge and {sup 74}Ge single crystals

    SciTech Connect (OSTI)

    Itoh, K.

    1992-10-01

    Isotopically enriched {sup 70}Ge and {sup 74}Ge single crystals were successfully gown by a newly developed vertical Bridgman method. The system allows us to reliably grow high purity Ge single crystals of approximately 1 cm{sup 3} volume. To our knowledge, we have grown the first {sup 70}Ge single crystal. The electrically active chemical impurity concentration for both crystals was found to be {approximately}2 {times} cm{sup {minus}3} which is two order of magnitude better that of {sup 74}Ge crystals previously grown by two different groups. Isotopic enrichment of the {sup 70}Ge and the {sup 74}Ge crystals is 96.3% and 96.8%, respectively. The residual chemical impurities present in both crystals were identified as phosphorus, copper, aluminum, and indium. A wide variety of experiments which take advantage of the isotopic purity of our crystals are discussed.

  18. Gamma-Ray Bursts Above 1 GeV

    E-Print Network [OSTI]

    Matthew G. Baring

    1997-11-21

    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.

  19. Exclusive processes at JLab at 6 GeV

    SciTech Connect (OSTI)

    Kim, Andrey

    2015-01-01

    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.

  20. 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 ...

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

    E-Print Network [OSTI]

    Murray, James D.; Maga, Elizabeth A.

    2010-01-01

    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

  2. Xergy Ships First Breakthrough Water Heater Compressor to GE...

    Energy Savers [EERE]

    Xergy Ships First Breakthrough Water Heater Compressor to GE Xergy Ships First Breakthrough Water Heater Compressor to GE September 15, 2015 - 3:41pm Addthis Xergy Inc. and GE...

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

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

    who want to learn more about GE and its global Research Centers. For this purpose, the Aero & Thermal Systems groups of GE Global Research and representatives from several GE...

  4. Ge-on-Si laser for silicon photonics

    E-Print Network [OSTI]

    Camacho-Aguilera, Rodolfo Ernesto

    2013-01-01

    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 (<1x109cm-2) and point defects Ge ...

  5. Bimetric gravity and dark matter

    E-Print Network [OSTI]

    Laura Bernard; Luc Blanchet; Lavinia Heisenberg

    2015-07-10

    We review some recent proposals for relativistic models of dark matter in the context of bimetric gravity. The aim is to solve the problems of cold dark matter (CDM) at galactic scales, and to reproduce the phenomenology of the modified Newtonian dynamics (MOND), while still being in agreement with the standard cosmological model $\\Lambda$-CDM at large scales. In this context a promising alternative is dipolar dark matter (DDM) in which two different species of dark matter particles are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. The phenomenology of MOND then results from a mechanism of gravitational polarization. Probably the best formulation of the model is within the framework of recently developed massive bigravity theories. Then the gravitational sector of the model is safe by construction, but a ghostly degree of freedom in the decoupling limit is still present in the dark matter sector. Future work should analyse the cosmological solutions of the model and check the post-Newtonian parameters in the solar system.

  6. 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

    2014-06-11

    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.

  7. Axions - Motivation, limits and searches

    E-Print Network [OSTI]

    Georg G. Raffelt

    2006-11-09

    The axion solution of the strong CP problem provides a number of possible windows to physics beyond the standard model, notably in the form of searches for solar axions and for galactic axion dark matter, but in a broader context also inspires searches for axion-like particles in pure laboratory experiments. We briefly review the motivation for axions, astrophysical limits, their possible cosmological role, and current searches for axions and axion-like particles.

  8. 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)

    2014-03-03

    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}.

  9. 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. Try watching this video on www.youtube.com, or enable...

  10. Work & Life at San Ramon | GE Global Research

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

    new window) Click to share on Tumblr (Opens in new window) Employee Organizations GE Software Women's Network TBD Celebrations GE Software Technology Conference This event allows...

  11. Rocket Science? No, It's Harder | GE Global Research

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

    says Juan Albeniz, Business Program Manager, Oil & Gas at GE Global Research Europe. Juan Albeniz, Business Program Manager, Oil & Gas at GE Global Research, Europe Juan...

  12. 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

  13. Hollow nuclear matter

    E-Print Network [OSTI]

    Gao-Chan Yong

    2015-12-18

    It is generally considered that an atomic nucleus is always compact. Based on the isospin-dependent Boltzmann nuclear transport model, here I show that large block nuclear matter or excited nuclear matter may both be hollow. And the size of inner bubble in these matter is affected by the charge number of nuclear matter. Existence of hollow nuclear matter may have many implications in nuclear or atomic physics or astrophysics as well as some practical applications.

  14. Hollow nuclear matter

    E-Print Network [OSTI]

    Yong, Gao-Chan

    2015-01-01

    It is generally considered that an atomic nucleus is always compact. Based on the isospin-dependent Boltzmann nuclear transport model, here I show that large block nuclear matter or excited nuclear matter may both be hollow. And the size of inner bubble in these matter is affected by the charge number of nuclear matter. Existence of hollow nuclear matter may have many implications in nuclear or atomic physics or astrophysics as well as some practical applications.

  15. 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)

    2014-02-15

    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.

  16. 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)

    2013-03-21

    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.

  17. 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

  18. Dark Matter Through the Neutrino Portal

    E-Print Network [OSTI]

    Adam Falkowski; Jose Juknevich; Jessie Shelton

    2009-08-13

    We consider a model of dark matter whose most prominent signature is a monochromatic flux of TeV neutrinos from the galactic center. As an example of a general scenario, we consider a specific model where the dark matter is a fermion in the adjoint representation of a hidden SU(N) gauge group that confines at GeV energies. The absence of light fermionic states in the dark sector ensures stability of dark matter on cosmological time scales. Dark matter couples to the standard model via the neutrino portal, that is, the singlet operator H L constructed from the Higgs and lepton doublets, which is the lowest dimensional fermionic singlet operator in the standard model. This coupling prompts dark matter decay where the dominant decay channel has one neutrino (and at least one dark glueball) in the final state. Other decay channels with charged standard model particles involve more particles in the final state and are therefore suppressed by phase space. In consequence, the standard indirect detection signals like gamma-ray photons, antiprotons and positrons are suppressed with respect to the neutrino signal. This coupling via the neutrino portal is most robustly constrained by Super-Kamiokande, which restricts the dark matter lifetime to be larger than 10^25 seconds. In the near future, the scenario will be probed by the new generation of neutrino telescopes. ANTARES will be sensitive to a dark matter lifetime of order 10^26 seconds, while IceCube/DeepCore can probe a lifetime as large as 10^27 seconds.

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

    SciTech Connect (OSTI)

    Liu, Hao; Gao, G. Y. Hu, Lei; Ni, Yun; Zu, Fengxia; Zhu, Sicong; Wang, Shuling; Yao, K. L.

    2014-01-21

    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.

  20. Low radioactivity argon dark matter search results from the DarkSide-50 experiment

    E-Print Network [OSTI]

    Agnes, P; Albuquerque, I F M; Alexander, T; Alton, A K; Arisaka, K; Back, H O; Baldin, B; Biery, K; Bonfini, G; Bossa, M; Bottino, B; Brigatti, A; Brodsky, J; Budano, F; Bussino, S; Cadeddu, M; Cadonati, L; Cadoni, M; Calaprice, F; Canci, N; Candela, A; Cao, H; Cariello, M; Carlini, M; Catalanotti, S; Cavalcante, P; Chepurnov, A; Cocco, A G; Covone, G; Crippa, L; D'Angelo, D; D'Incecco, M; Davini, S; De Cecco, S; De Deo, M; De Vincenzi, M; Derbin, A; Devoto, 25 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; Giganti, C; Goretti, A M; Granato, F; Grandi, L; Gromov, M; Guan, M; Guardincerri, Y; Hackett, B R; Herner, K; Hungerford, E V; Ianni, Al; Ianni, An; James, I; Jollet, C; Keeter, K; Kendziora, C L; Kobychev, V; Koh, G; Korablev, D; Korga, G; Kubankin, A; Li, X; Lissia, M; Lombardi, P; Luitz, S; Ma, Y; Machulin, I N; Mandarano, A; Mari, S M; Maricic, J; Marini, L; Martoff, C J; Meregaglia, A; Meyers, P D; Miletic, T; Milincic, R; Montanari, D; Monte, A; Montuschi, M; Monzani, M; Mosteiro, P; Mount, B J; Muratova, V N; Musico, P; Napolitano, J; Nelson, A; Odrowski, S; Orsini, M; Ortica, F; Pagani, L; Pallavicini, M; Pantic, E; Parmeggiano, S; Pelczar, K; Pelliccia, N; Perasso, S; Pocar, A; Pordes, S; Pugachev, D A; Qian, H; Randle, K; Ranucci, G; Razeto, A; Reinhold, B; Renshaw, A L; Romani, A; Rossi, B; Rossi, N; Rountree, D; Sablone, D; Saggese, P; Saldanha, R; Sands, W; Sangiorgio, S; Savarese, C; Segreto, E; Semenov, D A; Shields, E; Singh, P N; Skorokhvatov, M D; Smallcomb, M; Smirnov, O; Sotnikov, A; Stanford, C; Suvorov, Y; Tartaglia, R; Tatarowicz, J; Testera, G; Tonazzo, A; Trinchese, P; Unzhakov, E V; Vishneva, A; Vogelaar, B; Wada, M; Walker, S; Wang, H; Wang, Y; Watson, A W; Westerdale, S; Wilhelmi, J; Wojcik, M M; Xiang, X; Xu, J; Yang, C; Yoo, J; Zavatarelli, S; Zec, A; Zhong, W; Zhu, C; Zuzel, G

    2015-01-01

    The DarkSide-50 dark matter search reports the first results obtained using a target of low-radioactivity argon extracted from underground sources. The experiment is located at the Laboratori Nazionali del Gran Sasso and uses a two-phase time projection chamber as a detector. A total of 155 kg of low radioactivity argon has been obtained, and we have determined that underground argon is depleted in Ar-39 by a factor (1.4 +- 0.2) x 10^3 relative to atmospheric argon. The underground argon was also found to contain (2.05 +- 0.13) mBq/kg of Kr-85. We found no evidence for dark matter in the form of WIMPs in 70.9 live-days of data with a fiducial mass of (36.9 +- 0.6) kg. When combined with our preceding search with an atmospheric argon target, we set a 90 % C.L. upper limit on the WIMP-nucleon spin-independent cross section of 2.0 x 10^-44 cm^2 (8.6 x 10^-44 cm^2, 8.0 x 10^-43 cm^2 ) for a WIMP mass of 100 GeV/c^2 (1 TeV/c^2 , 10 TeV/c^2 ).

  1. Design Constraints for a WIMP Dark Matter and pp Solar Neutrino Liquid Neon Scintillation Detector

    E-Print Network [OSTI]

    M. G. Boulay; A. Hime; J. Lidgard

    2004-10-18

    Detailed Monte-Carlo simulations were used to evaluate the performance of a liquid neon scintillation detector for dark matter and low-energy solar neutrino interactions. A maximum-likelihood event vertex fitter including PMT time information was developed, which significantly improves position resolution over spatial-only algorithms, and substantially decreases the required detector size and achievable analysis energy threshold. The ultimate sensitivity to WIMP dark matter and the pp flux uncertainty are evaluated as a function of detector size. The dependence on the neon scintillation and PMT properties are evaluated. A 300 cm radius detector would allow a ~13 keV threshold, a pp flux uncertainty of ~1%, and limits on the spin-independent WIMP-nucleon cross-section of ~10^{-46} cm^2 for a 100 GeV WIMP, using commercially available PMTs. Detector response calibration and background requirements for a precision pp measurement are defined. Internal radioactivity requirements for uranium, thorium, and krypton are specified, and it is shown that the PMT data could be used for an in-situ calibration of the troublesome krypton-85. A set of measurements of neon scintillation properties and PMT characteristics are outlined which will be needed in order to evaluate feasibility and fully optimize the design of a neon-based detector.

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

    SciTech Connect (OSTI)

    Mandic, Vuk

    2004-06-01

    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.

  3. 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.

  4. Researching NDE, Additive Manufacturing |GE Global Research

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

    I never thought I would get the incredible opportunity to become a summer intern at the GE Global Research Center, amongst such brilliant and tenacious individuals. I have been...

  5. GE's Christine Furstoss Named to NACIE

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

    in Niskayuna, NY, Christine is responsible for working with both R&D leaders at GE's industrial businesses and with strategic partners to set strategy for growth, and to...

  6. GE Announces Vic Abate as New Chief Technology Officer | GE Global...

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

    Industrial Internet and Brilliant Factory. This transition marks another chapter in GE's transformation to become the world's premiere Digital Industrial company. Enabled by a...

  7. 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

  8. Significant Gamma Lines from Inert Higgs Dark Matter

    E-Print Network [OSTI]

    Michael Gustafsson; Erik Lundstrom; Lars Bergstrom; Joakim Edsjo

    2007-10-05

    One way to unambiguously confirm the existence of particle dark matter and determine its mass would be to detect its annihilation into monochromatic gamma-rays in upcoming telescopes. One of the most minimal models for dark matter is the inert doublet model, obtained by adding another Higgs doublet with no direct coupling to fermions. For a mass between 40 and 80 GeV, the lightest of the new inert Higgs particles can give the correct cosmic abundance of cold dark matter in agreement with current observations. We show that for this scalar dark matter candidate, the annihilation signal of monochromatic \\gamma\\gamma and Z\\gamma final states would be exceptionally strong. The energy range and rates for these gamma-ray line signals make them ideal to search for with the soon upcoming GLAST satellite.

  9. Wino dark matter under siege

    SciTech Connect (OSTI)

    Cohen, Timothy; Lisanti, Mariangela; Pierce, Aaron; Slatyer, Tracy R. E-mail: mlisanti@princeton.edu E-mail: tslatyer@mit.edu

    2013-10-01

    A fermion triplet of SU(2){sub L} — a wino — is a well-motivated dark matter candidate. This work shows that present-day wino annihilations are constrained by indirect detection experiments, with the strongest limits coming from H.E.S.S. and Fermi. The bounds on wino dark matter are presented as a function of mass for two scenarios: thermal (winos constitute a subdominant component of the dark matter for masses less than 3.1 TeV) and non-thermal (winos comprise all the dark matter). Assuming the NFW halo model, the H.E.S.S. search for gamma-ray lines excludes the 3.1 TeV thermal wino; the combined H.E.S.S. and Fermi results completely exclude the non-thermal scenario. Uncertainties in the exclusions are explored. Indirect detection may provide the only probe for models of anomaly plus gravity mediation where the wino is the lightest superpartner and scalars reside at the 100 TeV scale.

  10. Cosmic antiprotons as a probe for neutralino dark matter?

    E-Print Network [OSTI]

    Lars Bergstrom; Joakim Edsjo; Piero Ullio

    1999-06-02

    The flux of cosmic ray antiprotons from neutralino annihilations in the galactic halo is computed for a large sample of models in the Minimal Supersymmetric extension of the Standard Model. We also revisit the problem of estimating the background of low-energy cosmic ray induced secondary antiprotons, taking into account their subsequent interactions (and energy loss) and the presence of nuclei in the interstellar matter. We point out that in some cases the optimal kinetic energy to search for a signal from supersymmetric dark matter is above several GeV, rather than the traditional sub-GeV region. The large astrophysical uncertainties involved do not allow the exclusion of any of the MSSM models we consider, on the basis of current data.

  11. Direct Dark Matter Searches with CDMS and XENON

    E-Print Network [OSTI]

    Kaixuan Ni; Laura Baudis

    2006-11-09

    The Cryogenic Dark Matter Search (CDMS) and XENON experiments aim to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering on the target nuclei. The experiments use different techniques to suppress background event rates to the minimum, and at the same time, to achieve a high WIMP detection rate. The operation of cryogenic Ge and Si crystals of the CDMS-II experiment in the Soudan mine yielded the most stringent spin-independent WIMP-nucleon cross-section (~10^{-43} cm^2) at a WIMP mass of 60 GeV/c^2. The two-phase xenon detector of the XENON10 experiment is currently taking data in the Gran Sasso underground lab and promising preliminary results were recently reported. Both experiments are expected to increase their WIMP sensitivity by a one order of magnitude in the scheduled science runs for 2007.

  12. 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

    2010-03-15

    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.

  13. Predictions on mass of Higgs portal scalar dark matter from Higgs inflation and flat potential

    E-Print Network [OSTI]

    Yuta Hamada; Hikaru Kawai; Kin-ya Oda

    2015-01-25

    We consider the Higgs portal $Z_2$ scalar model as the minimal extension of the Standard Model (SM) to incorporate the dark matter. We find that the dark matter mass is bounded to be lighter than 1000\\,GeV within the framework that we have proposed earlier, where the Higgs inflation occurs above the SM cutoff $\\Lambda$, thanks to the fact that the Higgs potential becomes much smaller than its typical value in the SM: $V\\ll\\Lambda^4$. We can further fix the dark matter mass to be $400\\text{GeV}< m_\\text{DM}<470\\text{GeV}$ if we impose that the cutoff is at the string scale $\\Lambda\\sim10^{17}\\text{GeV}$ and that the Higgs potential becomes flat around $\\Lambda$, as is required by the multiple point principle or by the Higgs inflation at the critical point. This prediction is testable by the dark matter detection experiments in the near future. In this framework, the dark matter and top quark masses are strongly correlated, which is also testable.

  14. Exploring nu signals in dark matter detectors

    E-Print Network [OSTI]

    Roni Harnik; Joachim Kopp; Pedro A. N. Machado

    2015-08-03

    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 each 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.

  15. Asymmetric dark matter

    SciTech Connect (OSTI)

    Kumar, Jason

    2014-06-24

    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.

  16. Design of programmable matter

    E-Print Network [OSTI]

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

    2008-01-01

    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 ...

  17. 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

  18. 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

  19. 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

  20. 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

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

    E-Print Network [OSTI]

    Abbas Farmany; Amin Farmany; Mohammad Mahmoodi

    2006-07-07

    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.

  2. Dark Matter and Cosmic Rays from Light Gauginos

    E-Print Network [OSTI]

    Glennys R. Farrar

    1997-04-13

    An attractive class of SUSY-breaking mechanisms predicts a photino mass of order 1 GeV. Relic photinos can naturally account for the observed dark matter. Detection of these light photinos is discussed and contrasted with conventional WIMPs. In this scenario the gluino mass is about 100 MeV. The lightest gluino-containing baryon could account for the recently observed ultra-high energy cosmic rays, which violate the GZK bound.

  3. 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

    2000-05-30

    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.

  4. Isospin-violating dark matter from a double portal

    SciTech Connect (OSTI)

    Bélanger, Genevičve; Goudelis, Andreas; Park, Jong-Chul; Pukhov, Alexander E-mail: andreas.goudelis@lapth.cnrs.fr E-mail: pukhov@lapth.cnrs.fr

    2014-02-01

    We study a simple model that can give rise to isospin-violating interactions of Dirac fermion asymmetric dark matter to protons and neutrons through the interference of a scalar and U(1)' gauge boson contribution. The model can yield a large suppression of the elastic scattering cross section off Xenon relative to Silicon thus reconciling CDMS-Si and LUX results while being compatible with LHC findings on the 126 GeV Higgs, electroweak precision tests and flavour constraints.

  5. 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)

    2013-12-04

    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.

  6. High-efficiency GaAs/Ge monolithic tandem solar cells

    SciTech Connect (OSTI)

    Tobin, S.P.; Vernon, S.M.; Bajgar, C.; Haven, V.E.; Geoffroy, L.M.; Lillington, D.R.

    1988-05-01

    High photovoltaic efficiency and light weight are important criteria for spacecraft power applications. Present GaAs cells are approaching their efficiency limits, but are not efficient or light enough for future needs. The authors have investigated tandem cells of GaAs grown by MOCVD on thin Ge to address both higher efficiency and reduced weight. GaAs/Ge monolithic tandem cells of 4-cm/sup 2/ area have been produced with independently verified efficiencies up to 21.7 percent (AMO, one sun, 25/sup 0/C, total area). Under AM1.5 Global conditions, efficiencies are up to 24.3 percent. These are the highest one-sun efficiencies reported for GaAs/Ge cells, and the highest efficiency for a two-terminal monolithic tandem cell.

  7. 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

  8. Fermionic dark matter with pseudo-scalar Yukawa interaction

    SciTech Connect (OSTI)

    Ghorbani, Karim

    2015-01-01

    We consider a renormalizable extension of the standard model whose fermionic dark matter (DM) candidate interacts with a real singlet pseudo-scalar via a pseudo-scalar Yukawa term while we assume that the full Lagrangian is CP-conserved in the classical level. When the pseudo-scalar boson develops a non-zero vacuum expectation value, spontaneous CP-violation occurs and this provides a CP-violated interaction of the dark sector with the SM particles through mixing between the Higgs-like boson and the SM-like Higgs boson. This scenario suggests a minimal number of free parameters. Focusing mainly on the indirect detection observables, we calculate the dark matter annihilation cross section and then compute the DM relic density in the range up to m{sub DM} = 300 GeV.We then find viable regions in the parameter space constrained by the observed DM relic abundance as well as invisible Higgs decay width in the light of 125 GeV Higgs discovery at the LHC. We find that within the constrained region of the parameter space, there exists a model with dark matter mass m{sub DM} ? 38 GeV annihilating predominantly into b quarks, which can explain the Fermi-LAT galactic gamma-ray excess.

  9. Atomic ionization by keV-scale pseudoscalar dark-matter particles

    SciTech Connect (OSTI)

    Dzuba, V. A.; Flambaum, V. V.; Pospelov, M.

    2010-05-15

    Using the relativistic Hartree-Fock approximation, we calculate the rates of atomic ionization by absorption of pseudoscalar particles in the mass range from 10 to {approx}50 keV. We present numerical results for atoms relevant for the direct dark-matter searches (e.g. Ar, Ge, I and Xe), as well as the analytical formula which fits numerical calculations with few per cent accuracy and may be used for multielectron atoms, molecules and condensed matter systems.

  10. Measuring 10-1000 GeV Cosmic Ray Electrons with GLAST/LAT

    E-Print Network [OSTI]

    Alexander A. Moiseev; Jonathan F. Ormes; Igor V. Moskalenko

    2007-06-06

    We present here the capabilities of the GLAST Large Area Telescope to detect cosmic ray high-energy (HE) electrons in the energy range from 10 GeV to 1 TeV. We also discuss the science topics that can be investigated with HE electron data and quantify the results with LAT instrument simulations. The science topics include CR propagation, calibration of the IC gamma-ray model, testing hypotheses regarding the origin of HE energy cosmic-ray electrons, searching for any signature of Kaluza Klein Dark Matter annihilation, and measuring the HE electron anisotropy. We expect to detect ~ 107 electrons above 20 GeV per year of LAT operation.

  11. Osmotic pressure of matter and vacuum energy

    E-Print Network [OSTI]

    G. E. Volovik

    2009-10-04

    The walls of the box which contains matter represent a membrane that allows the relativistic quantum vacuum to pass but not matter. That is why the pressure of matter in the box may be considered as the analog of the osmotic pressure. However, we demonstrate that the osmotic pressure of matter is modified due to interaction of matter with vacuum. This interaction induces the nonzero negative vacuum pressure inside the box, as a result the measured osmotic pressure becomes smaller than the matter pressure. As distinct from the Casimir effect, this induced vacuum pressure is the bulk effect and does not depend on the size of the box. This effect dominates in the thermodynamic limit of the infinite volume of the box. Analog of this effect has been observed in the dilute solution of 3He in liquid 4He, where the superfluid 4He plays the role of the non-relativistic quantum vacuum, and 3He atoms play the role of matter.

  12. Big Questions: Dark Matter

    SciTech Connect (OSTI)

    Lincoln, Don

    2013-12-05

    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.

  13. Big Questions: Dark Matter

    ScienceCinema (OSTI)

    Lincoln, Don

    2014-08-07

    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.

  14. Hunting for dark matter subhalos among the Fermi-LAT sources with VERITAS

    E-Print Network [OSTI]

    Nieto, Daniel

    2015-01-01

    The distribution of dark matter in the Galaxy, according to state-of-the-art simulations, shows not only a smooth halo component but also a rich substructure where a hierarchy of dark matter subhalos of different masses is found. We present a search for potential dark matter subhalos in our Galaxy exploiting the high (HE, 100 MeV -- 100 GeV) and very-high-energy (VHE, >100 GeV) gamma-ray bands. We assume a scenario where the dark matter is composed of weakly interacting massive particles of mass over 100 GeV, and is capable of self-annihilation into standard model products. Under such a hypothesis, most of the photons created by the annihilation of dark matter particles are predicted to lay in the HE gamma-ray band, where the Fermi-Large Area Telescope is the most sensitive instrument to date. However, the distinctive spectral cut-off located at the dark matter particle mass is expected in the VHE gamma-ray band, thus making imaging atmospheric Cherenkov telescopes like VERITAS the best suited instruments for...

  15. 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

  16. Light Higgses and Dark Matter Bob McElrath

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    , making DAMA more sensitive to light dark matter. Furthermore, a "wind" passing through our local region not produce any 0 or high-energy photons from e+e- final state, due to COMPTEL and EGRET limits on gamma rays

  17. Systematic uncertainties from halo asphericity in dark matter searches

    SciTech Connect (OSTI)

    Bernal, Nicolás; Forero-Romero, Jaime E.; Garani, Raghuveer; Palomares-Ruiz, Sergio E-mail: je.forero@uniandes.edu.co E-mail: sergio.palomares.ruiz@ific.uv.es

    2014-09-01

    Although commonly assumed to be spherical, dark matter halos are predicted to be non-spherical by N-body simulations and their asphericity has a potential impact on the systematic uncertainties in dark matter searches. The evaluation of these uncertainties is the main aim of this work, where we study the impact of aspherical dark matter density distributions in Milky-Way-like halos on direct and indirect searches. Using data from the large N-body cosmological simulation Bolshoi, we perform a statistical analysis and quantify the systematic uncertainties on the determination of local dark matter density and the so-called J factors for dark matter annihilations and decays from the galactic center. We find that, due to our ignorance about the extent of the non-sphericity of the Milky Way dark matter halo, systematic uncertainties can be as large as 35%, within the 95% most probable region, for a spherically averaged value for the local density of 0.3-0.4 GeV/cm {sup 3}. Similarly, systematic uncertainties on the J factors evaluated around the galactic center can be as large as 10% and 15%, within the 95% most probable region, for dark matter annihilations and decays, respectively.

  18. An Ultimate Target for Dark Matter Searches

    E-Print Network [OSTI]

    Kfir Blum; Yanou Cui; Marc Kamionkowski

    2014-12-10

    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.

  19. 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)

    2014-07-28

    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.

  20. 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

    2004-11-15

    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.

  1. 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

  2. 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

  3. Maximum patch method for directional dark matter detection

    SciTech Connect (OSTI)

    Henderson, Shawn; Monroe, Jocelyn; Fisher, Peter [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Laboratory for Nuclear Science, MIT Kavli Institute for Astrophysics and Space Research, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2008-07-01

    Present and planned dark matter detection experiments search for WIMP-induced nuclear recoils in poorly known background conditions. In this environment, the maximum gap statistical method provides a way of setting more sensitive cross section upper limits by incorporating known signal information. We give a recipe for the numerical calculation of upper limits for planned directional dark matter detection experiments, that will measure both recoil energy and angle, based on the gaps between events in two-dimensional phase space.

  4. A Simple Recipe for the 111 and 128 GeV Lines

    E-Print Network [OSTI]

    JiJi Fan; Matthew Reece

    2013-08-03

    Recently evidence for gamma ray lines at energies of approximately 111 and 128 GeV has been found in Fermi-LAT data from the center of the galaxy and from unassociated point sources. Many explanations in terms of dark matter particle pairs annihilating to gamma gamma and gamma Z have been suggested, but these typically require very large couplings or mysterious coincidences in the masses of several new particles to fit the signal strength. We propose a simple novel explanation in which dark matter is part of a multiplet of new states which all have mass near 260 GeV as a result of symmetry. Two dark matter particles annihilate to a pair of neutral particles in this multiplet which subsequently decay to gamma gamma and gamma Z. For example, one may have a triplet of pseudo-Nambu-Goldstone bosons, charged pions and a neutral pion, where the charged pions are stabilized by their charge under a new U(1) symmetry and the slightly lighter neutral pion state decays to gamma gamma and gamma Z. The symmetry structure of such a model explains the near degeneracy in masses needed for the resulting photons to have a line-like shape and the large observed flux. The tunable lifetime of the neutral state allows such models to go unseen at direct detection or collider experiments that can constrain most other explanations. However, nucleosynthesis constraints on the neutral pion lifetime fix a minimum necessary coupling between the new multiplet and the Standard Model. The spectrum is predicted to be not a line but a box with a width of order a few GeV, smaller than but on the order of the Fermi-LAT resolution.

  5. Higgs inflation and Higgs portal dark matter with right-handed neutrinos

    E-Print Network [OSTI]

    Naoyuki Haba; Hiroyuki Ishida; Ryo Takahashi

    2015-05-02

    We investigate the Higgs inflation and the Higgs portal dark matter with the right-handed neutrino. The dark matter and the right-handed neutrino in the Higgs inflation play important roles in explaining the recent experimental results of the Higgs and top masses, and the cosmic microwave background by BICEP2 at the same time. This inflation model predicts $805~{\\rm GeV} \\lesssim m_{\\rm DM} \\lesssim1220~{\\rm GeV}$ for the DM mass, $1.05 \\times10^{14}~{\\rm GeV} \\lesssim M_R \\lesssim 2.04 \\times10^{14}~{\\rm GeV}$ for the right-handed neutrino mass, and $8.42 \\lesssim \\xi \\lesssim 12.4$ for the non-minimal coupling within $m_H=125.6 \\pm 0.35~{\\rm GeV}$ for the Higgs and $M_t=173.34 \\pm 0.76~{\\rm GeV}$ for the top masses.

  6. DEAP-3600 Dark Matter Search

    E-Print Network [OSTI]

    P. -A. Amaudruz; M. Batygov; B. Beltran; J. Bonatt; M. G. Boulay; B. Broerman; J. F. Bueno; A. Butcher; B. Cai; M. Chen; R. Chouinard; B. T. Cleveland; K. Dering; J. DiGioseffo; F. Duncan; T. Flower; R. Ford; P. Giampa; P. Gorel; K. Graham; D. R. Grant; E. Guliyev; A. L. Hallin; M. Hamstra; P. Harvey; C. J. Jillings; M. Ku?niak; I. Lawson; O. Li; P. Liimatainen; P. Majewski; A. B. McDonald; T. McElroy; K. McFarlane; J. Monroe; A. Muir; C. Nantais; C. Ng; A. J. Noble; C. Ouellet; K. Palladino; P. Pasuthip; S. J. M. Peeters; T. Pollmann; W. Rau; F. Retičre; N. Seeburn; K. Singhrao; P. Skensved; B. Smith; T. Sonley; J. Tang; E. Vázquez-Jáuregui; L. Veloce; J. Walding; M. Ward

    2014-10-27

    The DEAP-3600 experiment is located 2 km underground at SNOLAB, in Sudbury, Ontario. It is a single-phase detector that searches for dark matter particle interactions within a 1000-kg fiducial mass target of liquid argon. A first generation prototype detector (DEAP-1) with a 7-kg liquid argon target mass demonstrated a high level of pulse-shape discrimination (PSD) for reducing $\\beta$/$\\gamma$ backgrounds and helped to develop low radioactivity techniques to mitigate surface-related $\\alpha$ backgrounds. Construction of the DEAP-3600 detector is nearly complete and commissioning is starting in 2014. The target sensitivity to spin-independent scattering of Weakly Interacting Massive Particles (WIMPs) on nucleons of 10$^{-46}$ cm$^2$ will allow one order of magnitude improvement in sensitivity over current searches at 100 GeV WIMP mass. This paper presents an overview and status of the DEAP-3600 project and discusses plans for a future multi-tonne experiment, DEAP-50T.

  7. 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.

    2015-02-01

    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

  8. Updated 8/28/2014 New GE Requirements & Environmental Studies Advising

    E-Print Network [OSTI]

    Updated 8/28/2014 New GE Requirements & Environmental Studies Advising Course Concentration(s) Lower Division GE Upper Division GE Overlay(s) AIS 310

  9. 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.

  10. 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 and Non-Newtonian Fluids l Dimensions and Units of Viscosity l Viscometer Types l Capillary M. Kostic must be supplied (1) to create viscous flow units by breaking bonds between atoms and molecules, and (2

  11. Fourth generation quark mass limits in CKM-element space

    E-Print Network [OSTI]

    Christian J. Flacco; Daniel Whiteson; Matthew Kelly

    2011-01-25

    We present a reanalysis of CDF data to extend limits on individual fourth-generation quark masses from particular flavor-mixing rates to the entire space of possible mixing values. Measurements from CDF have set individual limits on masses, $m_{b'}$ and $m_{t'}$, at the level of $335$--$385$ GeV assuming specific and favorable flavor-mixing rates. We consider the space of possible values for the mixing rates and find that the CDF data imply limits of $290$ GeV and greater over a wide range of mixing scenarios. We also analyze the limits from the perspective of a four-generation CKM matrix. We find that present experimental constraints on CKM elements do not suggest further constraints on fourth-generation quark masses.

  12. 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

    2015-04-09

    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.

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

    E-Print Network [OSTI]

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

    2015-01-01

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

    E-Print Network [OSTI]

    JiJi Fan; Matthew Reece

    2013-07-16

    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.

  15. Matter: Space without Time

    E-Print Network [OSTI]

    Yousef Ghazi-Tabatabai

    2012-11-19

    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.

  16. Effects of Ge replacement in GeTe by [Ag+Sb] on thermoelectric...

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

    in GeTe by Ag+Sb on thermoelectric properties and NMR spectra Requirements for student: general physics and chemistry courses, and desire to work in experimental laboratory. This...

  17. 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)

    2014-09-21

    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.

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

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

    offered 19 programs and counted 375 participants; this year, Girls Who Code will offer 60 programs reaching close to 1,200 girls in nine cities nationwide. GE joins other...

  19. Sensitivity of CTA to dark matter signals from the Galactic Center

    E-Print Network [OSTI]

    Mathias Pierre; Jennifer M. Siegal-Gaskins; Pat Scott

    2014-10-13

    (abridged) The Galactic Center is one of the most promising targets for indirect detection of dark matter with gamma rays. We investigate the sensitivity of the upcoming Cherenkov Telescope Array (CTA) to dark matter annihilation and decay in the Galactic Center. As the inner density profile of the Milky Way's dark matter halo is uncertain, we study the impact of the slope of the Galactic density profile, inwards of the Sun, on the prospects for detecting a dark matter signal with CTA. We find that the sensitivity achieved by CTA to annihilation signals is strongly dependent on the inner profile slope, whereas the dependence is more mild in the case of dark matter decay. Surprisingly, we find that the optimal choice of signal and background regions is virtually independent of the assumed density profile. For the fiducial case of a Navarro-Frenk-White profile, we find that CTA will be able to probe annihilation cross sections well below the canonical thermal relic value for dark matter masses from a few tens of GeV up to $\\sim 5$ TeV for annihilation to $\\tau^{+}\\tau^{-}$, and will achieve only a slightly weaker sensitivity for annihilation to $b\\bar{b}$ or $\\mu^{+}\\mu^{-}$. CTA will improve significantly on current sensitivity to annihilation signals for dark matter masses above $\\sim 100$ GeV, covering parameter space that is complementary to that probed by searches with the Fermi Large Area Telescope. The interpretation of apparent excesses in the measured cosmic-ray electron and positron spectra as signals of dark matter decay will also be testable with CTA observations of the Galactic Center. We demonstrate that both for annihilation and for decay, including spectral information for hard channels (such as $\\mu^{+}\\mu^{-}$ and $\\tau^{+}\\tau^{-}$) leads to enhanced sensitivity for dark matter masses above $m_{\\rm DM}\\sim 200$ GeV.

  20. Dark-matter harmonics beyond annual modulation

    SciTech Connect (OSTI)

    Lee, Samuel K.; Lisanti, Mariangela; Safdi, Benjamin R. E-mail: mlisanti@princeton.edu

    2013-11-01

    The count rate at dark-matter direct-detection experiments should modulate annually due to the motion of the Earth around the Sun. We show that higher-frequency modulations, including daily modulation, are also present and in some cases are nearly as strong as the annual modulation. These higher-order modes are particularly relevant if (i) the dark matter is light, O(10) GeV, (ii) the scattering is inelastic, or (iii) velocity substructure is present; for these cases, the higher-frequency modes are potentially observable at current and ton-scale detectors. We derive simple expressions for the harmonic modes as functions of the astrophysical and geophysical parameters describing the Earth's orbit, using an updated expression for the Earth's velocity that corrects a common error in the literature. For an isotropic halo velocity distribution, certain ratios of the modes are approximately constant as a function of nuclear recoil energy. Anisotropic distributions can also leave observable features in the harmonic spectrum. Consequently, the higher-order harmonic modes are a powerful tool for identifying a potential signal from interactions with the Galactic dark-matter halo.

  1. Energy Secretary Chu to Tour GE Global Research Advanced Manufacturing...

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

    Energy Secretary Chu to Tour GE Global Research Advanced Manufacturing Lab Energy Secretary Chu to Tour GE Global Research Advanced Manufacturing Lab May 24, 2012 - 10:54am Addthis...

  2. Butterfly-Inspired Thermal Imaging | GE Global Research

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

    GE Innovation and Manufacturing in Europe 2-4-13-v-3d-printing-medical-devices Additive Manufacturing Demonstration at GE Global Research 2-3-10-v Crowdsourcing...

  3. What Happens in Research-Based Design | GE Global Research

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

    paths we have at GE Global Research ("GE Leaders are Researchers Too",). The field of gas turbine heat transfer is growing in importance, and as a result, we have a lot of job...

  4. Cosmology with Mimetic Matter

    SciTech Connect (OSTI)

    Chamseddine, Ali H.; Mukhanov, Viatcheslav; Vikman, Alexander E-mail: viatcheslav.Mukhanov@lmu.de

    2014-06-01

    We consider minimal extensions of the recently proposed Mimetic Dark Matter and show that by introducing a potential for the mimetic non-dynamical scalar field we can mimic nearly any gravitational properties of the normal matter. In particular, the mimetic matter can provide us with inflaton, quintessence and even can lead to a bouncing nonsingular universe. We also investigate the behaviour of cosmological perturbations due to a mimetic matter. We demonstrate that simple mimetic inflation can produce red-tilted scalar perturbations which are largely enhanced over gravity waves.

  5. 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.

  6. Stable Higgs Bosons - new candidate for cold dark matter -

    E-Print Network [OSTI]

    Yutaka Hosotani

    2010-03-31

    The Higgs boson is in the backbone of the standard model of electroweak interactions. It must exist in some form for achieving unification of interactions. In the gauge-Higgs unification scenario the Higgs boson becomes a part of the extra-dimensional component of gauge fields. The Higgs boson becomes absolutely stable in a class of the gauge-Higgs unification models, serving as a promising candidate for cold dark matter in the universe. The observed relic abundance of cold dark matter is obtained with the Higgs mass around 70 GeV. The Higgs-nucleon scattering cross section is found to be close to the recent CDMS II and XENON10 bounds in the direct detection of dark matter. In collider experiments stable Higgs bosons are produced in a pair, appearing as missing energies and momenta so that the way of detecting Higgs bosons must be altered.

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

    E-Print Network [OSTI]

    Shao-Long Chen; Yue Zhang

    2011-06-20

    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.

  8. The Past and Future of Light Dark Matter Direct Detection

    E-Print Network [OSTI]

    Jonathan H. Davis

    2015-06-12

    We review the status and future of direct searches for light dark matter. We start by answering the question: `Whatever happened to the light dark matter anomalies?' i.e. the fate of the potential dark matter signals observed by the CoGeNT, CRESST-II, CDMS-Si and DAMA/LIBRA experiments. We discuss how the excess events in the first two of these experiments have been explained by previously underestimated backgrounds. For DAMA we summarise the progress and future of mundane explanations for the annual modulation reported in its event rate. Concerning the future of direct detection we focus on the irreducible background from solar neutrinos. We explain broadly how it will affect future searches and summarise efforts to mitigate its effects.

  9. 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)

    2014-01-07

    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.

  10. 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

    2015-02-05

    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

  11. 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)

    2014-03-07

    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.

  12. Maximally incompressible neutron star matter

    E-Print Network [OSTI]

    Timothy S. Olson

    2000-12-07

    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.

  13. Cosmological effects of coupled dark matter

    E-Print Network [OSTI]

    Sophie C. F. Morris; Anne M. Green; Antonio Padilla; Ewan R. M. Tarrant

    2013-10-15

    Many models have been studied that contain more than one species of dark matter and some of these couple the Cold Dark Matter (CDM) to a light scalar field. In doing this we introduce additional long range forces, which in turn can significantly affect our estimates of cosmological parameters if not properly accounted for. It is, therefore, important to study these models and their resulting cosmological implications. We present a model in which a fraction of the total cold dark matter density is coupled to a scalar field. We study the background and perturbation evolution and calculate the resulting Cosmic Microwave Background anisotropy spectra. The greater the fraction of dark matter coupled to the scalar field and the stronger the coupling strength, the greater the deviation of the background evolution from LCDM. Previous work, with a single coupled dark matter species, has found an upper limit on the coupling strength of order O(0.1). We find that with a coupling of this magnitude more than half the dark matter can be coupled to a scalar field without producing any significant deviations from LCDM.

  14. 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

  15. MOTION OF ELECTRON-HOLE DROPS IN Ge

    E-Print Network [OSTI]

    Westervelt, R.M.

    2011-01-01

    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

  16. 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 ...

  17. Gravitational mass of relativistic matter and antimatter

    E-Print Network [OSTI]

    Tigran Kalaydzhyan

    2015-07-09

    The universality of free fall, the weak equivalence principle (WEP), is a cornerstone of the general theory of relativity, the most precise theory of gravity confirmed in all experiments up to date. The WEP states the equivalence of the inertial, $m$, and gravitational, $m_g$, masses and was tested in numerous occasions with normal matter at relatively low energies. However, there is no proof for the matter and antimatter at high energies. For the antimatter the situation is even less clear -- current direct observations of trapped antihydrogen suggest the limits $-65 International Linear Collider (ILC) and Compact Linear Collider (CLIC).

  18. Phenomenology of Light Gauginos: I. Motivation, Masses, Lifetimes and Limits

    E-Print Network [OSTI]

    Glennys R. Farrar

    1995-08-14

    I explore an economical variant on supersymmetric standard models which may be indicated on cosmological grounds and is shown to have no SUSY-CP problem. Demanding radiative electroweak symmetry breaking suggests that the Higgs is light; other scalar masses may be ~ 100-200 GeV or less. In this case the gluino and photino, while massless at tree level, have 1-loop masses m(gluino) ~ 100 - 600 MeV and m(photino) ~ 100 - 1000 MeV. New hadrons with mass ~ 1 - 3 GeV are predicted and their lifetimes estimated. Existing experimental limits are discussed.

  19. Energy and matter

    E-Print Network [OSTI]

    Gobato, Ricardo; Fedrigo, Desire Francine Gobato

    2015-01-01

    Our work is an approach between matter and energy. Using the famous equation E = mc^2, Einstein and the Law of Universal Gravitation of Newton, we estimate that a small amount matter converted into energy is needed to lift, using the gravitational potential energy equation on the surface, a mountain of solid iron or even Mount Everest.

  20. Dark matter searches

    E-Print Network [OSTI]

    Baudis, Laura

    2015-01-01

    One of the major challenges of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the scales of galaxies up to the largest cosmological scales. The dark matter could be made of new, yet undiscovered elementary particles, with allowed masses and interaction strengths with normal matter spanning an enormous range. Axions, produced non-thermally in the early universe, and weakly interacting massive particles (WIMPs), which froze out of thermal equilibrium with a relic density matching the observations, represent two well-motivated, generic classes of dark matter candidates. Dark matter axions could be detected by exploiting their predicted coupling to two photons, where the highest sensitivity is reached by experiments using a microwave cavity permeated by a strong magnetic field. WIMPs could be directly observed via scatters off atomic nuclei in underground, ultr...

  1. Dark matter axions

    E-Print Network [OSTI]

    P. Sikivie

    2009-09-04

    The hypothesis of an `invisible' axion was made by Misha Shifman and others, approximately thirty years ago. It has turned out to be an unusually fruitful idea, crossing boundaries between particle physics, astrophysics and cosmology. An axion with mass of order $10^{-5}$ eV (with large uncertainties) is one of the leading candidates for the dark matter of the universe. It was found recently that dark matter axions thermalize and form a Bose-Einstein condensate (BEC). Because they form a BEC, axions differ from ordinary cold dark matter (CDM) in the non-linear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multipoles. Because there is evidence for these phenomena, unexplained with ordinary CDM, an argument can be made that the dark matter is axions.

  2. Dissipation of dark matter

    E-Print Network [OSTI]

    Hermano Velten; Dominik J. Schwarz

    2012-10-01

    Fluids often display dissipative properties. We explore dissipation in the form of bulk viscosity in the cold dark matter fluid. We constrain this model using current data from supernovae, baryon acoustic oscillations and the cosmic microwave background. Considering the isotropic and homogeneous background only, viscous dark matter is allowed to have a bulk viscosity $\\lesssim 10^7$ Pa$\\cdot$s, also consistent with the expected integrated Sachs-Wolfe effect (which plagues some models with bulk viscosity). We further investigate the small-scale formation of viscous dark matter halos, which turns out to place significantly stronger constraints on the dark matter viscosity. The existence of dwarf galaxies is guaranteed only for much smaller values of the dark matter viscosity, $\\lesssim 10^{-3}$ Pa$\\cdot$s.

  3. Testing Higgs portal dark matter via $Z$ fusion at a linear collider

    E-Print Network [OSTI]

    Shinya Kanemura; Shigeki Matsumoto; Takehiro Nabeshima; Hiroyuki Taniguchi

    2011-02-25

    We investigate the possibility of detecting dark matter at TeV scale linear colliders in the scenario where the dark matter is a massive particle weakly interacting only with the Higgs boson $h$ in the low energy effective theory (the Higgs portal dark matter scenario). The dark matter in this scenario would be difficult to be tested at the CERN Large Hadron Collider when the decay of the Higgs boson into a dark matter pair is not kinematically allowed. We study whether even in such a case the dark matter $D$ can be explored or not via the $Z$ boson fusion process at the International Linear Collider and also at a multi TeV lepton collider. It is found that for the collision energy $\\sqrt{S}>1$ TeV with the integrated luminosity 1 ab$^{-1}$, the signal ($e^{\\pm}e^-\\to e^{\\pm}e^-h^\\ast \\to e^{\\pm}e^-DD$) can be seen after appropriate kinematic cuts. In particular, when the dark matter is a fermion or a vector, which is supposed to be singlet under the standard gauge symmetry, the signal with the mass up to 100 GeV can be tested for the Higgs boson mass to be 120 GeV.

  4. Constraints on Light Dark Matter from Single-Photon Decays of Heavy Quarkonium

    E-Print Network [OSTI]

    Fernandez, Nicolas; Stengel, Patrick

    2015-01-01

    We investigate constraints on the interactions of light dark matter with Standard Model quarks in a framework with effective contact operators mediating the decay of heavy flavor bound state quarkonium to dark matter and a photon. When considered in combination with decays to purely invisible final states, constraints from heavy quarkonium decays at high intensity electron-positron colliders can complement missing energy searches at high energy colliders and provide sensitivity to dark matter masses difficult to probe at direct and indirect detection experiments. We calculate the approximate limits on the branching fraction for $\\Upsilon (1 S)$ decays to dark matter and a photon. Given the approximate limits on the branching fractions for all dimension 6 or lower contact operators, we present the corresponding limits on the interaction strength for each operator and the inferred limits on dark matter-nucleon scattering. Complementary constraints on dark matter annihilation from gamma-ray searches from dwarf s...

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

    SciTech Connect (OSTI)

    Cao, Qing

    2012-07-26

    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

  6. 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

    2009-07-01

    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.

  7. Particle Production at 3 GeV X. Ding, UCLA

    E-Print Network [OSTI]

    McDonald, Kirk

    = 50m 0.02976 (neg: 0.01206, pos: 0.01770) Carbon 3 GeV, Z = 0m 0.03341 (neg: 0.01370, pos: 0.01971) Mercury 3 GeV, Z = 50 m 0.02096 (neg: 0.01070, pos: 0.01026) Mercury 3 GeV, Z = 0 m 0.02496 (neg: 0.01273, pos: 0.01223) Mercury 8 GeV, Z = 50 m 0.0263 (neg: 0.0136, pos: 0.0127) Mercury 8 GeV, Z = 0m 0

  8. Dark Matter and the Baryon Asymmetry

    E-Print Network [OSTI]

    Glennys R. Farrar; Gabrijela Zaharijas

    2005-10-06

    We present a mechanism to generate the baryon asymmetry of the Universe which preserves the net baryon number created in the Big Bang. If dark matter particles carry baryon number $B_X$, and $\\sigma^{\\rm annih}_{\\bar{X}} < \\sigma^{\\rm annih}_{X} $, the $\\bar{X}$'s freeze out at a higher temperature and have a larger relic density than $X$'s. If $m_X \\lsi 4.5 B_X $GeV and the annihilation cross sections differ by $\\mathcal{O}$(10%) or more, this type of scenario naturally explains the observed $\\Omega_{DM} \\approx 5 \\Omega_b$. Two concrete examples are given, one of which can be excluded on observational grounds.

  9. Photon and Eta Production in p+Pb and p+C Collisions at sqrt{sNN} = 17.4 GeV

    E-Print Network [OSTI]

    WA98 Collaboration

    2012-11-02

    Measurements of direct photon production in p+Pb and p+C collisions at $\\sqrt{s_\\mathrm{NN}} = 17.4\\mathrm{GeV}$ are presented. Upper limits on the direct photon yield as a function of $p_\\mathrm{T}$ are derived and compared to the results for Pb+Pb collisions at $\\sqrt{s_\\mathrm{NN}} = 17.3$ GeV. The production of the $\\eta$ meson, which is an important input to the direct photon signal extraction, has been determined in the $\\eta \\rightarrow 2\\gamma$ channel for p+C collisions at $\\sqrt{s_\\mathrm{NN}} = 17.4\\mathrm{GeV}$.

  10. 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)

    2012-09-24

    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.

  11. 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

  12. 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)

    2009-01-28

    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.

  13. Relativistic Laser-Matter Interactions

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

    Relativistic Laser-Matter Interactions Relativistic Laser-Matter Interactions Enabling the next generation of intense particle accelerators Contact Juan Fernandez (505) 667-6575...

  14. 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

  15. 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

  16. Axion hot dark matter bounds after Planck

    SciTech Connect (OSTI)

    Archidiacono, Maria; Hannestad, Steen; Mirizzi, Alessandro; Raffelt, Georg; Wong, Yvonne Y.Y. E-mail: sth@phys.au.dk E-mail: raffelt@mpp.mpg.de

    2013-10-01

    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.

  17. Study of Centrality Dependence of Transverse Momentum Spectra of Hadrons and the Freeze-out Parameters at root(sNN) of 62.4 GeV, 130 GeV and 200 GeV

    E-Print Network [OSTI]

    Saeed Uddin; Riyaz Ahmed Bhat; Inam-ul Bashir

    2014-12-05

    We attempt to describe the rapidity distribution of P, P-bar, K+ and K- for the most central Au+Au collisions at root(sNN) of 62.4 GeV,130 GeV and 200 GeV. The transverse momentum spectra of strange as well as non-strange hadrons e.g. P, P-bar, K+, K-, Lambda, Lambda-bar, Cascade,Cascade-bar and (Omega + Omega-bar) are studied for the whole centrality classes at all the three RHIC energies. The experimental data of the transverse momentum spectra and the rapidity distributions are well reproduced. This is done by using a statistical thermal freeze-out model which incorporates the rapidity (collision) axis as well as transverse direction boosts developed within an expanding hot and dense hadronic fluid (fireball) till the final freeze-out. We determine the thermo-chemical freeze-out conditions particularly in terms of temperature, baryon chemical potential and collective flow effect parameters for different particle species. The parameters indicate occurrence of freeze-out of the singly and doubly strange hyperon species at somewhat earlier times during the evolution of the fireball. Dependence of the freeze-out parameters on the degree of centrality is also described and it is found that the kinetic temperature increases and collective flow effect decreases with decreasing centrality at all energies studied. The nuclear transparency effect is also studied and it is clear from our model that the nuclear matter becomes more transparent at the highest RHIC energy compared to lower RHIC energies. The contribution of heavier hadronic resonance decay is taken into account.

  18. Pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV: Evidence for the onset of deconfinement

    E-Print Network [OSTI]

    NA49 Collaboration

    2007-10-15

    Results on charged pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV are presented and compared to data at lower and higher energies. A rapid change of the energy dependence is observed around 30A GeV for the yields of pions and kaons as well as for the shape of the transverse mass spectra. The change is compatible with the prediction that the threshold for production of a state of deconfined matter at the early stage of the collisions is located at low SPS energies.

  19. Axion BEC Dark Matter

    E-Print Network [OSTI]

    Erken, Ozgur; Tam, Heywood; Yang, Qiaoli

    2011-01-01

    Cold dark matter axions thermalize through gravitational self-interactions and form a Bose-Einstein condensate when the photon temperature reaches approximately 500 eV. Axion Bose-Einstein condensation provides an opportunity to distinguish axions from the other dark matter candidates on the basis of observation. The rethermalization of axions that are about to fall in a galactic potential well causes them to acquire net overall rotation, whereas ordinary cold dark matter falls in with an irrotational velocity field. The inner caustics of galactic halos are different in the two cases.

  20. Axion BEC Dark Matter

    E-Print Network [OSTI]

    Ozgur Erken; Pierre Sikivie; Heywood Tam; Qiaoli Yang

    2011-11-16

    Cold dark matter axions thermalize through gravitational self-interactions and form a Bose-Einstein condensate when the photon temperature reaches approximately 500 eV. Axion Bose-Einstein condensation provides an opportunity to distinguish axions from the other dark matter candidates on the basis of observation. The rethermalization of axions that are about to fall in a galactic potential well causes them to acquire net overall rotation, whereas ordinary cold dark matter falls in with an irrotational velocity field. The inner caustics of galactic halos are different in the two cases.

  1. Dark Matter 2014

    E-Print Network [OSTI]

    Marc Schumann

    2015-01-06

    This article gives an overview on the status of experimental searches for dark matter at the end of 2014. The main focus is on direct searches for weakly interacting massive particles (WIMPs) using underground-based low-background detectors, especially on the new results published in 2014. WIMPs are excellent dark matter candidates, predicted by many theories beyond the standard model of particle physics, and are expected to interact with the target nuclei either via spin-independent (scalar) or spin-dependent (axial-vector) couplings. Non-WIMP dark matter candidates, especially axions and axion-like particles are also briefly discussed.

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

    SciTech Connect (OSTI)

    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.

    2012-01-30

    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.

  3. 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.; et al

    2012-01-30

    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.

  4. Effective Models for Dark Matter at the International Linear Collider

    E-Print Network [OSTI]

    Daniel Schmeier

    2013-08-20

    Weakly interacting massive particles (WIMPs) form a promising solution to the dark matter problem and many experiments are now searching for these particles. Using effective field theories to describe the interaction of the WIMP with the Standard Model has proven successful in providing an easy way to compare the different experimental results. In this work, we show how effective operators can be formally derived from a UV-complete underlying theory, and we analyse these operators in different experimental contexts. We put our main focus on the expected sensitivity of the International Linear Collider (ILC) in searching for WIMPs by looking at events with single photons in the final state. Furthermore, we show explicit evaluations of the relic density measurements from the Wilkinson Microwave Anisotropy Probe and the XENON Dark Matter Project direct detection measurements to compare to the expected ILC results. We find that the ILC serves as a unique tool to probe possible WIMP interactions with the Standard Model for dark matter masses below 10 GeV. This extends to masses up to 490 GeV in cases where the interaction is spin-dependent or leptophilic.

  5. 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

    2007-12-17

    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.

  6. Maximum Likelihood Signal Extraction Method Applied to 3.4 years of CoGeNT Data

    E-Print Network [OSTI]

    C. E. Aalseth; P. S. Barbeau; J. Diaz Leon; J. E. Fast; T. W. Hossbach; A. Knecht; M. S. Kos; M. G. Marino; H. S. Miley; M. L. Miller; J. L. Orrell

    2015-02-05

    CoGeNT has taken data for over 3 years, with 1136 live days of data accumulated as of April 23, 2013. We report on the results of a maximum likelihood analysis to extract any possible dark matter signal present in the collected data. The maximum likelihood signal extraction uses 2-dimensional probability density functions (PDFs) to characterize the anticipated variations in dark matter interaction rates for given observable nuclear recoil energies during differing periods of the Earth's annual orbit around the Sun. Cosmogenic and primordial radioactivity backgrounds are characterized by their energy signatures and in some cases decay half-lives. A third parameterizing variable -- pulse rise-time -- is added to the likelihood analysis to characterize slow rising pulses described in prior analyses. The contribution to each event category is analyzed for various dark matter signal hypotheses including a dark matter standard halo model and a case with free oscillation parameters (i.e., amplitude, period, and phase). The best-fit dark matter signal is in close proximity to previously reported results. We find that the significance of the extracted dark matter signal remains well below evidentiary at 1.7 $\\sigma$.

  7. Matter & Energy Civil Engineering

    E-Print Network [OSTI]

    Rogers, John A.

    See Also: Matter & Energy Detectors· Optics· Civil Engineering· Engineering· Nature of Water Yonggang Huang, Joseph Cummings Professor of Civil and Environmental Engineering and Mechanical Engineering· Electronics· Reference Photography· Infrared· Mechanical engineering · Optics· ScienceDaily (Jan. 17, 2011

  8. 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 ...

  9. Matter & Energy Electronics

    E-Print Network [OSTI]

    Suslick, Kenneth S.

    See also: Matter & Energy Detectors· Electronics· Technology· Medical Technology· Weapons Technology · Organic Chemistry· Reference Hydrogen chloride· Photography· Catalytic converter· Nanomedicine a series of tiny colored dots ­ each a different pigment ­ on an inert backing such as paper, plastic

  10. The Heart of Matter

    E-Print Network [OSTI]

    Rohini M. Godbole

    2010-06-30

    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. Hot and dark matter

    E-Print Network [OSTI]

    D'Eramo, Francesco

    2012-01-01

    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, ...

  12. 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)

    2014-02-21

    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.

  13. The dark matter self-interaction and its impact on the critical mass for dark matter evaporations inside the sun

    E-Print Network [OSTI]

    Chian-Shu Chen; Fei-Fan Lee; Guey-Lin Lin; Yen-Hsun Lin

    2014-12-21

    We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 ~ 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube- PINGU using the annihilation channels $\\chi\\chi\\rightarrow\

  14. Dark matter searches

    E-Print Network [OSTI]

    Laura Baudis

    2015-09-02

    One of the major challenges of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the scales of galaxies up to the largest cosmological scales. The dark matter could be made of new, yet undiscovered elementary particles, with allowed masses and interaction strengths with normal matter spanning an enormous range. Axions, produced non-thermally in the early universe, and weakly interacting massive particles (WIMPs), which froze out of thermal equilibrium with a relic density matching the observations, represent two well-motivated, generic classes of dark matter candidates. Dark matter axions could be detected by exploiting their predicted coupling to two photons, where the highest sensitivity is reached by experiments using a microwave cavity permeated by a strong magnetic field. WIMPs could be directly observed via scatters off atomic nuclei in underground, ultra low-background detectors, or indirectly, via secondary radiation produced when they pair annihilate. They could also be generated at particle colliders such as the LHC, where associated particles produced in the same process are to be detected. After a brief motivation and an introduction to the phenomenology of particle dark matter detection, I will discuss the most promising experimental techniques to search for axions and WIMPs, addressing their current and future science reach, as well as their complementarity.

  15. A Search for Pulsations from Geminga Above 100 GeV with VERITAS

    E-Print Network [OSTI]

    Aliu, E; Archer, A; Aune, T; Barnacka, A; Beilicke, M; Benbow, W; Bird, R; Buckley, J H; Bugaev, V; Byrum, K; Cardenzana, J V; Cerruti, M; Chen, X; Ciupik, L; Connolly, M P; Cui, W; Dickinson, H J; Dumm, J; Eisch, J D; Errando, M; Falcone, A; Feng, Q; Finley, J P; Fleischhack, H; Fortin, P; Fortson, L; Furniss, A; Gillanders, G H; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Hakansson, N; Hanna, D; Holder, J; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kertzman, M; Kieda, D; Krennrich, F; Kumar, S; Lang, M J; Lyutikov, M; Madhavan, A S; Maier, G; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Mukherjee, R; Nieto, D; de Bhroithe, A O'Faolain; Ong, R A; Otte, A N; Park, N; Pohl, M; Popkow, A; Prokoph, H; Pueschel, E; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Santander, M; Sembroski, G H; Shahinyan, K; Smith, A W; Staszak, D; Telezhinsky, I; Tucci, J V; Tyler, J; Varlotta, A; Vincent, S; Wakely, S P; Weinstein, A; Williams, D A; Zajczyk, A; Zitzer, B

    2014-01-01

    We present the results of 71.6 hours of observations of the Geminga pulsar (PSR J0633+1746) with the VERITAS very-high-energy gamma-ray telescope array. Data taken with VERITAS between November 2007 and February 2013 were phase-folded using a Geminga pulsar timing solution derived from data recorded by the XMM-\\emph{Newton} and \\emph{Fermi}-LAT space telescopes. No significant pulsed emission above 100 GeV is observed, and we report upper limits at the 95% confidence level on the integral flux above 135 GeV (spectral analysis threshold) of 4.0$\\times10^{-13}$ s$^{-1}$ cm$^{-2}$ and 1.7$\\times10^{-13}$ s$^{-1}$ cm$^{-2}$ for the two principal peaks in the emission profile. These upper limits, placed in context with phase-resolved spectral energy distributions determined from five years of data from the \\emph{Fermi}-LAT, constrain possible hardening of the Geminga pulsar emission spectra above $\\sim$50 GeV.

  16. Colon Cancer Mapping | 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsiclouddenDVA N C E D BGene NetworkNuclearDNP 20082 P2014 CollegiateVanderbilt, GE Team

  17. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit theCovalent Bonding in Actinide SandwichCrayCrosscuttingGE, MIT Build

  18. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit theCovalent Bonding in Actinide SandwichCrayCrosscuttingGE, MIT

  19. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass mapSpeeding access| Department ofStephenSkinner,Past and Present EERE Budget PastGE's

  20. Game Changing Technology | 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation Current HABFESOpportunities Nuclear PhysicsGE GlobalGetting&Tools »GambitI

  1. A Large Scale Double Beta and Dark Matter Experiment: GENIUS

    E-Print Network [OSTI]

    J. Hellmig; H. V. Klapdor-Kleingrothaus

    1998-01-21

    The recent results from the HEIDELBERG-MOSCOW experiment have demonstrated the large potential of double beta decay to search for new physics beyond the Standard Model. To increase by a major step the present sensitivity for double beta decay and dark matter search much bigger source strengths and much lower backgrounds are needed than used in experiments under operation at present or under construction. We present here a study of a project proposed recently, which would operate one ton of 'naked' enriched GErmanium-detectors in liquid NItrogen as shielding in an Underground Setup (GENIUS). It improves the sensitivity to neutrino masses to 0.01 eV. A ten ton version would probe neutrino masses even down to 10^-3 eV. The first version would allow to test the atmospheric neutrino problem, the second at least part of the solar neutrino problem. Both versions would allow in addition significant contributions to testing several classes of GUT models. These are especially tests of R-parity breaking supersymmetry models, leptoquark masses and mechanism and right-handed W-boson masses comparable to LHC. The second issue of the experiment is the search for dark matter in the universe. The entire MSSM parameter space for prediction of neutralinos as dark matter particles could be covered already in a first step of the full experiment - with the same purity requirements but using only 100 kg of 76Ge or even of natural Ge - making the experiment competitive to LHC in the search for supersymmetry. The layout of the proposed experiment is discussed and the shielding and purity requirements are studied using GEANT Monte Carlo simulations. As a demonstration of the feasibility of the experiment first results of operating a 'naked' Ge detector in liquid nitrogen are presented.

  2. Dark Matter Searches for Monoenergetic Neutrinos Arising from Stopped Meson Decay in the Sun

    E-Print Network [OSTI]

    Carsten Rott; Seongjin In; Jason Kumar; David Yaylali

    2015-10-01

    Dark matter can be gravitationally captured by the Sun after scattering off solar nuclei. Annihilations of the dark matter trapped and accumulated in the centre of the Sun could result in one of the most detectable and recognizable signals for dark matter. Searches for high-energy neutrinos produced in the decay of annihilation products have yielded extremely competitive constraints on the spin-dependent scattering cross sections of dark matter with nuclei. Recently, the low energy neutrino signal arising from dark-matter annihilation to quarks which then hadronize and shower has been suggested as a competitive and complementary search strategy. These high-multiplicity hadronic showers give rise to a large amount of pions which will come to rest in the Sun and decay, leading to a unique sub-GeV neutrino signal. We here improve on previous works by considering the monoenergetic neutrino signal arising from both pion and kaon decay. We consider searches at liquid scintillation, liquid argon, and water Cherenkov detectors and find very competitive sensitivities for few-GeV dark matter masses.

  3. Phase diagram of dilute cosmic matter

    E-Print Network [OSTI]

    Yoritaka Iwata

    2012-02-21

    Enhancement of nuclear pasta formation due to multi-nucleus simultaneous collision is presented based on time-dependent density functional calculations with periodic boundary condition. This calculation corresponds to the situation with density lower than the known low-density existence limit of the nuclear pasta phase. In order to evaluate the contribution from three-nucleus simultaneous collisions inside the cosmic matter, the possibility of multi-nucleus simultaneous collisions is examined by a systematic Monte-Carlo calculation, and the mean free path of a nucleus is obtained. Consequently the low-density existence limit of the nuclear pasta phase is formed to be lower than believed up to now.

  4. 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

  5. Phenomenology of Dirac Neutralino Dark Matter

    SciTech Connect (OSTI)

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

    2013-09-01

    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.

  6. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsicloudden DocumentationAccommodations Accommodations LosUnderground Reservoirs -

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

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankADVANCED MANUFACTURINGEnergyPlan | Department ofSUPPLEMENTSwitzerland|ofSessions |2Energy 71 - In3 -4

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

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankADVANCED MANUFACTURINGEnergyPlan | Department ofSUPPLEMENTSwitzerland|ofSessions |2Energy 71 - In37 -

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

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematics And Statistics » USAJobs Search USAJobs SearchWater-SavingofCode | Department2 16 I N S|5 - In6 -

  10. Dark matter vs. astrophysics in the interpretation of AMS-02 electron and positron data

    E-Print Network [OSTI]

    Mattia Di Mauro; Fiorenza Donato; Nicolao Fornengo; Andrea Vittino

    2015-07-24

    We perform a detailed quantitative analysis of the recent AMS-02 electron and positron data. We investigate the interplay between the emission from primary astrophysical sources, namely Supernova Remnants and Pulsar Wind Nebulae, and the contribution from a dark matter annihilation or decay signal. Our aim is to assess the information that can be derived on dark matter properties when both dark matter and primary astrophysical sources are assumed to jointly contribute to the leptonic observables measured by the AMS-02 experiment. We investigate both the possibility to set robust constraints on the dark matter annihilation/decay rate and the possibility to look for dark matter signals within realistic models that take into account the full complexity of the astrophysical background. Our results show that AMS-02 data enable to probe efficiently vast regions of the dark matter parameter space and, in some cases, to set constraints on the dark matter annihilation/decay rate that are comparable or even stronger with respect to the ones that can be derived from other indirect detection channels. For dark matter annihilation into muons, the bounds leave room for a possible joint DM+astro interpretation of the data, with a dark matter mass in the 50-80 GeV range (depending on the pulsars modeling) and an annihilation cross section in the range (0.7 {\\div} 3) times the thermal cross section.

  11. Cs6Ge8Zn: A Zintl Phase with Isolated Heteroatomic Clusters of Ge8Zn

    E-Print Network [OSTI]

    a single phase of Cs6Ge8Zn.8 The plate-like crystals of the compound are brittle, black, and with coal-like luster. Single-crystal studies unveiled a new type of cluster formation, a dimer of corner different types. The clusters of type A have only a horizontal mirror plane (Cm) while the clusters of type

  12. Dark Matter and the Baryon Asymmetry of the Universe

    E-Print Network [OSTI]

    Glennys R. Farrar; Gabrijela Zaharijas

    2004-07-06

    We present a mechanism to generate the baryon asymmetry of the Universe which preserves the net baryon number created in the Big Bang. If dark matter particles carry baryon number $B_X$, and $\\sigma^{\\rm annih}_{\\bar{X}} < \\sigma^{\\rm annih}_{X} $, the $\\bar{X}$'s freeze out at a higher temperature and have a larger relic density than $X$'s. If $m_X \\lsi 4.5 B_X $GeV and the annihilation cross sections differ by $\\gsi 10%$, this type of scenario naturally explains the observed $\\Omega_{DM} \\approx 5 \\Omega_b$.

  13. 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)

    2014-10-21

    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.

  14. The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter

    SciTech Connect (OSTI)

    Daylan, Tansu; Finkbeiner, Douglas P.; Hooper, Dan; Linden, Tim; Portillo, Stephen K. N.; Rodd, Nicholas L.; Slatyer, Tracy R.

    2014-02-26

    Past studies have identified a spatially extended excess of ~1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter. We revisit and scrutinize this signal with the intention of further constraining its characteristics and origin. By applying cuts to the Fermi event parameter CTBCORE, we suppress the tails of the point spread function and generate high resolution gamma-ray maps, enabling us to more easily separate the various gamma-ray components. Within these maps, we find the GeV excess to be robust and highly statistically significant, with a spectrum, angular distribution, and overall normalization that is in good agreement with that predicted by simple annihilating dark matter models. For example, the signal is very well fit by a 31-40 GeV dark matter particle annihilating to b quarks with an annihilation cross section of sigma v = (1.4-2.0) x 10^-26 cm^3/s (normalized to a local dark matter density of 0.3 GeV/cm^3). Furthermore, we confirm that the angular distribution of the excess is approximately spherically symmetric and centered around the dynamical center of the Milky Way (within ~0.05 degrees of Sgr A*), showing no sign of elongation along or perpendicular to the Galactic Plane. The signal is observed to extend to at least 10 degrees from the Galactic Center, disfavoring the possibility that this emission originates from millisecond pulsars.

  15. The Proposed Majorana 76Ge Double-Beta Decay Experiment

    SciTech Connect (OSTI)

    Aalseth, Craig E.; Anderson, Dale N.; Arthur, Richard J.; Avignone, Frank T.; Baktash, Cryus; Ball, Thedore; Barabash, Alexander S.; Bertrand, F.; Brodzinski, Ronald L.; Brudanin, V.; Bugg, William; Champagne, A. E.; Chan, Yuen-Dat; Cianciolo, Thomas V.; Collar, J. I.; Creswick, R. W.; Descovich, M.; Di Marco, Marie; Doe, P. J.; Dunham, Glen C.; Efremenko, Yuri; Egerov, V.; Ejiri, H.; Elliott, Steven R.; Emanuel, A.; Fallon, Paul; Farach, H. A.; Gaitskell, R. J.; Gehman, Victor; Grzywacz, Robert; Hallin, A.; Hazma, R.; Henning, R.; Hime, Andrew; Hossbach, Todd W.; Jordan, David V.; Kazkaz, K.; Kephart, Jeremy; King, G. S.; Kochetov, Oleg; Konovalov, S.; Kouzes, Richard T.; Lesko, Kevin; Luke, P.; Luzum, M.; Macchiavelli, A. O.; McDonald, A.; Mei, Dongming; Miley, Harry S.; Mills, G. B.; Mokhtarani, A.; Nomachi, Masaharu; Orrell, John L.; Palms, John M.; Poon, Alan; Radford, D. C.; Reeves, James H.; Robertson, R. G. H.; Runkle, Robert C.; Rykaczewski, Krzysztof P.; Saburov, Konstantin; Sandukovsky, Viatcheslav; Sonnenschein, Andrew; Tornow, W.; Tull, C.; van de Water, R. G.; Vanushin, Igor; Vetter, Kai; Warner, Ray A.; Wilkerson, John F.; Wouters, Jan M.; Young , A. R.; Yumatov, V.

    2005-01-01

    The proposed Majorana experiment is based on an array of segmented intrinsic Ge detectors with a total mass of 500 kg of Ge isotopically enriched to 86% in 76Ge. Background reduction will be accomplished by: material selection, detector segmentation, pulse shape analysis, electro-formation of copper parts, and granularity of detector spacing. The predicted experimental sensitivity for measurement of the neutrinoless double-beta decay mode of 76Ge, over a data acquisition period of 5000 kg•y, is ~ 4?1027 y.

  16. GE funds initiative to support STEM initiatives in Oklahoma ...

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

    investment in Oklahoma reflects GE's commitment to skills development for the future. "Growth and development go hand-in-hand with educational excellence, strength in science,...

  17. CMC technology revolutionary for aviation, power | GE Global...

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

    in new window) Novel CMC technology revolutionizes aircraft engines, turbines CMCs - Ceramic Matrix Composites - are a revolutionary material invented by GE scientists that offer...

  18. Heteroepitaxial Ge-on-Si by DC magnetron sputtering

    SciTech Connect (OSTI)

    Steglich, Martin; Schrempel, Frank; Füchsel, Kevin; Kley, Ernst-Bernhard; Patzig, Christian; Berthold, Lutz; Höche, Thomas; Tünnermann, Andreas; Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Albert-Einstein-Str. 7, 07745 Jena

    2013-07-15

    The growth of Ge on Si(100) by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380°C. Typical Stransky-Krastanov growth is observed at 410°C. At lower temperatures (320°C), films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed.

  19. Construction progresses at GE's Oil & Gas Technology Center ...

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

    Home > Impact > Construction 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)...

  20. RADIATION DAMAGE RESISTANCE OF REVERSE ELECTRODE GE COAXIAL DETECTORS

    E-Print Network [OSTI]

    Pehl, Richard H.

    2011-01-01

    Parker, "Radiation Damage of Germanium Detectors", Bull. Am.to radiation damage between the two detectors was clearlyRADIATION DAMAGE RESISTANCE OF REVERSE ELECTRODE GE COAXIAL DETECTORS

  1. GE China Technology Center Wins Top 12 Most Innovative Practices...

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

    to our local markets and innovating technologies to meet the most urgent needs of Chinese society. Additionally, GE teams up with local customers to jointly develop innovative...

  2. The Wizard of Schenectady: Charles Proteus Steinmetz | GE Global...

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

    week the Smithsonian's "Past Imperfect" blog highlighted a man near and dear to the heart of GE Global Research, Charles Proteus Steinmetz. The article paints a really...

  3. Big Data and Analytics at Work | GE Global Research

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

    time analytics is required At GE we keep pace with these trends via the Industrial Internet, a highly connected ecosystem of intelligent machines, advanced analytics and people...

  4. A Sneak Peek Into Santa's Smarter Sleigh | GE Global Research

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

    legs a break. - An upgraded sleigh frame made from GE's high temperature Ceramic Matrix Composites (CMCs). The CMCs can withstand the heat of entry and reentry in earth's...

  5. 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...

  6. Thoughts From the 2012 Whitney Software Symposium | GE Global...

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

    Big Data, Modeling and Simulation, High Performance Computing and the Industrial Internet as key technological enablers of GE's Software initiatives. We enjoyed speakers from...

  7. EEDP and Other Leadership Programs | GE Global Research

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

    Ready to dive in? Apply for the program. GE Software Leadership Program The rise of the Industrial Internet requires a new breed of talent and organizational capability. New...

  8. WIMP matter power spectra and small scale power generation

    E-Print Network [OSTI]

    C. Boehm; H. Mathis; J. Devriendt; J. Silk

    2003-09-24

    Dark Matter (DM) is generally assumed to be massive, cold and collisionless from the structure formation point of view. A more correct statement however is that DM indeed experiences collisional damping, but on a scale which is supposed to be too small to be relevant for structure formation. The aim of this paper is to present a Cold (although ``collisional'') Dark Matter particle whose matter power spectrum is damped and see whether it is distinguishable from standard candidates. To achieve this purpose, we calculate the collisional damping and free-streaming scales of neutralinos and non conventional candidates (say light particles heavier than ~1 MeV but lighter than O(10) GeV). The latter can be considered as Cold Dark Matter (CDM) particles in the sense that they become non relativistic before their thermal decoupling epoch. Unlike neutralinos, however, their linear matter power spectrum can be damped on scales of ~ 10^3 Msol due to their interactions. Since these scales are of cosmological interest for structure formation, we perform a series of numerical simulations to obtain the corresponding non linear matter power spectra P(k)_{nl} at the present epoch. We show that because of small scale regeneration, they all resemble each other at low redshifts, i.e. become very similar to a typical CDM matter power spectrum on all but the smallest scales. Therefore, even if lensing measurements at redshift below unity were to yield a P(k)_{nl} consistent with CDM models, this would not constitute a sufficiently robust evidence in favour of the neutralino to rule out alternative DM candidates.

  9. Response of a proportional counter to $^{37}$Ar and $^{71}$Ge: real spectra versus GEANT4 simulation

    E-Print Network [OSTI]

    D. Abdurashitov; Yu. Malyshkin; V. Matushko; B. Suerfu

    2015-09-09

    The energy deposition spectra of $^{37}$Ar and $^{71}$Ge in a miniature proportional counter are measured and compared in detail to the model response simulated with Geant4. The spectrum of $^{71}$Ge is measured with total statistics of 1.7$\\cdot$10$^8$ events and is presented for the first time. A certain modification of the Geant4 code, making it possible to trace the deexcitation of atomic shells properly, is suggested. After the modification Geant4 is able to reproduce a response of particle detectors in detail in a keV energy range. This feature is very important in the laboratory experiments that search for massive sterile neutrinos as well as for dark matter directly by detection of recoil nuclei. We expect this work to convince physicists to trust Geant4 simulations at low energies.

  10. Response of a proportional counter to $^{37}$Ar and $^{71}$Ge: real spectra versus GEANT4 simulation

    E-Print Network [OSTI]

    Abdurashitov, D; Matushko, V; Suerfu, B

    2015-01-01

    The energy deposition spectra of $^{37}$Ar and $^{71}$Ge in a miniature proportional counter are measured and compared in detail to the model response simulated with Geant4. The spectrum of $^{71}$Ge is measured with total statistics of 1.7$\\cdot$10$^8$ events and is presented for the first time. A certain modification of the Geant4 code, making it possible to trace the deexcitation of atomic shells properly, is suggested. After the modification Geant4 is able to reproduce a response of particle detectors in detail in a keV energy range. This feature is very important in the laboratory experiments that search for massive sterile neutrinos as well as for dark matter directly by detection of recoil nuclei. We expect this work to convince physicists to trust Geant4 simulations at low energies.

  11. Crystallization and collapse in relativistically degenerate matter

    SciTech Connect (OSTI)

    Akbari-Moghanjoughi, M.

    2013-04-15

    In this paper, it is shown that a mass density limit exists beyond which the relativistically degenerate matter would crystallize. The mass density limit, found here, is quite analogous to the mass limit predicted by Chandrasekhar for a type of compact stars called white dwarfs (M{sub Ch} Asymptotically-Equal-To 1.43 Solar Mass). In this study, the old problem of white dwarf core collapse, which has been previously investigated by Chandrasekhar using hydrostatic stability criteria, is revisited in the framework of the quantum hydrodynamics model by inspection of the charge screening at atomic scales in the relativistic degeneracy plasma regime taking into account the relativistic Fermi-Dirac statistics and electron interaction features such as the quantum statistical pressure, Coulomb attraction, electron exchange-correlation, and quantum recoil effects. It is revealed that the existence of ion correlation and crystallization of matter in the relativistically degenerate plasma puts a critical mass density limit on white dwarf core region. It is shown that a white dwarf star with a core mass density beyond this critical limit can undergo the spontaneous core collapse (SCC). The SCC phenomenon, which is dominantly caused by the electron quantum recoil effect (interference and localization of the electron wave function), leads to a new exotic state of matter. In such exotic state, the relativistic electron degeneracy can lead the white dwarf crystallized core to undergo the nuclear fusion and an ultimate supernova by means of the volume reduction (due to the enhanced compressibility) and huge energy release (due to the increase in cohesive energy), under the stars huge inward gravitational pressure. Moreover, it is found that the SCC phenomenon is significantly affected by the core composition (it is more probable for heavier plasmas). The critical mass density found here is consistent with the values calculated for core density of typical white dwarf stars.

  12. 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)

    2013-05-15

    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.

  13. Natural minimal dark matter

    E-Print Network [OSTI]

    Fabbrichesi, Marco

    2015-01-01

    We show how the Higgs boson mass is protected from the potentially large corrections due to the introduction of minimal dark matter if the new physics sector is made supersymmetric. The fermionic dark matter candidate (a 5-plet of $SU(2)_L$) is accompanied by a scalar state. The weak gauge sector is made supersymmetric and the Higgs boson is embedded in a supersymmetric multiplet. The remaining standard model states are non-supersymmetric. Non vanishing corrections to the Higgs boson mass only appear at three-loop level and the model is natural for dark matter masses up to 15 TeV--a value larger than the one required by the cosmological relic density. The construction presented stands as an example of a general approach to naturalness that solves the little hierarchy problem which arises when new physics is added beyond the standard model at an energy scale around 10 TeV.

  14. Limits on sterile neutrino contributions to neutrinoless double beta decay

    E-Print Network [OSTI]

    Barea, J; Iachello, F

    2015-01-01

    Nuclear matrix elements (NME) for exchange of arbitrary mass neutrinos are calculated in the interacting boson model (IBM-2). By combining the NME with the phase space factors (PSF), expected half-lives for neutrinos of mass $m_N$ and coupling $U_{eN}$ are estimated. Limits on sterile neutrinos with masses in the eV, keV, MeV-GeV, and TeV range are given.

  15. Limits on sterile neutrino contributions to neutrinoless double beta decay

    E-Print Network [OSTI]

    J. Barea; J. Kotila; F. Iachello

    2015-09-07

    Nuclear matrix elements (NME) for exchange of arbitrary mass neutrinos are calculated in the interacting boson model (IBM-2). By combining the NME with the phase space factors (PSF), expected half-lives for neutrinos of mass $m_N$ and coupling $U_{eN}$ are estimated. Limits on sterile neutrinos with masses in the eV, keV, MeV-GeV, and TeV range are given.

  16. Asymptotically Safe Dark Matter

    E-Print Network [OSTI]

    Francesco Sannino; Ian M. Shoemaker

    2015-08-05

    We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting phenomenology of this "asymptotically safe DM" is quite distinct. One interesting effect of this is to partially offset the low-energy constraints from direct detection experiments without affecting thermal freeze-out processes which occur at higher energies. High-energy collider and indirect annihilation searches are the primary ways to constrain or discover asymptotically safe dark matter.

  17. Safe Dark Matter

    E-Print Network [OSTI]

    Francesco Sannino; Ian M. Shoemaker

    2015-07-29

    We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting phenomenology of this "safe DM" is quite distinct. One interesting effect of this is to partially offset the low-energy constraints from direct detection experiments without affecting thermal freeze-out processes which occur at higher energies. High-energy collider and indirect annihilation searches are the primary ways to constrain or discover safe dark matter.

  18. Shell model description of Ge isotopes

    E-Print Network [OSTI]

    J. G. Hirsch; P. C. Srivastava

    2012-04-12

    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.

  19. 3 GeV Injector Design Handbook

    SciTech Connect (OSTI)

    Wiedemann, H.; /SLAC, SSRL

    2009-12-16

    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.

  20. Nucleon Resonances Near 2 GeV

    E-Print Network [OSTI]

    He, Jun

    2015-01-01

    The nucleon resonances near 2 GeV are investigated through the $\\Sigma$(1385) and $\\Lambda(1520)$ photoproductions within a Regge-plus-resonance approach based on the new experimental data released by the CLAS Collaboration. The $\\Delta(2000)$ and the $N(2120)$ are found essential to reproduce the experimental data and should be assigned as second $[\\Delta 5/2^+]$ and third $[N3/2^-]$ in the constituent quark model, respectively. A calculation of the binding energy and decay pattern supports that the $N(1875)$, which is listed in the PDG as the third $N3/2^-$ nucleon resonance instead of the $N(2120)$, is from the $\\Sigma(1385)K$ interaction rather than a three quark state.

  1. 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

  2. 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 ...

  3. Ge#ng Started on HokieSpeed

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Ge#ng Started on HokieSpeed Advanced Research Computing #12;Advanced Research Compu:ng;Advanced Research Compu:ng Important Login Informa:on · Account sheets provide login Compu:ng Ge#ng Started Steps 1. Sheet distributed provides your training account

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

    SciTech Connect (OSTI)

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

    2014-09-01

    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).

  5. Quantum Condensed Matter | Neutron Science | ORNL

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

    Quantum Condensed Matter SHARE Quantum Condensed Matter Neutron scattering is a uniquely powerful probe for measuring the structure and dynamics of condensed matter. As such it is...

  6. Quantum Condensed Matter | More Science | ORNL

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

    Quantum Condensed Matter SHARE Quantum Condensed Matter Neutron scattering is a uniquely powerful probe for measuring the structure and dynamics of condensed matter. As such it is...

  7. Investigation of Direct Injection Vehicle Particulate Matter...

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

    Direct Injection Vehicle Particulate Matter Emissions Investigation of Direct Injection Vehicle Particulate Matter Emissions This study focuses primarily on particulate matter mass...

  8. Upper limits on the total cosmic-ray luminosity of individual sources

    SciTech Connect (OSTI)

    Anjos, R.C.; De Souza, V.; Supanitsky, A.D. E-mail: vitor@ifsc.usp.br

    2014-07-01

    In this paper, upper limits on the total luminosity of ultra-high-energy cosmic-rays (UHECR) E > 10{sup 18} eV) are determined for five individual sources. The upper limit on the integral flux of GeV--TeV gamma-rays is used to extract the upper limit on the total UHECR luminosity of individual sources. The correlation between upper limit on the integral GeV--TeV gamma-ray flux and upper limit on the UHECR luminosity is established through the cascading process that takes place during propagation of the cosmic rays in the background radiation fields, as explained in reference [1]. Twenty-eight sources measured by FERMI-LAT, VERITAS and MAGIC observatories have been studied. The measured upper limit on the GeV--TeV gamma-ray flux is restrictive enough to allow the calculation of an upper limit on the total UHECR cosmic-ray luminosity of five sources. The upper limit on the UHECR cosmic-ray luminosity of these sources is shown for several assumptions on the emission mechanism. For all studied sources an upper limit on the ultra-high-energy proton luminosity is also set.

  9. Limit on the mass of a long-lived or stable gluino

    E-Print Network [OSTI]

    G. R. Farrar; R. Mackeprang; D. Milstead; J. P. Roberts

    2011-01-23

    We reinterpret the generic CDF charged massive particle limit to obtain a limit on the mass of a stable or long-lived gluino. Various sources of uncertainty are examined. The $R$-hadron spectrum and scattering cross sections are modeled based on known low-energy hadron physics and the resultant uncertainties are quantified and found to be small compared to uncertainties from the scale dependence of the NLO pQCD production cross sections. The largest uncertainty in the limit comes from the unknown squark mass: when the squark -- gluino mass splitting is small, we obtain a gluino mass limit of 407 GeV, while in the limit of heavy squarks the gluino mass limit is 397 GeV. For arbitrary (degenerate) squark masses, we obtain a lower limit of 322 GeV on the gluino mass. These limits apply for any gluino lifetime longer than $\\sim 30$ ns, and are the most stringent limits for such a long-lived or stable gluino.

  10. Tunguska Dark Matter Ball

    E-Print Network [OSTI]

    C. D. Froggatt; H. B. Nielsen

    2015-05-10

    It is suggested that the Tunguska event in June 1908 cm-large was due to a cm-large ball of a condensate of bound states of 6 top and 6 anti-top quarks containing highly compressed ordinary matter. Such balls are supposed to make up the dark matter as we earlier proposed. The expected rate of impact of this kind of dark matter ball with the earth seems to crudely match a time scale of 200 years between the impacts. The main explosion of the Tunguska event is explained in our picture as material coming out from deep within the earth, where it has been heated and compressed by the ball penetrating to a depth of several thousand km. Thus the effect has some similarity with volcanic activity as suggested by Kundt. We discuss the possible identification of kimberlite pipes with earlier Tunguska-like events. A discussion of how the dark matter balls may have formed in the early universe is also given.

  11. Energy Matters - Spring 2002

    SciTech Connect (OSTI)

    2002-03-01

    Quarterly newsletter from DOE's Industrial Technologies Program to promote the use of energy-efficient industrial systems. The focus of the Spring 2002 Issue of Energy Matters focuses on premium energy efficiency systems, with articles on new gas technologies, steam efficiency, the Augusta Newsprint Showcase, and more.

  12. Energy Matters - Fall 2002

    SciTech Connect (OSTI)

    2002-09-01

    Quarterly newsletter from DOE's Industrial Technologies Program to promote the use of energy-efficient industrial systems. This issue focus of this edition of the Energy Matters Newsletter is on energy and environmental issues. Read more about compressed air's role in productivity, making good motor decisions, and more.

  13. Subject Matters Introduction

    E-Print Network [OSTI]

    Subject Matters Introduction The AS and A Level subject choices you make when in Year 11 (or assessing applicants at the University of Cambridge, we consider not only the individual A Level subjects taken but also the combination of these. We generally prefer applicants to have taken certain subjects

  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. Dark Matter Searches

    E-Print Network [OSTI]

    Laura Baudis

    2005-11-29

    More than 90% of matter in the Universe could be composed of heavy particles, which were non-relativistic, or 'cold', when they froze-out from the primordial soup. I will review current searches for these hypothetical particles, both via interactions with nuclei in deep underground detectors, and via the observation of their annihilation products in the Sun, galactic halo and galactic center.

  16. 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)

    2014-02-10

    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.

  17. 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)

    2014-01-01

    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.

  18. 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 June 2013) The thermoelectric and physical properties of superlattices consisting of modulation doped

  19. 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

  20. 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)

    2013-09-14

    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.

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

    E-Print Network [OSTI]

    Yang, Q

    2010-01-01

    Cold dark matter axions form a Bose-Einstein condensate if the axions thermalize. Recently, it was found that they do thermalize when the photon temperature reaches T ~ 100 eV(f/10^12GeV)^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.

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

    E-Print Network [OSTI]

    Q. Yang

    2010-04-15

    Cold dark matter axions form a Bose-Einstein condensate if the axions thermalize. Recently, it was found that they do thermalize when the photon temperature reaches T ~ 100 eV(f/10^12GeV)^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. Dark Photons from the Center of the Earth: Smoking-Gun Signals of Dark Matter

    E-Print Network [OSTI]

    Jonathan L. Feng; Jordan Smolinsky; Philip Tanedo

    2015-09-24

    Dark matter may be charged under dark electromagnetism with a dark photon that kinetically mixes with the Standard Model photon. In this framework, dark matter will collect at the center of the Earth and annihilate into dark photons, which may reach the surface of the Earth and decay into observable particles. We determine the resulting signal rates, including Sommerfeld enhancements, which play an important role in bringing the Earth's dark matter population to their maximal, equilibrium value. For dark matter masses $m_X \\sim$ 100 GeV - 10 TeV, dark photon masses $m_{A'} \\sim$ MeV - GeV, and kinetic mixing parameters $\\varepsilon \\sim 10^{-9} - 10^{-7}$, the resulting electrons, muons, photons, and hadrons that point back to the center of the Earth are a smoking-gun signal of dark matter that may be detected by a variety of experiments, including neutrino telescopes, such as IceCube, and space-based cosmic ray detectors, such as Fermi-LAT and AMS. We determine the signal rates and characteristics, and show that large and striking signals---such as parallel muon tracks---are possible in regions of the $(m_{A'}, \\varepsilon)$ plane that are not probed by direct detection, accelerator experiments, or astrophysical observations.

  4. Dark Photons from the Center of the Earth: Smoking-Gun Signals of Dark Matter

    E-Print Network [OSTI]

    Feng, Jonathan L; Tanedo, Philip

    2015-01-01

    Dark matter may be charged under dark electromagnetism with a dark photon that kinetically mixes with the Standard Model photon. In this framework, dark matter will collect at the center of the Earth and annihilate into dark photons, which may reach the surface of the Earth and decay into observable particles. We determine the resulting signal rates, including Sommerfeld enhancements, which play an important role in bringing the Earth's dark matter population to their maximal, equilibrium value. For dark matter masses $m_X \\sim$ 100 GeV - 10 TeV, dark photon masses $m_{A'} \\sim$ MeV - GeV, and kinetic mixing parameters $\\varepsilon \\sim 10^{-9} - 10^{-7}$, the resulting electrons, muons, photons, and hadrons that point back to the center of the Earth are a smoking-gun signal of dark matter that may be detected by a variety of experiments, including neutrino telescopes, such as IceCube, and space-based cosmic ray detectors, such as Fermi-LAT and AMS. We determine the signal rates and characteristics, and show ...

  5. The Isotropic Radio Background and Annihilating Dark Matter

    SciTech Connect (OSTI)

    Hooper, Dan; Belikov, Alexander V.; Jeltema, Tesla E.; Linden, Tim; Profumo, Stefano; Slatyer, Tracy R.

    2012-11-01

    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.

  6. Universal Parametrization of Thermal Photon Rates in Hadronic Matter

    E-Print Network [OSTI]

    Matthew Heffernan; Paul Hohler; Ralf Rapp

    2014-11-25

    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.

  7. The Search for Dark Matter

    SciTech Connect (OSTI)

    Orrell, John

    2013-11-20

    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.

  8. The Search for Dark Matter

    ScienceCinema (OSTI)

    Orrell, John

    2014-07-24

    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.

  9. 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.

    2001-03-01

    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 ...

  10. Dark Matter and Synchrotron Emission from Galactic Center Radio Filaments

    SciTech Connect (OSTI)

    Linden, Tim; Hooper, Dan; Yusef-Zadeh, Farhad

    2011-11-10

    The inner degrees of the Galactic center contain a large population of filamentary structures observed at radio frequencies. These so-called non-thermal radio filaments (NRFs) trace magnetic field lines and have attracted significant interest due to their hard (S_v ~ -0.1 +/- 0.4) synchrotron emission spectra. The origin of these filaments remains poorly understood. We show that the electrons and positrons created through the annihilations of a relatively light (~5-10 GeV) dark matter particle with the cross section predicted for a simple thermal relic can provide a compelling match to the intensity, spectral shape, and flux variation of the NRFs. Furthermore, the characteristics of the dark matter particle necessary to explain the synchrotron emission from the NRFs is consistent with those required to explain the excess gamma-ray emission observed from the Galactic center by the Fermi-LAT, as well as the direct detection signals observed by CoGeNT and DAMA/LIBRA.

  11. 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.

    2008-01-01

    +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

  12. ALFVEN-WAVE OSCILLATIONS IN A SPHERE, WITH APPLICATIONS TO ELECTRON-HOLE DROPS IN Ge

    E-Print Network [OSTI]

    Markiewicz, R.S.

    2011-01-01

    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

  13. NUCLEATION PHENOMENA IN THE FORMATION OF ELECTRON-HOLE DROPS IN Ge

    E-Print Network [OSTI]

    Westervelt, R.M.

    2010-01-01

    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

  14. Photo-oxidation of Ge Nanocrystals: Kinetic Measurements by In Situ Raman Spectroscopy

    E-Print Network [OSTI]

    2008-01-01

    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

  15. Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)

    E-Print Network [OSTI]

    Guchhait, S.

    2011-01-01

    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

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

    E-Print Network [OSTI]

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

    2011-08-17

    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.

  17. MAGIC upper limits on the GRB 090102 afterglow

    E-Print Network [OSTI]

    Aleksi?, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Fidalgo, D Carreto; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Farina, E; Ferenc, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giavitto, G; Godinovi?, N; Muńoz, A González; Gozzini, S R; Hadasch, D; Hayashida, M; Herrero, A; Hildebrand, D; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Knoetig, M L; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Meucci, M; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nilsson, K; Nishijima, K; Nowak, N; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Partini, S; Persic, M; Prada, F; Moroni, P G Prada; Prandini, E; Preziuso, S; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Rügamer, S; Saggion, A; Saito, T; Saito, K; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Stamatescu, V; Stamerra, A; Steinbring, T; Storz, J; Sun, S; Suri?, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzi?, T; Tescaro, D; Teshima, M; Thaele, J; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Vogler, P; Wagner, R M; Zandanel, F; Zanin, R; Bouvier, A; Tajima, H; Longo, F

    2013-01-01

    Indications of a GeV component in the emission from GRBs are known since the EGRET observations during the 1990's and they have been confirmed by the data of the Fermi satellite. These results have, however, shown that our understanding of GRB physics is still unsatisfactory. The new generation of Cherenkov observatories and in particular the MAGIC telescope, allow for the first time the possibility to extend the measurement of GRBs from several tens up to hundreds of GeV energy range. Both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy photons (E>30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms, which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB 090102 (z=1.547) field and Fermi Large Area Telescope (LAT) data in the same time interval are analysed to derive upper limits of the ...

  18. 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)

    2013-12-04

    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.

  19. GeO{sub 2}/Ge structure submitted to annealing in deuterium: Incorporation pathways and associated oxide modifications

    SciTech Connect (OSTI)

    Bom, N. M.; Soares, G. V.; Hartmann, S.; Bordin, A.; Radtke, C.

    2014-10-06

    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.

  20. Transient and temperature-dependent phenomena in Ge:Be and Ge:Zn far infrared photoconductors

    SciTech Connect (OSTI)

    Haegel, N.M.

    1985-11-01

    An experimental study of the transient and temperature-dependent behavior of Ge:Be and Ge:Zn photoconductors has been performed under the low background photon flux conditions (p dot approx. = 10/sup 8/ photons/second) typical of astronomy and astrophysics applications. The responsivity of Ge:Be and Ge:Zn detectors is strongly temperature-dependent in closely compensated material, and the effect of compensation on free carrier lifetime in Ge:Be has been measured using the photo-Hall effect technique. Closely compensated material has been obtained by controlling the concentration of novel hydrogen-related shallow acceptor complexes, A(Be,H) and A(Zn,H), which exist in doped crystals grown under a H/sub 2/ atmosphere. A review of selection criteria for multilevel materials for optimum photoconductor performance is included. 55 refs., 47 figs.

  1. Compressively strained Ge trigate p-MOSFETs

    E-Print Network [OSTI]

    Chern, Winston

    2012-01-01

    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 ...

  2. Ion beam synthesis of SiGe alloy layers

    SciTech Connect (OSTI)

    Im, Seongil

    1994-05-01

    Procedures required for minimizing structural defects generated during ion beam synthesis of SiGe alloy layers were studied. Synthesis of 200 mm SiGe alloy layers by implantation of 120-keV Ge ions into <100> oriented Si wafers yielded various Ge peak concentrations after the following doses, 2{times}10{sup 16}cm{sup {minus}2}, 3{times}10{sup 16}cm{sup {minus}2} (mid), and 5{times}10{sup 16}cm{sup {minus}2} (high). Following implantation, solid phase epitaxial (SPE) annealing in ambient N2 at 800C for 1 hr. resulted in only slight redistribution of the Ge. Two kinds of extended defects were observed in alloy layers over 3{times}l0{sup 16}cm{sup {minus}2}cm dose at room temperature (RT): end-of-range (EOR) dislocation loops and strain-induced stacking faults. Density of EOR dislocation loops was much lower in alloys produced by 77K implantation than by RT implantation. Decreasing the dose to obtain 5 at% peak Ge concentration prevents strain relaxation, while those SPE layers with more than 7 at% Ge peak show high densities of misfit- induced stacking faults. Sequential implantation of C following high dose Ge implantation (12 at% Ge peak concentration in layer) brought about a remarkable decrease in density of misfit-induced stacking faults. For peak implanted C > 0.55 at%, stacking fault generation in the epitaxial layer was suppressed, owing to strain compensation by C atoms in the SiGe lattice. A SiGe alloy layer with 0.9 at% C peak concentration under a 12 at% Ge peak exhibited the best microstructure. Results indicate that optimum Ge/C ratio for strain compensation is between 11 and 22. The interface between amorphous and regrown phases (a/c interface) had a dramatic morphology change during its migration to the surface. Initial <100> planar interface decomposes into a <111> faceted interface, changing the growth kinetics; this is associated with strain relaxation by stacking fault formation on (111) planes in the a/c interface.

  3. 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

  4. Directional detection of dark matter streams

    E-Print Network [OSTI]

    Ciaran A. J. O'Hare; Anne M. Green

    2014-11-11

    Directional detection of WIMPs, in which the energies and directions of the recoiling nuclei are measured, currently presents the only prospect for probing the local velocity distribution of Galactic dark matter. We investigate the extent to which future directional detectors would be capable of probing dark matter substructure in the form of streams. We analyse the signal expected from a Sagittarius-like stream and also explore the full parameter space of stream speed, direction, dispersion and density. Using a combination of non-parametric directional statistics, a profile likelihood ratio test and Bayesian parameter inference we find that within acceptable exposure times (O(10) kg yr for cross sections just below the current exclusion limits) future directional detectors will be sensitive to a wide range of stream velocities and densities. We also examine and discuss the importance of the energy window of the detector.

  5. Gravitational mass of relativistic matter and antimatter

    E-Print Network [OSTI]

    Tigran Kalaydzhyan

    2015-10-07

    The universality of free fall, the weak equivalence principle (WEP), is a cornerstone of the general theory of relativity, the most precise theory of gravity confirmed in all experiments up to date. The WEP states the equivalence of the inertial, $m$, and gravitational, $m_g$, masses and was tested in numerous occasions with normal matter at relatively low energies. However, there is no proof for the matter and antimatter at high energies. For the antimatter the situation is even less clear -- current direct observations of trapped antihydrogen suggest the limits $-65 solar gravitational potential. Our result clearly rules out the speculated antigravity. By considering the absolute potential of the Local Supercluster (LS), we also predict the bounds $1 - 4\\times 10^{-7} < m_g/m < 1 + 2\\times 10^{-7}$ for an electron and positron. Finally, we comment on a possibility of performing complementary tests at the future International Linear Collider (ILC) and Compact Linear Collider (CLIC).

  6. Medical Imaging Technology | 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shines light on dark matter By SarahMODELING Release date: Todd A.FebruaryMaking

  7. 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

    2015-05-09

    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.

  8. The MAJORANA DEMONSTRATOR: A search for neutrinoless double-beta decay of ??Ge

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

    Xu, W.; Abgrall, N.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Buuck, M.; Byram, D.; Caldwell, A. S.; et al

    2015-05-01

    Neutrinoless double-beta (0???) 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, with a total of 40-kg Germanium detectors,more »to search for the 0??? decay of ??Ge 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 ??Ge 0??? 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.« less

  9. 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

    2015-01-01

    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...

  10. Possibility of Testing the Light Dark Matter Hypothesis with the Alpha Magnetic Spectrometer

    SciTech Connect (OSTI)

    Hooper, Dan; Xue, Wei

    2013-01-01

    The spectrum and morphology of gamma-rays from the Galactic Center and the spectrum of synchrotron emission observed from the Milky Way's radio filaments have each been interpreted as possible signals of $\\sim$7-10 GeV dark matter particles annihilating in the Inner Galaxy. In dark matter models capable of producing these signals, the annihilations should also generate significant fluxes of $\\sim$7-10 GeV positrons which can lead to a distinctive bump-like feature in local cosmic ray positron spectrum. In this letter, we show that while such a feature would be difficult to detect with PAMELA, it would likely be identifiable by the currently operating AMS experiment. As no known astrophysical sources or mechanisms are likely to produce such a sharp feature, the observation of a positron bump at around 7-10 GeV would significantly strengthen the case for a dark matter interpretation of the reported gamma-ray and radio anomalies.

  11. Levitating Dark Matter

    E-Print Network [OSTI]

    Nemanja Kaloper; Antonio Padilla

    2009-10-07

    A sizable fraction of the total energy density of the universe may be in heavy particles with a net dark $U(1)'$ charge comparable to its mass. When the charges have the same sign the cancellation between their gravitational and gauge forces may lead to a mismatch between different measures of masses in the universe. Measuring galactic masses by orbits of normal matter, such as galaxy rotation curves or lensing, will give the total mass, while the flows of dark matter agglomerates may yield smaller values if the gauge repulsion is not accounted for. If distant galaxies which house light beacons like SNe Ia contain such dark particles, the observations of their cosmic recession may mistake the weaker forces for an extra `antigravity', and infer an effective dark energy equation of state smaller than the real one. In some cases, including that of a cosmological constant, these effects can mimic $wdark energy, or superhorizon effects.

  12. Rigid particulate matter sensor

    DOE Patents [OSTI]

    Hall, Matthew (Austin, TX)

    2011-02-22

    A sensor to detect particulate matter. The sensor includes a first rigid tube, a second rigid tube, a detection surface electrode, and a bias surface electrode. The second rigid tube is mounted substantially parallel to the first rigid tube. The detection surface electrode is disposed on an outer surface of the first rigid tube. The detection surface electrode is disposed to face the second rigid tube. The bias surface electrode is disposed on an outer surface of the second rigid tube. The bias surface electrode is disposed to face the detection surface electrode on the first rigid tube. An air gap exists between the detection surface electrode and the bias surface electrode to allow particulate matter within an exhaust stream to flow between the detection and bias surface electrodes.

  13. Self-Interacting Dark Matter

    E-Print Network [OSTI]

    Benjamin D. Wandelt; Romeel Dave; Glennys R. Farrar; Patrick C. McGuire; David N. Spergel; Paul J. Steinhardt

    2000-06-28

    Spergel and Steinhardt have recently proposed the concept of dark matter with strong self-interactions as a means to address numerous discrepancies between observations of dark matter halos on subgalactic scales and the predictions of the standard collisionless dark matter picture. We review the motivations for this scenario and discuss some recent, successful numerical tests. We also discuss the possibility that the dark matter interacts strongly with ordinary baryonic matter, as well as with itself. We present a new analysis of the experimental constraints and re-evaluate the allowed range of cross-section and mass.

  14. Bound-state formation for thermal relic dark matter and unitarity

    SciTech Connect (OSTI)

    Harling, Benedict von; Petraki, Kalliopi E-mail: kpetraki@nikhef.nl

    2014-12-01

    We show that the relic abundance of thermal dark matter annihilating via a long-range interaction, is significantly affected by the formation and decay of dark matter bound states in the early universe, if the dark matter mass is above a few TeV . We determine the coupling required to obtain the observed dark matter density, taking into account both the direct 2-to-2 annihilations and the formation of bound states, and provide an analytical fit. We argue that the unitarity limit on the inelastic cross-section is realized only if dark matter annihilates via a long-range interaction, and we determine the upper bound on the mass of thermal-relic dark matter to be about 197 (139) TeV for (non)-self-conjugate dark matter.

  15. Unruh effect for neutrinos interacting with accelerated matter

    E-Print Network [OSTI]

    Maxim Dvornikov

    2015-08-27

    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.

  16. Unruh effect for neutrinos interacting with accelerated matter

    E-Print Network [OSTI]

    Dvornikov, Maxim

    2015-01-01

    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.

  17. Hidden vector dark matter

    E-Print Network [OSTI]

    Thomas Hambye

    2010-03-16

    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.

  18. Cosmology with matter diffusion

    SciTech Connect (OSTI)

    Calogero, Simone; Velten, Hermano E-mail: velten@cce.ufes.br

    2013-11-01

    We construct a viable cosmological model based on velocity diffusion of matter particles. In order to ensure the conservation of the total energy-momentum tensor in the presence of diffusion, we include a cosmological scalar field ? which we identify with the dark energy component of the universe. The model is characterized by only one new degree of freedom, the diffusion parameter ?. The standard ?CDM model can be recovered by setting ? = 0. If diffusion takes place (? > 0) the dynamics of the matter and of the dark energy fields are coupled. We argue that the existence of a diffusion mechanism in the universe may serve as a theoretical motivation for interacting models. We constrain the background dynamics of the diffusion model with Supernovae, H(z) and BAO data. We also perform a perturbative analysis of this model in order to understand structure formation in the universe. We calculate the impact of diffusion both on the CMB spectrum, with particular attention to the integrated Sachs-Wolfe signal, and on the matter power spectrum P(k). The latter analysis places strong constraints on the magnitude of the diffusion mechanism but does not rule out the model.

  19. GeV Emission from Collisional Magnetized Gamma Ray Bursts

    E-Print Network [OSTI]

    P. Mészáros; M. J. Rees

    2011-04-26

    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.

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

    E-Print Network [OSTI]

    M. J. Tannenbaum

    2006-07-28

    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.

  1. 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)

    2006-09-11

    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.

  2. Search for scalar leptons in e+e- collisions at centre-of-mass energies up to 209GeV

    E-Print Network [OSTI]

    ALEPH Collaboration

    2001-12-07

    A search for selectron, smuon and stau pair production is performed with the data collected by the ALEPH detector at LEP at centre-of-mass energies up to 209 GeV. The numbers of candidate events are consistent with the background predicted by the Standard Model. Final mass limits from ALEPH are reported.

  3. Search for direct photons in p+Pb and p+C collisions at sqrt(sNN) = 17.4 GeV

    E-Print Network [OSTI]

    Christoph Baumann; for the WA98 collaboration

    2008-04-28

    Upper limits on direct photon production were determined as a function of the transverse momentum for 0.7 photon measurements in Pb+Pb collisions at sqrt(sNN) = 17.3 GeV by WA98. Implications for a possible thermal direct photon contribution are discussed.

  4. Dark matter effective field theory scattering in direct detection experiments

    E-Print Network [OSTI]

    K. Schneck; B. Cabrera; D. G. Cerdeno; V. Mandic; H. E. Rogers; R. Agnese; A. J. Anderson; M. Asai; D. Balakishiyeva; D. Barker; R. Basu Thakur; D. A. Bauer; J. Billard; A. Borgland; D. Brandt; P. L. Brink; R. Bunker; D. O. Caldwell; R. Calkins; H. Chagani; Y. Chen; J. Cooley; B. Cornell; C. H. Crewdson; P. Cushman; M. Daal; P. C. F. Di Stefano; T. Doughty; L. Esteban; S. Fallows; E. Figueroa-Feliciano; G. L. Godfrey; S. R. Golwala; J. Hall; H. R. Harris; T. Hofer; D. Holmgren; L. Hsu; M. E. Huber; D. M. Jardin; A. Jastram; O. Kamaev; B. Kara; M. H. Kelsey; A. Kennedy; A. Leder; B. Loer; E. Lopez Asamar; P. Lukens; R. Mahapatra; K. A. McCarthy; N. Mirabolfathi; R. A. Moffatt; J. D. Morales Mendoza; S. M. Oser; K. Page; W. A. Page; R. Partridge; M. Pepin; A. Phipps; K. Prasad; M. Pyle; H. Qiu; W. Rau; P. Redl; A. Reisetter; Y. Ricci; A. Roberts; T. Saab; B. Sadoulet; J. Sander; R. W. Schnee; S. Scorza; B. Serfass; B. Shank; D. Speller; D. Toback; S. Upadhyayula; A. N. Villano; B. Welliver; J. S. Wilson; D. H. Wright; X. Yang; S. Yellin; J. J. Yen; B. A. Young; J. Zhang

    2015-06-22

    We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  5. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation Current HABFESOpportunities Nuclear Physics (NP)aboutRio deCooperation atThe GE

  6. UNCERTAINTY MEASURES AND LIMITING DISTRIBUTIONS FOR FILAMENT ESTIMATION

    E-Print Network [OSTI]

    UNCERTAINTY MEASURES AND LIMITING DISTRIBUTIONS FOR FILAMENT ESTIMATION By Yen-Chi Chen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 1. Introduction. A filament is a one-dimensional, smooth, connected structure embedded in a multi-dimensional space. Filaments arise in many applications. For example, matter in the universe tends to concentrate

  7. 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)

    2014-05-19

    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.

  8. When Knowing Early Matters: Gossip, Percolation and Nash Equilibria

    E-Print Network [OSTI]

    Aldous, David J.

    When Knowing Early Matters: Gossip, Percolation and Nash Equilibria David J. Aldous Abstract arbitrarily slowly. But selfish agent behavior leads to Nash equilibria which (in the n limit) may be efficient (Nash payoff = social optimum payoff) or wasteful (0 Nash payoff

  9. Disorder resistivity of solid neutron-star matter

    E-Print Network [OSTI]

    P. B. Jones

    2004-11-01

    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.

  10. 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)

    2013-02-25

    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.

  11. 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)

    2014-03-10

    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.

  12. 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 ...

  13. 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)

    2014-04-01

    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.

  14. 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) ...

  15. Discovery of Isotopes of Elements with Z $\\ge$ 100

    E-Print Network [OSTI]

    M. Thoennessen

    2012-03-09

    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.

  16. 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 ...

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

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

    GE, OCAST and OSSM Partner to Launch "STEM Empowers OK" Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new...

  18. "Big Picture" Process Modeling Tools |GE Global Research

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

    Using process modeling tools to attain cost-effective results for GE customers Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click...

  19. ORNL Partners with GE on New Hybrid | ornl.gov

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

    electric storage water heater, positioning GE to be the first company to meet the energy-saving standard. According to DOE, using devices that meet these criteria should save...

  20. Kids Invention: Vision of the Future |GE Global Research

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

    and Bring your Child to Work Day, to student mentoring, teaching in the class room, Invention Convention and Science Day. To take the message nationally, GE teamed up with the...

  1. The Need for Biological Computation System Models | GE Global...

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

    2012.10.09 Hello everyone, I'm Maria Zavodszky and I work in the Computational Biology and Biostatistics Lab at GE Global Research in Niskayuna, New York. This being our...

  2. Demonstration of 2nd Generation Ducted GE "Brillion" Hybrid Water

    E-Print Network [OSTI]

    sharing partners. #12;Project Synopsis Evaluate the performance and demand response (DR) of the Gen II GE/frequency response) in the PNW and nationwide (Lu et al, 2011; Diao et al 2012) The demand response characteristics

  3. Carrier Density Modulation in Ge Heterostructure by Ferroelectric Switching

    SciTech Connect (OSTI)

    Ponath, Patrick; Fredrickson, Kurt; Posadas, Agham B.; Ren, Yuan; Vasudevan, Rama K; Okatan, Mahmut Baris; Jesse, Stephen; Aoki, Toshihiro; McCartney, Martha; Smith, David J; Kalinin, Sergei V; Lai, Keji; Demkov, Alexander A.

    2015-01-01

    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.

  4. 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....

  5. Modeling of 10 GeV-1 TeV laser-plasma accelerators using Lorentz booster simulations

    SciTech Connect (OSTI)

    Vay, J.-L.; Geddes, C.G.R.; Esarey, E.; Esarey, E.; Leemans, W.P.; Cormier-Michel, E.; Grote, D.P.

    2011-12-01

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98 130405 (2007)] allows direct and e#14;fficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness.

  6. Stellar convective cores as dark matter probes

    E-Print Network [OSTI]

    Jordi Casanellas; Isa M. Brandăo; Yveline Lebreton

    2015-05-06

    The recent detection of a convective core in a main-sequence solar-type star is used here to test particular models of dark matter (DM) particles, those with masses and scattering cross sections in the range of interest for the DM interpretation of the positive results in several DM direct detection experiments. If DM particles do not effectively self-annihilate after accumulating inside low-mass stars (e.g. in the asymmetric DM scenario) their conduction provides an efficient mechanism of energy transport in the stellar core. For main-sequence stars with masses between 1.1 and 1.3 Msun, this mechanism may lead to the suppression of the inner convective region expected to be present in standard stellar evolution theory. The asteroseismic analysis of the acoustic oscillations of a star can prove the presence/absence of such a convective core, as it was demonstrated for the first time with the Kepler field main-sequence solar-like pulsator, KIC 2009505. Studying this star we found that the asymmetric DM interpretation of the results in the CoGeNT experiment is incompatible with the confirmed presence of a small convective core in KIC 2009505.

  7. Anti-helium from Dark Matter annihilations

    E-Print Network [OSTI]

    Marco Cirelli; Nicolao Fornengo; Marco Taoso; Andrea Vittino

    2014-10-21

    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.

  8. Strange Particles from Dense Hadronic Matter

    E-Print Network [OSTI]

    Johann Rafelski; Jean Letessier; Ahmed Tounsi

    2002-09-25

    After a brief survey of the remarkable accomplishments of the current heavy ion collision experiments up to 200A GeV, we address in depth the role of strange particle production in the search for new phases of matter in these collisions. In particular, we show that the observed enhancement pattern of otherwise rarely produced multistrange antibaryons can be consistently explained assuming color deconfinement in a localized, rapidly disintegrating hadronic source. We develop the theoretical description of this source, and in particular study QCD based processes of strangeness production in the deconfined, thermal quark-gluon plasma phase, allowing for approach to chemical equilibrium and dynamical evolution. We also address thermal charm production. Using a rapid hadronization model we obtain final state particle yields, providing detailed theoretical predictions about strange particle spectra and yields as function of heavy ion energy. Our presentation is comprehensive and self-contained: we introduce in considerable detail the procedures used in data interpretation, discuss the particular importance of selected experimental results and show how they impact the theoretical developments.

  9. 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

  10. Quantum Limits of Thermometry

    E-Print Network [OSTI]

    Thomas M. Stace

    2010-06-08

    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.

  11. Superconnections and Matter

    E-Print Network [OSTI]

    Roepstorff, G

    1998-01-01

    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.

  12. Superconnections and Matter

    E-Print Network [OSTI]

    G. Roepstorff

    2000-08-17

    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.

  13. 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)

    2010-12-01

    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.

  14. Thermodynamics of electroweak matter

    E-Print Network [OSTI]

    A. Gynther

    2006-09-21

    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.

  15. Dark Matter Velocity Spectroscopy

    E-Print Network [OSTI]

    Eric G. Speckhard; Kenny C. Y. Ng; John F. Beacom; Ranjan Laha

    2015-07-31

    Dark matter decays or annihilations that produce line-like spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming experiments will reach the required 0.1% level. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.

  16. Dark matter axions

    SciTech Connect (OSTI)

    Sikivie, P. (California Univ., Santa Barbara, CA (United States). Inst. for Theoretical Physics Florida Univ., Gainesville, FL (United States). Dept. of Physics)

    1992-01-01

    The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)

  17. Dark matter axions

    SciTech Connect (OSTI)

    Sikivie, P. [California Univ., Santa Barbara, CA (United States). Inst. for Theoretical Physics]|[Florida Univ., Gainesville, FL (United States). Dept. of Physics

    1992-09-01

    The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)

  18. Materials/Condensed Matter

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformationJesse BergkampCentermillion toMSDSMaterials andMaterials/Condensed Matter Print

  19. Search for Dark Matter in the sky in the Fermi era This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Morselli, Aldo

    annihilation of dark matter particles is strong but there are competing astrophysical sources, such as pulsars is providing the measurement of the high energy (7 GeV to 1 TeV) cosmic ray electrons and positrons spectrum mainly on astrophysical sources of cosmic ray electrons and positrons which include the standard primary

  20. 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