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Sample records for supercdms wimp search

  1. Dedicated Searches for Low and High Mass Wimps with the SuperCDMS Soudan iZIP Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Welliver, Bradford [Florida State Univ., Tallahassee, FL (United States)

    2016-01-01

    Recent cosmological evidence suggests most of the mass of the universe takes the form of a type of particle that we have not been able to directly detect. Nearly 80 years that have elapsed since the rst hints of this dark matter started to appear from astronomers without any direct detection. The high precision era of cosmology and unifying models of particle physics developed in the 20 th century have presented us with an exciting mystery at the intersection of these two elds that needs to be solved. SuperCDMS Soudan operates specialized germanium detectors (iZIPs) that are cooled to milliKelvin temperatures deep underground in the Soudan Underground Laboratory with the hope of detecting a rare collision between dark matter and a nucleus. A search for low-mass dark matter comes with multiple unique challenges since the background discrimination abilities of these detectors becomes less powerful at the low energies needed to probe low-mass dark matter since the signal to noise ratio deteriorates. Using a sophisticated background model via a pulse rescaling technique, SuperCDMS Soudan was able to produce a world leading exclusion limit on low-mass dark matter. Effort is to extend the analysis to higher masses require long running times during which many aspects of the detectors or the environment can change. Additional challenges are offered by the powerful background discrimination ability of the iZIP. The background distributions are well separated from the signal region, meaning most of the leakage arises from low-probability tails of the background distributions. In the absence of an enormous dataset, extrapolations from the bulk of the distribution are required. While attempting to obtain a model of gamma induced electron-recoils leaking into the signal region of the detector from high radius a curious asymmetry between the sides of the detectors was discovered potentially indicating an electronics or detector design problem. This thesis describes the physics

  2. Detector Simulation and WIMP Search Analysis for the Cryogenic Dark Matter Search Experiment

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, Kevin [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2013-06-01

    Astrophysical and cosmological measurements on the scales of galaxies, galaxy clusters, and the universe indicate that 85% of the matter in the universe is composed of dark matter, made up of non-baryonic particles that interact with cross-sections on the weak scale or lower. Hypothetical Weakly Interacting Massive Particles, or WIMPs, represent a potential solution to the dark matter problem, and naturally arise in certain Standard Model extensions. The Cryogenic Dark Matter Search (CDMS) collaboration aims to detect the scattering of WIMP particles from nuclei in terrestrial detectors. Germanium and silicon particle detectors are deployed in the Soudan Underground Laboratory in Minnesota. These detectors are instrumented with phonon and ionization sensors, which allows for discrimination against electromagnetic backgrounds, which strike the detector at rates orders of magnitude higher than the expected WIMP signal. This dissertation presents the development of numerical models of the physics of the CDMS detectors, implemented in a computational package collectively known as the CDMS Detector Monte Carlo (DMC). After substantial validation of the models against data, the DMC is used to investigate potential backgrounds to the next iteration of the CDMS experiment, known as SuperCDMS. Finally, an investigation of using the DMC in a reverse Monte Carlo analysis of WIMP search data is presented.

  3. A Search for Light Weakly-Interacting Massive Particles with SuperCDMS and Applications to Neutrino Physics

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Adam J. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-01-01

    Cosmological and astrophysical evidence indicates that 85% of the matter content of the universe is in the form of non-baryonic dark matter. A large number of experiments are currently undertaking searches for weakly-interacting massive particles (WIMPs), the leading class of particle candidates for dark matter. This thesis describes the results of such a search with the SuperCDMS experiment, which uses Ge detectors cooled to 50 mK to detect ionization and phonons produced by particle interactions. We perform a blind analysis of 577 kg d of exposure on 7 detectors targeting WIMPs with masses < 30GeV/$c^{2}$, where anomalous results have been reported by previous experiments. No significant excess is observed and we set an upper limit on the spin-independent WIMP-nucleon cross section of 1.2 x 10$^{-42}$ cm2 at 8 GeV/$c^{2}$ We also set constraints on dark matter interactions independent of the dark matter halo physics, as well as on annual modulation of a dark matter signal. Cryogenic detectors similar to SuperCDMS also have potential applications in neutrino physics. We study several configurations in which dark matter detectors could be used with an intense neutrino source to detect an unmeasured Standard Model process called coherent neutrino scattering. This process may be useful, for example, as a calibration for next-generation dark matter detectors, and for constraining eV-scale sterile neutrinos. In addition, small cryogenic X-ray detectors on sounding rockets with large fields-of-view have the unique ability to constrain sterile neutrino dark matter. We set limits on sterile neutrino dark matter using an observation by the XQC instrument, and discuss prospects for a future observation of the galactic center using the Micro-X instrument.

  4. Search for Low-Mass Dark Matter wtih SuperCDMS Soudan and Study of Shorted Electric Field Configurations in CDMS Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Schneck, Kristiana [Stanford Univ., CA (United States)

    2015-01-01

    The area of dark matter is one of the most interesting and exciting topics in physics today. Existing at the intersection of particle physics and astrophysics, the existence of a new dark matter particle can be used to explain many astrophysical and cosmological observations, as well as to reconcile outstanding issues in the standard model of particle physics. Experiments such as SuperCDMS are built to detect dark matter in the lab by looking for low-energy nuclear recoils produced by collisions between dark matter particles and atoms in terrestrial detectors. SuperCDMS Soudan is particularly well-suited to follow up on possible hints of low-mass dark matter seen by other recent experiments because of its low thresholds and excellent background discrimination. Analyzing SuperCDMS Soudan data to look for low-mass dark matter comes with particular challenges because of the low signal-to-noise very near threshold. However, with a detailed background model developed by scaling high-energy events down into the low-energy signal region, SuperCDMS Soudan produced worldleading limits on the existence of low-mass dark matter. In addition, a few SuperCDMS Soudan detectors experienced cold hardware problems that can affect the data collected. Of particular interest is one detector considered for the low-mass WIMP search that has one of its charge electrodes shorted to chassis ground. Three events were observed in this detector upon unblinding the SuperCDMS Soudan low-energy data, even though <1 event was expected based on pre-unblinding calulations. However, the data collected by the shorted detector may have been compromised since an electrode shorted to ground will modify the electric field in the detector. The SuperCDMS Detector Monte Carlo (DMC) provides an excellent way to model the effects of the modified electric field, so a new model of the expected backgrounds in the low-mass WIMP search is developed using the DMC to try to explain how the short may have affected the

  5. Boffins go underground searching for Wimps

    CERN Multimedia

    2003-01-01

    In a bid to identify the prime suspect for Dark Matter known as Weakly Interacting Massive Particles, or Wimps, British scientists have installed detectors 1100m down a salt mine at Boulby on the North Yorkshire moors (1/2 page).

  6. Optimizing EDELWEISS detectors for low-mass WIMP searches

    Science.gov (United States)

    Arnaud, Q.; Armengaud, E.; Augier, C.; Benoît, A.; Bergé, L.; Billard, J.; Broniatowski, A.; Camus, P.; Cazes, A.; Chapellier, M.; Charlieux, F.; de Jésus, M.; Dumoulin, L.; Eitel, K.; Foerster, N.; Gascon, J.; Giuliani, A.; Gros, M.; Hehn, L.; Jin, Y.; Juillard, A.; Kleifges, M.; Kozlov, V.; Kraus, H.; Kudryavtsev, V. A.; Le-Sueur, H.; Maisonobe, R.; Marnieros, S.; Navick, X.-F.; Nones, C.; Olivieri, E.; Pari, P.; Paul, B.; Poda, D.; Queguiner, E.; Rozov, S.; Sanglard, V.; Scorza, S.; Siebenborn, B.; Vagneron, L.; Weber, M.; Yakushev, E.; EDELWEISS Collaboration

    2018-01-01

    The physics potential of EDELWEISS detectors for the search of low-mass weakly interacting massive particles (WIMPs) is studied. Using a data-driven background model, projected exclusion limits are computed using frequentist and multivariate analysis approaches, namely, profile likelihood and boosted decision tree. Both current and achievable experimental performances are considered. The optimal strategy for detector optimization depends critically on whether the emphasis is put on WIMP masses below or above ˜5 GeV /c2 . The projected sensitivity for the next phase of the EDELWEISS-III experiment at the Modane Underground Laboratory (LSM) for low-mass WIMP search is presented. By 2018 an upper limit on the spin-independent WIMP-nucleon cross section of σSI=7 ×10-42 cm2 is expected for a WIMP mass in the range 2 - 5 GeV /c2 . The requirements for a future hundred-kilogram-scale experiment designed to reach the bounds imposed by the coherent scattering of solar neutrinos are also described. By improving the ionization resolution down to 50 eVe e , we show that such an experiment installed in an even lower background environment (e.g., at SNOLAB) together with an exposure of 1 000 kg .yr , should allow us to observe about 80 B 8 neutrino events after discrimination.

  7. Neutrino astronomy and search for WIMPs with MACRO

    CERN Document Server

    Bernardini, P

    2000-01-01

    Upward-going muons, induced primarily by atmospheric neutrinos, are used to search for neutrinos of astrophysical origin. No evidence has been found looking at the event direction and flux limits are obtained on candidate sources. A space-time correlation between gamma ray bursts and upward-going muons has been also investigated. Furthermore the search for a neutrino signal from the Earth and the Sun induced by weakly interacting massive particles (WIMP) has been updated. The number of events from the Sun and from the Earth is compatible with the background from atmospheric neutrinos. Therefore flux limits for different search cones have been estimated. Here we concentrate on neutralinos as WIMP candidates and limits depending on the neutralino mass are given and compared with the prediction of supersymmetric models. (11 refs).

  8. NEWSdm: Nuclear Emulsions for WIMP Search with directional measurement

    Directory of Open Access Journals (Sweden)

    Di Crescenzo A.

    2017-01-01

    Full Text Available Direct Dark Matter searches are nowadays one of the most exciting research topics. Several experimental efforts are concentrated on the development, construction, and operation of detectors looking for the scattering of target nuclei with Weakly Interactive Massive Particles (WIMPs. The measurement of the direction of WIMP-induced nuclear recoils is a challenging strategy to extend dark matter searches beyond the neutrino floor and provide an unambiguous signature of the detection of Galactic dark matter. Current directional experiments are based on the use of gas TPC whose sensitivity is strongly limited by the small achievable detector mass. We present an innovative directional experiment based on the use of a solid target made by newly developed nuclear emulsions and read-out systems reaching a position resolution of the order of 10 nm.

  9. NEWSdm: Nuclear Emulsions for WIMP Search with directional measurement

    Science.gov (United States)

    Di Crescenzo, A.

    2017-12-01

    Direct Dark Matter searches are nowadays one of the most exciting research topics. Several experimental efforts are concentrated on the development, construction, and operation of detectors looking for the scattering of target nuclei with Weakly Interactive Massive Particles (WIMPs). The measurement of the direction of WIMP-induced nuclear recoils is a challenging strategy to extend dark matter searches beyond the neutrino floor and provide an unambiguous signature of the detection of Galactic dark matter. Current directional experiments are based on the use of gas TPC whose sensitivity is strongly limited by the small achievable detector mass. We present an innovative directional experiment based on the use of a solid target made by newly developed nuclear emulsions and read-out systems reaching a position resolution of the order of 10 nm.

  10. WIMP search and a Cherenkov detector prototype for ILC polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, Christoph

    2011-10-15

    The planned International Linear Collider (ILC) will be an essential experiment to precisely determine the properties and structure of physics at the TeV scale. An important feature of the ILC is the possibility to use polarized electrons and positrons. In part 1 of this thesis, a model independent search for Weakly Interacting Massive Particles (WIMPs) at ILC is presented. The signal channel under study is direct WIMP pair production with associated Initial State Radiation (ISR), e{sup +}e{sup -} {yields} {chi}{chi}{gamma}, where the WIMPs leave the detector without any further interaction, and only the emitted photon is detected. From the energy spectrum of the detected photons the coupling structure, cross sections, masses and the quantum number of the dominant partial wave in the production process can be inferred. The analysis includes the dominant SM, as well as machine-induced backgrounds, and is performed using a full simulation of the ILD detector concept. For an integrated luminosity of L=500 fb{sup -1}, the signal cross sections can be measured to a precision of 3%, dominated by systematic uncertainties on the polarization measurement of the initial electrons and positrons. Masses can be measured to a precision of up to 2% by a comparison of the data photon spectrum to parametrized template spectra. In part 2 of this thesis, a Cherenkov detector prototype for Compton polarimetry at ILC is presented. For the polarization measurement a systematic uncertainty of {delta} P/P = 0.25% or better is envisioned. To achieve this goal, the Cherenkov detector has to be precisely aligned with the fan of Compton scattered electrons and its signal response needs to be highly linear. For the detector prototype data driven alignment strategies have been developed by comparing data recorded at the Elsa accelerator in Bonn, Germany, with detailed Geant4 simulations. With the use of multi-anode photomultipliers, data driven alignment strategies promise to provide the

  11. WIMP search and a Cherenkov detector prototype for ILC polarimetry

    International Nuclear Information System (INIS)

    Bartels, Christoph

    2011-10-01

    The planned International Linear Collider (ILC) will be an essential experiment to precisely determine the properties and structure of physics at the TeV scale. An important feature of the ILC is the possibility to use polarized electrons and positrons. In part 1 of this thesis, a model independent search for Weakly Interacting Massive Particles (WIMPs) at ILC is presented. The signal channel under study is direct WIMP pair production with associated Initial State Radiation (ISR), e + e - → χχγ, where the WIMPs leave the detector without any further interaction, and only the emitted photon is detected. From the energy spectrum of the detected photons the coupling structure, cross sections, masses and the quantum number of the dominant partial wave in the production process can be inferred. The analysis includes the dominant SM, as well as machine-induced backgrounds, and is performed using a full simulation of the ILD detector concept. For an integrated luminosity of L=500 fb -1 , the signal cross sections can be measured to a precision of 3%, dominated by systematic uncertainties on the polarization measurement of the initial electrons and positrons. Masses can be measured to a precision of up to 2% by a comparison of the data photon spectrum to parametrized template spectra. In part 2 of this thesis, a Cherenkov detector prototype for Compton polarimetry at ILC is presented. For the polarization measurement a systematic uncertainty of δ P/P = 0.25% or better is envisioned. To achieve this goal, the Cherenkov detector has to be precisely aligned with the fan of Compton scattered electrons and its signal response needs to be highly linear. For the detector prototype data driven alignment strategies have been developed by comparing data recorded at the Elsa accelerator in Bonn, Germany, with detailed Geant4 simulations. With the use of multi-anode photomultipliers, data driven alignment strategies promise to provide the required precision. At ILC, these

  12. Constraints on low-mass WIMPs from the EDELWEISS-III dark matter search

    Energy Technology Data Exchange (ETDEWEB)

    Armengaud, E.; De Boissière, T. [CEA Saclay, DSM/IRFU, Gif-sur-Yvette Cedex, 91191 France (France); Arnaud, Q.; Augier, C.; Benoît, A.; Billard, J.; Cazes, A.; Charlieux, F. [Institut de Physique Nucléaire de Lyon-UCBL, IN2P3-CNRS, 4 rue Enrico Fermi, Villeurbanne Cedex, 69622 France (France); Benoît, A.; Bres, G.; Camus, P. [Institut Néel, CNRS/UJF, 25 rue des Martyrs, BP 166, Grenoble, 38042 France (France); Bergé, L.; Broniatowski, A.; Chapellier, M.; Dumoulin, L. [CSNSM, Université Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, Orsay, 91405 France (France); Bergmann, T. [Karlsruher Institut für Technologie, Institut für Prozessdatenverarbeitung und Elektronik, Postfach 3640, Karlsruhe, 76021 Germany (Germany); Blümer, J. [Karlsruher Institut für Technologie, Institut für Experimentelle Kernphysik, Gaedestr. 1, Karlsruhe, 76128 Germany (Germany); Brudanin, V.; Filosofov, D. [JINR, Laboratory of Nuclear Problems, Joliot-Curie 6, Dubna, Moscow Region, 141980 Russian Federation (Russian Federation); Eitel, K., E-mail: eric.armengaud@cea.fr [Karlsruher Institut für Technologie, Institut für Kernphysik, Postfach 3640, Karlsruhe, 76021 Germany (Germany); and others

    2016-05-01

    We present the results of a search for elastic scattering from galactic dark matter in the form of Weakly Interacting Massive Particles (WIMPs) in the 4–30 GeV/ c {sup 2} mass range. We make use of a 582 kg-day fiducial exposure from an array of 800 g Germanium bolometers equipped with a set of interleaved electrodes with full surface coverage. We searched specifically for ∼ 2.5–20 keV nuclear recoils inside the detector fiducial volume. As an illustration the number of observed events in the search for 5 (resp. 20) GeV/ c {sup 2} WIMPs are 9 (resp. 4), compared to an expected background of 6.1 (resp. 1.4). A 90% CL limit of 4.3 × 10{sup −40} cm{sup 2} (resp. 9.4 × 10{sup −44} cm{sup 2}) is set on the spin-independent WIMP-nucleon scattering cross-section for 5 (resp. 20) GeV/ c {sup 2} WIMPs. This result represents a 41-fold improvement with respect to the previous EDELWEISS-II low-mass WIMP search for 7 GeV/ c {sup 2} WIMPs. The derived constraint is in tension with hints of WIMP signals from some recent experiments, thus confirming results obtained with different detection techniques.

  13. Supersymmetry with Radiatively-Driven Naturalness: Implications for WIMP and Axion Searches

    Directory of Open Access Journals (Sweden)

    Kyu Jung Bae

    2015-05-01

    Full Text Available By insisting on naturalness in both the electroweak and quantum chromodynamics (QCD sectors of the minimal supersymmetric standard model (MSSM, the portrait for dark matter production is seriously modified from the usual weakly interacting massive particle (WIMP miracle picture. In supersymmetry (SUSY models with radiatively-driven naturalness (radiative natural SUSY or radiative natural SUSY (RNS which include a Dine–Fischler–Srednicki–Zhitnitsky (DFSZ-like solution to the strong charge-conjugation-parity (CP and SUSY \\(\\mu\\ problems, dark matter is expected to be an admixture of both axions and higgsino-like WIMPs. The WIMP/axion abundance calculation requires simultaneous solution of a set of coupled Boltzmann equations which describe quasi-stable axinos and saxions. In most of parameter space, axions make up the dominant contribution of dark matter although regions of WIMP dominance also occur. We show the allowed range of Peccei-Quinn (PQ scale \\(f_a\\ and compare to the values expected to be probed by the axion dark matter search experiment (ADMX axion detector in the near future. We also show WIMP detection rates, which are suppressed from usual expectations, because now WIMPs comprise only a fraction of the total dark matter. Nonetheless, ton-scale noble liquid detectors should be able to probe the entirety of RNS parameter space. Indirect WIMP detection rates are less propitious since they are reduced by the square of the depleted WIMP abundance.

  14. Advancing the Search for Dark Matter: from CDMS II to SuperCDMS

    Energy Technology Data Exchange (ETDEWEB)

    Hertel, Scott A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2012-09-01

    An overwhelming proportion of the universe (83% by mass) is composed of particles we know next to nothing about. Detecting these dark matter particles directly, through hypothesized weak-force-mediated recoils with nuclear targets here on earth, could shed light on what these particles are, how they relate to the standard model, and how the standard model ts within a more fundamental understanding. This thesis describes two such experimental eorts: CDMS II (2007-2009) and SuperCDMS Soudan (ongoing). The general abilities and sensitivities of both experiments are laid out, placing a special emphasis on the detector technology, and how this technology has evolved from the rst to the second experiment. Some topics on which I spent signicant eorts are described here only in overview (in particular the details of the CDMS II analysis, which has been laid out many times before), and some topics which are not described elsewhere are given a somewhat deeper treatment. In particular, this thesis is hopefully a good reference for those interested in the annual modulation limits placed on the low-energy portion of the CDMS II exposure, the design of the detectors for SuperCDMS Soudan, and an overview of the extremely informative data these detectors produce. It is an exciting time. The technology I've had the honor to work on the past few years provides a wealth of information about each event, more so than any other direct detection experiment, and we are still learning how to optimally use all this information. Initial tests from the surface and now underground suggest this technology has the background rejection abilities necessary for a planned 200kg experiment or even ton-scale experiment, putting us on the threshold of probing parameter space orders of magnitude from where the eld currently stands.

  15. Testing and Characterization of SuperCDMS Dark Matter Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Shank, Benjamin [Stanford Univ., CA (United States)

    2014-05-01

    The Cryogenic Dark Matter Search (SuperCDMS) relies on collection of phonons and charge carriers in semiconductors held at tens of milliKelvin as handles for detection of Weakly Interacting Massive Particles (WIMPs). This thesis begins with a brief overview of the direct dark matter search (Chapter 1) and SuperCDMS detectors (Chapter 2). In Chapter 3, a 3He evaporative refrigerator facility is described. Results from experiments performed in-house at Stanford to measure carrier transport in high-purity germanium (HPGe) crystals operated at sub-Kelvin temperatures are presented in Chapter 4. Finally, in Chapter 5 a new numerical model and a time-domain optimal filtering technique are presented, both developed for use with superconducting Transition Edge Sensors (TESs), that provide excellent event reconstruction for single particle interactions in detectors read out with superconducting W-TESs coupled to energy-collecting films of Al. This thesis is not intended to be read straight through. For those new to CDMS or dark matter searches, the first two chapters are meant to be a gentle introduction for experimentalists. They are by no means exhaustive. The remaining chapters each stand alone, with different audiences.

  16. A precision search for WIMPs with charged cosmic rays

    Science.gov (United States)

    Reinert, Annika; Winkler, Martin Wolfgang

    2018-01-01

    AMS-02 has reached the sensitivity to probe canonical thermal WIMPs by their annihilation into antiprotons. Due to the high precision of the data, uncertainties in the astrophysical background have become the most limiting factor for indirect dark matter detection. In this work we systematically quantify and—where possible—reduce uncertainties in the antiproton background. We constrain the propagation of charged cosmic rays through the combination of antiproton, B/C and positron data. Cross section uncertainties are determined from a wide collection of accelerator data and are—for the first time ever—fully taken into account. This allows us to robustly constrain even subdominant dark matter signals through their spectral properties. For a standard NFW dark matter profile we are able to exclude thermal WIMPs with masses up to 570 GeV which annihilate into bottom quarks. While we confirm a reported excess compatible with dark matter of mass around 80 GeV, its local (global) significance only reaches 2.2 σ (1.1 σ) in our analysis.

  17. The waning of the WIMP? A review of models, searches, and constraints

    Science.gov (United States)

    Arcadi, Giorgio; Dutra, Maíra; Ghosh, Pradipta; Lindner, Manfred; Mambrini, Yann; Pierre, Mathias; Profumo, Stefano; Queiroz, Farinaldo S.

    2018-03-01

    Weakly Interacting Massive Particles (WIMPs) are among the best-motivated dark matter candidates. No conclusive signal, despite an extensive search program that combines, often in a complementary way, direct, indirect, and collider probes, has been detected so far. This situation might change in near future due to the advent of one/multi-TON Direct Detection experiments. We thus, find it timely to provide a review of the WIMP paradigm with focus on a few models which can be probed at best by these facilities. Collider and Indirect Detection, nevertheless, will not be neglected when they represent a complementary probe.

  18. A modified detector concept for SuperCDMS: The HiZIP and its charge performance

    Science.gov (United States)

    Page, Kedar Mohan

    SuperCDMS is a leading direct dark matter search experiment which uses solid state detectors (Ge crystals) at milliKelvin temperatures to look for nuclear recoils caused by dark matter interactions in the detector. 'Weakly Interacting Massive Particles' (WIMPs) are the most favoured dark matter candidate particles. SuperCDMS, like many other direct dark matter search experiments, primarily looks for WIMPs. The measurement of both the ionization and the lattice vibration (phonon) signals from an interaction in the detector allow it to discriminate against electron recoils which are the main source of background for WIMP detection. SuperCDMS currently operates about 9 kgs worth of germanium detectors at the Soudan underground lab in northern Minnesota. In its next phase, SuperCDMS SNOLAB, it plans to use 100-200 kg of target mass (Ge) which would allow it to probe more of the interesting and unexplored parameter space for WIMPs predicted by theoretical models. The SuperCDMS Queen's Test Facility is a detector testing facility which is intended to serve detector testing and detector research and development purposes for the SuperCDMS experiment. A modified detector called the 'HiZIP' (Half-iZIP), which is reduced in complexity in comparison to the currently used iZIP (interleaved Z-sensitive Ionization and Phonon mediated) detectors, is studied in this thesis. The HiZIP detector design also serves to discriminate against background from multiple scatter events occurring close to the surfaces in a single detector. Studies carried out to compare the surface event leakage in the HiZIP detector using limited information from iZIP data taken at SuperCDMS test facility at UC Berkley produce a highly conservative upper limit of 5 out of 10,000 events at 90% confidence level. This upper limit is the best among many different HiZIP configurations that were investigated and is comparable to the upper limit calculated for an iZIP detector in the same way using the same data. A

  19. A Search for WIMP Dark Matter Using the First Five-Tower Run of the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Filippini, Jeffrey Peter [UC, Berkeley

    2008-01-01

    In recent decades astronomers and physicists have accumulated a vast array of evidence that the bulk of the universe's matter is in some non-baryonic form that remains undetected by electromagnetic means. This \\dark matter" resides in diuse halos surrounding galaxies and other cosmic structures. Particle theorists have proposed a wide array of candidates for its nature. One particularly promising class of candidates are Weakly Interacting Massive Particles (WIMPs): quanta with masses of order 100 GeV/c2 and interactions characteristic of the weak nuclear force. The Cryogenic Dark Matter Search (CDMS) experiment seeks to directly detect the rare elastic interactions of galactic WIMPs with terrestrial nuclei. To this end, CDMS operates an array of crystalline Ge and Si particle detectors in Soudan Underground Laboratory in northern Minnesota. These crystals are operated at millikelvin temperatures and instrumented to measure the ionization and athermal phonons generated by each particle interaction. This combination provides a powerful two-fold discrimination against the interactions of particles generated by radioactive decay and cosmogenic showers. This dissertation describes the commissioning, analysis, and results of the rst WIMP-search data runs of the CDMS experiment with its full complement of 5 \\Towers" of detectors. These data represent a substantial increase in target mass and exposure over previous CDMS results. The results of this work place the most stringent limits yet set upon the WIMP-nucleon spin-independent cross section for WIMP masses above 44 GeV/c2 , as well as setting competitive limits on spin-dependent WIMP-nucleon interactions. This work also outlines the larger context of this and other probes of the WIMP theory of dark matter, as well as some current development eorts toward a larger cryogenic experiment.

  20. Results and status of the Edelweiss Wimp search experiment

    International Nuclear Information System (INIS)

    Benoit, A.; Berge, L.; Blumer, J.; Broniatowski, A.; Censier, B.; Chabert, L.; Chambon, B.; Chapellier, M.; Chardin, G.; Charvin, P.; Jesus, M. de; Drain, D.; Di Stefano, P.; Dumoulin, L.; Eitel, K.; Fesquet, M.; Firucci, S.; Gascon, J.; Gerbier, G.; Gerlic, E.; Goldbach, C.; Goyot, M.; Gros, M.; Habermahl, F.; Horn, M.; Hadjout, J.P.; Herve, S.; Juillard, A.; Kikuchi, C.; Lesquen, A. de; Luca, M.; Mallet, J.; Marnieros, S.; Martineau, O.; Mosca, L.; Navick, X.F.; Nollez, G.; Pari, P.; Riccio, C.; Sanglard, V.; Stern, M.; Vagneron, L.; Villard, V.

    2005-01-01

    In the Edelweiss experiment, nuclear recoils induced by elastic collisions with WIMPs (weakly interacting massive particle) from the galactic halo are identified in low-temperature Ge detectors where the ratio of the heat and ionization signals provide an event-by-event discrimination of nuclear recoils from the dominant background coming from γ-rays interactions. The Edelweiss experiment is located in the Modane underground facility in order to cut the muon flux drastically. We present here the results obtained during the first part of the experiment named Edelweiss-I that ended in the beginning of 2004. Since october 2002, 3 optimized 320 grams detectors have been simultaneously operated at a regulated temperature of 0.017 K and about 50 kg*day were added to the previous published data. These data are still under analysis but preliminary results concerning the upper limit at 90% CL (confidence level) confirm the limit already published in 2002. The first run of Edelweiss-II is due to begin during summer 2005, we are expecting to gain 2 orders of magnitude in terms of detector sensitivity and reach 0.002 events/day*kg. (A.C.)

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

    International Nuclear Information System (INIS)

    Abrams, D.; Baudis, L.; Brink, P.L.; Cabrera, B.; Castle, J.P.; Chang, C.L.; Clarke, R.M.; Saab, T.; Akerib, D.S.; Bolozdynya, A.; Driscoll, D.; Kamat, S.; Perera, T.A.; Schnee, R.W.; Wang, G.; Armel-Funkhouser, M.S.; Golwala, S.R.; Hellmig, J.; Mandic, V.; Meunier, P.

    2002-01-01

    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 ∼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 3σ 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% confidence level (C.L.), and are incompatible with the model-independent annual-modulation signal of DAMA at 99.99% C.L. in the asymptotic limit

  2. A modified detector concept for SuperCDMS: The HiZIP and its charge performance

    Energy Technology Data Exchange (ETDEWEB)

    Page, Kedar Mohan [Queen' s U.

    2013-01-01

    SuperCDMS (Super Cryogenic Dark Matter Search) is a leading direct dark mat-ter search experiment which uses solid state detectors (Ge crystals) at milliKelvintemperatures to look for nuclear recoils caused by dark matter interactions in the de-tector. `Weakly Interacting Massive Particles' (WIMPs) are the most favoured darkmatter candidate particles. SuperCDMS, like many other direct dark matter searchexperiments, primarily looks for WIMPs. The measurement of both the ionizationand the lattice vibration (phonon) signals from an interaction in the detector allow itto discriminate against electron recoils which are the main source of background forWIMP detection.SuperCDMS currently operates about 9 kg of Ge detectors at the Soudan under-ground lab in northern Minnesota. In its next phase, SuperCDMS SNOLAB plansto use 100-200 kg of target mass (Ge) which would allow it to probe more of theinteresting and and as of yet unexplored parameter space for WIMPs predicted bytheoretical models. The SuperCDMS Queen's Test Facility is a detector test facilitywhich is intended to serve as detector testing and detector research and developmentpurposes for the SuperCDMS experiment.A modifed detector called the HiZIP (Half-iZIP), which is reduced in complex-ity in comparison to the currently used iZIP (interleaved Z-sensitive Ionization and Phonon mediated) detectors, is studied in this thesis. The HiZIP detector designalso serves to discriminate against background from multiple scatter events occurringclose to the surfaces in a single detector. Studies carried out to compare the surfaceevent leakage in the HiZIP detector using limited information from iZIP data takenat SuperCDMS test facility at UC Berkley produce a highly conservative upper limitof 5 out of 10,000 events at 90% condence level. This upper limit is the best amongmany different HiZIP congurations that were investigated and is comparable to theupper limit calculated for an HiZIP detector in the same way

  3. WIMP dark matter and supersymmetry searches with neutrino telescopes

    International Nuclear Information System (INIS)

    Fornengo, N.

    2011-01-01

    The particle physics interpretation of the missing-mass, or dark-matter, a problem of cosmological and astrophysical nature, is going to be placed under strong scrutiny in the next years. From the particle physics side, accelerator physics will deeply test theoretical ideas about new physics beyond the Standard Model, where a particle physics candidate to dark matter is often naturally obtained. From the astrophysical side, many probes are already providing a great deal of independent information on signals which can be produced by the galactic or extra-galactic dark matter. The current and new-generation experimental efforts are therefore going to place under deep scrutiny the theoretical explanations of the relevant signals. The ultimate hope is in fact to be able to disentangle a dark matter signal from the various sources of backgrounds. Neutrino telescopes are one of the prominent tools for looking at dark matter and search for a signal, the neutrino flux from Earth and Sun. In this neutrino dark matter searches share properties with both direct dark matter searches and cosmic-ray indirect dark matter searches, and therefore complement these different detection techniques.

  4. WIMP search in the mono-photon channel at the international linear collider

    Energy Technology Data Exchange (ETDEWEB)

    Habermehl, Moritz [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg (Germany); Universitaet Hamburg, Institut fuer Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg (Germany); List, Jenny [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg (Germany)

    2016-07-01

    The International Linear Collider (ILC) is a planned electron-positron collider with √(s) tunable from 250 to 500 GeV, with a possible upgrade to 1 TeV. Besides precision measurements of the Higgs boson its physics goals comprise searches for physics beyond the Standard Model, e.g. searches for Dark Matter. This collider search assumes the production of WIMPs in pairs. They are not visible in the detector but the energy carried away can be observed via an additional (''tag'') particle. Photon emission from the initial state leads to the almost model independent signature: e{sup +}e{sup -} → χχγ. As this analysis tests couplings between WIMPs and leptons it is complementary to analogues searches at the LHC. A precise study is facilitated by the clean environment of lepton colliders with small systematics of electroweak backgrounds. While the conceptual feasibility and the sensitivity reach of the ILC have been shown in the past, this talk focusses on the consequences for the detector design. The requirements for the central detector as well as for the instrumentation of the forward region are discussed in the context of the ILD detector concept.

  5. Search for WIMP dark matter produced in association with a Z boson with the ATLAS detector

    CERN Document Server

    Basalaev, Artem; The ATLAS collaboration

    2016-01-01

    The search for weakly interacting dark matter particle (WIMP) candidates produced in association with a Z boson is presented. Events with large missing transverse momentum and consistent with the decay of a Z boson into oppositely charged electron or muon pairs were selected in analysis. Background estimates and corresponding systematic uncertainties are shown. The limits on the mass scale of the contact interaction as a function of the dark matter particle mass and the limits on the coupling and scalar particle mediator mass for 8 TeV proton-proton collisions data are presented. Prospects for analysis using 13 TeV proton-proton collisions data are discussed.

  6. Development of low-background CsI(Tl) crystals for WIMP search

    International Nuclear Information System (INIS)

    Lee, H.S.; Bhang, H.; Hahn, I.S.; Hwang, M.J.; Kim, H.J.; Kim, S.C.; Kim, S.K.; Kim, S.Y.; Kim, T.Y.; Kim, Y.D.; Kwak, J.W.; Kwon, Y.J.; Lee, J.; Lee, J.I.; Lee, M.J.; Li, J.; Myung, S.S.; Park, H.; Zhu, J.J.

    2007-01-01

    Search for weakly interacting massive particles (WIMPs) is being carried out at the underground laboratory, Yangyang, Korea. Characteristics and internal background of CsI(Tl) crystal have been investigated. In our extensive R and D, we reduced internal background in the CsI(Tl) crystal. With the latest, we have achieved 5.50+/-0.10cpd (counts/keV/kg/day) at 10-15keV low-energy region. Further reduction of internal background is foreseen with the CsI powder lately produced

  7. Complementarity of WIMP Sensitivity with direct SUSY, Monojet and Dark Matter Searches in the MSSM

    CERN Document Server

    Arbey, Alexandre; Mahmoudi, Farvah

    2014-01-01

    This letter presents new results on the combined sensitivity of the LHC and underground dark matter search experiments to the lightest neutralino as WIMP candidate in the minimal Supersymmetric extension of the Standard Model. We show that monojet searches significantly extend the sensitivity to the neutralino mass in scenarios where scalar quarks are nearly degenerate in mass with it. The inclusion of the latest bound by the LUX experiment on the neutralino-nucleon spin-independent scattering cross section expands this sensitivity further, highlighting the remarkable complementarity of jets/$\\ell$s+MET and monojet at LHC and dark matter searches in probing models of new physics with a dark matter candidate. The qualitative results of our study remain valid after accounting for theoretical uncertainties.

  8. Exclusion limits on the WIMP nucleon elastic scattering cross-section from the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Golwala, Sunil Ramanlal [UC, Berkeley

    2000-01-01

    Extensive evidence indicates that a large fraction of the matter in the universe is nonluminous, nonbaryonic, and “cold” — nonrelativistic at the time matter began to dominate the energy density of the universe. Weakly Interacting Massive Particles (WIMPs) are an excellent candidate for nonbaryonic, cold dark matter. Minimal supersymmetry provides a natural WIMP candidate in the form of the lightest superpartner, with a typical mass Mδ ~ 100 GeV c-2 . WIMPs are expected to have collapsed into a roughly isothermal, spherical halo within which the visible portion of our galaxy resides. They would scatter off nuclei via the weak interaction, potentially allowingtheir direct detection. The Cryogenic Dark Matter Search (CDMS) employs Ge and Si detectors to search for WIMPs via their elastic-scatteringinteractions with nuclei while discriminatingagainst interactions of background particles. The former yield nuclear recoils while the latter produce electron recoils. The ionization yield (the ratio of ionization production to recoil energy in a semiconductor) of a particle interaction differs greatly for nuclear and electron recoils. CDMS detectors measure phonon and electron-hole-pair production to determine recoil energy and ionization yield for each event and thereby discriminate nuclear recoils from electron recoils. This dissertation reports new limits on the spin-independent WIMP-nucleon elastic-scattering cross section that exclude unexplored parameter space above 10 GeV c-2 WIMP mass and, at > 75% CL, the entire 3σ allowed region for the WIMP signal reported by the DAMA experiment. The experimental apparatus, detector performance, and data analysis are fully described.

  9. Results and status of the Edelweiss Wimp search experiment; Experience Edelweiss de recherche directe de Wimps: resultats et perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Benoit, A.; Berge, L.; Blumer, J.; Broniatowski, A.; Censier, B.; Chabert, L.; Chambon, B.; Chapellier, M.; Chardin, G.; Charvin, P.; Jesus, M. de; Drain, D.; Di Stefano, P.; Dumoulin, L.; Eitel, K.; Fesquet, M.; Firucci, S.; Gascon, J.; Gerbier, G.; Gerlic, E.; Goldbach, C.; Goyot, M.; Gros, M.; Habermahl, F.; Horn, M.; Hadjout, J.P.; Herve, S.; Juillard, A.; Kikuchi, C.; Lesquen, A. de; Luca, M.; Mallet, J.; Marnieros, S.; Martineau, O.; Mosca, L.; Navick, X.F.; Nollez, G.; Pari, P.; Riccio, C.; Sanglard, V.; Stern, M.; Vagneron, L.; Villard, V

    2005-07-01

    In the Edelweiss experiment, nuclear recoils induced by elastic collisions with WIMPs (weakly interacting massive particle) from the galactic halo are identified in low-temperature Ge detectors where the ratio of the heat and ionization signals provide an event-by-event discrimination of nuclear recoils from the dominant background coming from {gamma}-rays interactions. The Edelweiss experiment is located in the Modane underground facility in order to cut the muon flux drastically. We present here the results obtained during the first part of the experiment named Edelweiss-I that ended in the beginning of 2004. Since october 2002, 3 optimized 320 grams detectors have been simultaneously operated at a regulated temperature of 0.017 K and about 50 kg*day were added to the previous published data. These data are still under analysis but preliminary results concerning the upper limit at 90% CL (confidence level) confirm the limit already published in 2002. The first run of Edelweiss-II is due to begin during summer 2005, we are expecting to gain 2 orders of magnitude in terms of detector sensitivity and reach 0.002 events/day*kg. (A.C.)

  10. Search for WIMP dark matter produced in association with a Z boson with the ATLAS detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00399337; The ATLAS collaboration

    2016-01-01

    The search for weakly interacting dark matter particle (WIMP) candidates produced in association with a Z boson with the ATLAS detector at the LHC is presented. Events with large missing transverse momentum and consistent with the decay of a Z boson into oppositely charged electron or muon pairs were selected in analysis. Background estimates and corresponding systematic uncertainties are shown. The limits on the mass scale of the contact interaction as a function of the dark matter particle mass and the limits on the coupling and scalar particle mediator mass for 8 TeV proton-proton collisions data are presented. Prospects for analysis using 13 TeV proton-proton collisions data are discussed.

  11. Results from the Super Cryogenic Dark Matter Search Experiment at Soudan

    Energy Technology Data Exchange (ETDEWEB)

    Agnese, R.; Aramaki, T.; Arnquist, I. J.; Baker, W.; Balakishiyeva, D.; Banik, S.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Binder, T.; Bowles, M. A.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Calkins, R.; Cartaro, C.; Cerdeño, D. G.; Chang, Y.; Chen, Y.; Cooley, J.; Cornell, B.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Fascione, E.; Figueroa-Feliciano, E.; Fritts, M.; Gerbier, G.; Germond, R.; Ghaith, M.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hong, Z.; Hoppe, E. W.; Hsu, L.; Huber, M. E.; Iyer, V.; Jardin, D.; Jastram, A.; Jena, C.; Kelsey, M. H.; Kennedy, A.; Kubik, A.; Kurinsky, N. A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; MacDonell, D.; Mahapatra, R.; Mandic, V.; Mast, N.; Miller, E. H.; Mirabolfathi, N.; Mohanty, B.; Morales Mendoza, J. D.; Nelson, J.; Orrell, J. L.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Penalver Martinez, M.; Pepin, M.; Phipps, A.; Poudel, S.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Reynolds, T.; Roberts, A.; Robinson, A. E.; Rogers, H. E.; Saab, T.; Sadoulet, B.; Sander, J.; Schneck, K.; Schnee, R. W.; Scorza, S.; Senapati, K.; Serfass, B.; Speller, D.; Stein, M.; Street, J.; Tanaka, H. A.; Toback, D.; Underwood, R.; Villano, A. N.; von Krosigk, B.; Welliver, B.; Wilson, J. S.; Wilson, M. J.; Wright, D. H.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, X.; Zhao, X.

    2018-02-01

    We report the result of a blinded search for Weakly Interacting Massive Particles (WIMPs) using the full SuperCDMS Soudan dataset. With an exposure of 1690 kg days, a single event was observed after unblinding, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP-nucleon cross section of 1.4x10^-44 (1.0x10^-44) cm^2 at 46 GeV/c^2 . These results set the strongest limits for WIMP-germanium-nucleus interactions for masses >12 GeV/c^2.

  12. Conceptual Design for SuperCDMS SNOLAB

    International Nuclear Information System (INIS)

    Brink, Paul

    2012-01-01

    Beyond the present dark matter direct detection experiment at the Soudan underground laboratory, the SuperCDMS Collaboration is engaged in R and D activities for a 100-kg scale germanium dark matter experiment nominally sited at SNOLAB (2070 m overburden of rock). The expected sensitivity after 3 years of running is 3 x 10 -46 cm 2 for the spin-independent cross section, an order of magnitude improvement over present exclusion limits for WIMP masses ∼80 GeV/c 2 . At this depth, and appropriate design of shielding and cryostat, neutron backgrounds will be negligible. The baseline design is an expanded version of CDMS II with Ge substrates (100 x 33 mm discs) instrumented with the iZIP phonon sensor layout to achieve the electron surface-event rejection power required.

  13. Low-Mass Dark Matter Search Results and Radiogenic Backgrounds for the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Pepin, Mark David [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-12-01

    An ever-increasing amount of evidence suggests that approximately one quarter of the energy in the universe is composed of some non-luminous, and hitherto unknown, “dark matter”. Physicists from numerous sub-fields have been working on and trying to solve the dark matter problem for decades. The common solution is the existence of some new type of elementary particle with particular focus on weakly interacting massive particles (WIMPs). One avenue of dark matter research is to create an extremely sensitive particle detector with the goal of directly observing the interaction of WIMPs with standard matter. The Cryogenic Dark Matter Search (CDMS) project operated at the Soudan Underground Laboratory from 2003–2015, under the CDMS II and SuperCDMS Soudan experiments, with this goal of directly detecting dark matter. The next installation, SuperCDMS SNOLAB, is planned for near-future operation. The reason the dark-matter particle has not yet been observed in traditional particle physics experiments is that it must have very small cross sections, thus making such interactions extremely rare. In order to identify these rare events in the presence of a background of known particles and interactions, direct detection experiments employ various types and amounts of shielding to prevent known backgrounds from reaching the instrumented detector(s). CDMS utilized various gamma and neutron shielding to such an effect that the shielding, and other experimental components, themselves were sources of background. These radiogenic backgrounds must be understood to have confidence in any WIMP-search result. For this dissertation, radiogenic background studies and estimates were performed for various analyses covering CDMS II, SuperCDMS Soudan, and SuperCDMS SNOLAB. Lower-mass dark matter t c2 inent in the past few years. The CDMS detectors can be operated in an alternative, higher-biased, mode v to decrease their energy thresholds and correspondingly increase their sensitivity

  14. SuperCDMS Underground Detector Fabrication Facility

    Energy Technology Data Exchange (ETDEWEB)

    Platt, M.; Mahapatra, R.; Bunker, Raymond A.; Orrell, John L.

    2018-03-01

    The SuperCDMS SNOLAB dark matter experiment processes Ge and Si crystals into fully tested phonon and ionization detectors at surface fabrication and test facilities. If not mitigated, it is anticipated that trace-level production of radioisotopes in the crystals due to exposure to cosmic rays at (or above) sea level will result in the dominant source of background events in future dark matter searches using the current SuperCDMS detector technology. Fabrication and testing of detectors in underground facilities shielded from cosmic radiation is one way to directly reduce production of trace levels of radioisotopes, thereby improving experimental sensitivity for the discovery of dark matter beyond the level of the current experiment. In this report, we investigate the cost and feasibility to establish a complete detector fabrication processing chain in an underground location to mitigate cosmogenic activation of the Ge and Si detector substrates. For a specific and concrete evaluation, we explore options for such a facility located at SNOLAB, an underground laboratory in Sudbury, Canada hosting the current and future experimental phases of SuperCDMS.

  15. A Search for WIMP Dark Matter Using an Optimized Chi-square Technique on the Final Data from the Cryogenic Dark Matter Search Experiment (CDMS II)

    Energy Technology Data Exchange (ETDEWEB)

    Manungu Kiveni, Joseph [Syracuse Univ., NY (United States)

    2012-12-01

    This dissertation describes the results of a WIMP search using CDMS II data sets accumulated at the Soudan Underground Laboratory in Minnesota. Results from the original analysis of these data were published in 2009; two events were observed in the signal region with an expected leakage of 0.9 events. Further investigation revealed an issue with the ionization-pulse reconstruction algorithm leading to a software upgrade and a subsequent reanalysis of the data. As part of the reanalysis, I performed an advanced discrimination technique to better distinguish (potential) signal events from backgrounds using a 5-dimensional chi-square method. This dataanalysis technique combines the event information recorded for each WIMP-search event to derive a backgrounddiscrimination parameter capable of reducing the expected background to less than one event, while maintaining high efficiency for signal events. Furthermore, optimizing the cut positions of this 5-dimensional chi-square parameter for the 14 viable germanium detectors yields an improved expected sensitivity to WIMP interactions relative to previous CDMS results. This dissertation describes my improved (and optimized) discrimination technique and the results obtained from a blind application to the reanalyzed CDMS II WIMP-search data.

  16. WIMP dark matter candidates and searches-current status and future prospects.

    Science.gov (United States)

    Roszkowski, Leszek; Sessolo, Enrico Maria; Trojanowski, Sebastian

    2018-06-01

    We review several current aspects of dark matter theory and experiment. We overview the present experimental status, which includes current bounds and recent claims and hints of a possible signal in a wide range of experiments: direct detection in underground laboratories, gamma-ray, cosmic ray, x-ray, neutrino telescopes, and the LHC. We briefly review several possible particle candidates for a weakly interactive massive particle (WIMP) and dark matter that have recently been considered in the literature. We pay particular attention to the lightest neutralino of supersymmetry as it remains the best motivated candidate for dark matter and also shows excellent detection prospects. Finally we briefly review some alternative scenarios that can considerably alter properties and prospects for the detection of dark matter obtained within the standard thermal WIMP paradigm.

  17. First 5 tower WIMP-search results from the Cryogenic Dark Matter Search with improved understanding of neutron backgrounds and benchmarking

    Energy Technology Data Exchange (ETDEWEB)

    Hennings-Yeomans, Raul [Case Western Reserve Univ., Cleveland, OH (United States)

    2009-02-01

    Non-baryonic dark matter makes one quarter of the energy density of the Universe and is concentrated in the halos of galaxies, including the Milky Way. The Weakly Interacting Massive Particle (WIMP) is a dark matter candidate with a scattering cross section with an atomic nucleus of the order of the weak interaction and a mass comparable to that of an atomic nucleus. The Cryogenic Dark Matter Search (CDMS-II) experiment, using Ge and Si cryogenic particle detectors at the Soudan Underground Laboratory, aims to directly detect nuclear recoils from WIMP interactions. This thesis presents the first 5 tower WIMP-search results from CDMS-II, an estimate of the cosmogenic neutron backgrounds expected at the Soudan Underground Laboratory, and a proposal for a new measurement of high-energy neutrons underground to benchmark the Monte Carlo simulations. Based on the non-observation of WIMPs and using standard assumptions about the galactic halo [68], the 90% C.L. upper limit of the spin-independent WIMPnucleon cross section for the first 5 tower run is 6.6 × 10-44cm2 for a 60 GeV/c2 WIMP mass. A combined limit using all the data taken at Soudan results in an upper limit of 4.6×10-44cm2 at 90% C.L.for a 60 GeV/c2 WIMP mass. This new limit corresponds to a factor of ~3 improvement over any previous CDMS-II limit and a factor of ~2 above 60 GeV/c 2 better than any other WIMP search to date. This thesis presents an estimation, based on Monte Carlo simulations, of the nuclear recoils produced by cosmic-ray muons and their secondaries (at the Soudan site) for a 5 tower Ge and Si configuration as well as for a 7 supertower array. The results of the Monte Carlo are that CDMS-II should expect 0.06 ± 0.02+0.18 -0.02 /kgyear unvetoed single nuclear recoils in Ge for the 5 tower configuration, and 0.05 ± 0.01+0.15 -0.02 /kg-year for the 7 supertower configuration. The systematic error is based on the available

  18. Prospects for SIMPLE 2000: a large-mass, low-background superheated droplet detector for WIMP searches

    International Nuclear Information System (INIS)

    Collar, J.I.; Girard, T.A.; Miley, H.S.; Waysand, G.

    2000-01-01

    The Superheated Instrument for Massive Particle searches (SIMPLE 2000) will consist of an array of 8-16 large active mass (approx. 15 g) superheated droplet detectors (SDDs) to be installed in the new underground laboratory of Rustrel-Pays d'Apt. Several factors make the use of SDDs an attractive approach for the detection of weakly interacting massive particles (WIMPs), namely their intrinsic insensitivity to minimally ionizing particles, high fluorine content, low cost and operation at near ambient pressure and temperature. We comment here on the fabrication, calibration and already-competitive first limits from prototype SDDs for SIMPLE, as well as on the expected immediate increase in sensitivity of the programme, which aims at an exposure of > 25 kg day during 2000. The ability of modest-mass fluorine-rich detectors to investigate regions of neutralino parameter space beyond the reach of the most ambitious cryogenic projects is pointed out. (author)

  19. Prospects for SIMPLE 2000: a large-mass, low-background superheated droplet detector for WIMP searches

    International Nuclear Information System (INIS)

    Collar, J I; Puibasset, J; Girard, T A; Limagne, D; Miley, H S; Waysand, G

    2000-01-01

    The Superheated Instrument for Massive Particle searches (SIMPLE 2000) will consist of an array of 8-16 large active mass (≅15 g) superheated droplet detectors (SDDs) to be installed in the new underground laboratory of Rustrel-Pays d'Apt. Several factors make the use of SDDs an attractive approach for the detection of weakly interacting massive particles (WIMPs), namely their intrinsic insensitivity to minimally ionizing particles, high fluorine content, low cost and operation at near ambient pressure and temperature. We comment here on the fabrication, calibration and already-competitive first limits from prototype SDDs for SIMPLE, as well as on the expected immediate increase in sensitivity of the programme, which aims at an exposure of > 25 kg day during 2000. The ability of modest-mass fluorine-rich detectors to investigate regions of neutralino parameter space beyond the reach of the most ambitious cryogenic projects is pointed out

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

    International Nuclear Information System (INIS)

    Akerib, D.S.; Bailey, C.N.; Dragowsky, M.R.; Driscoll, D.D.; Hennings-Yeomans, R.; Kamat, S.; Perera, T.A.; Schnee, R.W.; Wang, G.; Armel-Funkhouser, M.S.; Daal, M.; Filippini, J.; Lu, A.; Mandic, V.; Meunier, P.; Mirabolfathi, N.; Issac, M.C. Perillo; Rau, W.; Seitz, D.N.; Serfass, B.

    2005-01-01

    The Cryogenic Dark Matter Search (CDMS-II) employs low-temperature Ge and Si detectors to seek weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei. Simultaneous measurements of both ionization and phonon energy provide discrimination against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with >99.99% efficiency. Electromagnetic events very near the detector surface can mimic nuclear recoils because of reduced charge collection, but these surface events are rejected with >96% efficiency by using additional information from the phonon pulse shape. Efficient use of active and passive shielding, combined with the 2090 m.w.e. overburden at the experimental site in the Soudan mine, makes the background from neutrons negligible for this first exposure. All cuts are determined in a blind manner from in situ calibrations with external radioactive sources without any prior knowledge of the event distribution in the signal region. Resulting efficiencies are known to ∼10%. A single event with a recoil of 64 keV passes all of the cuts and is consistent with the expected misidentification rate of surface electron recoils. Under the assumptions for a standard dark matter halo, these data exclude previously unexplored parameter space for both spin-independent and spin-dependent WIMP-nucleon elastic scattering. The resulting limit on the spin-independent WIMP-nucleon elastic-scattering cross section has a minimum of 4x10 -43 cm 2 at a WIMP mass of 60 GeVc -2 . The minimum of the limit for the spin-dependent WIMP-neutron elastic-scattering cross section is 2x10 -37 cm 2 at a WIMP mass of 50 GeVc -2

  1. From superWIMPs to decaying dark matter. Models, bounds and indirect searches

    Energy Technology Data Exchange (ETDEWEB)

    Weniger, Christoph

    2010-06-15

    Despite lots of observational and theoretical efforts, the particle nature of dark matter remains unknown. Beyond the paradigmatic WIMPs (Weakly Interacting Massive Particles), many theoretically well motivated models exist where dark matter interacts much more weakly than electroweak with Standard Model particles. In this case new phenomena occur, like the decay of dark matter or the interference with the standard cosmology of the early Universe. In this thesis we study some of these aspects of superweakly coupled dark matter in general, and in the special case of hidden U(1){sub X} gauginos that kinetically mix with hypercharge. There, we will assume that the gauge group remains unbroken, similar to the Standard Model U(1){sub em}. We study different kinds of cosmological bounds, including bounds from thermal overproduction, from primordial nucleosynthesis and from structure formation. Furthermore, we study the possible cosmic-ray signatures predicted by this scenario, with emphasis on the electron and positron channel in light of the recent observations by PAMELA and Fermi LAT. Moreover we study the cosmic-ray signatures of decaying dark matter independently of concrete particle-physics models. In particular we analyze in how far the rise in the positron fraction above 10 GeV, as observed by PAMELA, can be explained by dark matter decay. Lastly, we concentrate on related predictions for gamma-ray observations with the Fermi LAT, and propose to use the dipole-like anisotropy of the prompt gamma-ray dark matter signal to distinguish exotic dark matter contributions from the extragalactic gamma-ray background. (orig.)

  2. From superWIMPs to decaying dark matter. Models, bounds and indirect searches

    International Nuclear Information System (INIS)

    Weniger, Christoph

    2010-06-01

    Despite lots of observational and theoretical efforts, the particle nature of dark matter remains unknown. Beyond the paradigmatic WIMPs (Weakly Interacting Massive Particles), many theoretically well motivated models exist where dark matter interacts much more weakly than electroweak with Standard Model particles. In this case new phenomena occur, like the decay of dark matter or the interference with the standard cosmology of the early Universe. In this thesis we study some of these aspects of superweakly coupled dark matter in general, and in the special case of hidden U(1) X gauginos that kinetically mix with hypercharge. There, we will assume that the gauge group remains unbroken, similar to the Standard Model U(1) em . We study different kinds of cosmological bounds, including bounds from thermal overproduction, from primordial nucleosynthesis and from structure formation. Furthermore, we study the possible cosmic-ray signatures predicted by this scenario, with emphasis on the electron and positron channel in light of the recent observations by PAMELA and Fermi LAT. Moreover we study the cosmic-ray signatures of decaying dark matter independently of concrete particle-physics models. In particular we analyze in how far the rise in the positron fraction above 10 GeV, as observed by PAMELA, can be explained by dark matter decay. Lastly, we concentrate on related predictions for gamma-ray observations with the Fermi LAT, and propose to use the dipole-like anisotropy of the prompt gamma-ray dark matter signal to distinguish exotic dark matter contributions from the extragalactic gamma-ray background. (orig.)

  3. Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes

    International Nuclear Information System (INIS)

    Armengaud, E.; Augier, C.; Benoit, A.; Berge, L.; Bluemer, J.; Broniatowski, A.; Brudanin, V.; Censier, B.; Chardin, G.; Chapellier, M.; Charlieux, F.; Coulter, P.; Cox, G.A.; Defay, X.; De Jesus, M.; Dolgorouki, Y.; Domange, J.; Dumoulin, L.

    2011-01-01

    The EDELWEISS-II Collaboration has completed a direct search for WIMP dark matter with an array of ten 400-g cryogenic germanium detectors in operation at the Laboratoire Souterrain de Modane. The combined use of thermal phonon sensors and charge collection electrodes with an interleaved geometry enables the efficient rejection of γ-induced radioactivity as well as near-surface interactions. A total effective exposure of 384 kg d has been achieved, mostly coming from fourteen months of continuous operation. Five nuclear recoil candidates are observed above 20 keV, while the estimated background is 3.0 events. The result is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 4.4x10 -8 pb is excluded at 90%CL for a WIMP mass of 85 GeV. New constraints are also set on models where the WIMP-nucleon scattering is inelastic.

  4. Prospects for SIMPLE 2000 A large-mass, low-background Superheated Droplet Detector for WIMP searches

    CERN Document Server

    Collar, J I; Girard, T A; Limagne, D; Miley, H S; Waysand, G

    2000-01-01

    SIMPLE 2000 ({\\underline S}uperheated {\\underline I}nstrument for {\\underline M}assive {\\underline P}artic{\\underline {LE}} searches) will consist of an array of eight to sixteen large active mass ($\\sim15$ g) Superheated Droplet Detectors(SDDs) to be installed in the new underground laboratory of Rustrel-Pays d'Apt. Several factors make of SDDs an attractive approach for the detection of Weakly Interacting Massive Particles (WIMPs), namely their intrinsic insensitivity to minimum ionizing particles, high fluorine content, low cost and operation near ambient pressure and temperature. We comment here on the fabrication, calibration and already-competitive first limits from SIMPLE prototype SDDs, as well as on the expected immediate increase in sensitivity of the program, which aims at an exposure of $>$25 kg-day during the year 2000. The ability of modest-mass fluorine-rich detectors to explore regions of neutralino parameter space beyond the reach of the most ambitious cryogenic projects is pointed out.

  5. Exotic particles at the LHC. Production via the Higgs portal and WIMP dark matter searches

    Energy Technology Data Exchange (ETDEWEB)

    Hessler, Andre Georg

    2016-09-05

    This thesis addresses two different aspects of the search for Physics Beyond the Standard Model at the Large Hadron Collider (LHC). First, and motivated by the recent discovery of a new interaction mediated by the Higgs boson, we systematically analyze the impact of the Higgs interaction on the production of new particles at the LHC. Second, we investigate the collider signatures of long-lived particles decaying into leptons and invisible energy, and which are predicted to exist in a class of neutrino mass models with a weakly interacting dark matter particle.

  6. 6th Patras workshop on axions, WIMPs and WISPs (PATRAS 2010). Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Baudis, Laura; Schumann, Marc (eds.)

    2010-11-15

    The following topics were dealt with: Axions, WIMPs, WISPs, and neutrinos in the universe, laboratory experimental searching for WISPs, astrophysical experimental searching for WISPs, direct and indirect detection of WIMPs, new ideas and developments, visions, large laboratories. (HSI)

  7. 6th Patras workshop on axions, WIMPs and WISPs (PATRAS 2010). Proceedings

    International Nuclear Information System (INIS)

    Baudis, Laura; Schumann, Marc

    2010-11-01

    The following topics were dealt with: Axions, WIMPs, WISPs, and neutrinos in the universe, laboratory experimental searching for WISPs, astrophysical experimental searching for WISPs, direct and indirect detection of WIMPs, new ideas and developments, visions, large laboratories. (HSI)

  8. Low-mass dark matter search with CDMSlite

    Energy Technology Data Exchange (ETDEWEB)

    Agnese, R.; Anderson, A. J.; Aralis, T.; Aramaki, T.; Arnquist, I. J.; Baker, W.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Binder, T.; Bowles, M. A.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Calkins, R.; Cartaro, C.; Cerdeño, D. G.; Chang, Y.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fascione, E.; Figueroa-Feliciano, E.; Fritts, M.; Gerbier, G.; Ghaith, M.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hong, Z.; Hoppe, E. W.; Hsu, L.; Huber, M. E.; Iyer, V.; Jardin, D.; Jastram, A.; Jena, C.; Kelsey, M. H.; Kennedy, A.; Kubik, A.; Kurinsky, N. A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; MacDonell, D.; Mahapatra, R.; Mandic, V.; Mast, N.; Miller, E. H.; Mirabolfathi, N.; Moffatt, R. A.; Mohanty, B.; Morales Mendoza, J. D.; Nelson, J.; Orrell, J. L.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Peñalver Martinez, M.; Phipps, A.; Poudel, S.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Reynolds, T.; Roberts, A.; Robinson, A. E.; Rogers, H. E.; Saab, T.; Sadoulet, B.; Sander, J.; Schneck, K.; Schnee, R. W.; Scorza, S.; Senapati, K.; Serfass, B.; Speller, D.; Stein, M.; Street, J.; Tanaka, H. A.; Toback, D.; Underwood, R.; Villano, A. N.; von Krosigk, B.; Welliver, B.; Wilson, J. S.; Wilson, M. J.; Wright, D. H.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, X.; Zhao, X.

    2018-01-01

    The SuperCDMS experiment is designed to directly detect WIMPs (Weakly Interacting Massive Particles) that may constitute the dark matter in our galaxy. During its operation at the Soudan Underground Laboratory, germanium detectors were run in the CDMSlite (Cryogenic Dark Matter Search low ionization threshold experiment) mode to gather data sets with sensitivity specifically for WIMPs with masses ${<}10$ GeV/$c^2$. In this mode, a large detector-bias voltage is applied to amplify the phonon signals produced by drifting charges. This paper presents studies of the experimental noise and its effect on the achievable energy threshold, which is demonstrated to be as low as 56 eV$_{\\text{ee}}$ (electron equivalent energy). The detector biasing configuration is described in detail, with analysis corrections for voltage variations to the level of a few percent. Detailed studies of the electric-field geometry, and the resulting successful development of a fiducial parameter, eliminate poorly measured events, yielding an energy resolution ranging from ${\\sim}$9 eV$_{\\text{ee}}$ at 0 keV to 101 eV$_{\\text{ee}}$ at ${\\sim}$10 keV$_{\\text{ee}}$. New results are derived for astrophysical uncertainties relevant to the WIMP-search limits, specifically examining how they are affected by variations in the most probable WIMP velocity and the galactic escape velocity. These variations become more important for WIMP masses below 10 GeV/$c^2$. Finally, new limits on spin-dependent low-mass WIMP-nucleon interactions are derived, with new parameter space excluded for WIMP masses ${\\lesssim}$3 GeV/$c^2$.

  9. Proceedings of the 4th Patras workshop on axions, WIMPs and WISPs

    Energy Technology Data Exchange (ETDEWEB)

    Lindner, Axel; Redondo, Javier; Ringwald, Andreas [eds.

    2008-08-15

    The following topics were dealt with: Physical foundations for WIMPs, axions, and WISPS, signals from astrophysical sources, direct searches for dark matter WIMPs, new theoretical developments, new experimental approaches. (HSI)

  10. Proceedings of the 4th Patras workshop on axions, WIMPs and WISPs

    International Nuclear Information System (INIS)

    Lindner, Axel; Redondo, Javier; Ringwald, Andreas

    2008-08-01

    The following topics were dealt with: Physical foundations for WIMPs, axions, and WISPS, signals from astrophysical sources, direct searches for dark matter WIMPs, new theoretical developments, new experimental approaches. (HSI)

  11. Working Group Report: WIMP Dark Matter Direct Detection

    International Nuclear Information System (INIS)

    Cushman, P.; Galbiati, C.; McKinsey, D. N.; Robertson, H.; Tait, T. M.P.

    2013-01-01

    As part of the Snowmass process, the Cosmic Frontier WIMP Direct Detection subgroup (CF1) has drawn on input from the Cosmic Frontier and the broader Particle Physics community to produce this document. The charge to CF1 was (a) to summarize the current status and projected sensitivity of WIMP direct detection experiments worldwide, (b) motivate WIMP dark matter searches over a broad parameter space by examining a spectrum of WIMP models, (c) establish a community consensus on the type of experimental program required to explore that parameter space, and (d) identify the common infrastructure required to practically meet those goals.

  12. Working Group Report: WIMP Dark Matter Direct Detection

    Energy Technology Data Exchange (ETDEWEB)

    Cushman, P.; Galbiati, C.; McKinsey, D. N.; Robertson, H.; Tait, T. M.P.

    2013-10-30

    As part of the Snowmass process, the Cosmic Frontier WIMP Direct Detection subgroup (CF1) has drawn on input from the Cosmic Frontier and the broader Particle Physics community to produce this document. The charge to CF1 was (a) to summarize the current status and projected sensitivity of WIMP direct detection experiments worldwide, (b) motivate WIMP dark matter searches over a broad parameter space by examining a spectrum of WIMP models, (c) establish a community consensus on the type of experimental program required to explore that parameter space, and (d) identify the common infrastructure required to practically meet those goals.

  13. 5th Patras workshop on axions, WIMPs and WISPs (PATRAS 2009). Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Jaeckel, Joerg; Lindner, Axel; Redondo, Javier [eds.

    2010-06-15

    The following topics were dealt with: Direct searches for dark matter, indirect searches for WIMPS, photon generation and laser polarization experiments, direct axion signals, theoretic WISP developments. (HSI)

  14. 5th Patras workshop on axions, WIMPs and WISPs (PATRAS 2009). Proceedings

    International Nuclear Information System (INIS)

    Jaeckel, Joerg; Lindner, Axel; Redondo, Javier

    2010-06-01

    The following topics were dealt with: Direct searches for dark matter, indirect searches for WIMPS, photon generation and laser polarization experiments, direct axion signals, theoretic WISP developments. (HSI)

  15. Wimps and stellar structure

    International Nuclear Information System (INIS)

    Bouquet, A.; Salati, P.

    1988-01-01

    We present the results of an analytic approximation to compute the effects of WIMPs on stellar structures in a self-consistent way. We examine in particular the case of the Sun and of horizontal branch stars

  16. Search of low-mass WIMPs with a p -type point contact germanium detector in the CDEX-1 experiment

    Science.gov (United States)

    Zhao, W.; Yue, Q.; Kang, K. J.; Cheng, J. P.; Li, Y. J.; Wong, H. T.; Lin, S. T.; Chang, J. P.; Chen, J. H.; Chen, Q. H.; Chen, Y. H.; Deng, Z.; Du, Q.; Gong, H.; Hao, X. Q.; He, H. J.; He, Q. J.; Huang, H. X.; Huang, T. R.; Jiang, H.; Li, H. B.; Li, J.; Li, J.; Li, J. M.; Li, X.; Li, X. Y.; Li, Y. L.; Lin, F. K.; Liu, S. K.; Lü, L. C.; Ma, H.; Ma, J. L.; Mao, S. J.; Qin, J. Q.; Ren, J.; Ren, J.; Ruan, X. C.; Sharma, V.; Shen, M. B.; Singh, L.; Singh, M. K.; Soma, A. K.; Su, J.; Tang, C. J.; Wang, J. M.; Wang, L.; Wang, Q.; Wu, S. Y.; Wu, Y. C.; Xianyu, Z. Z.; Xiao, R. Q.; Xing, H. Y.; Xu, F. Z.; Xu, Y.; Xu, X. J.; Xue, T.; Yang, L. T.; Yang, S. W.; Yi, N.; Yu, C. X.; Yu, H.; Yu, X. Z.; Zeng, M.; Zeng, X. H.; Zeng, Z.; Zhang, L.; Zhang, Y. H.; Zhao, M. G.; Zhou, Z. Y.; Zhu, J. J.; Zhu, W. B.; Zhu, X. Z.; Zhu, Z. H.; CDEX Collaboration

    2016-05-01

    The CDEX-1 experiment conducted a search of low-mass (events is observed after the subtraction of the known background. Using 335.6 kg-days of data, exclusion constraints on the weakly interacting massive particle-nucleon spin-independent and spin-dependent couplings are derived.

  17. Science plumbs new depths in hunt for Wimps

    CERN Multimedia

    Benfield, C

    2003-01-01

    Lord Sainsbury has officially opened a laboratory in the salt mine at Boulby near Whitby. The lab is searching for WIMPs and was recently awarded 3.1 millions pounds by PPARC to upgrade the facility (1 page).

  18. Development of low background CsI(Tl) and NaI(Tl) crystals for WIMP search

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Su [Department of Physics, Ewha Womans University, Seoul 120-750 (Korea, Republic of)

    2015-08-17

    We have developed low background CsI(Tl) and NaI(Tl) crystals to search for weakly interacting massive particles as well as to verify the origin of the annual modulation signal observed by the DAMA/LIBRA experiment. Extensive studies about the contamination mechanisim of {sup 137}Cs in CsI powder lead to the growth of ultra-low-background CsI(Tl) crystals. Similar approaches for NaI(Tl) crystals have been applied to reduce internal backgrounds to less than 0.5 counts/kg/day/keV. Status and understanding of backgrounds and background reduction in NaI(Tl) crystals will be discussed.

  19. To catch a WIMP

    International Nuclear Information System (INIS)

    Goldsmith, Donald.

    1995-01-01

    In the rush to account for the missing ''dark matter'' in the universe, many teams of cosmologists are setting up experiments to prove the existence of a hypothetical form of matter called weakly interacting massive particles, or WIMPS. The innovative research ideas developed by these teams are described and compared briefly. (UK)

  20. The WIMP Paradigm: Current Status

    International Nuclear Information System (INIS)

    Feng, Jonathan

    2011-01-01

    The WIMP paradigm is the glue that joins together much of the high energy and cosmic frontiers. It postulates that most of the matter in the Universe is made of weakly-interacting massive particles, with implications for a broad range of experiments and observations. I will review the WIMP paradigm's underlying motivations, its current status in view of rapid experimental progress on several fronts, and recent theoretical variations on the WIMP paradigm theme.

  1. Projected sensitivity of the SuperCDMS SNOLAB experiment

    Energy Technology Data Exchange (ETDEWEB)

    Agnese, R.; Anderson, A. J.; Aramaki, T.; Arnquist, I.; Baker, W.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Borgland, A.; Bowles, M. A.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Calkins, R.; Cartaro, C.; Cerdeño, D. G.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Fritts, M.; Gerbier, G.; Ghaith, M.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hong, Z.; Hoppe, E.; Hsu, L.; Huber, M. E.; Iyer, V.; Jardin, D.; Jastram, A.; Kelsey, M. H.; Kennedy, A.; Kubik, A.; Kurinsky, N. A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; Mandic, V.; Mast, N.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Orrell, J. L.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Poudel, S.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Roberts, A.; Robinson, A. E.; Rogers, H. E.; Saab, T.; Sadoulet, B.; Sander, J.; Schneck, K.; Schnee, R. W.; Serfass, B.; Speller, D.; Stein, M.; Street, J.; Tanaka, H. A.; Toback, D.; Underwood, R.; Villano, A. N.; von Krosigk, B.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, X.; Zhao, X.

    2017-04-07

    SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass (< 10 GeV/c$^2$) particles that may constitute dark matter by using cryogenic detectors of two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~ 1 x 10$^{-43}$ cm$^2$ for a dark matter particle mass of 1 GeV/c$^2$, and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark matter. A detailed calibration of the detector response to low energy recoils will be needed to optimize running conditions of the HV detectors and to interpret their data for dark matter searches. Low-activity shielding, and the depth of SNOLAB, will reduce most backgrounds, but cosmogenically produced $^{3}$H and naturally occurring $^{32}$Si will be present in the detectors at some level. Even if these backgrounds are x10 higher than expected, the science reach of the HV detectors would be over three orders of magnitude beyond current results for a dark matter mass of 1 GeV/c$^2$. The iZIP detectors are relatively insensitive to variations in detector response and backgrounds, and will provide better sensitivity for dark matter particle masses (> 5 GeV/c$^2$). The mix of detector types (HV and iZIP), and targets (germanium and silicon), planned for the experiment, as well as flexibility in how the detectors are operated, will allow us to maximize the low-mass reach, and understand the backgrounds that the experiment will encounter. Upgrades to the experiment, perhaps with a variety of ultra-low-background cryogenic detectors, will extend dark matter sensitivity down to the "neutrino floor", where coherent scatters of solar neutrinos become a limiting background.

  2. Understanding WIMP-baryon interactions with direct detection: a roadmap

    International Nuclear Information System (INIS)

    Gluscevic, Vera; Peter, Annika H.G.

    2014-01-01

    We study prospects of dark-matter direct-detection searches for probing non-relativistic effective theory for WIMP-baryon scattering. We simulate a large set of noisy recoil-energy spectra for different scattering scenarios (beyond the standard momentum-independent contact interaction), for Generation 2 and futuristic experiments. We analyze these simulations and quantify the probability of successfully identifying the operator governing the scattering, if a WIMP signal is observed. We find that the success rate depends on a combination of factors: the WIMP mass, the mediator mass, the type of interaction, and the experimental energy window. For example, for a 20 GeV WIMP, Generation 2 is only likely to identify the right operator if the interaction is Coulomb-like, and is unlikely to do so in any other case. For a WIMP with a mass of 200 GeV or higher, success is almost guaranteed. We also find that, regardless of the scattering model and the WIMP parameters, a single Generation 2 experiment is unlikely to successfully discern the momentum dependence of the underlying operator on its own, but prospects improve drastically when experiments with different target materials and energy windows are analyzed jointly. Furthermore, we examine the quality of parameter estimation and degeneracies in the multi-dimensional parameter space of the effective theory. We find in particular that the resulting WIMP mass estimates can be severely biased if data are analyzed assuming the standard (momentum-independent) operator while the actual operator has momentum-dependence. Finally, we evaluate the ultimate reach of direct detection, finding that the prospects for successful operator selection prior to reaching the irreducible backgrounds are excellent, if the signal is just below the current limits, but slim if Generation 2 does not report WIMP detection

  3. The Fraternal WIMP Miracle

    CERN Document Server

    Craig, Nathaniel

    2015-01-01

    We identify and analyze thermal dark matter candidates in the fraternal twin Higgs model and its generalizations. The relic abundance of fraternal twin dark matter is set by twin weak interactions, with a scale tightly tied to the weak scale of the Standard Model by naturalness considerations. As such, the dark matter candidates benefit from a "fraternal WIMP miracle," reproducing the observed dark matter abundance for dark matter masses between 50 and 150 GeV. However, the couplings dominantly responsible for dark matter annihilation do not lead to interactions with the visible sector. The direct detection rate is instead set via fermionic Higgs portal interactions, which are likewise constrained by naturalness considerations but parametrically weaker than those leading to dark matter annihilation. The predicted direct detection cross section is close to current LUX bounds and presents an opportunity for the next generation of direct detection experiments.

  4. Background Characterization and Discrimination in the Final Analysis of the CDMS II Phase of the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Fritts, Matthew C. [Univ. of Minnesota, Minneapolis, MN (United States)

    2011-02-01

    The Cryogenic Dark Matter Search (CDMS) is designed to detectWeakly-Interacting Massive Particles (WIMPs) in the Milky Way halo. The phase known as CDMS II was performed in the Soudan Underground Laboratory. The final set of CDMS II data, collected in 2007-8 and referred to as Runs 125-8, represents the largest exposure to date for the experiment. We seek collisions between WIMPs and atomic nuclei in disk-shaped germanium and silicon detectors. A key design feature is to keep the rate of collisions from known particles producing WIMP-like signals very small. The largest category of such background is interactions with electrons in the detectors that occur very close to one of the faces of the detector. The next largest category is collisions between energetic neutrons that bypass the experimental shielding and nuclei in the detectors. Analytical efforts to discriminate these backgrounds and to estimate the rate at which such discrimination fails have been refined and improved throughout each phase of CDMS. Next-generation detectors for future phases of CDMS require testing at cryogenic test facilities. One such facility was developed at the University of Minnesota in 2007 and has been used continuously since then to test detectors for the next phase of the experiment, known as SuperCDMS.

  5. Projected sensitivity of the SuperCDMS SNOLAB experiment

    Energy Technology Data Exchange (ETDEWEB)

    Agnese, R.; Anderson, A. J.; Aramaki, T.; Arnquist, I.; Baker, W.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Borgland, A.; Bowles, M. A.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Calkins, R.; Cartaro, C.; Cerdeño, D. G.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Fritts, M.; Gerbier, G.; Ghaith, M.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hong, Z.; Hoppe, E.; Hsu, L.; Huber, M. E.; Iyer, V.; Jardin, D.; Jastram, A.; Kelsey, M. H.; Kennedy, A.; Kubik, A.; Kurinsky, N. A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; Mandic, V.; Mast, N.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Orrell, J. L.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Poudel, S.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Roberts, A.; Robinson, A. E.; Rogers, H. E.; Saab, T.; Sadoulet, B.; Sander, J.; Schneck, K.; Schnee, R. W.; Serfass, B.; Speller, D.; Stein, M.; Street, J.; Tanaka, H. A.; Toback, D.; Underwood, R.; Villano, A. N.; von Krosigk, B.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, X.; Zhao, X.

    2017-04-01

    SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass particles (with masses ≤ 10 GeV/c^2) that may constitute dark matter by using cryogenic detectors of two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~1×10^-43 cm^2 for a dark matter particle mass of 1 GeV/c^2, and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark matter. A detailed calibration of the detector response to low-energy recoils will be needed to optimize running conditions of the HV detectors and to interpret their data for dark matter searches. Low-activity shielding, and the depth of SNOLAB, will reduce most backgrounds, but cosmogenically produced H-3 and naturally occurring Si-32 will be present in the detectors at some level. Even if these backgrounds are 10 times higher than expected, the science reach of the HV detectors would be over 3 orders of magnitude beyond current results for a dark matter mass of 1 GeV/c^2. The iZIP detectors are relatively insensitive to variations in detector response and backgrounds, and will provide better sensitivity for dark matter particles with masses ≳5 GeV/c^2. The mix of detector types (HV and iZIP), and targets (germanium and silicon), planned for the experiment, as well as flexibility in how the detectors are operated, will allow us to maximize the low-mass reach, and understand the backgrounds that the experiment will encounter. Upgrades to the experiment, perhaps with a variety of ultra-low-background cryogenic detectors, will extend dark matter sensitivity down to the “neutrino floor,” where coherent scatters of solar neutrinos become a limiting background.

  6. The Cryogenic Dark Matter Search: First 5-Tower Data and Improved Understanding of Ionization Collection

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Catherine N. [Case Western Reserve Univ., Cleveland, OH (United States)

    2010-01-01

    The Cryogenic Dark Matter Search (CDMS) is searching for Weakly Interacting Massive Particles (WIMPs) with cryogenic particle detectors. These detectors have the ability to discriminate between nuclear recoil candidate and electron recoil background events by collecting both phonon and ionization energy from recoils in the detector crystals. The CDMS-II experiment has completed analysis of the first data runs with 30 semiconductor detectors at the Soudan Underground Laboratory, resulting in a world leading WIMP-nucleon spin-independent cross section limit for WIMP masses above 44 GeV/c2. As CDMS aims to achieve greater WIMP sensitivity, it is necessary to increase the detector mass and discrimination between signal and background events. Incomplete ionization collection results in the largest background in the CDMS detectors as this causes electron recoil background interactions to appear as false candidate events. Two primary causes of incomplete ionization collection are surface and bulk trapping. Recent work has been focused on reducing surface trapping through the modification of fabrication methods for future detectors. Analyzing data taken with test devices has shown that hydrogen passivation of the amorphous silicon blocking layer worsens surface trapping. Additional data has shown that the iron-ion implantation used to lower the critical temperature of the tungsten transition-edge sensors causes a degradation of the ionization collection. Using selective implantation on future detectors may improve ionization collection for events near the phonon side detector surface. Bulk trapping is minimized by neutralizing ionized lattice impurities. Detector investigations at testing facilities and in situ at the experimental site have provided methods to optimize the neutralization process and monitor running conditions to maintain full ionization collection. This work details my contribution to the 5-tower data taking, monitoring, and analysis effort as

  7. Dark Matter: Looking for WIMPs in the Galactic Halo

    International Nuclear Information System (INIS)

    Akerib, Daniel S.

    2006-01-01

    Overwhelming observational evidence indicates that most of the matter in the Universe consists of non-baryonic dark matter. One possibility is that the dark matter is Weakly-Interacting Massive Particles (WIMPs) that were produced in the early Universe. These relics could comprise the Milky Way's dark halo and provide evidence for new particle physics, such as Supersymmetry. After reviewing some of the evidence for dark matter and the WIMP hypothesis, I will describe the strategy for searching for WIMPs, along with a survey of the current status and outlook. In particular, dark matter searches have begun to explore the region of parameter space where SUSY particles could provide dark matter candidates. I will also mention some of the recent theoretical work on dark matter candidates which is being done in anticipation of the turn-on of the LHC and as part of the active R and D on the ILC. Finally, a vigorous detector development program promises significant advances in WIMP sensitivity in the coming years

  8. A dark-matter search using the final CDMS II dataset and a novel detector of surface radiocontamination

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Zeeshan [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2012-01-01

    Substantial evidence from galaxies, galaxy clusters, and cosmological scales suggests that ~85% of the matter of our universe is invisible. The missing matter, or "dark matter" is likely composed of non-relativistic, non-baryonic particles, which have very rare interactions with baryonic matter and with one another. Among dark matter candidates, Weakly Interacting Massive Particles (WIMPs) are particularly well motivated. In the early universe, thermally produced particles with weak-scale mass and interactions would `freeze out’ at the correct density to be dark matter today. Extensions to the Standard Model of particle physics, such as Supersymmetry, which solve gauge hierarchy and coupling unification problems, naturally provide such particles. Interactions of WIMPs with baryons are expected to be rare, but might be detectable in low-noise detectors. The Cryogenic Dark Matter Search (CDMS) experiment uses ionization- and phonon- sensitive germanium particle detectors to search for such interactions. CDMS detectors are operated at the Soudan Underground Laboratory in Minnesota, within a shielded environment to lower cosmogenic and radioactive background. The combination of phonon and ionization signatures from the detectors provides excellent residual-background rejection. This dissertation presents improved techniques for phonon calibration of CDMS II detectors and the analysis of the final CDMS II dataset with 612 kg-days of exposure. We set a limit of 3.8x10$^{-}$44 cm$^{2}$ on WIMP-nucleon spin-independent scattering cross section for a WIMP mass of 70 GeV/c$^{2}$. At the time this analysis was published, these data presented the most stringent limits on WIMP scattering for WIMP masses over 42 GeV/c$^{2}$, ruling out previously unexplored parameter space. Next-generation rare-event searches such as SuperCDMS, COUPP, and CLEAN will be limited in sensitivity, unless they achieve stringent control of the surface radioactive contamination on their detectors. Low

  9. Looking for the WIMP next door

    Science.gov (United States)

    Evans, Jared A.; Gori, Stefania; Shelton, Jessie

    2018-02-01

    We comprehensively study experimental constraints and prospects for a class of minimal hidden sector dark matter (DM) models, highlighting how the cosmological history of these models informs the experimental signals. We study simple `secluded' models, where the DM freezes out into unstable dark mediator states, and consider the minimal cosmic history of this dark sector, where coupling of the dark mediator to the SM was sufficient to keep the two sectors in thermal equilibrium at early times. In the well-motivated case where the dark mediators couple to the Standard Model (SM) via renormalizable interactions, the requirement of thermal equilibrium provides a minimal, UV-insensitive, and predictive cosmology for hidden sector dark matter. We call DM that freezes out of a dark radiation bath in thermal equilibrium with the SM a WIMP next door, and demonstrate that the parameter space for such WIMPs next door is sharply defined, bounded, and in large part potentially accessible. This parameter space, and the corresponding signals, depend on the leading interaction between the SM and the dark mediator; we establish it for both Higgs and vector portal interactions. In particular, there is a cosmological lower bound on the portal coupling strength necessary to thermalize the two sectors in the early universe. We determine this thermalization floor as a function of equilibration temperature for the first time. We demonstrate that direct detection experiments are currently probing this cosmological lower bound in some regions of parameter space, while indirect detection signals and terrestrial searches for the mediator cut further into the viable parameter space. We present regions of interest for both direct detection and dark mediator searches, including motivated parameter space for the direct detection of sub-GeV DM.

  10. Cosmological radio emission induced by WIMP Dark Matter

    International Nuclear Information System (INIS)

    Fornengo, N.; Regis, M.; Lineros, R.; Taoso, M.

    2012-01-01

    We present a detailed analysis of the radio synchrotron emission induced by WIMP dark matter annihilations and decays in extragalactic halos. We compute intensity, angular correlation, and source counts and discuss the impact on the expected signals of dark matter clustering, as well as of other astrophysical uncertainties as magnetic fields and spatial diffusion. Bounds on dark matter microscopic properties are then derived, and, depending on the specific set of assumptions, they are competitive with constraints from other indirect dark matter searches. At GHz frequencies, dark matter sources can become a significant fraction of the total number of sources with brightness below the microJansky level. We show that, at this level of fluxes (which are within the reach of the next-generation radio surveys), properties of the faint edge of differential source counts, as well as angular correlation data, can become an important probe for WIMPs

  11. Cosmological radio emission induced by WIMP Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Fornengo, N.; Regis, M. [Dipartimento di Fisica Teorica, Università di Torino, via P. Giuria 1, I-10125 Torino (Italy); Lineros, R.; Taoso, M., E-mail: fornengo@to.infn.it, E-mail: rlineros@ific.uv.es, E-mail: regis@to.infn.it, E-mail: mtaoso@phas.ubc.ca [IFIC, CSIC-Universidad de Valencia, Ed. Institutos, Apdo. Correos 22085, E-46071 Valencia (Spain)

    2012-03-01

    We present a detailed analysis of the radio synchrotron emission induced by WIMP dark matter annihilations and decays in extragalactic halos. We compute intensity, angular correlation, and source counts and discuss the impact on the expected signals of dark matter clustering, as well as of other astrophysical uncertainties as magnetic fields and spatial diffusion. Bounds on dark matter microscopic properties are then derived, and, depending on the specific set of assumptions, they are competitive with constraints from other indirect dark matter searches. At GHz frequencies, dark matter sources can become a significant fraction of the total number of sources with brightness below the microJansky level. We show that, at this level of fluxes (which are within the reach of the next-generation radio surveys), properties of the faint edge of differential source counts, as well as angular correlation data, can become an important probe for WIMPs.

  12. Projected WIMP Sensitivity of the LUX-ZEPLIN (LZ) Dark Matter Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Akerib, D.S.; et al.

    2018-02-16

    LUX-ZEPLIN (LZ) is a next generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with Weakly Interacting Massive Particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000 live day run using a 5.6 tonne fiducial mass, LZ is projected to exclude at 90% confidence level spin-independent WIMP-nucleon cross sections above $1.6 \\times 10^{-48}$ cm$^{2}$ for a 40 $\\mathrm{GeV}/c^{2}$ mass WIMP. Additionally, a $5\\sigma$ discovery potential is projected reaching cross sections below the existing and projected exclusion limits of similar experiments that are currently operating. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of $2.7 \\times 10^{-43}$ cm$^{2}$ ($8.1 \\times 10^{-42}$ cm$^{2}$) for a 40 $\\mathrm{GeV}/c^{2}$ mass WIMP is expected. With construction well underway, LZ is on track for underground installation at SURF in 2019 and will start collecting data in 2020.

  13. Constraints on WIMP masses and interactions

    International Nuclear Information System (INIS)

    Enqvist, K.

    1991-01-01

    It is shown that cosmology, experiments and unitarity considerations limit the mass and coupling g' of a generic, heavy WIMP from the above as well as from the below. There are absolute lower limits of 4x10 -5 g and 6x10 -5 g for the couplings of Diracn and Majorana WIMPs, respectively. In U(1)' models cosmology implies an upper limit of about 1 TeV on the Z' and on the WIMP masses, but only in the absence of Z-Z' mixing. (orig.)

  14. Beyond WIMP: From Theory to Detection of Sub-GeV Dark Matter

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    The existence of dark matter has been well established with overwhelming evidence, but its particle identity is still unknown. For more than three decades, significant theoretical and experimental efforts have been directed towards the search for a Weakly Interacting Massive Particle (WIMP), often overlooking other possibilities. The lack of an unambiguous positive WIMP signal, at both indirect- and direct-detection experiments and at the LHC, stresses the need to expand dark matter research into additional theoretical scenarios and, more importantly, to develop new experimental capabilities that go beyond the limitations of WIMP detection. In this talk I will discuss new theoretical ideas and experimental avenues for searching for light, sub-GeV dark matter. Some emphasis will be given to direct detection experiments, where several new strategies to directly detect dark matter particles with MeV to GeV mass, far below standard direct detection capabilities, are developed.

  15. Joint Rome Workshop "Challenges in the Dark Sector: Alternatives to the WIMP paradigm”

    CERN Document Server

    2015-01-01

    Identifying what Dark Matter (DM) is, as well as its nature and properties, remains a major challenge for both theoretical and experimental astroparticle physics communities. In the past decades, WIMP DM has been the most hunted candidate, with the result that nowadays WIMPS are cornered by large amounts of experimental data from Direct Detection, Indirect Detection, and Collider Experiments. If no WIMP signal is detected in the next few years, the possibility that this very appealing theoretical idea is not what Nature has chosen will become even more compelling and will boost theoretical studies and experimental searches for non-WIMP alternatives for DM. The aim of this 3-day meeting is to convene experts on alternatives to the WIMP paradigm to stimulate informal discussions on different possibilities (dark photons, axion-like particles, Majorons, self-interacting dark sectors, just to mention a few). We plan to have only three or four talks each day, and plenty of time to discuss implications of these DM s...

  16. Ionization Collection in Detectors of the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Phipps, Arran T.J. [Univ. of California, Berkeley, CA (United States)

    2016-01-01

    Determining the composition of dark matter is at the forefront of modern scientific research. There is compelling evidence for the existence of vast quantities of dark matter throughout the universe, however it has so-far eluded all direct detection efforts and its identity remains a mystery. Weakly interacting massive particles (WIMPs) are a favored dark matter candidate and have been the primary focus of direct detection for several decades. The Cryogenic Dark Matter Search (CDMS) has developed the Z-dependent Ionization and Phonon (ZIP) detector to search for such particles. Typically made from germanium, these detectors are capable of distinguishing between electromagnetic background and a putative WIMP signal through the simultaneous measurement of ionization and phonons produced by scattering events. CDMS has operated several arrays of these detectors at the Soudan Underground Laboratory (Soudan, MN, USA) resulting in many competitive (often world-leading) WIMP exclusion limits. This dissertation focuses on ionization collection in these detectors under the sub-Kelvin, low electric field, and high crystal purity conditions unique to CDMS. The design and performance of a fully cryogenic HEMT-based amplifier capable of achieving the SuperCDMS SNOLAB ionization energy resolution goal of 100 eVee is presented. The experimental apparatus which has been used to record electron and hole properties under CDMS conditions is described. Measurements of charge transport, trapping, and impact ionization as a function of electric field in two CDMS detectors are shown, and the ionization collection efficiency is determined. The data is used to predict the error in the nuclear recoil energy scale under both CDMSlite and iZIP operating modes. A two species, two state model is developed to describe how ionization collection and space charge generation in CDMS detectors are controlled by the presence of “overcharged” D- donor and A+ acceptor impurity states. The thermal

  17. Improved EDELWEISS-III sensitivity for low-mass WIMPs using a profile likelihood approach

    Energy Technology Data Exchange (ETDEWEB)

    Hehn, L. [Karlsruher Institut fuer Technologie, Institut fuer Kernphysik, Karlsruhe (Germany); Armengaud, E.; Boissiere, T. de; Gros, M.; Navick, X.F.; Nones, C.; Paul, B. [CEA Saclay, DSM/IRFU, Gif-sur-Yvette Cedex (France); Arnaud, Q. [Univ Lyon, Universite Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique Nucleaire de Lyon, Lyon (France); Queen' s University, Kingston (Canada); Augier, C.; Billard, J.; Cazes, A.; Charlieux, F.; Jesus, M. de; Gascon, J.; Juillard, A.; Queguiner, E.; Sanglard, V.; Vagneron, L. [Univ Lyon, Universite Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique Nucleaire de Lyon, Lyon (France); Benoit, A.; Camus, P. [Institut Neel, CNRS/UJF, Grenoble (France); Berge, L.; Chapellier, M.; Dumoulin, L.; Giuliani, A.; Le-Sueur, H.; Marnieros, S.; Olivieri, E.; Poda, D. [CSNSM, Univ. Paris-Sud, CNRS/IN2P3, Universite Paris-Saclay, Orsay (France); Bluemer, J. [Karlsruher Institut fuer Technologie, Institut fuer Kernphysik, Karlsruhe (Germany); Karlsruher Institut fuer Technologie, Institut fuer Experimentelle Kernphysik, Karlsruhe (Germany); Broniatowski, A. [CSNSM, Univ. Paris-Sud, CNRS/IN2P3, Universite Paris-Saclay, Orsay (France); Karlsruher Institut fuer Technologie, Institut fuer Experimentelle Kernphysik, Karlsruhe (Germany); Eitel, K.; Kozlov, V.; Siebenborn, B. [Karlsruher Institut fuer Technologie, Institut fuer Kernphysik, Karlsruhe (Germany); Foerster, N.; Heuermann, G.; Scorza, S. [Karlsruher Institut fuer Technologie, Institut fuer Experimentelle Kernphysik, Karlsruhe (Germany); Jin, Y. [Laboratoire de Photonique et de Nanostructures, CNRS, Route de Nozay, Marcoussis (France); Kefelian, C. [Univ Lyon, Universite Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique Nucleaire de Lyon, Lyon (France); Karlsruher Institut fuer Technologie, Institut fuer Experimentelle Kernphysik, Karlsruhe (Germany); Kleifges, M.; Tcherniakhovski, D.; Weber, M. [Karlsruher Institut fuer Technologie, Institut fuer Prozessdatenverarbeitung und Elektronik, Karlsruhe (Germany); Kraus, H. [University of Oxford, Department of Physics, Oxford (United Kingdom); Kudryavtsev, V.A. [University of Sheffield, Department of Physics and Astronomy, Sheffield (United Kingdom); Pari, P. [CEA Saclay, DSM/IRAMIS, Gif-sur-Yvette (France); Piro, M.C. [CSNSM, Univ. Paris-Sud, CNRS/IN2P3, Universite Paris-Saclay, Orsay (France); Rensselaer Polytechnic Institute, Troy, NY (United States); Rozov, S.; Yakushev, E. [JINR, Laboratory of Nuclear Problems, Dubna, Moscow Region (Russian Federation); Schmidt, B. [Karlsruher Institut fuer Technologie, Institut fuer Kernphysik, Karlsruhe (Germany); Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2016-10-15

    We report on a dark matter search for a Weakly Interacting Massive Particle (WIMP) in the mass range m{sub χ} element of [4, 30] GeV/c{sup 2} with the EDELWEISS-III experiment. A 2D profile likelihood analysis is performed on data from eight selected detectors with the lowest energy thresholds leading to a combined fiducial exposure of 496 kg-days. External backgrounds from γ- and β-radiation, recoils from {sup 206}Pb and neutrons as well as detector intrinsic backgrounds were modelled from data outside the region of interest and constrained in the analysis. The basic data selection and most of the background models are the same as those used in a previously published analysis based on boosted decision trees (BDT) [1]. For the likelihood approach applied in the analysis presented here, a larger signal efficiency and a subtraction of the expected background lead to a higher sensitivity, especially for the lowest WIMP masses probed. No statistically significant signal was found and upper limits on the spin-independent WIMP-nucleon scattering cross section can be set with a hypothesis test based on the profile likelihood test statistics. The 90 % C.L. exclusion limit set for WIMPs with m{sub χ} = 4 GeV/c{sup 2} is 1.6 x 10{sup -39} cm{sup 2}, which is an improvement of a factor of seven with respect to the BDT-based analysis. For WIMP masses above 15 GeV/c{sup 2} the exclusion limits found with both analyses are in good agreement. (orig.)

  18. Dark matter search

    International Nuclear Information System (INIS)

    Bernabei, R.

    2003-01-01

    Some general arguments on the particle Dark Matter search are addressed. The WIMP direct detection technique is mainly considered and recent results obtained by exploiting the annual modulation signature are summarized. (author)

  19. Dark matter search

    Energy Technology Data Exchange (ETDEWEB)

    Bernabei, R [Dipto. di Fisica, Universita di Roma ' Tor Vergata' and INFN, sez. Roma2, Rome (Italy)

    2003-08-15

    Some general arguments on the particle Dark Matter search are addressed. The WIMP direct detection technique is mainly considered and recent results obtained by exploiting the annual modulation signature are summarized. (author)

  20. Beyond WIMPs: the Quark (Anti Nugget Dark Matter

    Directory of Open Access Journals (Sweden)

    Zhitnitsky Ariel

    2017-01-01

    Full Text Available We review a testable dark matter (DM model outside of the standard WIMP paradigm. The model is unique in a sense that the observed ratio Ωdark ≃ Ωvisible for visible and dark matter densities finds its natural explanation as a result of their common QCD origin when both types of matter (DM and visible are formed during the QCD phase transition and both are proportional to single dimensional parameter of the system, Λqcd. We argue that the charge separation effect also inevitably occurs during the same QCD phase transition in the presence of the CP odd axion field a(x. It leads to preferential formation of one species of nuggets on the scales of the visible Universe where the axion field a(x is coherent. A natural outcome of this preferential evolution is that only one type of the visible baryons (not anti- baryons remain in the system after the nuggets complete their formation. Unlike conventional WIMP dark matter candidates, the nuggets and anti-nuggets are strongly interacting but macroscopically large objects. The rare events of annihilation of the anti-nuggets with visible matter lead to a number of observable effects. We argue that the relative intensities for a number of measured excesses of emission from the centre of galaxy (covering more than 11 orders of magnitude are determined by standard and well established physics. At the same time the absolute intensity of emission is determined by a single new fundamental parameter of the theory, the axion mass, 10−6eV ≲ ma ≲ 10−3eV. Finally, we comment on implications of these studies for the axion search experiments, including microwave cavity and the Orpheus experiments.

  1. The Diurnal Variation of the Wimp Detection Event Rates in Directional Experiments

    CERN Document Server

    Vergados, J D

    2009-01-01

    The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Modern particle theories naturally provide viable cold dark matter candidates with masses in the GeV-TeV region. Supersymmetry provides the lightest supersymmetric particle (LSP), theories in extra dimensions supply the lightest Kaluza-Klein particle (LKP) etc. The nature of dark matter can only be unraveled only by its direct detection in the laboratory. All such candidates will be called WIMPs (Weakly Interacting Massive Particles). In any case the direct dark matter search, which amounts to detecting the recoiling nucleus, following its collision with WIMP, is central to particle physics and cosmology. In this work we briefly review the theoretical elements relevant to the direct dark matter detection experiments, paying particular attention to directional experiments. i.e experiments in which, not only the energy but the direction of the recoiling nucleus is ob...

  2. Direct detection of dark matter with the EDELWEISS-III experiment: signals induced by charge trapping, data analysis and characterization of cryogenic detector sensitivity to low-mass WIMPs

    International Nuclear Information System (INIS)

    Arnaud, Quentin

    2015-01-01

    The EDELWEISS-III experiment is dedicated to direct dark matter searches aiming at detecting WIMPS. These massive particles should account for more than 80% of the mass of the Universe and be detectable through their elastic scattering on nuclei constituting the absorber of a detector. As the expected WIMP event rate is extremely low ( 20 GeV). Finally, a study dedicated to the optimization of solid cryogenic detectors to low mass WIMP searches is presented. This study is performed on simulated data using a statistical test based on a profiled likelihood ratio that allows for statistical background subtraction and spectral shape discrimination. This study combined with results from Run308, has lead the EDELWEISS experiment to favor low mass WIMP searches ( [fr

  3. Planck-scale effects on WIMP dark matter

    Directory of Open Access Journals (Sweden)

    Sofiane M Boucenna

    2014-01-01

    Full Text Available There exists a widely known conjecture that gravitational effects violate global symmetries. We study the effect of global-symmetry violating higher-dimension operators induced by Planck-scale physics on the properties of WIMP dark matter. Using an effective description, we show that the lifetime of the WIMP dark matter candidate can satisfy cosmological bounds under reasonable assumptions regarding the strength of the dimension-five operators. On the other hand, the indirect WIMP dark matter detection signal is significantly enhanced due to new decay channels.

  4. Radon mitigation for the SuperCDMS SNOLAB dark matter experiment

    Science.gov (United States)

    Street, J.; Bunker, R.; Miller, E. H.; Schnee, R. W.; Snyder, S.; So, J.

    2018-01-01

    A potential background for the SuperCDMS SNOLAB dark matter experiment is from radon daughters that have plated out onto detector surfaces. To reach desired backgrounds, understanding plate-out rates during detector fabrication as well as mitigating radon in surrounding air is critical. A radon mitigated cleanroom planned at SNOLAB builds upon a system commissioned at the South Dakota School of Mines & Technology (SD Mines). The ultra-low radon cleanroom at SD Mines has air supplied by a vacuum-swing-adsorption radon mitigation system that has achieved >1000× reduction for a cleanroom activity consistent with zero and <0.067 Bq m-3 at 90% confidence. Our simulation of this system, validated against calibration data, provides opportunity for increased understanding and optimization for this and future systems.

  5. Identifying WIMP dark matter from particle and astroparticle data

    Science.gov (United States)

    Bertone, Gianfranco; Bozorgnia, Nassim; Kim, Jong Soo; Liem, Sebastian; McCabe, Christopher; Otten, Sydney; Ruiz de Austri, Roberto

    2018-03-01

    One of the most promising strategies to identify the nature of dark matter consists in the search for new particles at accelerators and with so-called direct detection experiments. Working within the framework of simplified models, and making use of machine learning tools to speed up statistical inference, we address the question of what we can learn about dark matter from a detection at the LHC and a forthcoming direct detection experiment. We show that with a combination of accelerator and direct detection data, it is possible to identify newly discovered particles as dark matter, by reconstructing their relic density assuming they are weakly interacting massive particles (WIMPs) thermally produced in the early Universe, and demonstrating that it is consistent with the measured dark matter abundance. An inconsistency between these two quantities would instead point either towards additional physics in the dark sector, or towards a non-standard cosmology, with a thermal history substantially different from that of the standard cosmological model.

  6. WIMP-nucleus scattering in chiral effective theory

    Science.gov (United States)

    Cirigliano, Vincenzo; Graesser, Michael L.; Ovanesyan, Grigory

    2012-10-01

    We discuss long-distance QCD corrections to the WIMP-nucleon(s) interactions in the framework of chiral effective theory. For scalar-mediated WIMP-quark interactions, we calculate all the next-to-leading-order corrections to the WIMP-nucleus elastic cross-section, including two-nucleon amplitudes and recoil-energy dependent shifts to the single-nucleon scalar form factors. As a consequence, the scalar-mediated WIMP-nucleus cross-section cannot be parameterized in terms of just two quantities, namely the neutron and proton scalar form factors at zero momentum transfer, but additional parameters appear, depending on the short-distance WIMP-quark interaction. Moreover, multiplicative factorization of the cross-section into particle, nuclear and astro-particle parts is violated. In practice, while the new effects are of the natural size expected by chiral power counting, they become very important in those regions of parameter space where the leading order WIMP-nucleus amplitude is suppressed, including the so-called "isospin-violating dark matter" regime. In these regions of parameter space we find order-of-magnitude corrections to the total scattering rates and qualitative changes to the shape of recoil spectra.

  7. TREX-DM: a low-background Micromegas-based TPC for low-mass WIMP detection

    Energy Technology Data Exchange (ETDEWEB)

    Iguaz, F.J.; Garza, J.G.; Castel, J.F.; Cebrian, S.; Dafni, T.; Garcia, J.A.; Irastorza, I.G.; Lagraba, A.; Luzon, G.; Peiro, A. [Universidad de Zaragoza, Grupo de Fisica Nuclear y Astroparticulas, Zaragoza (Spain); Aznar, F. [Universidad de Zaragoza, Grupo de Fisica Nuclear y Astroparticulas, Zaragoza (Spain); Universidad de Zaragoza, Centro Universitario de la Defensa, Zaragoza (Spain)

    2016-10-15

    If Dark Matter is made of Weakly Interacting Massive Particles (WIMPs) with masses below ∝20 GeV, the corresponding nuclear recoils in mainstream WIMP experiments are of energies too close, or below, the experimental threshold. Gas Time Projection Chambers (TPCs) can be operated with a variety of target elements, offer good tracking capabilities and, on account of the amplification in gas, very low thresholds are achievable. Recent advances in electronics and in novel radiopure TPC readouts, especially micro-mesh gas structure (Micromegas), are improving the scalability and low-background prospects of gaseous TPCs. Here we present TREX-DM, a prototype to test the concept of a Micromegas-based TPC to search for low-mass WIMPs. The detector is designed to host an active mass of ∝0.300 kg of Ar at 10 bar, or alternatively ∝0.160 kg of Ne at 10 bar, with an energy threshold below 0.4 keVee, and is fully built with radiopure materials. We will describe the detector in detail, the results from the commissioning phase on surface, as well as a preliminary background model. The anticipated sensitivity of this technique may go beyond current experimental limits for WIMPs of masses of 2-8 GeV. (orig.)

  8. Results from the search for dark matter in the Milky Way with 9 years of data of the ANTARES neutrino telescope

    NARCIS (Netherlands)

    Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M.C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coelho, J.A.B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; De Bonis, G.; Distefano, C.; Di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Felis, I.; Fusco, L.A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Grégoire, T.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A.J.; Hello, Y.; Hernández-Rey, J.J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C.W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J.A.; Mathieu, A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Pavalas, G.E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Roensch, K.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D.F.E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Schüssler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, T.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; Van Elewyck, V.; Vivolo, D.; Vizzoca, A.; Wagner, S.; Wilms, J.; Zornoza, J.D.; Zúñiga, J.

    2017-01-01

    Using data recorded with the ANTARES telescope from 2007 to 2015, a new search for dark matter annihilation in the Milky Way has been performed. Three halo models and five annihilation channels, WIMP + WIMP -> b (b) over bar, W+W-, tau(+)tau(-), mu(+)mu(-) and v (v) over bar, with WIMP masses

  9. Limits on the Spin-Dependent WIMP-Nucleon Cross Sections from the First Science Run of the ZEPLIN-III Experiment

    International Nuclear Information System (INIS)

    Lebedenko, V. N.; Bewick, A.; Currie, A.; Davidge, D.; Dawson, J.; Horn, M.; Howard, A. S.; Jones, W. G.; Joshi, M.; Liubarsky, I.; Lyons, K.; Quenby, J. J.; Sumner, T. J.; Thorne, C.; Walker, R. J.; Araujo, H. M.; Edwards, B.; Barnes, E. J.; Ghag, C.; Murphy, A. StJ.

    2009-01-01

    We present new experimental constraints on the WIMP-nucleon spin-dependent elastic cross sections using data from the first science run of ZEPLIN-III, a two-phase xenon experiment searching for galactic dark matter weakly interacting massive particles based at the Boulby mine. Analysis of ∼450 kg·days fiducial exposure allow us to place a 90%-confidence upper limit on the pure WIMP-neutron cross section of σ n =1.9x10 -2 pb at 55 GeV/c 2 WIMP mass. Recent calculations of the nuclear spin structure based on the Bonn charge-dependent nucleon-nucleon potential were used for the odd-neutron isotopes 129 Xe and 131 Xe. These indicate that the sensitivity of xenon targets to the spin-dependent WIMP-proton interaction could be much lower than implied by previous calculations, whereas the WIMP-neutron sensitivity is impaired only by a factor of ∼2.

  10. First low WIMP mass results in EDELWEISS III experiment

    Energy Technology Data Exchange (ETDEWEB)

    Scorza, Silvia [Karlsruher Institut fuer Technologie, Institut fuer Experimentelle Kernphysik, Postfach 3640, Karlsruhe (Germany); Collaboration: EDELWEISS-Collaboration

    2016-07-01

    The EDELWEISS-III collaboration is operating an experiment for the direct detection of Weakly Interacting Massive Particle (WIMPs) dark matter in the low radioactivity environment of the Modane Underground Laboratory. It consists of twenty-four advanced high purity germanium detectors operating at 18 mK in a dilution refrigerator in order to identify rare nuclear recoils induced by elastic scattering of WIMPs from our Galactic halo. The current EDELWEISS-III program, including improvements of the background, data-acquisition and the configuration is detailed. Sources of background along with the rejection techniques are discussed. Detector performances and a first low WIMP mass analysis of data acquired in a long-term campaign are presented as well.

  11. The WIMP Forest: Indirect Detection of a Chiral Square

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, Gianfranco; Jackson, C.B.; Shaughnessy, Gabe; Tait, Tim M.P.; Vallinotto, Alberto

    2009-04-01

    The spectrum of photons arising from WIMP annihilation carries a detailed imprint of the structure of the dark sector. In particular, loop-level annihilations into a photon and another boson can in principle lead to a series of lines (a WIMP forest) at energies up to the WIMP mass. A specific model which illustrates this feature nicely is a theory of two universal extra dimensions compactified on a chiral square. Aside from the continuum emission, which is a generic prediction of most dark matter candidates, we find a 'forest' of prominent annihilation lines that, after convolution with the angular resolution of current experiments, leads to a distinctive (2-bump plus continuum) spectrum, which may be visible in the near future with the Fermi Gamma-Ray Space Telescope (formerly known as GLAST).

  12. No WIMP mini-spikes in dwarf spheroidal galaxies

    NARCIS (Netherlands)

    Wanders, M.; Bertone, G.; Volonteri, M.; Weniger, C.

    2015-01-01

    The formation of black holes inevitably affects the distribution of dark and baryonic matter in their vicinity, leading to an enhancement of the dark matter density, called spike, and if dark matter is made of WIMPs, to a strong enhancement of the dark matter annihilation rate. Spikes at the center

  13. WIMP detection and slow ion dynamics in carbon nanotube arrays

    CERN Document Server

    Cavoto, G.; Cocina, F.; Ferretti, J.; Polosa, A.D.

    2016-06-24

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs (~ 10 GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with ...

  14. WIMP detection and slow ion dynamics in carbon nanotube arrays

    International Nuclear Information System (INIS)

    Cavoto, G.; Cirillo, E.N.M.; Cocina, F.; Ferretti, J.; Polosa, A.D.

    2016-01-01

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs (∼ 11 GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with respect to CNT directions. New constraints are obtained on how to devise the CNT arrays to maximize the target channeling efficiency. (orig.)

  15. WIMP detection and slow ion dynamics in carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Cavoto, G. [INFN Sezione di Roma, Rome (Italy); Cirillo, E.N.M. [Sapienza Universita di Roma, Dipartimento SBAI, Rome (Italy); Cocina, F. [Sapienza Universita di Roma, Dipartimento di Fisica, Rome (Italy); Ferretti, J. [Sapienza Universita di Roma, Dipartimento di Fisica (Italy); INFN Sezione di Roma, Rome (Italy); Polosa, A.D. [Sapienza Universita di Roma, Dipartimento di Fisica (Italy); CERN, Theory Division, Geneva (Switzerland); INFN Sezione di Roma, Rome (Italy)

    2016-06-15

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs (∼ 11 GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with respect to CNT directions. New constraints are obtained on how to devise the CNT arrays to maximize the target channeling efficiency. (orig.)

  16. WIMP detection and slow ion dynamics in carbon nanotube arrays.

    Science.gov (United States)

    Cavoto, G; Cirillo, E N M; Cocina, F; Ferretti, J; Polosa, A D

    2016-01-01

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs ([Formula: see text] GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with respect to CNT directions. New constraints are obtained on how to devise the CNT arrays to maximize the target channeling efficiency.

  17. ZEPLIN-II limits on WIMP-nucelon interactions

    International Nuclear Information System (INIS)

    Alner, G. J.; Bungau, C.; Camanzi, B.; Durkin, T.; Edwards, B.; Lewin, J. D.; Luescher, R.; Preece, R. M.; Smith, N. J. T.; Smith, P. F.; Sumner, T. J.; Thorne, C.; Araujo, H. M.; Bewick, A.; Davidge, D.; Dawson, J.; Howard, A. S.; Jones, W. G.; Joshi, M.; Lebedenko, V. N.

    2009-01-01

    ZEPLIN II is a two-phase xenon detector designed to detect dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Following the first 31-day underground run in Boulby Mine, UK, the collaboration published dark matter limits in January 2007; the first such limits using two-phase xenon technology. We outline the key detector design, performance and results here.

  18. A Dark Matter Search with MALBEK

    Science.gov (United States)

    Giovanetti, G. K.; Abgrall, N.; Aguayo, E.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Byram, D.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Cuesta, C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Elliott, S. R.; Fast, J. E.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Goett, J.; Green, M. P.; Gruszko, J.; Guiseppe, V. E.; Gusev, K.; Hallin, A. L.; Hazama, R.; Hegai, A.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Keeter, K. J.; Kidd, M. F.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; MacMullin, J.; MacMullin, S.; Martin, R. D.; Meijer, S.; Mertens, S.; Nomachi, M.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Phillips, D. G.; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Schubert, A. G.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Suriano, A. M.; Thompson, J.; Timkin, V.; Tornow, W.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.

    The Majorana Demonstrator is an array of natural and enriched high purity germanium detectors that will search for the neutrinoless double-beta decay of 76Ge and perform a search for weakly interacting massive particles (WIMPs) with masses below 10 GeV. As part of the Majorana research and development efforts, we have deployed a modified, low-background broad energy germanium detector at the Kimballton Underground Research Facility. With its sub-keV energy threshold, this detector is sensitive to potential non-Standard Model physics, including interactions with WIMPs. We discuss the backgrounds present in the WIMP region of interest and explore the impact of slow surface event contamination when searching for a WIMP signal.

  19. Limits on light WIMPs with a 1 kg-scale germanium detector at 160 eVee physics threshold at the China Jinping Underground Laboratory

    Science.gov (United States)

    Yang, Li-Tao; Li, Hau-Bin; Yue, Qian; Kang, Ke-Jun; Cheng, Jian-Ping; Li, Yuan-Jing; Tsz-King Wong, Henry; Aǧartioǧlu, M.; An, Hai-Peng; Chang, Jian-Ping; Chen, Jing-Han; Chen, Yun-Hua; Deng, Zhi; Du, Qiang; Gong, Hui; He, Li; Hu, Jin-Wei; Hu, Qing-Dong; Huang, Han-Xiong; Jia, Li-Ping; Jiang, Hao; Li, Hong; Li, Jian-Min; Li, Jin; Li, Xia; Li, Xue-Qian; Li, Yu-Lan; Lin, Fong-Kay; Lin, Shin-Ted; Liu, Shu-Kui; Liu, Zhong-Zhi; Ma, Hao; Ma, Jing-Lu; Pan, Hui; Ren, Jie; Ruan, Xi-Chao; Sevda, B.; Sharma, Vivek; Shen, Man-Bin; Singh, Lakhwinder; Singh, Manoj Kumar; Tang, Chang-Jian; Tang, Wei-You; Tian, Yang; Wang, Ji-Min; Wang, Li; Wang, Qing; Wang, Yi; Wu, Shi-Yong; Wu, Yu-Cheng; Xing, Hao-Yang; Xu, Yin; Xue, Tao; Yang, Song-Wei; Yi, Nan; Yu, Chun-Xu; Yu, Hai-Jun; Yue, Jian-Feng; Zeng, Xiong-Hui; Zeng, Ming; Zeng, Zhi; Zhang, Yun-Hua; Zhao, Ming-Gang; Zhao, Wei; Zhou, Ji-Fang; Zhou, Zu-Ying; Zhu, Jing-Jun; Zhu, Zhong-Hua; CDEX Collaboration

    2018-01-01

    We report results of a search for light weakly interacting massive particle (WIMP) dark matter from the CDEX-1 experiment at the China Jinping Underground Laboratory (CJPL). Constraints on WIMP-nucleon spin-independent (SI) and spin-dependent (SD) couplings are derived with a physics threshold of 160 eVee, from an exposure of 737.1 kg-days. The SI and SD limits extend the lower reach of light WIMPs to 2 GeV and improve over our earlier bounds at WIMP mass less than 6 GeV. Supported by the National Key Research and Development Program of China (2017YFA0402200, 2017YFA0402201), the National Natural Science Foundation of China (11175099, 11275107, 11475117, 11475099, 11475092, 11675088), the National Basic Research Program of China (973 Program) (2010CB833006). We thank the support of grants from the Tsinghua University Initiative Scientific Research Program (20121088494, 20151080354) and the Academia Sinica Investigator Award 2011-15, contracts 103-2112-M-001-024 and 104-2112-M-001-038-MY3 from the Ministry of Science and Technology of Taiwan.

  20. The EDELWEISS dark matter search programme for 2017 and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Eitel, Klaus [Karlsruher Institut fuer Technologie, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe (Germany); Collaboration: EDELWEISS-Collaboration

    2016-07-01

    Starting from the achieved sensitivity of EDELWEISS-III with its FID800 Ge detector technology, we present the planning for the next measurement phase. This will concentrate on the usage of Ge bolometers with voltage-assisted amplified heat signals (so-called Neganov-Luke mode) to explore the parameter space for low mass WIMPs (down to m 1GeV). Significant improvements in sensitivity can be realised with a moderate exposure of 350 kg.d within the next 2 years. Beyond 2017, the already existing cooperation with SuperCDMS should lead to a common experimental infrastructure in SNOLAB. Current R and D activities, sensitivity projections and the project towards the SNOLAB cryogenic facility are presented.

  1. WIMP Dark Matter interpretation of Higgs results

    CERN Document Server

    Wang, Renjie; The ATLAS collaboration

    2017-01-01

    The results from searching for dark matter either directly from invisible decay of Higgs bosons or in association with a Higgs boson at the LHC are presented. No significant excess is found beyond the Standard Model prediction, and upper limits are set on the production cross section times branching fraction using data collected in proton-proton collisions at center-of-mass energies of 13 TeV by the ATLAS and CMS detectors. An interpreted upper limit is presented on the allowed dark matter-nucleon scattering cross section.

  2. The search for Dark Matter in our galaxy; Suche nach Dunkler Materie in unserer Galaxie

    Energy Technology Data Exchange (ETDEWEB)

    Eitel, K. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Kernphysik; Boer, W. de [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Experimentelle Kernphysik

    2007-07-01

    The matter content in galaxies like the Milky Way as well as in the entire Universe is dominated by Dark Matter (DM). The nature of this DM is one of the great enigmas of modern astroparticle physics. A promising candidate for this DM is a weakly interacting massive particle (WIMP). DM can then be detected directly via rare elastic collisions of WIMPs with atomic nuclei in a well shielded underground detector or via the decay products from the annihilation of two WIMPs. Energetic gamma rays in cosmic radiation might therefore indicate an indirect signal of DM particles in our galaxy. We present two experimental approaches to search for WIMP Dark Matter. (orig.)

  3. Searching for the dark universe by the DAMA experiment

    International Nuclear Information System (INIS)

    Bernabei, R.; Amato, M.; Belli, P.; Cappella, F.; Cerulli, R.; Dai, C.J.; Ignesti, G.; Incicchitti, A.; Kuang, H.H.; Ma, J.M.; Montecchia, F.; Nozzoli, F.; Ye, Z.P.; Prosperi, D.

    2003-01-01

    DAMA is searching for rare processes by developing and using several kinds of radiopure scintillators. In particular, here the results released so far on the WIMP annual modulation signature are discussed and next perspectives are shortly addressed

  4. Track theory and nuclear photographic emulsions for Dark Matter searches

    International Nuclear Information System (INIS)

    Ditlov, V.A.

    2013-01-01

    This work is devoted to the analysis of possibilities of nuclear emulsions for Dark Matter search, particles of which can produce slow recoil-nuclei. Tracks of such recoil-nuclei in developed nuclear emulsion consist from several emulsion grains. The analysis was carried out with Monte-Carlo calculations made on the basis of the Track Theory and the various factors influencing Dark Matter particles registration efficiency were investigated. Problems, which should be solved for optimal utilization of nuclear emulsions in Dark Matter search, were formulated. B ody - Highlights: ► Specific features of Dark Matter Search in nuclear photographic emulsions. ► Track theory for WIMP search in nuclear emulsions. ► Primary efficiency for single WIMP registration. ► Properties of primary WIMP registration efficiency. ► Primary registration efficiency of WIMP flow

  5. Operating the GridPix detector in dark matter search experiments

    NARCIS (Netherlands)

    Schön, R.; Alfonsi, M.; Hemink, G.; Decowski, M.P.; van Bakel, N.; van der Graaf, H.

    2013-01-01

    The DARWIN (dark matter WIMP search with noble liquids) design study aims to use liquid argon and liquid xenon targets to look for nuclear recoils due to weakly interacting massive particles (WIMPs). To measure the recoil energy in dual-phase noble gas time projection chambers the combination of

  6. 7th Patras workshop on axions, WIMPs and WISPs (PATRAS 2011). Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Zioutas, Konstantin; Schumann, Marc (eds.)

    2011-12-15

    The year 2011 was an exciting period to work on the ''dark side'' of the Universe. Several experimental claims of the direct detection of WIMP dark matter were challenged by the restrictive limits of several others. Dedicated experiments searching for axions, another well motivated dark matter candidate, and for axion-like particles continued to improve their limits and got an additional boost by puzzling astrophysical observations and new developments in theory. The LHC collected an unexpectedly large amount of data and started to produce results at an amazing speed. And finally, this year's Nobel price of physics was awarded to the observation of the accelerating expansion of the Universe, an effect which might be related to dark energy, whose nature remain among the biggest mysteries in physics. These exciting topics and many more important aspects of particle- and astroparticle physics were discussed between experimentalists and theorists at the 7th Patras Workshop on Axions, WIMPs, and WISPs. The workshop took place from June 27 - July 1, 2011, in the Royal Myconian and Myconian Imperial Resorts Hotels on the Greek island of Mykonos. As in the previous years, it was a very fruitful and lively meeting in an inspiring and open atmosphere, which allowed for many open and constructive discussions also on controversial topics. The scientific exchange, the beautiful scenery of the island, the venue itself, the food, an excursion to the ancient ruins of Delos, and finally an amazing conference dinner made this meeting really unique. The ''spirit'' of the workshop and its atmosphere cannot be brought to paper, but many of its scientific highlights are collected in these proceedings. We are looking forward to the 8th Patras Workshop, which will be held in Chicago (USA) July 18-22, 2012. It will be organized jointly by our US colleagues Andrei Afanasev (JLAB), Oliver Baker (Yale), and William Wester (FNAL).

  7. 7th Patras workshop on axions, WIMPs and WISPs (PATRAS 2011). Proceedings

    International Nuclear Information System (INIS)

    Zioutas, Konstantin; Schumann, Marc

    2011-12-01

    The year 2011 was an exciting period to work on the ''dark side'' of the Universe. Several experimental claims of the direct detection of WIMP dark matter were challenged by the restrictive limits of several others. Dedicated experiments searching for axions, another well motivated dark matter candidate, and for axion-like particles continued to improve their limits and got an additional boost by puzzling astrophysical observations and new developments in theory. The LHC collected an unexpectedly large amount of data and started to produce results at an amazing speed. And finally, this year's Nobel price of physics was awarded to the observation of the accelerating expansion of the Universe, an effect which might be related to dark energy, whose nature remain among the biggest mysteries in physics. These exciting topics and many more important aspects of particle- and astroparticle physics were discussed between experimentalists and theorists at the 7th Patras Workshop on Axions, WIMPs, and WISPs. The workshop took place from June 27 - July 1, 2011, in the Royal Myconian and Myconian Imperial Resorts Hotels on the Greek island of Mykonos. As in the previous years, it was a very fruitful and lively meeting in an inspiring and open atmosphere, which allowed for many open and constructive discussions also on controversial topics. The scientific exchange, the beautiful scenery of the island, the venue itself, the food, an excursion to the ancient ruins of Delos, and finally an amazing conference dinner made this meeting really unique. The ''spirit'' of the workshop and its atmosphere cannot be brought to paper, but many of its scientific highlights are collected in these proceedings. We are looking forward to the 8th Patras Workshop, which will be held in Chicago (USA) July 18-22, 2012. It will be organized jointly by our US colleagues Andrei Afanasev (JLAB), Oliver Baker (Yale), and William Wester (FNAL).

  8. Readout technologies for directional WIMP Dark Matter detection

    International Nuclear Information System (INIS)

    Battat, J.B.R.; Irastorza, I.G.; Aleksandrov, A.; Asada, T.; Baracchini, E.; Billard, J.; Bosson, G.; Bourrion, O.; Bouvier, J.; Buonaura, A.; Burdge, K.; Cebrián, S.

    2016-01-01

    The measurement of the direction of WIMP-induced nuclear recoils is a compelling but technologically challenging strategy to provide an unambiguous signature of the detection of Galactic dark matter. Most directional detectors aim to reconstruct the dark-matter-induced nuclear recoil tracks, either in gas or solid targets. The main challenge with directional detection is the need for high spatial resolution over large volumes, which puts strong requirements on the readout technologies. In this paper we review the various detector readout technologies used by directional detectors. In particular, we summarize the challenges, advantages and drawbacks of each approach, and discuss future prospects for these technologies.

  9. An intermediate framework between WIMP, FIMP, and EWIP dark matter

    International Nuclear Information System (INIS)

    Yaguna, Carlos E.

    2012-01-01

    WIMP (Weakly Interacting Massive Particle), FIMP (Feebly interacting Massive Particle) and EWIP (Extremely Weakly Interacting Particle) dark matter are different theoretical frameworks that have been postulated to explain the dark matter. In this paper we examine an intermediate scenario that combines features from these three frameworks. It consists of a weakly interacting particle — à la WIMP — that does not reach thermal equilibrium in the early Universe — à la FIMP — and whose relic density is determined by the reheating temperature of the Universe — à la EWIP. As an example, an explicit realization of this framework, based on the singlet scalar model of dark matter, is analyzed in detail. In particular, the relic density is studied as a function of the parameters of the model, and the new viable region within this intermediate scenario is determined. Finally, it is shown that this alternative framework of dark matter allows for arbitrarily heavy dark matter particles and that it suggests a connection between dark matter and inflation

  10. Thermalization time scales for WIMP capture by the Sun in effective theories

    Energy Technology Data Exchange (ETDEWEB)

    Widmark, A., E-mail: axel.widmark@fysik.su.se [The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, SE-106 91 Stockholm (Sweden)

    2017-05-01

    I study the process of dark matter capture by the Sun, under the assumption of a Weakly Interacting Massive Particle (WIMP), in the framework of non-relativistic effective field theory. Hypothetically, WIMPs from the galactic halo can scatter against atomic nuclei in the solar interior, settle to thermal equilibrium with the solar core and annihilate to produce an observable flux of neutrinos. In particular, I examine the thermalization process using Monte-Carlo integration of WIMP trajectories. I consider WIMPs in a mass range of 10–1000 GeV and WIMP-nucleon interaction operators with different dependence on spin and transferred momentum. I find that the density profiles of captured WIMPs are in accordance with a thermal profile described by the Sun's gravitational potential and core temperature. Depending on the operator that governs the interaction, the majority of the thermalization time is spent in either the solar interior or exterior. If normalizing the WIMP-nuclei interaction strength to a specific capture rate, I find that the thermalization time differs at most by 3 orders of magnitude between operators. In most cases of interest, the thermalization time is many orders of magnitude shorter than the age of the solar system.

  11. Generalized spin-dependent WIMP-nucleus interactions and the DAMA modulation effect

    Energy Technology Data Exchange (ETDEWEB)

    Scopel, Stefano; Yoon, Kook-Hyun; Yoon, Jong-Hyun, E-mail: scopel@sogang.ac.kr, E-mail: koreasds@naver.com, E-mail: pledge200@gmail.com [Department of Physics, Sogang University, Seoul (Korea, Republic of)

    2015-07-01

    Guided by non-relativistic Effective Field Theory (EFT) we classify the most general spin-dependent interactions between a fermionic Weakly Interacting Massive Particle (WIMP) and nuclei, and within this class of models we discuss the viability of an interpretation of the DAMA modulation result in terms of a signal from WIMP elastic scatterings using a halo-independent approach. We find that, although several relativistic EFT's can lead to a spin-dependent cross section, in some cases with an explicit, non-negligible dependence on the WIMP incoming velocity, three main scenarios can be singled out in the non-relativistic limit which approximately encompass them all, and that only differ by their dependence on the transferred momentum. For two of them compatibility between DAMA and other constraints is possible for a WIMP mass below 30 GeV, but only for a WIMP velocity distribution in the halo of our Galaxy which departs from a Maxwellian. This is achieved by combining a suppression of the WIMP effective coupling to neutrons (to evade constraints from xenon and germanium detectors) to an explicit quadratic or quartic dependence of the cross section on the transferred momentum (that leads to a relative enhancement of the expected rate off sodium in DAMA compared to that off fluorine in droplet detectors and bubble chambers). For larger WIMP masses the same scenarios are excluded by scatterings off iodine in COUPP.

  12. Simultaneous Generation of WIMP Miracle-like Densities of Baryons and Dark Matter

    International Nuclear Information System (INIS)

    McDonald, John

    2012-01-01

    The observed density of dark matter is of the magnitude expected for a thermal relic weakly-interacting massive particle (WIMP). In addition, the observed baryon density is within an order of magnitude of the dark matter density. This suggests that the baryon density is physically related to a typical thermal relic WIMP dark matter density. We present a model which simultaneously generates thermal relic WIMP-like densities for both baryons and dark matter by modifying a large initial baryon asymmetry. Production of unstable scalars carrying baryon number at the LHC would be a clear signature of the model.

  13. Gravitationally induced particle production and its impact on the WIMP abundance

    Directory of Open Access Journals (Sweden)

    I. Baranov

    2015-12-01

    Full Text Available A large set of independent astronomical observations have provided a strong evidence for nonbaryonic dark matter in the Universe. One of the most investigated candidates is an unknown long-lived Weakly Interacting Massive Particle (WIMP which was in thermal equilibrium with the primeval plasma. Here we investigate the WIMP abundance based on the relativistic kinetic treatment for gravitationally induced particle production recently proposed in the literature (Lima and Baranov, 2014 [16]. The new evolution equation is deduced and solved both numerically and through a semi-analytical approach. The predictions of the WIMP observables are discussed and compared with the ones obtained in the standard approach.

  14. Results from a Search for Dark Matter in the Complete LUX Exposure

    Science.gov (United States)

    Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Bramante, R.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chiller, A. A.; Chiller, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Edwards, B. N.; Faham, C. H.; Fiorucci, S.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gibson, K. R.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Ihm, M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lee, C.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Phelps, P.; Reichhart, L.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stephenson, S.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.; LUX Collaboration

    2017-01-01

    We report constraints on spin-independent weakly interacting massive particle (WIMP)-nucleon scattering using a 3.35 ×1 04 kg day exposure of the Large Underground Xenon (LUX) experiment. A dual-phase xenon time projection chamber with 250 kg of active mass is operated at the Sanford Underground Research Facility under Lead, South Dakota (USA). With roughly fourfold improvement in sensitivity for high WIMP masses relative to our previous results, this search yields no evidence of WIMP nuclear recoils. At a WIMP mass of 50 GeV c-2 , WIMP-nucleon spin-independent cross sections above 2.2 ×10-46 cm2 are excluded at the 90% confidence level. When combined with the previously reported LUX exposure, this exclusion strengthens to 1.1 ×10-46 cm2 at 50 GeV c-2 .

  15. DarkSide-50, a background free experiment for dark matter searches

    International Nuclear Information System (INIS)

    Bossa, M

    2014-01-01

    The existence of dark matter is inferred from gravitational effects, but its nature remains a deep mystery. One possibility, motivated by considerations in elementary particle physics, is that dark matter consists of elementary particles, such as the hypothesized Weakly Interacting Massive Particles (WIMPs), with mass ∼ 100 GeV and cross-section ∼ 10 −47 cm 2 , that can be gravitationally trapped inside our galaxy and revealed by their scattering on nuclei. It should be possible to detect WIMPs directly, as the orbital motion of the WIMPs composing the dark matter halo pervading the galaxy should result in WIMP-nucleus collisions of sufficient energy to be observable in the laboratory. The DarkSide-50 experiment is a direct WIMP search using a Liquid Argon Time Projection Chamber (LAr-TPC) with an active mass of 50 kg with a high sensitivity and an ultra-low background detector

  16. Limits on Spin-Dependent WIMP-Nucleon Cross Section Obtained from the Complete LUX Exposure

    Science.gov (United States)

    Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chiller, A. A.; Chiller, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Edwards, B. N.; Faham, C. H.; Fallon, S. R.; Fiorucci, S.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lee, C.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Reichhart, L.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stephenson, S.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Velan, V.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.; LUX Collaboration

    2017-06-01

    We present experimental constraints on the spin-dependent WIMP-nucleon elastic cross sections from the total 129.5 kg yr exposure acquired by the Large Underground Xenon experiment (LUX), operating at the Sanford Underground Research Facility in Lead, South Dakota (USA). A profile likelihood ratio analysis allows 90% C.L. upper limits to be set on the WIMP-neutron (WIMP-proton) cross section of σn=1.6 ×10-41 cm2 (σp=5 ×10-40 cm2 ) at 35 GeV c-2 , almost a sixfold improvement over the previous LUX spin-dependent results. The spin-dependent WIMP-neutron limit is the most sensitive constraint to date.

  17. Model-independent determination of the WIMP mass from direct dark matter detection data

    International Nuclear Information System (INIS)

    Drees, Manuel; Shan, Chung-Lin

    2008-01-01

    Weakly interacting massive particles (WIMPs) are one of the leading candidates for dark matter. We develop a model-independent method for determining the mass m χ of the WIMP by using data (i.e. measured recoil energies) of direct detection experiments. Our method is independent of the as yet unknown WIMP density near the Earth, of the form of the WIMP velocity distribution, as well as of the WIMP–nucleus cross section. However, it requires positive signals from at least two detectors with different target nuclei. In a background-free environment, m χ ∼50 GeV could in principle be determined with an error of ∼35% with only 2 × 50 events; in practice, upper and lower limits on the recoil energy of signal events, imposed to reduce backgrounds, can increase the error. The method also loses precision if m χ significantly exceeds the mass of the heaviest target nucleus used

  18. Search for Dark Matter Interactions using Ionization Yield in Liquid Xenon

    Science.gov (United States)

    Uvarov, Sergey

    Cosmological observations overwhelmingly support the existence of dark matter which constitutes 87% of the universe's total mass. Weakly Interacting Massive Particles (WIMPs) are a prime candidate for dark matter, and the Large Underground Xenon (LUX) experiment aims to a direct-detection of a WIMP-nucleon interaction. The LUX detector is a dual-phase xenon time-projection chamber housed 4,850 feet underground at Sanford Underground Research Facility in Lead, South Dakota. We present the ionization-only analysis of the LUX 2013 WIMP search data. In the 1.04 x 104 kg-days exposure, thirty events were observed out of the 24.8 expected from radioactive backgrounds. We employ a cut-and-count method to set a 1-sided 90% C.L. upper limit for spin-independent WIMP-nucleon cross-sections. A zero charge yield for nuclear-recoils below 0.7 keV is included upper limit calculation. This ionization-only analysis excludes an unexplored region of WIMP-nucleon cross-section for low-mass WIMPs achieving 1.56 x 10-43 cm2 WIMP-nucleon cross-section exclusion for a 5.1 GeV/ c2 WIMP.

  19. Status and low background considerations for the CRESST dark matter search

    International Nuclear Information System (INIS)

    Buehler, M.; Zerle, L.; Proebst, F.; Rulofs, A.; Schanda, U.; Seidel, W.; Absmaier, C.; Booth, N.E.; Bucci, C.; Cooper, S.; Feilitzsch, F. v.; Ferger, P.; Forster, G.; Gabutti, A.; Hoess, C.; Hoehne, J.; Igalson, J.; Kellner, E.; Koch, M.; Loidl, M.; Meier, O.; Nucciotti, A.; Nagel, U.; Putte, M.J.J. v.d.; Salmon, G.L.; Sisti, M.; Stodolsky, L.; Stolovich, A.

    1996-01-01

    We are preparing the CRESST experiment to search for dark matter WIMPs using cryogenic detectors with superconducting phase transition thermometers. In the first stage we plan to use four 250 g sapphire detectors with thresholds of 0.5 keV and resolutions of 0.2 keV at 1 keV. This will provide sensitivity to WIMP masses below 10 GeV, and is thus complementary to other dark matter searches. (orig.)

  20. The phenomenology of superWIMP dark matter scenariow with long-lived sleptons

    Energy Technology Data Exchange (ETDEWEB)

    Heisig, Jan

    2013-08-15

    We study the phenomenology of a supersymmetric scenario where the next-to-lightest superparticle (NLSP) is the charged slepton and is long-lived due to a lightest superparticle (LSP) which is a super weakly interacting massive particle (superWIMP), like the gravitino. This has far-reaching consequences for the cosmological history of the universe on the one hand and for the signatures at colliders on the other hand. We do not assume any high-scale model for the mediation of SUSY breaking to the MSSM but work along the lines of simplified models and the phenomenological MSSM (pMSSM). In a first part, we investigate the LHC sensitivity and its dependence on the superparticle spectrum with an emphasis on strong production and decay. We formulate appropriate simplified models that allow to conservatively approximate the signal efficiencies of arbitrary spectra from a small number of decisive parameters. We found that the application of simplified models is especially suitable in the considered scenario. Devising cuts that yield a large detection efficiency in the whole parameter space, we determine the discovery and exclusion potential of the LHC. We found that the prominent signature of long-lived sleptons allows to extract more robust constraints on the parameter space than for the widely studied case of a neutralino LSP scenario. In addition, we study the implications of the recent LHC results on the cosmological validity of a superWIMP Dark Matter scenario with a long-lived stau NLSP. Therefore, we work in a pMSSM framework and perform a Monte Carlo scan over the pMSSM parameter space highlighting the implications of a Higgs around 125 GeV and the nullsearches for heavy stable charged particles at the 7 and 8TeV LHC. Further, we consider bounds from MSSM Higgs searches, from flavor and precision observables as well as from the theoretical requirement of vacuum stability. In particular we work out the impact on the allowed range for the stau yield after freeze

  1. The phenomenology of superWIMP dark matter scenariow with long-lived sleptons

    International Nuclear Information System (INIS)

    Heisig, Jan

    2013-08-01

    We study the phenomenology of a supersymmetric scenario where the next-to-lightest superparticle (NLSP) is the charged slepton and is long-lived due to a lightest superparticle (LSP) which is a super weakly interacting massive particle (superWIMP), like the gravitino. This has far-reaching consequences for the cosmological history of the universe on the one hand and for the signatures at colliders on the other hand. We do not assume any high-scale model for the mediation of SUSY breaking to the MSSM but work along the lines of simplified models and the phenomenological MSSM (pMSSM). In a first part, we investigate the LHC sensitivity and its dependence on the superparticle spectrum with an emphasis on strong production and decay. We formulate appropriate simplified models that allow to conservatively approximate the signal efficiencies of arbitrary spectra from a small number of decisive parameters. We found that the application of simplified models is especially suitable in the considered scenario. Devising cuts that yield a large detection efficiency in the whole parameter space, we determine the discovery and exclusion potential of the LHC. We found that the prominent signature of long-lived sleptons allows to extract more robust constraints on the parameter space than for the widely studied case of a neutralino LSP scenario. In addition, we study the implications of the recent LHC results on the cosmological validity of a superWIMP Dark Matter scenario with a long-lived stau NLSP. Therefore, we work in a pMSSM framework and perform a Monte Carlo scan over the pMSSM parameter space highlighting the implications of a Higgs around 125 GeV and the nullsearches for heavy stable charged particles at the 7 and 8TeV LHC. Further, we consider bounds from MSSM Higgs searches, from flavor and precision observables as well as from the theoretical requirement of vacuum stability. In particular we work out the impact on the allowed range for the stau yield after freeze

  2. arXiv Uncertainties in WIMP Dark Matter Scattering Revisited

    CERN Document Server

    Ellis, John; Olive, Keith A.

    We revisit the uncertainties in the calculation of spin-independent scattering matrix elements for the scattering of WIMP dark matter particles on nuclear matter. In addition to discussing the uncertainties due to limitations in our knowledge of the nucleonic matrix elements of the light quark scalar densities , we also discuss the importances of heavy quark scalar densities , and comment on uncertainties in quark mass ratios. We analyze estimates of the light-quark densities made over the past decade using lattice calculations and/or phenomenological inputs. We find an uncertainty in the combination that is larger than has been assumed in some phenomenological analyses, and a range of that is smaller but compatible with earlier estimates. We also analyze the importance of the {\\cal O}(\\alpha_s^3) calculations of the heavy-quark matrix elements that are now available, which provide an important refinement of the calculation of the spin-independent scattering cross section. We use for illustration a benchmar...

  3. Radon-related Backgrounds in the LUX Dark Matter Search

    Science.gov (United States)

    Bradley, A.; Akerib, D. S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Bernard, E.; Bernstein, A.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chapman, J. J.; Chiller, A. A.; Chiller, C.; Coffey, T.; Currie, A.; de Viveiros, L.; Dobi, A.; Dobson, J.; Druszkiewicz, E.; Edwards, B.; Faham, C. H.; Fiorucci, S.; Flores, C.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gibson, K. R.; Gilchriese, M. G. D.; Hall, C.; Hertel, S. A.; Horn, M.; Huang, D. Q.; Ihm, M.; Jacobsen, R. G.; Kazkaz, K.; Knoche, R.; Larsen, N. A.; Lee, C.; Lindote, A.; Lopes, M. I.; Malling, D. C.; Mannino, R.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H.; Neves, F.; Ott, R. A.; Pangilinan, M.; Parker, P. D.; Pease, E. K.; Pech, K.; Phelps, P.; Reichhart, L.; Shutt, T.; Silva, C.; Solovov, V. N.; Sorensen, P.; O'Sullivan, K.; Sumner, T. J.; Szydagis, M.; Taylor, D.; Tennyson, B.; Tiedt, D. R.; Tripathi, M.; Uvarov, S.; Verbus, J. R.; Walsh, N.; Webb, R.; White, J. T.; Witherell, M. S.; Wolfs, F. L. H.; Woods, M.; Zhang, C.

    The LUX detector is currently in operation at the Davis Campus at the 4850' level of the Sanford Underground Research Facility (SURF) in Lead, SD to directly search for WIMP dark matter. Knowing the type and rate of backgrounds is critical in a rare, low energy event search, and LUX was designed, constructed, and deployed to mitigate backgrounds, both internal and external. An important internal background are decays of radon and its daughters. These consist of alpha decays, which are easily tagged and are a tracer of certain backgrounds, and beta decays, some of which are not as readily tagged and present a background for the WIMP search. We report on studies of alpha decay and discuss implications for the WIMP search.

  4. Searching for the annual modulation of dark matter signal with the GENIUS-TF experiment

    International Nuclear Information System (INIS)

    Tomei, C.; Dietz, A.; Krivosheina, I.; Klapdor-Kleingrothaus, H.V.

    2003-01-01

    The annual modulation of the recoil spectrum observed in an underground detector is well known as the main signature of a possible WIMP signal. The GENIUS-TF experiment, under construction in the Gran Sasso National Laboratory, can search for the annual modulation of the Dark Matter signal using 40 kg of naked-Ge detectors in liquid nitrogen. Starting from a set of data simulated under the hypothesis of modulation and using different methods, we show the potential of GENIUS-TF for extracting the modulated signal and the expected WIMP mass and WIMP cross-section

  5. Dark matter search experiment with CaF2(Eu) scintillator at Kamioka Observatory

    International Nuclear Information System (INIS)

    Shimizu, Y.; Minowa, M.; Suganuma, W.; Inoue, Y.

    2006-01-01

    We report recent results of a WIMP dark matter search experiment using 310 g of CaF 2 (Eu) scintillator at Kamioka Observatory. We chose a highly radio-pure crystal, PMTs and radiation shields, so that the background rate decreased considerably. We derived limits on the spin dependent WIMP-proton and WIMP-neutron coupling coefficients, a p and a n . The limits excluded a part of the parameter space allowed by the annual modulation observation of the DAMA NaI experiment

  6. Halo-independent determination of the unmodulated WIMP signal in DAMA: the isotropic case

    Energy Technology Data Exchange (ETDEWEB)

    Gondolo, Paolo [Department of Physics, University of Utah, 115 South 1400 East #201, Salt Lake City, Utah 84112-0830 (United States); Scopel, Stefano, E-mail: paolo.gondolo@utah.edu, E-mail: scopel@sogang.ac.kr [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of)

    2017-09-01

    We present a halo-independent determination of the unmodulated signal corresponding to the DAMA modulation if interpreted as due to dark matter weakly interacting massive particles (WIMPs). First we show how a modulated signal gives information on the WIMP velocity distribution function in the Galactic rest frame from which the unmodulated signal descends. Then we describe a mathematically-sound profile likelihood analysis in which the likelihood is profiled over a continuum of nuisance parameters (namely, the WIMP velocity distribution). As a first application of the method, which is very general and valid for any class of velocity distributions, we restrict the analysis to velocity distributions that are isotropic in the Galactic frame. In this way we obtain halo-independent maximum-likelihood estimates and confidence intervals for the DAMA unmodulated signal. We find that the estimated unmodulated signal is in line with expectations for a WIMP-induced modulation and is compatible with the DAMA background+signal rate. Specifically, for the isotropic case we find that the modulated amplitude ranges between a few percent and about 25% of the unmodulated amplitude, depending on the WIMP mass.

  7. Optimizing SuperCDMS phonon energy sensitivity by studying quasiparticle transport in Al films

    Science.gov (United States)

    Yen, Jeffrey; Shank, Benjamin; Cabrera, Blas; Moffatt, Robert; Redl, Peter; Brink, Paul; Tomada, Astrid; Cherry, Matt; Young, Betty; Tortorici, Teddy; Kreikebaum, John Mark

    2014-03-01

    In order to further improve the phonon energy sensitivity of Cryogenic Dark Matter Search (CDMS) detectors, we studied quasiparticle transport at ~ 40 mK in superconducting Al films similar in geometry to those used for CDMS detectors. Test structures of Al were deposited and photolithographically patterned on Si wafers using the same production-line equipment used to fabricate kg-scale CDMS detectors. Three Al film lengths and two film thicknesses were used in this study. In the test experiments described here, an 55Fe source was used to excite a NaCl reflector, producing 2.6 keV x-rays that hit our test devices after passing through a collimator. The impinging x-rays broke Cooper pairs in the Al films, producing quasiparticles that propagated into W transition edge sensors (TESs) coupled to the ends of the Al films. In this talk, we will give the motivation behind these studies, describe our experimental setup, and compare our data to results obtained using signal processing models constructed from basic physical parameters. We show that a non-linear, non-stationary optimal filter applied to the data allows us to precisely measure quasiparticle diffusion and other aspects of energy transport in our thin-film Al-W test devices. These results are being used to further optimize next-generation CDMS detectors.

  8. Dark matter search with the PICASSO experiment

    International Nuclear Information System (INIS)

    Archambault, S.; Debris, F.; Giroux, G.; Jakson, C.M.; Kumaratunga, S.; Lafreniere, M.; Laurin, M.; Lessard, L.; Martin, J.-P.; Piro, M.-C.; Scallon, O.; Starinski, N.; Zacek, V.; Behnke, E.; Grace, E.; Bhattacharjee, P.; Bhattacharya, S.; Das, M.; Saha, S.; Seth, S.; Dai, X.; Davour, A.; Kamaha, A.; Levy, C.; Noble, A.J.; Xie, T.; Dhungana, N.; Farine, J.; Podviyanuk, R.; Wichoski, U.; Gagnebin, S.; Krauss, C.; MacDonald, R.P.; Marlisov, D.; Mitra, P.; Lawson, L.; Pospisil, S.; Stekl, I.

    2012-01-01

    A low background PICASSO experiment to search for dark matter is in progress at the Sudbury Neutrino Observatory (Canada) by using 10 detectors with total target mass of 0.72 kg of 19 F and exposure time of 114 kgd. Recoil energy thresholds are 1.7 keV which allows the sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs) with masses below 10 GeV/c 2 . No dark matter signal was found till now. The limits in the spin dependent sector were obtained for WIMP masses of 20 GeV/c 2 with a cross section on protons of σ p sd = 0.032 pb (90% C.L.), in the spin independent sector close to the low WIMP mass region of 7 GeV/c 2 with cross section on protons σ p Sl =1.41 · 10 -4 pb (90 % C.L.)

  9. Accurate calculations of the WIMP halo around the Sun and prospects for its gamma-ray detection

    International Nuclear Information System (INIS)

    Sivertsson, Sofia; Edsjoe, Joakim

    2010-01-01

    Galactic weakly interacting massive particles (WIMPs) may scatter off solar nuclei to orbits gravitationally bound to the Sun. Once bound, the WIMPs continue to lose energy by repeated scatters in the Sun, eventually leading to complete entrapment in the solar interior. While the density of the bound population is highest at the center of the Sun, the only observable signature of WIMP annihilations inside the Sun is neutrinos. It has been previously suggested that although the density of WIMPs just outside the Sun is lower than deep inside, gamma rays from WIMP annihilation just outside the surface of the Sun, in the so-called WIMP halo around the Sun, may be more easily detected. We here revisit this problem using detailed Monte Carlo simulations and detailed composition and structure information about the Sun to estimate the size of the gamma-ray flux. Compared to earlier simpler estimates, we find that the gamma-ray flux from WIMP annihilations in the solar WIMP halo would be negligible; no current or planned detectors would be able to detect this flux.

  10. Power corrections to the universal heavy WIMP-nucleon cross section

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chien-Yi; Hill, Richard J.; Solon, Mikhail P.; Wijangco, Alexander M.

    2018-06-01

    WIMP-nucleon scattering is analyzed at order $1/M$ in Heavy WIMP Effective Theory. The $1/M$ power corrections, where $M\\gg m_W$ is the WIMP mass, distinguish between different underlying UV models with the same universal limit and their impact on direct detection rates can be enhanced relative to naive expectations due to generic amplitude-level cancellations at leading order. The necessary one- and two-loop matching calculations onto the low-energy effective theory for WIMP interactions with Standard Model quarks and gluons are performed for the case of an electroweak SU(2) triplet WIMP, considering both the cases of elementary fermions and composite scalars. The low-velocity WIMP-nucleon scattering cross section is evaluated and compared with current experimental limits and projected future sensitivities. Our results provide the most robust prediction for electroweak triplet Majorana fermion dark matter direct detection rates; for this case, a cancellation between two sources of power corrections yields a small total $1/M$ correction, and a total cross section close to the universal limit for $M \\gtrsim {\\rm few} \\times 100\\,{\\rm GeV}$. For the SU(2) composite scalar, the $1/M$ corrections introduce dependence on underlying strong dynamics. Using a leading chiral logarithm evaluation, the total $1/M$ correction has a larger magnitude and uncertainty than in the fermionic case, with a sign that further suppresses the total cross section. These examples provide definite targets for future direct detection experiments and motivate large scale detectors capable of probing to the neutrino floor in the TeV mass regime.

  11. Power corrections to the universal heavy WIMP-nucleon cross section

    Science.gov (United States)

    Chen, Chien-Yi; Hill, Richard J.; Solon, Mikhail P.; Wijangco, Alexander M.

    2018-06-01

    WIMP-nucleon scattering is analyzed at order 1 / M in Heavy WIMP Effective Theory. The 1 / M power corrections, where M ≫mW is the WIMP mass, distinguish between different underlying UV models with the same universal limit and their impact on direct detection rates can be enhanced relative to naive expectations due to generic amplitude-level cancellations at leading order. The necessary one- and two-loop matching calculations onto the low-energy effective theory for WIMP interactions with Standard Model quarks and gluons are performed for the case of an electroweak SU(2) triplet WIMP, considering both the cases of elementary fermions and composite scalars. The low-velocity WIMP-nucleon scattering cross section is evaluated and compared with current experimental limits and projected future sensitivities. Our results provide the most robust prediction for electroweak triplet Majorana fermion dark matter direct detection rates; for this case, a cancellation between two sources of power corrections yields a small total 1 / M correction, and a total cross section close to the universal limit for M ≳ few × 100GeV. For the SU(2) composite scalar, the 1 / M corrections introduce dependence on underlying strong dynamics. Using a leading chiral logarithm evaluation, the total 1 / M correction has a larger magnitude and uncertainty than in the fermionic case, with a sign that further suppresses the total cross section. These examples provide definite targets for future direct detection experiments and motivate large scale detectors capable of probing to the neutrino floor in the TeV mass regime.

  12. Impacts of WIMP dark matter upon stellar evolution: main-sequence stars

    CERN Document Server

    Scott, Pat; Edsjo, Joakim

    2008-01-01

    The presence of large amounts of WIMP dark matter in stellar cores has been shown to have significant effects upon models of stellar evolution. We present a series of detailed grids of WIMP-influenced stellar models for main sequence stars, computed using the DarkStars code. We describe the changes in stellar structure and main sequence evolution which occur for masses ranging from 0.3 to 2.0 solar masses and metallicities from Z = 0.0003-0.02, as a function of the rate of energy injection by WIMPs. We then go on to show what rates of energy injection can be obtained using realistic orbital parameters for stars near supermassive black holes, including detailed considerations of dark matter halo velocity and density profiles. Capture and annihilation rates are strongly boosted when stars follow elliptical rather than circular orbits, causing WIMP annihilation to provide up to 100 times the energy of hydrogen fusion in stars at the Galactic centre.

  13. Simultaneous generation of WIMP miracle-like densities of baryons and dark matter

    International Nuclear Information System (INIS)

    McDonald, John

    2011-01-01

    The observed density of dark matter is of the magnitude expected for a thermal relic weakly-interacting massive particle (WIMP). In addition, the observed baryon density is within an order of magnitude of the dark matter density. This suggests that the baryon density is physically related to a typical thermal relic WIMP dark matter density. We present a model which simultaneously generates thermal relic WIMP-like densities for both baryons and dark matter by modifying a large initial baryon asymmetry. Dark matter is due to O(100) GeV gauge singlet scalars produced in the annihilation of the O(TeV) colored scalars which are responsible for the final thermal WIMP-like baryon asymmetry. The requirement of no baryon washout implies that there are two gauge singlet scalars. The low-temperature transfer of the asymmetry to conventional baryons can be understood if the long-lived O(TeV) colored scalars have large hypercharge, |Y|>4/3. Production of such scalars at the LHC would be a clear signature of the model.

  14. Ultra-cold WIMPs relics of non-standard pre-BBN cosmologies

    CERN Document Server

    Gelmini, Graciela B

    2008-01-01

    We point out that in scenarios in which the Universe evolves in a non-standard manner during and after the kinetic decoupling of weakly interacting massive particles (WIMPs), these relics can be much colder than in standard cosmological scenarios (i.e. can be ultra-cold), possibly leading to the formation of smaller first objects in hierarchical structure formation scenarios.

  15. Calculated WIMP signals at the ANDES laboratory: comparison with northern and southern located dark matter detectors

    Science.gov (United States)

    Civitarese, O.; Fushimi, K. J.; Mosquera, M. E.

    2016-12-01

    Weakly interacting massive particles (WIMPs) are possible components of the Universe’s dark matter (DM). The detection of WIMPs is signaled by the recoil of the atomic nuclei which form a detector. CoGeNT at the Soudan Underground Laboratory (SUL) and DAMA at the Laboratori Nazionali del Gran Sasso (LNGS) have reported data on annual modulation of signals attributed to WIMPs. Both experiments are located in laboratories in the Northern Hemisphere. DM detectors are planned to operate (or already operate) in laboratories in the Southern Hemisphere, including SABRE at Stawell Underground Physics Laboratory (SUPL) in Australia, and DM-ICE in Antarctica. In this work we have analyzed the dependence of diurnal and annual modulation of signals, pertaining to the detection of WIMP, on the coordinates of the laboratory, for experiments which may be performed in the planned new Agua Negra Deep Experimental Site (ANDES) underground facility, to be built in San Juan, Argentina. We made predictions for NaI and Ge-type detectors placed in ANDES, to compare with DAMA, CoGeNT, SABRE and DM-ICE arrays, and found that the diurnal modulation of the signals, at the ANDES site, is amplified at its maximum value, both for NaI (Ge)-type detectors, while the annual modulation remains unaffected by the change in coordinates from north to south.

  16. Calculated WIMP signals at the ANDES laboratory: comparison with northern and southern located dark matter detectors

    International Nuclear Information System (INIS)

    Civitarese, O; Mosquera, M E; Fushimi, K J

    2016-01-01

    Weakly interacting massive particles (WIMPs) are possible components of the Universe’s dark matter (DM). The detection of WIMPs is signaled by the recoil of the atomic nuclei which form a detector. CoGeNT at the Soudan Underground Laboratory (SUL) and DAMA at the Laboratori Nazionali del Gran Sasso (LNGS) have reported data on annual modulation of signals attributed to WIMPs. Both experiments are located in laboratories in the Northern Hemisphere. DM detectors are planned to operate (or already operate) in laboratories in the Southern Hemisphere, including SABRE at Stawell Underground Physics Laboratory (SUPL) in Australia, and DM-ICE in Antarctica. In this work we have analyzed the dependence of diurnal and annual modulation of signals, pertaining to the detection of WIMP, on the coordinates of the laboratory, for experiments which may be performed in the planned new Agua Negra Deep Experimental Site (ANDES) underground facility, to be built in San Juan, Argentina. We made predictions for NaI and Ge-type detectors placed in ANDES, to compare with DAMA, CoGeNT, SABRE and DM-ICE arrays, and found that the diurnal modulation of the signals, at the ANDES site, is amplified at its maximum value, both for NaI (Ge)-type detectors, while the annual modulation remains unaffected by the change in coordinates from north to south. (paper)

  17. Neutrinos from WIMP annihilations obtained using a full three-flavor Monte Carlo approach

    International Nuclear Information System (INIS)

    Blennow, Mattias; Ohlsson, Tommy; Edsjö, Joakim

    2008-01-01

    Weakly interacting massive particles (WIMPs) are one of the main candidates for making up the dark matter in the Universe. If these particles make up the dark matter, then they can be captured by the Sun or the Earth, sink to the respective cores, annihilate, and produce neutrinos. Thus, these neutrinos can be a striking dark matter signature at neutrino telescopes looking towards the Sun and/or the Earth. Here, we improve previous analyses on computing the neutrino yields from WIMP annihilations in several respects. We include neutrino oscillations in a full three-flavor framework as well as all effects from neutrino interactions on the way through the Sun (absorption, energy loss, and regeneration from tau decays). In addition, we study the effects of non-zero values of the mixing angle θ 13 as well as the normal and inverted neutrino mass hierarchies. Our study is performed in an event-based setting which makes these results very useful both for theoretical analyses and for building a neutrino telescope Monte Carlo code. All our results for the neutrino yields, as well as our Monte Carlo code, are publicly available. We find that the yield of muon-type neutrinos from WIMP annihilations in the Sun is enhanced or suppressed, depending on the dominant WIMP annihilation channel. This effect is due to an effective flavor mixing caused by neutrino oscillations. For WIMP annihilations inside the Earth, the distance from source to detector is too small to allow for any significant amount of oscillations at the neutrino energies relevant for neutrino telescopes

  18. Search for weakly interacting massive particles with the Cryogenic Dark Matter Search experiment

    Energy Technology Data Exchange (ETDEWEB)

    Saab, Tarek [Stanford U.

    2002-01-01

    From individual galaxies, to clusters of galaxies, to in between the cushions of your sofa, Dark Matter appears to be pervasive on every scale. With increasing accuracy, recent astrophysical measurements, from a variety of experiments, are arriving at the following cosmological model : a flat cosmology (Ωk = 0) with matter and energy densities contributing roughly 1/3 and 2/3 (Ωm = 0.35, ΩΛ = 0.65). Of the matter contribution, it appears that only ~ 10% (Ωb ~ 0.04) is attributable to baryons. Astrophysical measurements constrain the remaining matter to be non-realtivistic, interacting primarily gravitationally. Various theoretical models for such Dark Matter exist. A leading candidate for the non-baryonic matter are Weakly Interacting Massive Particles (dubbed WIMPS). These particles, and their relic density may be naturally explained within the framework of Super-Symmetry theories. SuperSymmetry also offers predictions as to the scattering rates of WIMPs with baryonic matter allowing for the design and tailoring of experiments that search specifically for the WIMPs. The Cryogenic Dark Matter Search experiment is searching for evidence of WIMP interactions in crystals of Ge and Si. Using cryogenic detector technology to measure both the phonon and ionization response to a particle recoil the CDMS detectors are able to discriminate between electron and nuclear recoils, thus reducing the large rates of electron recoil backgrounds to levels with which a Dark Matter search is not only feasible, but far-reaching. This thesis will describe in some detail the physical principles behind the CDMS detector technology, highlighting the final step in the evolution of the detector design and characterization techniques. In addition, data from a 100 day long exposure of the current run at the Stanford Underground Facility will be presented, with focus given to detector performance as well as to the implications on allowable WIMP mass - cross-section parameter space.

  19. GENIUS and the Genius TF: A New Observatory for WIMP Dark Matter and Neutrinoless Double Beta Decay

    OpenAIRE

    Klapdor-Kleingrothaus, H. V.; Majorovits, B.

    2001-01-01

    The GENIUS proposal is described and some of it's physics potential is outlined. Also in the light of the contradictive results from the DAMA and CDMS experiments the Genius TF, a new experimental setup is proposed. The Genius TF could probe the DAMA evidence region using the WIMP nucleus recoil signal and WIMP annual modulation signature simultaneously. Besides that it can prove the long term feasibility of the detector technique to be implemented into the GENIUS setup and will in this sense...

  20. A Study of Nuclear Recoils in Liquid Argon Time Projection Chamber for the Direct Detection of WIMP Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huajie [Princeton Univ., NJ (United States)

    2014-11-01

    Robust results of WIMP direct detection experiments depend on rm understandings of nuclear recoils in the detector media. This thesis documents the most comprehensive study to date on nuclear recoils in liquid argon - a strong candidate for the next generation multi-ton scale WIMP detectors. This study investigates both the energy partition from nuclear recoil energy to secondary modes (scintillation and ionization) and the pulse shape characteristics of scintillation from nuclear recoils.

  1. WIMP dark matter candidates and searches—current status and future prospects

    Science.gov (United States)

    Roszkowski, Leszek; Sessolo, Enrico Maria; Trojanowski, Sebastian

    2018-06-01

    We review several current aspects of dark matter theory and experiment. We overview the present experimental status, which includes current bounds and recent claims and hints of a possible signal in a wide range of experiments: direct detection in underground laboratories, gamma-ray, cosmic ray, x-ray, neutrino telescopes, and the LHC. We briefly review several possible particle candidates for a weakly interactive massive particle (WIMP) and dark matter that have recently been considered in the literature. We pay particular attention to the lightest neutralino of supersymmetry as it remains the best motivated candidate for dark matter and also shows excellent detection prospects. Finally we briefly review some alternative scenarios that can considerably alter properties and prospects for the detection of dark matter obtained within the standard thermal WIMP paradigm.

  2. Halo-independent analysis of direct detection data for light WIMPs

    International Nuclear Information System (INIS)

    Nobile, Eugenio Del; Gelmini, Graciela B.; Huh, Ji-Haeng; Gondolo, Paolo

    2013-01-01

    We present a halo-independent analysis of direct detection data on ''light WIMPs'', i.e. weakly interacting massive particles with mass close to or below 10 GeV/c 2 . We include new results from silicon CDMS detectors (bounds and excess events), the latest CoGeNT acceptances, and recent measurements of low sodium quenching factors in NaI crystals. We focus on light WIMPs with spin-independent isospin-conserving and isospin-violating interactions with nucleons. For these dark matter candidates we find that a low quenching factor would make the DAMA modulation incompatible with a reasonable escape velocity for the dark matter halo, and that the tension among experimental data tightens in both the isospin-conserving and isospin-violating scenarios. We also find that a new although milder tension appears between the CoGeNT and DAMA annual modulations on one side and the silicon excess events on the other, in that it seems difficult to interpret them as the modulated and unmodulated aspects of the same WIMP dark matter signal

  3. WIMP-nucleon cross-section results from the second science run of ZEPLIN-III

    Energy Technology Data Exchange (ETDEWEB)

    Akimov, D.Yu. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Araujo, H.M., E-mail: h.araujo@imperial.ac.uk [High Energy Physics Group, Blackett Laboratory, Imperial College London (United Kingdom); Barnes, E.J. [School of Physics and Astronomy, SUPA University of Edinburgh (United Kingdom); Belov, V.A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bewick, A. [High Energy Physics Group, Blackett Laboratory, Imperial College London (United Kingdom); Burenkov, A.A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Chepel, V. [LIP-Coimbra and Department of Physics of the University of Coimbra (Portugal); Currie, A. [High Energy Physics Group, Blackett Laboratory, Imperial College London (United Kingdom); DeViveiros, L. [LIP-Coimbra and Department of Physics of the University of Coimbra (Portugal); Edwards, B. [Particle Physics Department, STFC Rutherford Appleton Laboratory, Chilton (United Kingdom); Ghag, C.; Hollingsworth, A. [School of Physics and Astronomy, SUPA University of Edinburgh (United Kingdom); Horn, M.; Jones, W.G. [High Energy Physics Group, Blackett Laboratory, Imperial College London (United Kingdom); Kalmus, G.E. [Particle Physics Department, STFC Rutherford Appleton Laboratory, Chilton (United Kingdom); Kobyakin, A.S.; Kovalenko, A.G. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Lebedenko, V.N. [High Energy Physics Group, Blackett Laboratory, Imperial College London (United Kingdom); Lindote, A. [LIP-Coimbra and Department of Physics of the University of Coimbra (Portugal); Particle Physics Department, STFC Rutherford Appleton Laboratory, Chilton (United Kingdom); Lopes, M.I. [LIP-Coimbra and Department of Physics of the University of Coimbra (Portugal); and others

    2012-03-13

    We report experimental upper limits on WIMP-nucleon elastic scattering cross sections from the second science run of ZEPLIN-III at the Boulby Underground Laboratory. A raw fiducial exposure of 1344 kg Dot-Operator days was accrued over 319 days of continuous operation between June 2010 and May 2011. A total of eight events was observed in the signal acceptance region in the nuclear recoil energy range 7-29 keV, which is compatible with background expectations. This allows the exclusion of the scalar cross-section above 4.8 Multiplication-Sign 10{sup -8} pb near 50 GeV/c{sup 2} WIMP mass with 90% confidence. Combined with data from the first run, this result improves to 3.9 Multiplication-Sign 10{sup -8} pb. The corresponding WIMP-neutron spin-dependent cross-section limit is 8.0 Multiplication-Sign 10{sup -3} pb. The ZEPLIN programme reaches thus its conclusion at Boulby, having deployed and exploited successfully three liquid xenon experiments of increasing reach.

  4. WIMP-nucleon cross-section results from the second science run of ZEPLIN-III

    International Nuclear Information System (INIS)

    Akimov, D.Yu.; Araújo, H.M.; Barnes, E.J.; Belov, V.A.; Bewick, A.; Burenkov, A.A.; Chepel, V.; Currie, A.; DeViveiros, L.; Edwards, B.; Ghag, C.; Hollingsworth, A.; Horn, M.; Jones, W.G.; Kalmus, G.E.; Kobyakin, A.S.; Kovalenko, A.G.; Lebedenko, V.N.; Lindote, A.; Lopes, M.I.

    2012-01-01

    We report experimental upper limits on WIMP-nucleon elastic scattering cross sections from the second science run of ZEPLIN-III at the Boulby Underground Laboratory. A raw fiducial exposure of 1344 kg⋅days was accrued over 319 days of continuous operation between June 2010 and May 2011. A total of eight events was observed in the signal acceptance region in the nuclear recoil energy range 7-29 keV, which is compatible with background expectations. This allows the exclusion of the scalar cross-section above 4.8×10 -8 pb near 50 GeV/c 2 WIMP mass with 90% confidence. Combined with data from the first run, this result improves to 3.9×10 -8 pb. The corresponding WIMP-neutron spin-dependent cross-section limit is 8.0×10 -3 pb. The ZEPLIN programme reaches thus its conclusion at Boulby, having deployed and exploited successfully three liquid xenon experiments of increasing reach.

  5. Search for Dark Matter Satellites Using the Fermi-Lat

    Science.gov (United States)

    Ackermann, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; hide

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-16

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

  7. The Cryogenic Dark Matter Search (CDMS-II) Experiment: First Results from the Soudan Mine

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Clarence Leeder [Stanford Univ., CA (United States)

    2004-09-01

    There is an abundance of evidence that the majority of the mass of the universe is in the form of non-baryonic non-luminous matter that was non-relativistic at the time when matter began to dominate the energy density. Weakly Interacting Massive Particles, or WIMPs, are attractive cold dark matter candidates because they would have a relic abundance today of ~0.1 which is consistent with precision cosmological measurements. WIMPs are also well motivated theoretically. Many minimal supersymmetric extensions of the Standard Model have WIMPs in the form of the lightest supersymmetric partner, typically taken to be the neutralino. The CDMS II experiment searches for WIMPs via their elastic scattering off of nuclei. The experiment uses Ge and Si ZIP detectors, operated at <50 mK, which simultaneously measure the ionization and athermal phonons produced by the scattering of an external particle. The dominant background for the experiment comes from electromagnetic interactions taking place very close to the detector surface. Analysis of the phonon signal from these interactions makes it possible to discriminate them from interactions caused by WIMPs. This thesis presents the details of an important aspect of the phonon pulse shape analysis known as the ''Lookup Table Correction''. The Lookup Table Correction is a position dependent calibration of the ZIP phonon response which improves the rejection of events scattering near the detector surface. The CDMS collaboration has recently commissioned its experimental installation at the Soudan Mine. This thesis presents an analysis of the data from the first WIMP search at the Soudan Mine. The results of this analysis set the world's lowest exclusion limit making the CDMS II experiment at Soudan the most sensitive WIMP search to this date.

  8. A Low-Threshold Analysis of Data from the Cryogenic Dark Matter Search Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Bunker, Raymond [Univ. of California, Santa Barbara, CA (United States)

    2011-12-01

    Although dark matter appears to constitute over 80% of the matter in the Universe, its composition is a mystery. Astrophysical observations suggest that the luminous portions of the Galaxy are embedded in a halo of darkmatter particles. Weakly Interacting Massive Particles (WIMPs) are the most studied class of dark-matter candidates and arise naturally within the context of many weak-scale supersymmetric theories. Direct-detection experiments like the Cryogenic Dark Matter Search (CDMS) strive to discern the kinetic energy of recoiling nuclei resulting from WIMP interactions with terrestrial matter. This is a considerable challenge in which the low (expected) rate of WIMP interactions must be distinguished from an overwhelming rate due to known types of radiation. An incontrovertible positive detection has remained elusive. However, a few experiments have recorded data that appear consistent with a low-mass WIMP. This thesis describes an attempt to probe the favored parameter space. To increase sensitivity to low-mass WIMPs, a low-threshold technique with improved sensitivity to small energy depositions is applied to CDMS shallowsite data. Four germanium and two silicon detectors were operated between December 2001 and June 2002, yielding 118 days of exposure. By sacrificing some of the CDMS detectors’ ability to discriminate signal from background, energy thresholds of ~1 and ~2 keV were achieved for three of the germanium and both silicon detectors, respectively. A large number of WIMP candidate events are observed, most of which can be accounted for by misidentification of background sources. No conclusive evidence for a low-mass WIMP signal is found. The observed event rates are used to set upper limits on the WIMPnucleon scattering cross section as a function of WIMP mass. Interesting parameter space is excluded for WIMPs with masses below ~9GeV/c2. Under standard assumptions, the parameter space favored by interpretations of other experiments

  9. Direct detection of WIMPs: implications of a self-consistent truncated isothermal model of the Milky Way's dark matter halo

    Science.gov (United States)

    Chaudhury, Soumini; Bhattacharjee, Pijushpani; Cowsik, Ramanath

    2010-09-01

    Direct detection of Weakly Interacting Massive Particle (WIMP) candidates of Dark Matter (DM) is studied within the context of a self-consistent truncated isothermal model of the finite-size dark halo of the Galaxy. The halo model, based on the ``King model'' of the phase space distribution function of collisionless DM particles, takes into account the modifications of the phase-space structure of the halo due to the gravitational influence of the observed visible matter in a self-consistent manner. The parameters of the halo model are determined by a fit to a recently determined circular rotation curve of the Galaxy that extends up to ~ 60 kpc. Unlike in the Standard Halo Model (SHM) customarily used in the analysis of the results of WIMP direct detection experiments, the velocity distribution of the WIMPs in our model is non-Maxwellian with a cut-off at a maximum velocity that is self-consistently determined by the model itself. For our halo model that provides the best fit to the rotation curve data, the 90% C.L. upper limit on the WIMP-nucleon spin-independent cross section from the recent results of the CDMS-II experiment, for example, is ~ 5.3 × 10-8 pb at a WIMP mass of ~ 71 GeV. We also find, using the original 2-bin annual modulation amplitude data on the nuclear recoil event rate seen in the DAMA experiment, that there exists a range of small WIMP masses, typically ~ 2-16 GeV, within which DAMA collaboration's claimed annual modulation signal purportedly due to WIMPs is compatible with the null results of other experiments. These results, based as they are on a self-consistent model of the dark matter halo of the Galaxy, strengthen the possibility of low-mass (lsim10 GeV) WIMPs as a candidate for dark matter as indicated by several earlier studies performed within the context of the SHM. A more rigorous analysis using DAMA bins over smaller intervals should be able to better constrain the ``DAMA regions'' in the WIMP parameter space within the context of

  10. The Cryogenic Dark Matter Search and Background Rejection with Event Position Information

    International Nuclear Information System (INIS)

    Wang, Gen-sheng

    2005-01-01

    Evidence from observational cosmology and astrophysics indicates that about one third of the universe is matter, but that the known baryonic matter only contributes to the universe at 4%. A large fraction of the universe is cold and non-baryonic matter, which has important role in the universe structure formation and its evolution. The leading candidate for the non-baryonic dark matter is Weakly Interacting Massive Particles (WIMPs), which naturally occurs in the supersymmetry theory in particle physics. The Cryogenic Dark Matter Search (CDMS) experiment is searching for evidence of a WIMP interaction off an atomic nucleus in crystals of Ge and Si by measuring simultaneously the phonon energy and ionization energy of the interaction in the CDMS detectors. The WIMP interaction energy is from a few keV to tens of keV with a rate less than 0.1 events/kg/day. To reach the goal of WIMP detection, the CDMS experiment has been conducted in the Soudan mine with an active muon veto and multistage passive background shields. The CDMS detectors have a low energy threshold and background rejection capabilities based on ionization yield. However, betas from contamination and other radioactive sources produce surface interactions, which have low ionization yield, comparable to that of bulk nuclear interactions. The low-ionization surface electron recoils must be removed in the WIMP search data analysis. An emphasis of this thesis is on developing the method of the surface-interaction rejection using location information of the interactions, phonon energy distributions and phonon timing parameters. The result of the CDMS Soudan run118 92.3 live day WIMP search data analysis is presented, and represents the most sensitive search yet performed

  11. The Cryogenic Dark Matter Search and Background Rejection with Event Position Information

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Gensheng [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics

    2005-01-01

    Evidence from observational cosmology and astrophysics indicates that about one third of the universe is matter, but that the known baryonic matter only contributes to the universe at 4%. A large fraction of the universe is cold and non-baryonic matter, which has important role in the universe structure formation and its evolution. The leading candidate for the non-baryonic dark matter is Weakly Interacting Massive Particles (WIMPs), which naturally occurs in the supersymmetry theory in particle physics. The Cryogenic Dark Matter Search (CDMS) experiment is searching for evidence of a WIMP interaction off an atomic nucleus in crystals of Ge and Si by measuring simultaneously the phonon energy and ionization energy of the interaction in the CDMS detectors. The WIMP interaction energy is from a few keV to tens of keV with a rate less than 0.1 events/kg/day. To reach the goal of WIMP detection, the CDMS experiment has been conducted in the Soudan mine with an active muon veto and multistage passive background shields. The CDMS detectors have a low energy threshold and background rejection capabilities based on ionization yield. However, betas from contamination and other radioactive sources produce surface interactions, which have low ionization yield, comparable to that of bulk nuclear interactions. The low-ionization surface electron recoils must be removed in the WIMP search data analysis. An emphasis of this thesis is on developing the method of the surface-interaction rejection using location information of the interactions, phonon energy distributions and phonon timing parameters. The result of the CDMS Soudan run118 92.3 live day WIMP search data analysis is presented, and represents the most sensitive search yet performed.

  12. Further results on the WIMP annual modulation signature by DAMA/NaI

    International Nuclear Information System (INIS)

    Bernabei, R.; Belli, P.; Cappella, F.

    2005-01-01

    The ≅ 100 kg highly radiopure NaI(Tl) set-up of the DAMA project (DAMA/NaI) has investigated the model- independent WIMP annual modulation signature over seven annual cycles for a total exposure of 107731 kg x day, obtaining a model-independent evidence for the presence of a dark matter particle component in the galactic halo at 6.3 σ C.L.. Some of the many possible corollary model-dependent quests for the candidate particle have been investigated with the total exposure as well

  13. CPN/Tools: A Post-WIMP Interface for Editing and Simulating Coloured Petri Nets

    DEFF Research Database (Denmark)

    Andersen, Peter; Beaudouin-Lafon, Michel; Mackay, Wendy E.

    2001-01-01

    traditional ideas about user interfaces, getting rid of pull-down menus, scrollbars, and even selection, while providing the same or greater functionality. It also uses the new and much faster CPN simulator and features incremental syntax checking of the nets. CPN/Tools requires an OpenGL graphics accelerator......CPN/Tools is a major redesign of the popular Design/CPN tool from the University of Aarhus CPN group. The new interface is based on advanced, post-WIMP interaction techniques, including bi-manual interaction, toolglasses and marking menus and a new metaphor for managing the workspace. It challenges...

  14. The use of twin-screen-based WIMPS in spacecraft control

    Science.gov (United States)

    Klim, R. D.

    1990-10-01

    The ergonomic problems of designing a sophisticated Windows Icons Mouse Pop-up (WIMP) based twin screen workstation are outlined. These same problems will be encountered by future spacecraft controllers. The design of a modern, advanced workstation for use on a distributed multicontrol center in a multisatellite control system is outlined. The system uses access control mechanisms to ensure that only authorized personnel can undertake certain operations on the workstation. Rules governing the use of windowing features, screen attributes, icons, keyboard and mouse in spacecraft control are discussed.

  15. Prospects of indirect searches for dark matter at INO

    Science.gov (United States)

    Choubey, Sandhya; Ghosh, Anushree; Tiwari, Deepak

    2018-05-01

    The annihilation of Weakly Interactive Massive Particles (WIMP) in the centre of the sun could give rise to neutrino fluxes. We study the prospects of searching for these neutrinos at the upcoming Iron CALorimeter (ICAL) detector to be housed at the India-based Neutrino Observatory (INO). We perform ICAL simulations to obtain the detector efficiencies and resolutions in order to simulate muon events in ICAL due to neutrinos coming from annihilation of WIMP in the mass range mχ = (3‑100) GeV . The atmospheric neutrinos pose a major background for these indirect detection studies and can be reduced using the fact that the signal comes only from the direction of the sun. For a given WIMP mass, we find the opening angle θ90 such that 90 % of the signal events are contained within this angle and use this cone-cut criteria to reduce the atmospheric neutrino background. The reduced background is then weighted by the solar exposure function at INO to obtain the final background spectrum for a given WIMP mass. We perform a χ2 analysis and present expected exclusion regions in the σSD‑mχ and σSI‑mχ, where σSD and σSI are the WIMP-nucleon Spin-Dependent (SD) and Spin-Independent (SI) scattering cross-section, respectively. For a 10 years exposure and mχ=25 GeV, the expected 90 % C.L. exclusion limit is found to be σSD < 6.87× 10‑41 cm2 and σSI < 7.75× 10‑43 cm2 for the τ+ τ‑ annihilation channel and σSD < 1.14× 10‑39 cm2 and σSI < 1.30× 10‑41 cm2 for the b bar b channel, assuming 100 % branching ratio for each of the WIMP annihilation channel.

  16. First search for dark matter annihilations in the Earth with the IceCube detector

    Energy Technology Data Exchange (ETDEWEB)

    Aartsen, M.G.; Hill, G.C.; Robertson, S.; Wallace, A.; Whelan, B.J. [University of Adelaide, Department of Physics, Adelaide (Australia); Abraham, K.; Bernhard, A.; Coenders, S.; Holzapfel, K.; Huber, M.; Jurkovic, M.; Krings, K.; Resconi, E.; Turcati, A.; Veenkamp, J. [Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Ackermann, M.; Bernardini, E.; Blot, S.; Bretz, H.P.; Franckowiak, A.; Gluesenkamp, T.; Jacobi, E.; Karg, T.; Kintscher, T.; Kunwar, S.; Mohrmann, L.; Nahnhauer, R.; Satalecka, K.; Spiering, C.; Stasik, A.; Stoessl, A.; Strotjohann, N.L.; Terliuk, A.; Usner, M.; Santen, J. van; Yanez, J.P. [DESY, Zeuthen (Germany); Adams, J. [University of Canterbury, Department of Physics and Astronomy, Private Bag 4800, Christchurch (New Zealand); Aguilar, J.A.; Ansseau, I.; Heereman, D.; Meagher, K.; Meures, T.; O' Murchadha, A.; Pinat, E.; Raab, C. [Universite Libre de Bruxelles, Science Faculty CP230, Brussels (Belgium); Ahlers, M.; Braun, J.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Fahey, S.; Feintzeig, J.; Ghorbani, K.; Gladstone, L.; Griffith, Z.; Halzen, F.; Hanson, K.; Jero, K.; Karle, A.; Kauer, M.; Kelley, J.L.; Kheirandish, A.; Krueger, C.; Mancina, S.; McNally, F.; Merino, G.; Sabbatini, L.; Tobin, M.N.; Tosi, D.; Vandenbroucke, J.; Rossem, M. van; Wandkowsky, N.; Wendt, C.; Westerhoff, S.; Wille, L.; Xu, D.L. [University of Wisconsin, Department of Physics and Wisconsin IceCube Particle Astrophysics Center, Madison, WI (United States); Ahrens, M.; Bohm, C.; Dumm, J.P.; Finley, C.; Flis, S.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M. [Stockholm University, Department of Physics, Oskar Klein Centre, Stockholm (Sweden); Altmann, D.; Anton, G.; Katz, U.; Kittler, T.; Tselengidou, M. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Centre for Astroparticle Physics, Erlangen (Germany); Andeen, K. [Marquette University, Department of Physics, Milwaukee, WI (United States); Anderson, T.; Dunkman, M.; Eller, P.; Huang, F.; Keivani, A.; Lanfranchi, J.L.; Pankova, D.V.; Quinnan, M.; Tesic, G.; Weiss, M.J. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Archinger, M.; Baum, V.; Boeser, S.; Pino Rosendo, E. del; Di Lorenzo, V.; Eberhardt, B.; Ehrhardt, T.; Foesig, C.C.; Koepke, L.; Krueckl, G.; Peiffer, P.; Sandroos, J.; Steuer, A.; Wiebe, K. [University of Mainz, Institute of Physics, Mainz (Germany); Argueelles, C.; Axani, S.; Collin, G.H.; Conrad, J.M.; Jones, B.J.P.; Moulai, M. [Massachusetts Institute of Technology, Department of Physics, Cambridge, MA (United States); Auffenberg, J.; Bissok, M.; Glagla, M.; Glauch, T.; Haack, C.; Hansmann, B.; Hansmann, T.; Kemp, J.; Konietz, R.; Leuermann, M.; Leuner, J.; Penek, Oe.; Raedel, L.; Reimann, R.; Rongen, M.; Schimp, M.; Schoenen, S.; Schumacher, L.; Stahlberg, M.; Stettner, J.; Vehring, M.; Vogel, E.; Wallraff, M.; Wickmann, S.; Wiebusch, C.H. [RWTH Aachen University, III. Physikalisches Institut, Aachen (Germany); Bai, X. [South Dakota School of Mines and Technology, Physics Department, Rapid City, SD (United States); Barwick, S.W.; Yodh, G. [University of California, Department of Physics and Astronomy, Irvine, CA (United States); Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K. [University of California, Department of Physics, Berkeley, CA (United States); Beatty, J.J. [Ohio State University, Department of Physics and Center for Cosmology and Astro-Particle Physics, Columbus, OH (United States); Ohio State University, Department of Astronomy, Columbus, OH (United States); Becker Tjus, J.; Bos, F.; Eichmann, B.; Kroll, M.; Mandelartz, M.; Schoeneberg, S.; Tenholt, F. [Ruhr-Universitaet Bochum, Fakultaet fuer Physik and Astronomie, Bochum (Germany); Becker, K.H.; Bindig, D.; Helbing, K.; Hickford, S.; Hoffmann, R.; Kopper, S.; Lauber, F.; Naumann, U.; Obertacke Pollmann, A.; Soldin, D. [University of Wuppertal, Department of Physics, Wuppertal (Germany); BenZvi, S.; Cross, R. [University of Rochester, Department of Physics and Astronomy, Rochester, NY (United States); Berley, D.; Blaufuss, E.; Cheung, E.; Felde, J.; Friedman, E.; Hellauer, R.; Hoffman, K.D.; Maunu, R.; Olivas, A.; Schmidt, T.; Song, M.; Sullivan, G.W. [University of Maryland, Department of Physics, College Park, MD (United States); Besson, D.Z. [University of Kansas, Department of Physics and Astronomy, Lawrence, KS (United States); Binder, G.; Gerhardt, L.; Klein, S.R.; Miarecki, S.; Tatar, J. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Collaboration: IceCube Collaboration; and others

    2017-02-15

    We present the results of the first IceCube search for dark matter annihilation in the center of the Earth. Weakly interacting massive particles (WIMPs), candidates for dark matter, can scatter off nuclei inside the Earth and fall below its escape velocity. Over time the captured WIMPs will be accumulated and may eventually self-annihilate. Among the annihilation products only neutrinos can escape from the center of the Earth. Large-scale neutrino telescopes, such as the cubic kilometer IceCube Neutrino Observatory located at the South Pole, can be used to search for such neutrino fluxes. Data from 327 days of detector livetime during 2011/2012 were analyzed. No excess beyond the expected background from atmospheric neutrinos was detected. The derived upper limits on the annihilation rate of WIMPs in the Earth and the resulting muon flux are an order of magnitude stronger than the limits of the last analysis performed with data from IceCube's predecessor AMANDA. The limits can be translated in terms of a spin-independent WIMP-nucleon cross section. For a WIMP mass of 50 GeV this analysis results in the most restrictive limits achieved with IceCube data. (orig.)

  17. Results from the two-tower run of the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Reisetter, Angela Jean [Minnesota U.

    2005-01-01

    The Cryogenic Dark Matter Search has completed two runs at the Soudan Underground Laboratory In the second, two towers of detectors were operated from March to August 2004. CDMS used Ge and Si ZIP (Z-sensitive, Ionization, and Phonon) detectors, operated at 50mK, to look for Weakly Interacting Massive Particles (WIMPs) which may make up most of the dark matter in our universe. These detectors are surrounded by lead and polyethylene shielding as well as an active muon veto. These shields, as well as the overburden of Soudan rock, provide a low background environment for the detectors. The ZIP detectors record the ratio of ionization signal to phonon signal to discriminate between nuclear recoils, characteristic of WIMPs and neutrons, and electron recoils, characteristic of gamma and beta backgrounds. They also provide timing information from the four phonon channels that is used to reject surface events, for which ionization collection is poor. A blind analysis, dened using calibration data taken in situ throughout the run, provides a denition of the WIMP signal region by rejecting backgrounds. This analysis applied to the WIMP search data gives a limit on the spin independent WIMP-nucleon cross-section that is an order of magnitude lower than any other experiment has published.

  18. Measurement of Nuclear Recoils in the CDMS II Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Fallows, Scott Mathew [Univ. of Minnesota, Minneapolis, MN (United States)

    2014-12-01

    The Cryogenic Dark Matter Search (CDMS) experiment is designed to directly detect elastic scatters of weakly-interacting massive dark matter particles (WIMPs), on target nuclei in semiconductor crystals composed of Si and Ge. These scatters would occur very rarely, in an overwhelming background composed primarily of electron recoils from photons and electrons, as well as a smaller but non-negligible background of WIMP-like nuclear recoils from neutrons. The CDMS II generation of detectors simultaneously measure ionization and athermal phonon signals from each scatter, allowing discrimination against virtually all electron recoils in the detector bulk. Pulse-shape timing analysis allows discrimination against nearly all remaining electron recoils taking place near detector surfaces. Along with carefully limited neutron backgrounds, this experimental program allowed for \\background- free" operation of CDMS II at Soudan, with less than one background event expected in each WIMP-search analysis. As a result, exclusionary upper-limits on WIMP-nucleon interaction cross section were placed over a wide range of candidate WIMP masses, ruling out large new regions of parameter space.

  19. First search for dark matter annihilations in the Earth with the IceCube detector

    International Nuclear Information System (INIS)

    Aartsen, M.G.; Hill, G.C.; Robertson, S.; Wallace, A.; Whelan, B.J.; Abraham, K.; Bernhard, A.; Coenders, S.; Holzapfel, K.; Huber, M.; Jurkovic, M.; Krings, K.; Resconi, E.; Turcati, A.; Veenkamp, J.; Ackermann, M.; Bernardini, E.; Blot, S.; Bretz, H.P.; Franckowiak, A.; Gluesenkamp, T.; Jacobi, E.; Karg, T.; Kintscher, T.; Kunwar, S.; Mohrmann, L.; Nahnhauer, R.; Satalecka, K.; Spiering, C.; Stasik, A.; Stoessl, A.; Strotjohann, N.L.; Terliuk, A.; Usner, M.; Santen, J. van; Yanez, J.P.; Adams, J.; Aguilar, J.A.; Ansseau, I.; Heereman, D.; Meagher, K.; Meures, T.; O'Murchadha, A.; Pinat, E.; Raab, C.; Ahlers, M.; Braun, J.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Fahey, S.; Feintzeig, J.; Ghorbani, K.; Gladstone, L.; Griffith, Z.; Halzen, F.; Hanson, K.; Jero, K.; Karle, A.; Kauer, M.; Kelley, J.L.; Kheirandish, A.; Krueger, C.; Mancina, S.; McNally, F.; Merino, G.; Sabbatini, L.; Tobin, M.N.; Tosi, D.; Vandenbroucke, J.; Rossem, M. van; Wandkowsky, N.; Wendt, C.; Westerhoff, S.; Wille, L.; Xu, D.L.; Ahrens, M.; Bohm, C.; Dumm, J.P.; Finley, C.; Flis, S.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M.; Altmann, D.; Anton, G.; Katz, U.; Kittler, T.; Tselengidou, M.; Andeen, K.; Anderson, T.; Dunkman, M.; Eller, P.; Huang, F.; Keivani, A.; Lanfranchi, J.L.; Pankova, D.V.; Quinnan, M.; Tesic, G.; Weiss, M.J.; Archinger, M.; Baum, V.; Boeser, S.; Pino Rosendo, E. del; Di Lorenzo, V.; Eberhardt, B.; Ehrhardt, T.; Foesig, C.C.; Koepke, L.; Krueckl, G.; Peiffer, P.; Sandroos, J.; Steuer, A.; Wiebe, K.; Argueelles, C.; Axani, S.; Collin, G.H.; Conrad, J.M.; Jones, B.J.P.; Moulai, M.; Auffenberg, J.; Bissok, M.; Glagla, M.; Glauch, T.; Haack, C.; Hansmann, B.; Hansmann, T.; Kemp, J.; Konietz, R.; Leuermann, M.; Leuner, J.; Penek, Oe.; Raedel, L.; Reimann, R.; Rongen, M.; Schimp, M.; Schoenen, S.; Schumacher, L.; Stahlberg, M.; Stettner, J.; Vehring, M.; Vogel, E.; Wallraff, M.; Wickmann, S.; Wiebusch, C.H.; Bai, X.; Barwick, S.W.; Yodh, G.; Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K.; Beatty, J.J.; Becker Tjus, J.; Bos, F.; Eichmann, B.; Kroll, M.; Mandelartz, M.; Schoeneberg, S.; Tenholt, F.; Becker, K.H.; Bindig, D.; Helbing, K.; Hickford, S.; Hoffmann, R.; Kopper, S.; Lauber, F.; Naumann, U.; Obertacke Pollmann, A.; Soldin, D.; BenZvi, S.; Cross, R.; Berley, D.; Blaufuss, E.; Cheung, E.; Felde, J.; Friedman, E.; Hellauer, R.; Hoffman, K.D.; Maunu, R.; Olivas, A.; Schmidt, T.; Song, M.; Sullivan, G.W.; Besson, D.Z.; Binder, G.; Gerhardt, L.; Klein, S.R.; Miarecki, S.; Tatar, J.

    2017-01-01

    We present the results of the first IceCube search for dark matter annihilation in the center of the Earth. Weakly interacting massive particles (WIMPs), candidates for dark matter, can scatter off nuclei inside the Earth and fall below its escape velocity. Over time the captured WIMPs will be accumulated and may eventually self-annihilate. Among the annihilation products only neutrinos can escape from the center of the Earth. Large-scale neutrino telescopes, such as the cubic kilometer IceCube Neutrino Observatory located at the South Pole, can be used to search for such neutrino fluxes. Data from 327 days of detector livetime during 2011/2012 were analyzed. No excess beyond the expected background from atmospheric neutrinos was detected. The derived upper limits on the annihilation rate of WIMPs in the Earth and the resulting muon flux are an order of magnitude stronger than the limits of the last analysis performed with data from IceCube's predecessor AMANDA. The limits can be translated in terms of a spin-independent WIMP-nucleon cross section. For a WIMP mass of 50 GeV this analysis results in the most restrictive limits achieved with IceCube data. (orig.)

  20. Large-scale nuclear structure calculations for spin-dependent WIMP scattering with chiral effective field theory currents

    OpenAIRE

    Klos, P.; Menéndez, J.; Gazit, D.; Schwenk, A.

    2013-01-01

    We perform state-of-the-art large-scale shell-model calculations of the structure factors for elastic spin-dependent WIMP scattering off 129,131Xe, 127I, 73Ge, 19F, 23Na, 27Al, and 29Si. This comprehensive survey covers the non-zero-spin nuclei relevant to direct dark matter detection. We include a pedagogical presentation of the formalism necessary to describe elastic and inelastic WIMP-nucleus scattering. The valence spaces and nuclear interactions employed have been previously used in nucl...

  1. Constraints on light WIMP candidates from the isotropic diffuse gamma-ray emission

    International Nuclear Information System (INIS)

    Arina, Chiara; Tytgat, Michel H.G.

    2011-01-01

    Motivated by the measurements reported by direct detection experiments, most notably DAMA, CDMS-II, CoGeNT and Xenon10/100, we study further the constraints that might be set on some light dark matter candidates, M DM ∼ few GeV, using the Fermi-LAT data on the isotropic gamma-ray diffuse emission. In particular, we consider a Dirac fermion singlet interacting through a new Z' gauge boson, and a scalar singlet S interacting through the Higgs portal. Both candidates are WIMP (Weakly Interacting Massive Particles), i.e. they have an annihilation cross-section in the pbarn range. Also they may both have a spin-independent elastic cross section on nucleons in the range required by direct detection experiments. Although being generic WIMP candidates, because they have different interactions with Standard Model particles, their phenomenology regarding the isotropic diffuse gamma-ray emission is quite distinct. In the case of the scalar singlet, the one-to-one correspondence between its annihilation cross-section and its spin-independent elastic scattering cross-section permits to express the constraints from the Fermi-LAT data in the direct detection exclusion plot, σ n 0 −M DM . Depending on the astrophysics, we argue that it is possible to exclude the singlet scalar dark matter candidate at 95% confidence level. The constraints on the Dirac singlet interacting through a Z' are comparatively weaker

  2. Asymmetric WIMP Dark Matter in the presence of DM/anti-DM oscillations

    International Nuclear Information System (INIS)

    Zaharijas, G.

    2014-01-01

    The general class of 'Asymmetric Dark Matter (DM)' scenarios assumes the existence of a primordial particle/anti-particle asymmetry in the dark matter sector related to the asymmetry in the baryonic one, as a way to achieve the observed similarity between the baryonic and dark matter energy densities today. Focusing on this framework we study the effect of oscillations between dark matter and its anti-particle on the re-equilibration of the initial asymmetry. We calculate the evolution of the dark matter relic abundance and show how oscillations re-open the parameter space of asymmetric dark matter models, in particular in the direction of allowing large (WIMP-scale) DM masses. We found in particular that a typical WIMP with a mass at the EW scale (about 1 TeV) having a primordial asymmetry of the same order as the baryon asymmetry, naturally gets the correct relic abundance if the δm mass term is in the ∼ meV range. This turns out to be a natural value for fermionic DM arising from the higher dimensional operator H 2 DM 2 /Λ where H is the Higgs field and Λ ∼ M Pl . Finally, we constrain the parameter space in this framework by applying up-to-date bounds from indirect detection signals on annihilating DM

  3. Consequences of DM/antiDM Oscillations for Asymmetric WIMP Dark Matter

    CERN Document Server

    Cirelli, Marco; Servant, Geraldine; Zaharijas, Gabrijela

    2012-01-01

    Assuming the existence of a primordial asymmetry in the dark sector, a scenario usually dubbed Asymmetric Dark Matter (aDM), we study the effect of oscillations between dark matter and its antiparticle on the re-equilibration of the initial asymmetry before freeze-out, which enable efficient annihilations to recouple. We calculate the evolution of the DM relic abundance and show how oscillations re-open the parameter space of aDM models, in particular in the direction of allowing large (WIMP-scale) DM masses. A typical wimp with a mass at the EW scale (\\sim 100 GeV - 1 TeV) presenting a primordial asymmetry of the same order as the baryon asymmetry naturally gets the correct relic abundance if the DM-number-violating Delta(DM) = 2 mass term is in the \\sim meV range. The re-establishment of annihilations implies that constraints from the accumulation of aDM in astrophysical bodies are evaded. On the other hand, the ordinary bounds from BBN, CMB and indirect detection signals on annihilating DM have to be consi...

  4. Searching for dark matter with neutrino telescopes

    International Nuclear Information System (INIS)

    Hooper, Dan; Silk, Joseph

    2004-01-01

    One of the most interesting mysteries of astrophysics is the puzzle of dark matter. Although numerous techniques have been explored and developed to detect this elusive substance, its nature remains unknown. One such method uses large high-energy neutrino telescopes to look for the annihilation products of dark matter annihilations. In this paper, we briefly review this technique. We describe the calculations used to find the rate of capture of WIMPs in the Sun or Earth and the spectrum of neutrinos produced in the resulting dark matter annihilations. We will discuss these calculations within the context of supersymmetry and models with universal extra dimensions, the lightest supersymmetric particle and lightest Kaluza-Klein particle providing the WIMP candidate in these cases, respectively. We will also discuss the status of some of the experiments relevant to these searches: AMANDA, IceCube and ANTARES

  5. A Bio-Inspired Model-Based Approach for Context-Aware Post-WIMP Tele-Rehabilitation

    Directory of Open Access Journals (Sweden)

    Víctor López-Jaquero

    2016-10-01

    Full Text Available Tele-rehabilitation is one of the main domains where Information and Communication Technologies (ICT have been proven useful to move healthcare from care centers to patients’ home. Moreover, patients, especially those carrying out a physical therapy, cannot use a traditional Window, Icon, Menu, Pointer (WIMP system, but they need to interact in a natural way, that is, there is a need to move from WIMP systems to Post-WIMP ones. Moreover, tele-rehabilitation systems should be developed following the context-aware approach, so that they are able to adapt to the patients’ context to provide them with usable and effective therapies. In this work a model-based approach is presented to assist stakeholders in the development of context-aware Post-WIMP tele-rehabilitation systems. It entails three different models: (i a task model for designing the rehabilitation tasks; (ii a context model to facilitate the adaptation of these tasks to the context; and (iii a bio-inspired presentation model to specify thoroughly how such tasks should be performed by the patients. Our proposal overcomes one of the limitations of the model-based approach for the development of context-aware systems supporting the specification of non-functional requirements. Finally, a case study is used to illustrate how this proposal can be put into practice to design a real world rehabilitation task.

  6. PICASSO, COUPP and PICO - search for dark matter with bubble chambers

    Directory of Open Access Journals (Sweden)

    Amole C.

    2015-01-01

    Full Text Available The PICASSO and COUPP collaborations use superheated liquid detectors to search for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs. These experiments, located in the underground laboratory of SNOLAB, Canada, detect phase transitions triggered by nuclear recoils in the keV range induced by interactions with WIMPs. We present details of the construction and operation of these detectors as well as the results, obtained by several years of observations. We also introduce PICO, a joint effort of the two collaborations to build a second generation ton-scale bubble chamber with 250 liters of active liquid.

  7. Search for dark matter annihilation in the earth using the ANTARES neutrino telescope

    NARCIS (Netherlands)

    Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.J.; Avgitas, T.; Baret, B.; Barrios-Marti, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M.C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coelho, J.A.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; De Bonis, G.; Distefano, C.; Di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsasser, D.; Enzenhofer, A.; Felis, I.; Fusco, L.A.; Galata, S.; Gay, P.; Geisselsoder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Grégoire, T.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A.J.; Hello, Y.; Hernandez-Rey, J.J.; Hofestadt, J.; Hugon, C.; Hossl, J.; Illuminati, G.; James, C.W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kiessling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefevre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martinez-Mora, J.A.; Mathieu, A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Pavalas, G.E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Roensch, K.; Sanchez-Losa, A.; Saldana, M.; Salvadori, I.; Samtleben, D.F.E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Schussler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallee, C.; Van Elewyck, V.; Vivolo, D.; Vizzoca, A.; Wagner, S.; Wilms, J.; Zornoza, J.D.; Zuniga, J.

    2017-01-01

    A search for a neutrino signal from WIMP pair annihilations in the centre of the Earth has been performed with the data collected with the ANTARES neutrino telescope from 2007 to 2012. The event selection criteria have been developed and tuned to maximise the sensitivity of the experiment to such a

  8. Dark Matter Search with sub-keV Germanium Detectors at the China Jinping Underground Laboratory

    International Nuclear Information System (INIS)

    Yue Qian; Wong, Henry T

    2012-01-01

    Germanium detectors with sub-keV sensitivities open a window to search for low-mass WIMP dark matter. The CDEX-TEXONO Collaboration is conducting the first research program at the new China Jinping Underground Laboratory with this approach. The status and plans of the laboratory and the experiment are discussed.

  9. Twenty-three ionization heat detectors for the Dark Matter search with EDELWEISS-II

    International Nuclear Information System (INIS)

    Navick, X.-F.; Beeman, J.; Carty, M.; Chapellier, M.; Gerbier, G.; Granelli, R.; Herve, S.; Karolak, M.; Nizery, F.; Schwamm, F.; Villar, V.

    2006-01-01

    The first phase of the EDELWEISS-II Dark Matter search is under construction. In this phase, 23 detectors with NTD thermal sensors are going to be used for the direct detection of WIMPs. In this paper, we are describing the production, mounting, monitoring and storage techniques, together with the different characteristics of the detectors and their variations

  10. Dark Matter searches at ATLAS

    CERN Document Server

    Cortes-Gonzalez, Arely; The ATLAS collaboration

    2016-01-01

    If Dark Matter interacts weakly with the Standard Model it can be produced at the LHC. It can be identified via initial state radiation (ISR) of the incoming partons, leaving a signature in the detector of the ISR particle (jet, photon, Z or W) recoiling off of the invisible Dark Matter particles, resulting in a large momentum imbalance. Many signatures of large missing transverse momentum recoiling against jets, photons, heavy-flavor quarks, weak gauge bosons or Higgs bosons provide an interesting channel for Dark Matter searches. These LHC searches complement those from (in)direct detection experiments. Results of these searches with the ATLAS experiment, in both effective field theory and simplified models with pair WIMP production are discussed. Both 8TeV and 13TeV pp collision data has been used in these results.

  11. First Dark Matter Search Results from the XENON1T Experiment.

    Science.gov (United States)

    Aprile, E; Aalbers, J; Agostini, F; Alfonsi, M; Amaro, F D; Anthony, M; Arneodo, F; Barrow, P; Baudis, L; Bauermeister, B; Benabderrahmane, M L; Berger, T; Breur, P A; Brown, A; Brown, A; Brown, E; Bruenner, S; Bruno, G; Budnik, R; Bütikofer, L; Calvén, J; Cardoso, J M R; Cervantes, M; Cichon, D; Coderre, D; Colijn, A P; Conrad, J; Cussonneau, J P; Decowski, M P; de Perio, P; Di Gangi, P; Di Giovanni, A; Diglio, S; Eurin, G; Fei, J; Ferella, A D; Fieguth, A; Fulgione, W; Gallo Rosso, A; Galloway, M; Gao, F; Garbini, M; Gardner, R; Geis, C; Goetzke, L W; Grandi, L; Greene, Z; Grignon, C; Hasterok, C; Hogenbirk, E; Howlett, J; Itay, R; Kaminsky, B; Kazama, S; Kessler, G; Kish, A; Landsman, H; Lang, R F; Lellouch, D; Levinson, L; Lin, Q; Lindemann, S; Lindner, M; Lombardi, F; Lopes, J A M; Manfredini, A; Mariş, I; Marrodán Undagoitia, T; Masbou, J; Massoli, F V; Masson, D; Mayani, D; Messina, M; Micheneau, K; Molinario, A; Morå, K; Murra, M; Naganoma, J; Ni, K; Oberlack, U; Pakarha, P; Pelssers, B; Persiani, R; Piastra, F; Pienaar, J; Pizzella, V; Piro, M-C; Plante, G; Priel, N; Rauch, L; Reichard, S; Reuter, C; Riedel, B; Rizzo, A; Rosendahl, S; Rupp, N; Saldanha, R; Dos Santos, J M F; Sartorelli, G; Scheibelhut, M; Schindler, S; Schreiner, J; Schumann, M; Scotto Lavina, L; Selvi, M; Shagin, P; Shockley, E; Silva, M; Simgen, H; Sivers, M V; Stein, A; Thapa, S; Thers, D; Tiseni, A; Trinchero, G; Tunnell, C; Vargas, M; Upole, N; Wang, H; Wang, Z; Wei, Y; Weinheimer, C; Wulf, J; Ye, J; Zhang, Y; Zhu, T

    2017-11-03

    We report the first dark matter search results from XENON1T, a ∼2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042±12)-kg fiducial mass and in the [5,40]  keV_{nr} energy range of interest for weakly interacting massive particle (WIMP) dark matter searches, the electronic recoil background was (1.93±0.25)×10^{-4}  events/(kg×day×keV_{ee}), the lowest ever achieved in such a dark matter detector. A profile likelihood analysis shows that the data are consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10  GeV/c^{2}, with a minimum of 7.7×10^{-47}  cm^{2} for 35-GeV/c^{2} WIMPs at 90% C.L.

  12. First Dark Matter Search Results from the XENON1T Experiment

    Science.gov (United States)

    Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; di Gangi, P.; di Giovanni, A.; Diglio, S.; Eurin, G.; Fei, J.; Ferella, A. D.; Fieguth, A.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Gardner, R.; Geis, C.; Goetzke, L. W.; Grandi, L.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Howlett, J.; Itay, R.; Kaminsky, B.; Kazama, S.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Lin, Q.; Lindemann, S.; Lindner, M.; Lombardi, F.; Lopes, J. A. M.; Manfredini, A.; Mariş, I.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Messina, M.; Micheneau, K.; Molinario, A.; Morâ, K.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Pizzella, V.; Piro, M.-C.; Plante, G.; Priel, N.; Rauch, L.; Reichard, S.; Reuter, C.; Riedel, B.; Rizzo, A.; Rosendahl, S.; Rupp, N.; Saldanha, R.; Dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Shockley, E.; Silva, M.; Simgen, H.; Sivers, M. V.; Stein, A.; Thapa, S.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C.; Vargas, M.; Upole, N.; Wang, H.; Wang, Z.; Wei, Y.; Weinheimer, C.; Wulf, J.; Ye, J.; Zhang, Y.; Zhu, T.; Xenon Collaboration

    2017-11-01

    We report the first dark matter search results from XENON1T, a ˜2000 -kg -target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042 ±12 )-kg fiducial mass and in the [5 ,40 ] keVnr energy range of interest for weakly interacting massive particle (WIMP) dark matter searches, the electronic recoil background was (1.93 ±0.25 )×10-4 events /(kg ×day ×keVee) , the lowest ever achieved in such a dark matter detector. A profile likelihood analysis shows that the data are consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10 GeV /c2 , with a minimum of 7.7 ×10-47 cm2 for 35 -GeV /c2 WIMPs at 90% C.L.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mandic, Vuk [Univ. of California, Berkeley, CA (United States)

    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.

  14. Installation of the Cryogenic Dark Matter Search (CDMS)

    International Nuclear Information System (INIS)

    Barnes, P.D. Jr.; California Univ., Berkeley; Da Silva, A.; British Columbia Univ., Vancouver, BC; Akerib, D.S.; California Univ., Berkeley

    1996-01-01

    We discuss the status of a cryogenic dark matter search beginning operation in the Stanford Underground Facility. The detectors will be cooled in a specially designed cryostat connected to a modified side access Oxford 400 dilution refrigerator. We discuss two detector designs and performance, the cryostat construction and operation, and the multi-level shield surrounding the cryostat. Finally, we will examine the limits which we will be able to set on WIMP dark matter with this experiment. (orig.)

  15. Measurement of Nuclear Recoils in the CDMS II Dark Matter Search

    Science.gov (United States)

    Fallows, Scott M.

    The Cryogenic Dark Matter Search (CDMS) experiment is designed to directly detect elastic scatters of weakly-interacting massive dark matter particles (WIMPs), on target nuclei in semiconductor crystals composed of Si and Ge. These scatters would occur very rarely, in an overwhelming background composed primarily of electron recoils from photons and electrons, as well as a smaller but non-negligible background of WIMP-like nuclear recoils from neutrons. The CDMS~II generation of detectors simultaneously measure ionization and athermal phonon signals from each scatter, allowing discrimination against virtually all electron recoils in the detector bulk. Pulse-shape timing analysis allows discrimination against nearly all remaining electron recoils taking place near detector surfaces. Along with carefully limited neutron backgrounds, this experimental program allowed for "background-free'' operation of CDMS~II at Soudan, with less than one background event expected in each WIMP-search analysis. As a result, exclusionary upper-limits on WIMP-nucleon interaction cross section were placed over a wide range of candidate WIMP masses, ruling out large new regions of parameter space. These results, like any others, are subject to a variety of systematic effects that may alter their final interpretations. A primary focus of this dissertation will be difficulties in precisely calibrating the energy scale for nuclear recoil events like those from WIMPs. Nuclear recoils have suppressed ionization signals relative to electron recoils of the same recoil energy, so the response of the detectors is calibrated differently for each recoil type. The overall normalization and linearity of the energy scale for electron recoils in CDMS~II detectors is clearly established by peaks of known gamma energy in the ionization spectrum of calibration data from a 133Ba source. This electron-equivalent keVee) energy scale enables calibration of the total phonon signal (keVt) by enforcing unity

  16. Solar atmospheric neutrinos and the sensitivity floor for solar dark matter annihilation searches

    Energy Technology Data Exchange (ETDEWEB)

    Argüelles, C.A. [Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge MA (United States); De Wasseige, G. [Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Brussels (Belgium); Fedynitch, A. [Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Jones, B.J.P., E-mail: caad@mit.edu, E-mail: gdewasse@vub.ac.be, E-mail: anatoli.fedynitch@desy.de, E-mail: ben.jones@uta.edu [University of Texas at Arlington, 108 Science Hall, 502 Yates St, Arlington TX (United States)

    2017-07-01

    Cosmic rays interacting in the solar atmosphere produce showers that result in a flux of high-energy neutrinos from the Sun. These form an irreducible background to indirect solar WIMP self-annihilation searches, which look for heavy dark matter particles annihilating into final states containing neutrinos in the Solar core. This background will eventually create a sensitivity floor for indirect WIMP self-annihilation searches analogous to that imposed by low-energy solar neutrino interactions for direct dark matter detection experiments. We present a new calculation of the flux of solar atmospheric neutrinos with a detailed treatment of systematic uncertainties inherent in solar atmospheric shower evolution, and we use this to derive the sensitivity floor for indirect solar WIMP annihilation analyses. We find that the floor lies less than one order of magnitude beyond the present experimental limits on spin-dependent WIMP-proton cross sections for some mass points, and that the high-energy solar atmospheric neutrino flux may be observable with running and future neutrino telescopes.

  17. Geneva University: Dark matter Search with the CDMS experiment

    CERN Multimedia

    Université de Genève

    2011-01-01

    Geneva University Physics Department 24, quai Ernest-Ansermet CH-1211 Geneva 4 Tel: (022) 379 62 73 Fax: (022) 379 69 92   Wednesday 21 September 2011 PARTICLE PHYSICS SEMINAR at 17.00 hrs – Stückelberg Auditorium “ Dark matter Search with the CDMS experiment ” Par Dr. Sebastian Arrenberg, Université de Zürich The Cryogenic Dark Matter Search experiment (CDMS) employs a total of 30 germanium and silicon detectors at the Soudan Underground Laboratory to detect weakly interacting massive particles (WIMPs) via their scattering from the target nuclei. Previous CDMS results, released in December 2009, set the world leading limit on the spin-independent WIMP-nucleon cross section above WIMP masses of ~50 GeV/c2 assuming elastic scattering.  In a subsequent analysis we investigated the inelastic dark matter scenario which was proposed to reconcile the disagreement between the results of DAMA/LIBRA and other existing dark matter searc...

  18. Search for magnetic inelastic dark matter with XENON100

    Energy Technology Data Exchange (ETDEWEB)

    Aprile, E.; Anthony, M. [Physics Department, Columbia University, New York, NY 10027 (United States); Aalbers, J.; Breur, P.A.; Brown, A. [Nikhef and the University of Amsterdam, Science Park, 1098XG Amsterdam (Netherlands); Agostini, F.; Bruno, G. [INFN-Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, 67100 L' Aquila (Italy); Alfonsi, M. [Institut für Physik and Exzellenzcluster PRISMA, Johannes Gutenberg-Universität Mainz, 55099 Mainz (Germany); Amaro, F.D. [LIBPhys, Department of Physics, University of Coimbra, 3004-516 Coimbra (Portugal); Arneodo, F.; Benabderrahmane, M.L. [New York University Abu Dhabi, Abu Dhabi (United Arab Emirates); Barrow, P.; Baudis, L. [Physik-Institut, University of Zurich, 8057 Zurich (Switzerland); Bauermeister, B.; Calvén, J. [Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova, Stockholm SE-10691 (Sweden); Berger, T.; Brown, E. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Bruenner, S. [Max-Planck-Institut für Kernphysik, 69117 Heidelberg (Germany); Budnik, R. [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Bütikofer, L., E-mail: lukas.buetikofer@lhep.unibe.ch, E-mail: xenon@lngs.infn.it [Physikalisches Institut, Universität Freiburg, 79104 Freiburg (Germany); and others

    2017-10-01

    We present the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II. This very distinct signature is predicted in the framework of magnetic inelastic dark matter which has been proposed to reconcile the modulation signal reported by the DAMA/LIBRA collaboration with the null results from other direct detection experiments. No candidate event has been found in the region of interest and upper limits on the WIMP's magnetic dipole moment are derived. The scenarios proposed to explain the DAMA/LIBRA modulation signal by magnetic inelastic dark matter interactions of WIMPs with masses of 58.0 GeV/c{sup 2} and 122.7 GeV/c{sup 2} are excluded at 3.3 σ and 9.3 σ, respectively.

  19. Results from the search for dark matter in the Milky Way with 9 years of data of the ANTARES neutrino telescope

    Directory of Open Access Journals (Sweden)

    A. Albert

    2017-06-01

    Full Text Available Using data recorded with the ANTARES telescope from 2007 to 2015, a new search for dark matter annihilation in the Milky Way has been performed. Three halo models and five annihilation channels, WIMP+WIMP→bb¯,W+W−,τ+τ−,μ+μ− and νν¯, with WIMP masses ranging from 50 GeVc2 to 100 TeVc2, were considered. No excess over the expected background was found, and limits on the thermally averaged annihilation cross-section were set.

  20. The Limiting background in a dark matter search at shallow depth

    Energy Technology Data Exchange (ETDEWEB)

    Perera, Thushara A. [Case Western Reserve U.

    2002-01-01

    A convincing body of evidence from observational and theoretical astrophysics suggests that matter in the universe is dominated by a non-luminous, non-baryonic, non-relativistic component. Weakly Interacting Massive Particles (WIMPs) are a proposed particle candidate that satisfy all of the above criteria. They are a front-runner among dark matter candidates because their predicted contribution to matter in the universe is cosmologically signicant and because they may arise naturally from supersymmetric (SUSY) models of particle physics. The Cryogenic Dark Matter Search (CDMS) employs advanced detectors sensitive to nuclear recoils caused by WIMP scatters and capable of rejecting ionizing backgrounds. The rst phase of the experiment, conducted at a shallow site, is limited by a background of neutrons which are indistinguishable from WIMPs in terms of the acquired data. By accounting for and statistically subtracting these neutrons, CDMS I provides the best dark matter limits to date over a wide range of WIMP masses above 10 GeV/c2 . These results also exclude the signal region claimed by the DAMA annual modulation search at a >71% condence level. The second phase of the experiment, located at a deep site, is scheduled to begin data acquisition in 2002. Due to longer exposures, larger detector mass, and low background rates at this site, data from CDMS II are expected to improve on present WIMP sensitivity by about two orders of magnitude. Emphasized in this work are the research topics in which I have been directly involved. These include the work described in Chapters 3 and 5 with regard to the development and use of simulation tools, detailed studies into the limiting neutron background, and the present understanding of this background in relation to CDMS I and CDMS II. I was also involved in several detector development projects in preparation for CDMS II. Analysis of test data from a ZIP detector, planned for use in CDMS II, is presented in Chapter 6.

  1. The search for decaying Dark Matter

    CERN Document Server

    Herder, J W den; Ruchayskiy, O.; Abazajian, K.; Frenk, C.; Hansen, S.; Jonker, P.; Kouveliotou, C.; Lesgourgues, J.; Neronov, A.; Ohashi, T.; Paerels, F.; Paltani, S.; Piro, L.; Pohl, M.; Shaposhnikov, M.; Silk, J.; Valle, J.W.F.

    2009-01-01

    We propose an X-ray mission called Xenia to search for decaying superweakly interacting Dark Matter particles (super-WIMP) with a mass in the keV range. The mission and its observation plan are capable of providing a major break through in our understanding of the nature of Dark Matter (DM). It will confirm, or reject, predictions of a number of particle physics models by increasing the sensitivity of the search for decaying DM by about two orders of magnitude through a wide-field imaging X-ray spectrometer in combination with a dedicated observation program. The proposed mission will provide unique limits on the mixing angle and mass of neutral leptons, right handed partners of neutrinos, which are important Dark Matter candidates. The existence of these particles is strongly motivated by observed neutrino flavor oscillations and the problem of baryon asymmetry of the Universe. In super-WIMP models, the details of the formation of the cosmic web are different from those of LambdaCDM. The proposed mission wil...

  2. An indirect search for dark matter using antideuterons: the GAPS experiment

    International Nuclear Information System (INIS)

    Hailey, C J

    2009-01-01

    The general antiparticle spectrometer (GAPS) experiment is an indirect dark matter search. GAPS detects the antideuterons produced in WIMP-WIMP annihilation, a generic feature in many theories beyond the Standard Model. Antideuterons are a nearly background free signature of exotic physics. GAPS has substantial discovery potential for dark matter within the minimal supersymmetric model and its extensions, and models with universal extra dimensions. GAPS complements underground experiments, reaching parts of supersymmetric parameter space unavailable to them, and working to better constrain the properties of dark matter where they overlap in parameter space. GAPS is designed to be launched from a balloon. GAPS is funded for a prototype flight in 2011, to be followed by a long duration balloon flight to execute its science program. We discuss recent theoretical investigations on antideuteron searches, and their implications for experiment design. We describe the GAPS experiment placing particular emphasis on recent investigations that represent technical or conceptual extensions of the original GAPS concept.

  3. Dark matter in the Reticulum II dSph: a radio search

    Science.gov (United States)

    Regis, Marco; Richter, Laura; Colafrancesco, Sergio

    2017-07-01

    We present a deep radio search in the Reticulum II dwarf spheroidal (dSph) galaxy performed with the Australia Telescope Compact Array. Observations were conducted at 16 cm wavelength, with an rms sensitivity of 0.01 mJy/beam, and with the goal of searching for synchrotron emission induced by annihilation or decay of weakly interacting massive particles (WIMPs). Data were complemented with observations on large angular scales taken with the KAT-7 telescope. We find no evidence for a diffuse emission from the dSph and we derive competitive bounds on the WIMP properties. In addition, we detect more than 200 new background radio sources. Among them, we show there are two compelling candidates for being the radio counterpart of the possible γ-ray emission reported by other groups using Fermi-LAT data.

  4. Dark matter in the Reticulum II dSph: a radio search

    International Nuclear Information System (INIS)

    Regis, Marco; Richter, Laura; Colafrancesco, Sergio

    2017-01-01

    We present a deep radio search in the Reticulum II dwarf spheroidal (dSph) galaxy performed with the Australia Telescope Compact Array. Observations were conducted at 16 cm wavelength, with an rms sensitivity of 0.01 mJy/beam, and with the goal of searching for synchrotron emission induced by annihilation or decay of weakly interacting massive particles (WIMPs). Data were complemented with observations on large angular scales taken with the KAT-7 telescope. We find no evidence for a diffuse emission from the dSph and we derive competitive bounds on the WIMP properties. In addition, we detect more than 200 new background radio sources. Among them, we show there are two compelling candidates for being the radio counterpart of the possible γ-ray emission reported by other groups using Fermi-LAT data.

  5. Intrinsic neutron background of nuclear emulsions for directional Dark Matter searches

    Science.gov (United States)

    Alexandrov, A.; Asada, T.; Buonaura, A.; Consiglio, L.; D'Ambrosio, N.; De Lellis, G.; Di Crescenzo, A.; Di Marco, N.; Di Vacri, M. L.; Furuya, S.; Galati, G.; Gentile, V.; Katsuragawa, T.; Laubenstein, M.; Lauria, A.; Loverre, P. F.; Machii, S.; Monacelli, P.; Montesi, M. C.; Naka, T.; Pupilli, F.; Rosa, G.; Sato, O.; Strolin, P.; Tioukov, V.; Umemoto, A.; Yoshimoto, M.

    2016-07-01

    Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark Matter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the neutron-induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.06 per year per kilogram, fully compatible with the design of a 10 kg × year exposure.

  6. Proposal to the Gran Sasso Laboratory for a dark matter search using cryogenic detectors

    International Nuclear Information System (INIS)

    Cooper, S.; Colling, P.; Ferger, P.; Frank, M.; Gebauer, H.J.; Nagel, U.; Nucciotti, A.; Proebst, F.; Rulofs, A.; Seidel, W.; Stodolsky, L.; Feilitzsch, F. v.; Forster, G.; Hallatschek, K.; Kellner, E.

    1993-11-01

    We request space and support from the Gran Sasso Laboratory for an experiment searching for dark matter WIMPs using cryogenic detectors. Our experiment is complementary to other dark matter searches in that it extends the sensitivity for WIMPs to the mass range below 10 GeV and that different target materials can be used within the same setup. The proposed experiment uses in the first stage a detector consisting of 1 kg of sapphire with a threshold of 0.5 keV and a resolution of 0.2 keV at 1 keV. The detector would be run at a temperature of 15-30 mK within a low-background setup. The first stage could be installed in 1995. The proposed setup allows for future expansion of the detector to 10-100 kg without major changes. (orig.)

  7. Search for gamma-ray spectral lines with the Fermi Large Area Telescope and dark matter implications

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D’Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Essig, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashida, M.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Izaguirre, E.; Jogler, T.; Kamae, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Malyshev, D.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romani, R. W.; Sánchez-Conde, M.; Schulz, A.; Sgrò, C.; Siegal-Gaskins, J.; Siskind, E. J.; Snyder, A.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Winer, B. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zaharijas, G.; Zimmer, S.

    2013-10-22

    Weakly interacting massive particles (WIMPs) are a theoretical class of particles that are excellent dark matter candidates. WIMP annihilation or decay may produce essentially monochromatic γ rays detectable by the Fermi Large Area Telescope (LAT) against the astrophysical γ -ray emission of the Galaxy. We have searched for spectral lines in the energy range 5–300 GeV using 3.7 years of data, reprocessed with updated instrument calibrations and an improved energy dispersion model compared to the previous Fermi-LAT Collaboration line searches. We searched in five regions selected to optimize sensitivity to different theoretically motivated dark matter density distributions. We did not find any globally significant lines in our a priori search regions and present 95% confidence limits for annihilation cross sections of self-conjugate WIMPs and decay lifetimes. Our most significant fit occurred at 133 GeV in our smallest search region and had a local significance of 3.3 standard deviations, which translates to a global significance of 1.5 standard deviations. We discuss potential systematic effects in this search, and examine the feature at 133 GeV in detail. We find that the use both of reprocessed data and of additional information in the energy dispersion model contributes to the reduction in significance of the linelike feature near 130 GeV relative to significances reported in other works. We also find that the feature is narrower than the LAT energy resolution at the level of 2 to 3 standard deviations, which somewhat disfavors the interpretation of the 133 GeV feature as a real WIMP signal.

  8. Status of the DAMIC Direct Dark Matter Search Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar-Arevalo, A.; et al.

    2015-09-30

    The DAMIC experiment uses fully depleted, high resistivity CCDs to search for dark matter particles. With an energy threshold $\\sim$50 eV$_{ee}$, and excellent energy and spatial resolutions, the DAMIC CCDs are well-suited to identify and suppress radioactive backgrounds, having an unrivaled sensitivity to WIMPs with masses $<$6 GeV/$c^2$. Early results motivated the construction of a 100 g detector, DAMIC100, currently being installed at SNOLAB. This contribution discusses the installation progress, new calibration efforts near the threshold, a preliminary result with 2014 data, and the prospects for physics results after one year of data taking.

  9. Low-Mass Dark Matter Search with the DarkSide-50 Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Agnes, P.; et al.

    2018-02-20

    We present the results of a search for dark matter WIMPs in the mass range below 20 GeV/c^2 using a target of low-radioactivity argon. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso (LNGS). The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 events/keVee/kg/day and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV/c^2 for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV/c^2.

  10. The Electronics and Data Acquisition System of the DarkSide Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Agnes, P.; et al.

    2014-12-09

    It is generally inferred from astronomical measurements that Dark Matter (DM) comprises approximately 27\\% of the energy-density of the universe. If DM is a subatomic particle, a possible candidate is a Weakly Interacting Massive Particle (WIMP), and the DarkSide-50 (DS) experiment is a direct search for evidence of WIMP-nuclear collisions. DS is located underground at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, and consists of three active, embedded components; an outer water veto (CTF), a liquid scintillator veto (LSV), and a liquid argon (LAr) time projection chamber (TPC). This paper describes the data acquisition and electronic systems of the DS detectors, designed to detect the residual ionization from such collisions.

  11. Bolometer's development for the detection of dark matter; Instrumentation autour de bolometres pour la recherche de matiere sombre WIMPs

    Energy Technology Data Exchange (ETDEWEB)

    Yvon, D

    2000-06-01

    The author reviews his contributions to the use of bolometers (cryogenic detectors) for the detection of wimps (weakly interactive massive particles). Wimps are detected through their elastic scattering on the nuclei of the detector, a heat signal, luminescence or ionization can be simultaneously detected (at least 2 signals are necessary to discard photon interactions). Bolometers operate at low temperatures (< 50 mK) so they allow very low detection threshold and resolution (< keV) with a full energy conversion for recoiling nuclei. In Saclay the technology of bolometers based on simultaneous detection of heat and ionisation has been developed and improvements have been studied (NbSi thin films bolometers). The first results obtained in the framework of the Edelweiss collaboration are presented. Other developments based on infra-red bolometry (Planck surveyor and Archeops projects) are briefly described. In an appendix the operating principle of a bolometer is presented. (A.C.)

  12. Top-philic dark matter within and beyond the WIMP paradigm

    Science.gov (United States)

    Garny, Mathias; Heisig, Jan; Hufnagel, Marco; Lülf, Benedikt

    2018-04-01

    We present a comprehensive analysis of top-philic Majorana dark matter that interacts via a colored t -channel mediator. Despite the simplicity of the model—introducing three parameters only—it provides an extremely rich phenomenology allowing us to accommodate the relic density for a large range of coupling strengths spanning over 6 orders of magnitude. This model features all "exceptional" mechanisms for dark matter freeze-out, including the recently discovered conversion-driven freeze-out mode, with interesting signatures of long-lived colored particles at colliders. We constrain the cosmologically allowed parameter space with current experimental limits from direct, indirect and collider searches, with special emphasis on light dark matter below the top mass. In particular, we explore the interplay between limits from Xenon1T, Fermi-LAT and AMS-02 as well as limits from stop, monojet and Higgs invisible decay searches at the LHC. We find that several blind spots for light dark matter evade current constraints. The region in parameter space where the relic density is set by the mechanism of conversion-driven freeze-out can be conclusively tested by R -hadron searches at the LHC with 300 fb-1 .

  13. A search for low-mass dark matter with the cryogenic dark matter search and the development of highly multiplexed phonon-mediated particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David Craig [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2012-01-01

    A wide variety of astrophysical observations indicate that approximately 85% of the matter in the universe is nonbaryonic and nonluminous. Understanding the nature of this "dark matter" is one of the most important outstanding questions in cosmology. Weakly Interacting Massive Particles (WIMPs) are a leading candidate for dark matter since they would be thermally produced in the early universe in the correct abundance to account for the observed relic density of dark matter. If WIMPs account for the dark matter, then rare interactions from relic WIMPs should be observable in terrestrial detectors. Recently, unexplained excess events in the DAMA/LIBRA, CoGeNT, and CRESST-II experiments have been interpreted as evidence of scattering from WIMPs with masses ~10 GeV and spin-independent scattering cross sections of 10-41-10-40 cm2. The Cryogenic Dark Matter Search (CDMS II) attempts to identify WIMP interactions using an array of cryogenic germanium and silicon particle detectors located at the Soudan Underground Laboratory in northern Minnesota. In this dissertation, data taken by CDMS II are reanalyzed using a 2 keV recoil energy threshold to increase the sensitivity to WIMPs with masses ~10 GeV. These data disfavor an explanation for the DAMA/LIBRA, CoGeNT, and CRESST-II results in terms of spin-independent elastic scattering of WIMPs with masses ≲12 GeV, under standard assumptions. At the time of publication, they provided the strongest constraints on spin-independent elastic scattering from 5-9 GeV, ruling out previously unexplored parameter space. To detect WIMPs or exclude the remaining parameter space favored by the most popular models will ultimately require detectors with target masses ≳1 ton, requiring an increase in mass by more than two orders of magnitude over CDMS II. For cryogenic detectors such as CDMS, scaling to such large target masses will require individual detector elements to be fabricated more quickly and cheaply, while

  14. New physics searches in ATLAS and relation to astroparticle physics

    CERN Document Server

    Giangiobbe, V; The ATLAS collaboration

    2014-01-01

    The existence of Dark Matter (DM) is by now well established, and the fit of the cosmological model parameters to various measurements lead to a density of the cold non-baryoninc matter representing 26.5% of the critical density. Despite this relatively large density, the nature of the DM remains unknown. Amongst the preferred candidates for DM are the Weakly Interacting Massive Particles (WIMPs) with a mass roughly between 10 GeV and a few TeV. An intensive search program for DM in solar system has been going on for the last decades, providing limits on the WIMP mass and cross-section, as well as hints of potential signal. The search of direct production of DM at LHC is complementary to the one performed by astrophysics experiments, providing an independent measurement. The ATLAS detector operating at LHC collected data from proton-proton collisions corresponding by now to a total integrated luminosity of 20.3 fb-1 with 8 TeV energy in the center of mass. This high energy and luminosity allows to check the v...

  15. Results from the first science run of the ZEPLIN-III dark matter search experiment

    International Nuclear Information System (INIS)

    Lebedenko, V. N.; Bewick, A.; Currie, A.; Davidge, D.; Dawson, J.; Horn, M.; Howard, A. S.; Jones, W. G.; Joshi, M.; Liubarsky, I.; Quenby, J. J.; Sumner, T. J.; Thorne, C.; Walker, R. J.; Araujo, H. M.; Edwards, B.; Barnes, E. J.; Ghag, C.; Murphy, A. St. J.; Scovell, P. R.

    2009-01-01

    The ZEPLIN-III experiment in the Palmer Underground Laboratory at Boulby uses a 12 kg two-phase xenon time-projection chamber to search for the weakly interacting massive particles (WIMPs) that may account for the dark matter of our Galaxy. The detector measures both scintillation and ionization produced by radiation interacting in the liquid to differentiate between the nuclear recoils expected from WIMPs and the electron-recoil background signals down to ∼10 keV nuclear-recoil energy. An analysis of 847 kg·days of data acquired between February 27, 2008, and May 20, 2008, has excluded a WIMP-nucleon elastic scattering spin-independent cross section above 8.1x10 -8 pb at 60 GeVc -2 with a 90% confidence limit. It has also demonstrated that the two-phase xenon technique is capable of better discrimination between electron and nuclear recoils at low-energy than previously achieved by other xenon-based experiments.

  16. First results from the NEWS-G direct dark matter search experiment at the LSM

    Science.gov (United States)

    Arnaud, Q.; Asner, D.; Bard, J.-P.; Brossard, A.; Cai, B.; Chapellier, M.; Clark, M.; Corcoran, E. C.; Dandl, T.; Dastgheibi-Fard, A.; Dering, K.; Di Stefano, P.; Durnford, D.; Gerbier, G.; Giomataris, I.; Gorel, P.; Gros, M.; Guillaudin, O.; Hoppe, E. W.; Kamaha, A.; Katsioulas, I.; Kelly, D. G.; Martin, R. D.; McDonald, J.; Muraz, J.-F.; Mols, J.-P.; Navick, X.-F.; Papaevangelou, T.; Piquemal, F.; Roth, S.; Santos, D.; Savvidis, I.; Ulrich, A.; Vazquez de Sola Fernandez, F.; Zampaolo, M.

    2018-01-01

    New Experiments With Spheres-Gas (NEWS-G) is a direct dark matter detection experiment using Spherical Proportional Counters (SPCs) with light noble gases to search for low-mass Weakly Interacting Massive Particles (WIMPs). We report the results from the first physics run taken at the Laboratoire Souterrain de Modane (LSM) with SEDINE, a 60 cm diameter prototype SPC operated with a mixture of Ne + CH4 (0.7%) at 3.1 bars for a total exposure of 9.6 kg · days. New constraints are set on the spin-independent WIMP-nucleon scattering cross-section in the sub-GeV/c2 mass region. We exclude cross-sections above 4.4 ×10-37cm2 at 90% confidence level (C.L.) for a 0.5 GeV/c2 WIMP. The competitive results obtained with SEDINE are promising for the next phase of the NEWS-G experiment: a 140 cm diameter SPC to be installed at SNOLAB by summer 2018.

  17. Cryogenic dark matter search (CDMS II): Application of neural networks and wavelets to event analysis

    Energy Technology Data Exchange (ETDEWEB)

    Attisha, Michael J. [Brown U.

    2006-01-01

    The Cryogenic Dark Matter Search (CDMS) experiment is designed to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs) via their elastic scattering interactions with nuclei. This dissertation presents the CDMS detector technology and the commissioning of two towers of detectors at the deep underground site in Soudan, Minnesota. CDMS detectors comprise crystals of Ge and Si at temperatures of 20 mK which provide ~keV energy resolution and the ability to perform particle identification on an event by event basis. Event identification is performed via a two-fold interaction signature; an ionization response and an athermal phonon response. Phonons and charged particles result in electron recoils in the crystal, while neutrons and WIMPs result in nuclear recoils. Since the ionization response is quenched by a factor ~ 3(2) in Ge(Si) for nuclear recoils compared to electron recoils, the relative amplitude of the two detector responses allows discrimination between recoil types. The primary source of background events in CDMS arises from electron recoils in the outer 50 µm of the detector surface which have a reduced ionization response. We develop a quantitative model of this ‘dead layer’ effect and successfully apply the model to Monte Carlo simulation of CDMS calibration data. Analysis of data from the two tower run March-August 2004 is performed, resulting in the world’s most sensitive limits on the spin-independent WIMP-nucleon cross-section, with a 90% C.L. upper limit of 1.6 × 10-43 cm2 on Ge for a 60 GeV WIMP. An approach to performing surface event discrimination using neural networks and wavelets is developed. A Bayesian methodology to classifying surface events using neural networks is found to provide an optimized method based on minimization of the expected dark matter limit. The discrete wavelet analysis of CDMS phonon pulses improves surface event discrimination in conjunction with the neural

  18. Search Help

    Science.gov (United States)

    Guidance and search help resource listing examples of common queries that can be used in the Google Search Appliance search request, including examples of special characters, or query term seperators that Google Search Appliance recognizes.

  19. Detection of WIMPs in the Edelweiss experiment. Study of the radioactive background noise and measurements with bolometers; Recherche des wimp's du halo galactique dans l'experience edelweiss: etude du bas bruit radioactif et mesures a l'aide de bolometres a double detection ionisation/chaleur

    Energy Technology Data Exchange (ETDEWEB)

    Miramonti, L. [CEA/Saclay, Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee (DAPNIA), 91 - Gif-sur-Yvette (France)]|[Paris-11 Univ., 91 - Orsay (France)

    1999-11-01

    This thesis is dedicated to the detection of black matter in the form of WIMPs (weakly interacting massive particle). The characteristics of the interaction of WIMPs with matter are recalled. The very low number of expected events (<1 event/day.Kg) implies a radioactive background noise as weak as possible, furthermore the exponential decrease of the interacting rate with increasing energy calls for detectors with very low thresholds. Bolometers present advantages in WIMPs detection: i) very good resolution and very low thresholds, ii) very broad range of materials that can be used as absorber, the only requirements are: a crystal structure, to be a diamagnetic isolator and to have a convenient Debye temperature, iii) the possibility of detecting ionizing or non-ionizing particles, iv) the possibility of identifying the incident particle by measuring both temperature and another parameter such as ionization or scintillation, and v) the possibility of localizing the interaction inside the absorber by detecting ballistic phonons. The problematic of radioactive background noise is presented and the answers to the different sources (cosmic radiation,natural and artificial radioactivity) generating the background noise are examined. The materials used in the building of the detector and cryostat must be carefully chosen, they should be as little radioactive as possible. The test benches used to select materials for the Edelweiss experiment are described. The first measurements concerning the detectors Ge-4 and Ge-7 are presented. (A.C.)

  20. Dark matter annihilations search in dwarf spheroidal galaxies with fermi

    International Nuclear Information System (INIS)

    Farnier, C.; Nuss, E.; Cohen-Tanugi, J.

    2011-01-01

    Launched in June 2008, the Fermi Gamma-ray Telescope includes a pair conversion detector designed for the 20 MeV to ∼300GeV gamma-ray sky study, the Large Area Telescope (LAT). Operating in all-sky survey mode, its excellent sensitivity and angular resolution will allow either to discover or constrain a signal coming through the annihilation of dark matter particles. Predicted by cold dark matter scenarios as the largest clumps, dwarf spheroidal galaxies are amongst the most attractive targets for indirect search of dark matter by gamma-ray experiments. We present here an overview of the Fermi LAT Dark Matter and New Physics Working Group efforts in the searches of gamma-ray fluxes coming from WIMP pair annihilations in dwarf spheroidal galaxies.

  1. EDELWEISS: dark matter search from phase 2 to phase 3

    International Nuclear Information System (INIS)

    Cazes, A.

    2014-01-01

    The EDELWEISS detector is located inside the Modane underground facility. The EDELWEISS-3 experiment searches for dark matter. Nuclear recoils are observed both by ionization and temperature measurements in Germanium bolometers; EDELWEISS-3 is an upgraded version of the EDELWEISS-2 experiment and will contain forty 800-g Ge detectors with a fully inter-digitized electrode readout scheme. Other improvements are the cryogenics, the shielding of the detectors and the front-end electronics that have been updated for improved data readout and noise reduction. Furthermore, a new analysis of EDELWEISS-2 data has been performed to extend the limits of Wimp search in the low mass region. The current status of EDELWEISS-3 will be discussed as well as the latest analysis results from EDELWEISS-2. (author)

  2. Status of dark matter searches in the boulby mine

    CERN Document Server

    Hart, S P

    2002-01-01

    We present the current status and future plans for dark matter searches in the Boulby Mine. A 50 kg array of NaI(Tl) crystals is under construction and a method of suppressing anomalous, fast signals in such detectors is described. Liquid Xe based detectors, with improved background rejection, are under development. The first of these, ZEPLIN I, is already deployed and uses pulse shape discrimination. ZEPLIN II and III measure the ratio of ionisation to scintillation by use of an electric field to extract ionisation from the liquid into a gas phase. Finally a low pressure gas drift chamber with directional sensitivity has been installed, larger versions of which will enable a search for correlations between any WIMP signal and galactic motion.

  3. Academic Training: Search for Dark Matter - Lecture series

    CERN Multimedia

    Françoise Benz

    2004-01-01

    28, 29, 30 June, 1 & 2 July ACADEMIC TRAINING LECTURE REGULAR PROGRAMME From 11:00 hrs - 28, 29 June, 1, 2 July, Main Auditorium bldg. 500. 30 June, Council Chamber bldg. 503 Search for Dark Matter B. Sadoulet / Univ. of California, Berkeley, USA In the first lecture, I will review the most recent cosmological evidence for the pervading dark matter in the universe and the emerging consensus that it is not ordinary matter. We will then focus on thermal particle candidates, which may have been produced in the hot early universe and stayed around to constitute dark matter: neutrinos and Weakly Interacting Massive Particles (WIMPs). I will emphasize what can be learnt from cosmology (e.g. the evidence for cold dark matter and the limits on neutrino masses). The third and the fourth lectures will be devoted the direct detection of WIMPs, its technical challenges and the present status. I will describe the recent advances from phonon-mediated detectors which currently provide the best limits and revi...

  4. Random searching

    International Nuclear Information System (INIS)

    Shlesinger, Michael F

    2009-01-01

    There are a wide variety of searching problems from molecules seeking receptor sites to predators seeking prey. The optimal search strategy can depend on constraints on time, energy, supplies or other variables. We discuss a number of cases and especially remark on the usefulness of Levy walk search patterns when the targets of the search are scarce.

  5. Search Patterns

    CERN Document Server

    Morville, Peter

    2010-01-01

    What people are saying about Search Patterns "Search Patterns is a delight to read -- very thoughtful and thought provoking. It's the most comprehensive survey of designing effective search experiences I've seen." --Irene Au, Director of User Experience, Google "I love this book! Thanks to Peter and Jeffery, I now know that search (yes, boring old yucky who cares search) is one of the coolest ways around of looking at the world." --Dan Roam, author, The Back of the Napkin (Portfolio Hardcover) "Search Patterns is a playful guide to the practical concerns of search interface design. It cont

  6. A search for non-baryonic dark matter using an ionisation bolometer in the edelweiss experiment

    International Nuclear Information System (INIS)

    Di Stefano, Ph.

    1998-01-01

    The EDELWEISS experiment is an underground direct-detection search for hypothetical supersymmetric WIMPs that might solve the problem of dark matter. We have employed a cryogenic 70 g germanium ionisation bolometer, in which a WIMP would scatter elastically off a nucleus, creating both a heat and an ionisation signal. To offset the various electronic noises present in our necessarily small signals, we have s applied an optimal filtering technique in the frequency domain. This allows us to reach resolutions of 1.2 keV FWHM at 122 keV on north channels. It also provides good separation right down to low energies between the expected signal of nuclear recoils, and the photonic background of electron recoils which ionize more for a given energy. Calibration data show that we are able to reject 99.7 % of this background, while keeping 95% of the signal. However, our 1.17 kg.days of data searching for WIMPs show a third population encroaching on the expected signal. This is probably due to low energy photons or electrons interacting in the outer layers of the crystal, where charges are incompletely collected. Nevertheless, by trading off half of the conserved signal, we still manage to reject 98.5 % of the background. Thus the raw rate of 40 evts/d/kg/keV yields a conservative 90 % upper limit on the signal of 0.6 evts/d/kg/keV. This represents nearly a three orders of magnitude improvement for EDELWEISS, and puts the predicted supersymmetric phase space within two orders of magnitude. (author)

  7. Report on Research in Experimental High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Rusack, Roger W. [Univ. of Minnesota, Minneapolis, MN (United States); Cushman, Priscilla [Univ. of Minnesota, Minneapolis, MN (United States); Poling, Ronald [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-01-06

    In the past three years the groups supported by the DOE have all made significant progress and posted major successes. The Minnesota CMS group has played leading roles in five data analyses and has had major roles in detector operations, the data management and the detector upgrades that are planned for for the LHC and those that are planned for the high-luminosity LHC. The CDMS-II experiment held the lead in WIMP sensitivity over the last decade, and is still the most sensitive detector in the world in the low WIMP mass region, with a recent 3σ hint of 8 GeV/c2 WIMP candidates in the silicon data. SuperCDMS, with three orders of magnitude better electron recoil background rejection, has been collecting data since October 2011. Since all dark matter experiments require a better understanding of neutron backgrounds to make further advances in sensitivity, Cushman has expanded the Minnesota effort on backgrounds to the national level, where she is leading a coordinated effort in neutron simulations for underground physics. The work of Mandic on 100 mm detectors both for Super-CDMS and beyond has advanced rapidly. Also at the Intensity Frontier, the BESIII experiment has had a successful year of operation largely focused on searches for and studies of new "charmonium-like" states above DD threshold. At least one new state has been observed so far, with hints of others. An intensive effort to understand their nature and gain new insight into the strong interaction continues. BESIII has also produced a large number of other results in charmonium decay and light-hadronic physics.

  8. Personalized Search

    CERN Document Server

    AUTHOR|(SzGeCERN)749939

    2015-01-01

    As the volume of electronically available information grows, relevant items become harder to find. This work presents an approach to personalizing search results in scientific publication databases. This work focuses on re-ranking search results from existing search engines like Solr or ElasticSearch. This work also includes the development of Obelix, a new recommendation system used to re-rank search results. The project was proposed and performed at CERN, using the scientific publications available on the CERN Document Server (CDS). This work experiments with re-ranking using offline and online evaluation of users and documents in CDS. The experiments conclude that the personalized search result outperform both latest first and word similarity in terms of click position in the search result for global search in CDS.

  9. Dark Matter searches using gravitational wave bar detectors: quark nuggets and newtorites

    CERN Document Server

    Bassan, M; D'Antonio, S.; Fafone, V.; Giordano, G.; Marini, A.; Minenkov, Y.; Modena, I.; Pallottino, G.V.; Pizzella, G.; Rocchi, A.; Ronga, F.; Visco, M.

    2016-01-01

    Many experiments have searched for supersymmetric WIMP dark matter, with null results. This may suggest to look for more exotic possibilities, for example compact ultra-dense quark nuggets, widely discussed in literature with several different names. Nuclearites are an example of candidate compact objects with atomic size cross section. After a short discussion on nuclearites, the result of a nuclearite search with the gravitational wave bar detectors Nautilus and Explorer is reported. The geometrical acceptance of the bar detectors is 19.5 $\\rm m^2$ sr, that is smaller than that of other detectors used for similar searches. However, the detection mechanism is completely different and is more straightforward than in other detectors. The experimental limits we obtain are of interest because, for nuclearites of mass less than $10^{-5}$ g, we find a flux smaller than that one predicted considering nuclearites as dark matter candidates. Particles with gravitational only interactions (newtorites) are another examp...

  10. Directional Sensitivity in Light-Mass Dark Matter Searches with Single-Electron-Resolution Ionization Detectors

    Science.gov (United States)

    Kadribasic, Fedja; Mirabolfathi, Nader; Nordlund, Kai; Sand, Andrea E.; Holmström, Eero; Djurabekova, Flyura

    2018-03-01

    We propose a method using solid state detectors with directional sensitivity to dark matter interactions to detect low-mass weakly interacting massive particles (WIMPs) originating from galactic sources. In spite of a large body of literature for high-mass WIMP detectors with directional sensitivity, no available technique exists to cover WIMPs in the mass range semiconductor detectors allow for directional sensitivity once properly calibrated. We examine the commonly used semiconductor material response to these low-mass WIMP interactions.

  11. Direct dark matter search by annual modulation in XMASS-I

    Science.gov (United States)

    Abe, K.; Hiraide, K.; Ichimura, K.; Kishimoto, Y.; Kobayashi, K.; Kobayashi, M.; Moriyama, S.; Nakahata, M.; Norita, T.; Ogawa, H.; Sekiya, H.; Takachio, O.; Takeda, A.; Yamashita, M.; Yang, B. S.; Kim, N. Y.; Kim, Y. D.; Tasaka, S.; Fushimi, K.; Liu, J.; Martens, K.; Suzuki, Y.; Xu, B. D.; Fujita, R.; Hosokawa, K.; Miuchi, K.; Onishi, Y.; Oka, N.; Takeuchi, Y.; Kim, Y. H.; Lee, J. S.; Lee, K. B.; Lee, M. K.; Fukuda, Y.; Itow, Y.; Kegasa, R.; Kobayashi, K.; Masuda, K.; Takiya, H.; Nishijima, K.; Nakamura, S.; Xmass Collaboration

    2016-08-01

    A search for dark matter was conducted by looking for an annual modulation signal due to the Earth's rotation around the Sun using XMASS, a single phase liquid xenon detector. The data used for this analysis was 359.2 live days times 832 kg of exposure accumulated between November 2013 and March 2015. When we assume Weakly Interacting Massive Particle (WIMP) dark matter elastically scattering on the target nuclei, the exclusion upper limit of the WIMP-nucleon cross section 4.3 ×10-41 cm2 at 8 GeV/c2 was obtained and we exclude almost all the DAMA/LIBRA allowed region in the 6 to 16 GeV/c2 range at ∼10-40 cm2. The result of a simple modulation analysis, without assuming any specific dark matter model but including electron/γ events, showed a slight negative amplitude. The p-values obtained with two independent analyses are 0.014 and 0.068 for null hypothesis, respectively. We obtained 90% C.L. upper bounds that can be used to test various models. This is the first extensive annual modulation search probing this region with an exposure comparable to DAMA/LIBRA.

  12. A SIMPLE Bubble Chamber for Dark Matter Searches: Testing and Development

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, A.R.; Fernandes, A.C.; Marques, J.G.; Kling, A. [C2TN, Instituto Superior Tecnico, Universidade de Lisboa, E.N. 10 - km 139.7, 2695-066 Bobadela, LRS (Portugal); Felizardo, M.; Girard, T.A. [Centro de Fisica Nuclear, Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003, Lisbon (Portugal); Lazaro, I. [Laboratoire Souterrain a Bas Bruit, UMS 3538 UNS/UAPV/CNRS, 84400 Rustrel-Pays d' Apt (France); Puibasset, J. [Centre de Recherche sur la Matiere Divisee CNRS et Universite d' Orleans, 45071 Orleans, 02 (France)

    2015-07-01

    SIMPLE (Superheated Instrument for Massive Particle Experiments) is one of only three experiments worldwide in search of evidence of astroparticle dark matter (WIMPs) using halocarbon-loaded superheated liquid (SHL) detectors. The 2012 Phase II SIMPLE measurements yielded the most restrictive exclusion contour in the spin-dependent (SD) sector of WIMP-proton interactions from a direct search experiment at the time, overlapping for the first time results previously obtained only indirectly [1]. In order to remain competitive with other experiments in the field, the next phase measurement requires larger exposure over shorter observation times with significantly improved neutron shielding. To increase exposure, SIMPLE plans, as a first step, to replace its superheated droplet detectors (SDDs), each containing an active mass of about 15 g of halocarbon, with bubble chambers capable of holding up to 20 kg of active halocarbon mass. We report on the development of the first 1 kg halocarbon SIMPLE bubble chamber prototype, including chamber recompression system design and testing and initial acoustic detection of bubble formation. (authors)

  13. Search Advertising

    OpenAIRE

    Cornière (de), Alexandre

    2016-01-01

    Search engines enable advertisers to target consumers based on the query they have entered. In a framework with horizontal product differentiation, imperfect product information and in which consumers incur search costs, I study a game in which advertisers have to choose a price and a set of relevant keywords. The targeting mechanism brings about three kinds of efficiency gains, namely lower search costs, better matching, and more intense product market price-competition. A monopolistic searc...

  14. Faceted Search

    CERN Document Server

    Tunkelang, Daniel

    2009-01-01

    We live in an information age that requires us, more than ever, to represent, access, and use information. Over the last several decades, we have developed a modern science and technology for information retrieval, relentlessly pursuing the vision of a "memex" that Vannevar Bush proposed in his seminal article, "As We May Think." Faceted search plays a key role in this program. Faceted search addresses weaknesses of conventional search approaches and has emerged as a foundation for interactive information retrieval. User studies demonstrate that faceted search provides more

  15. How to save the WIMP. Global analysis of a dark matter model with two s-channel mediators

    International Nuclear Information System (INIS)

    Duerr, Michael; Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwetz, Thomas; Vogl, Stefan

    2016-06-01

    A reliable comparison of different dark matter (DM) searches requires models that satisfy certain consistency requirements like gauge invariance and perturbative unitarity. As a well-motivated example, we study two-mediator DM (2MDM). The model is based on a spontaneously broken U(1)"' gauge symmetry and contains a Majorana DM particle as well as two s-channel mediators, one vector (the Z"') and one scalar (the dark Higgs). We perform a global scan over the parameters of the model assuming that the DM relic density is obtained by thermal freeze-out in the early Universe and imposing a large set of constraints: direct and indirect DM searches, monojet, dijet and dilepton searches at colliders, Higgs observables, electroweak precision tests and perturbative unitarity. We conclude that thermal DM is only allowed either close to an s-channel resonance or if at least one mediator is lighter than the DM particle. In these cases a thermal DM abundance can be obtained although DM couplings to the Standard Model are tiny. Interestingly, we find that vector-mediated DM-nucleon scattering leads to relevant constraints despite the velocity-suppressed cross section, and that indirect detection can be important if DM annihilations into both mediators are kinematically allowed.

  16. Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  17. Development of Time Projection Chambers with Micromegas for Rare Event Searches

    CERN Document Server

    Tomas, Alfredo; Villar, J A

    The Rare Event Searches is a heterogeneous field from the point of view of their physical motivations: double betha neutrinoless decay experiments, direct detection of WIMPs as well as axions and other WISPs (candidates for the DM, but also motivated by other questions from Particle Physics). The field is rather defined by the requirements of these experiments, essentially a very sensitive detector with low background which is usually operated in underground laboratories. The availability of a rich description of the event registered by the detector is a powerful tool for the discrimination of the signal from the background. The topological description of the interaction that can be delivered by a gaseous TPC is a useful source of information about the event. The generic requirements for a gaseous TPC that is intended for rare event searches are very good imaging capabilities, high gain and efficiency, stability and reliability and radio-purity, which could imply working with particular gases, in absence of q...

  18. Charge Transport Phenomena in Detectors of the Cryogenic Dark Matter Search

    Science.gov (United States)

    Sundqvist, Kyle

    2008-03-01

    The Cryogenic Dark Matter Search (CDMS) seeks to detect putative weakly-interacting massive particles (WIMPS), which could explain the dark matter problem in cosmology and particle physics. By simultaneously measuring the number of charge carriers and the energy in athermal phonons created by particle interactions in intrinsic Ge and Si crystals at a temperature of 40 mK, a signature response for each event is produced. This response, combined with phonon pulse-shape information, allows CDMS to actively discriminate candidate WIMP interactions with nuclei apart from electromagnetic radioactive background which interacts with electrons. The challenges associated with these techniques are unique. Carrier drift-fields are maintained at only a few V/cm, else drift-emitted Luke-Neganov phonons would dominate the phonons of the original interaction. Under such conditions, carrier scattering is dominated by zero-point fluctuations of the lattice ions. It has been an open question how well the 8 Kelvin data prominent in the literature depicts this case. We compare the simulated transport properties of electrons and holes in Ge at 40 mK and at 8 K, and apply this understanding to our detectors.

  19. Searching for Dark Matter in the Mono-Jet and Mono-Photon Channels with the ATLAS Detector

    CERN Document Server

    Ratti, Maria Giulia; Carminati, Leonardo

    This work presents searches for dark matter particles in the mono-jet and mono-photon final states using the data collected by the ATLAS experiment during 2015 and 2016. The thesis starts with an introduction to the basic concepts of the Standard Model, followed by a discussion of the dark matter problem and the WIMP hypothesis. The focus then shifts to the description of the experimental facilities to collect the data and reconstruct the collision events. Particular focus is put on the reconstruction and performance of the missing transverse momentum. After characterizing a few theoretical models predicting dark matter particles in the mono-photon and mono-jet final states, the searches in these two signatures are thoroughly discussed, with particular focus on the background estimation techniques. While no significant deviations from the Standard Model predictions are found, the results obtained by these searches further restrict the phase-space where the dark matter particles can lie.

  20. Autonomous search

    CERN Document Server

    Hamadi, Youssef; Saubion, Frédéric

    2012-01-01

    Autonomous combinatorial search (AS) represents a new field in combinatorial problem solving. Its major standpoint and originality is that it considers that problem solvers must be capable of self-improvement operations. This is the first book dedicated to AS.

  1. Direct detection of light anapole and magnetic dipole DM

    International Nuclear Information System (INIS)

    Nobile, Eugenio Del; Gelmini, Graciela B.; Huh, Ji-Haeng; Gondolo, Paolo

    2014-01-01

    We present comparisons of direct detection data for ''light WIMPs'' with an anapole moment interaction (ADM) and a magnetic dipole moment interaction (MDM), both assuming the Standard Halo Model (SHM) for the dark halo of our galaxy and in a halo-independent manner. In the SHM analysis we find that a combination of the 90% CL LUX and CDMSlite limits or the new 90% CL SuperCDMS limit by itself exclude the parameter space regions allowed by DAMA, CoGeNT and CDMS-II-Si data for both ADM and MDM. In our halo-independent analysis the new LUX bound excludes the same potential signal regions as the previous XENON100 bound. Much of the remaining signal regions is now excluded by SuperCDMS, while the CDMSlite limit is much above them. The situation is of strong tension between the positive and negative search results both for ADM and MDM. We also clarify the confusion in the literature about the ADM scattering cross section

  2. The Cryogenic Dark Matter Search low ionization-threshold experiment

    Energy Technology Data Exchange (ETDEWEB)

    Basu Thakur, Ritoban [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2014-01-01

    Over 80 years ago we discovered the presence of Dark Matter in our universe. Endeavors in astronomy and cosmology are in consensus with ever improving precision that Dark Matter constitutes an essential 27% of our universe. The Standard Model of Particle Physics does not provide any answers to the Dark Matter problem. It is imperative that we understand Dark Matter and discover its fundamental nature. This is because, alongside other important factors, Dark Matter is responsible for formation of structure in our universe. The very construct in which we sit is defined by its abundance. The Milky Way galaxy, hence life, wouldn't have formed if small over densities of Dark Matter had not caused sufficient accretion of stellar material. Marvelous experiments have been designed based on basic notions to directly and in-directly study Dark Matter, and the Cryogenic Dark Matter Search (CDMS) experiment has been a pioneer and forerunner in the direct detection field. Generations of the CDMS experiment were designed with advanced scientific upgrades to detect Dark Matter particles of mass O(100) GeV/c2. This mass-scale was set primarily by predictions from Super Symmetry. Around 2013 the canonical SUSY predictions were losing some ground and several observations (rather hints of signals) from various experiments indicated to the possibility of lighter Dark Matter of mass O(10) GeV/c2. While the SuperCDMS experiment was probing the regular parameter space, the CDMSlite experiment was conceived to dedicatedly search for light Dark Matter using a novel technology. "CDMSlite" stands for CDMS - low ionization threshold experiment. Here we utilize a unique electron phonon coupling mechanism to measure ionization generated by scattering of light particles. Typically signals from such low energy recoils would be washed under instrumental noise. In CDMSlite via generation of Luke-Neganov phonons we can detect the small ionization energies, amplified in

  3. Search strategies

    Science.gov (United States)

    Oliver, B. M.

    Attention is given to the approaches which would provide the greatest chance of success in attempts related to the discovery of extraterrestrial advanced cultures in the Galaxy, taking into account the principle of least energy expenditure. The energetics of interstellar contact are explored, giving attention to the use of manned spacecraft, automatic probes, and beacons. The least expensive approach to a search for other civilizations involves a listening program which attempts to detect signals emitted by such civilizations. The optimum part of the spectrum for the considered search is found to be in the range from 1 to 2 GHz. Antenna and transmission formulas are discussed along with the employment of matched gates and filters, the probable characteristics of the signals to be detected, the filter-signal mismatch loss, surveys of the radio sky, the conduction of targeted searches.

  4. Optimization of the energy resolution and of the radioactive background rejection for ionization-heat detectors equipped with thermometric thin films for the direct WIMPs detection

    International Nuclear Information System (INIS)

    Dolgorouky, Y.W.

    2008-09-01

    The EDELWEISS experiment aims at the direct detection of WIMPs as possible candidates for dark matter. It uses heat-and-ionization detectors that can discriminate these particles from the radioactive background. To date, this method is limited by events with incomplete charge collection that occur just beneath the detectors electrodes. In order to identify and reject these undesirable events, we have developed detectors equipped with thin films used both as thermometers - and hence sensitive to the transient athermal regime - and as electrodes for the charge collection. This thesis focuses on the optimization of such thin films regarding surface events rejection and on the modelling of the physical processes enabling this identification. The optimization must both maximize the fiducial volume and conserve an energy resolution such that the recoil energy threshold is of the order of 30 keV. Our work explores four generations of detectors each of which corresponds to successive evolutions in their conception. In all cases, the electrode-thermometer is an amorphous Anderson insulator NbSi thin film polarized by two interleaved comb-shaped niobium electrodes. In spite of constant progress in the successive detectors performances, the latest generation does not display the performances required for the EDELWEISS II experiment. Our work has shown the difficulty of the transient thermal signal modelling due to the complex contribution of the charge collection. This works has lead to new ideas regarding the detectors configuration, so that the athermal regime can be optimized to enhance both the rejection capability and the resolution. (author)

  5. Internet Search Engines

    OpenAIRE

    Fatmaa El Zahraa Mohamed Abdou

    2004-01-01

    A general study about the internet search engines, the study deals main 7 points; the differance between search engines and search directories, components of search engines, the percentage of sites covered by search engines, cataloging of sites, the needed time for sites appearance in search engines, search capabilities, and types of search engines.

  6. Search for Dark Matter In events with heavy quarks and missing transverse energy with the ATLAS detector

    CERN Document Server

    Afik, Yoav; The ATLAS collaboration

    2017-01-01

    A wide search program is being carried at the LHC under the hypothesis that Dark Matter (DM) consists of weakly interacting massive particles (WIMPs). Final states with heavy flavour quarks and large momentum imbalance represent an interesting discovery signature which allows to probe models with scalar or pseudo-scalar interactions between the Standard Model and the dark sector under the assumption of Minimal Flavour Violation. We present the most recent results of searches for DM produced in association with a pair of heavy flavour quarks (DM+HF) in ATLAS [1-2] based on 36.1 fb-1 of proton-proton collision data collected at a centre of mass energy of 13 TeV.

  7. Radiopurity of CaWO{sub 4} crystals for direct dark matter search with CRESST and EURECA

    Energy Technology Data Exchange (ETDEWEB)

    Muenster, Andrea [Physik Department E15, Technische Universitaet Muenchen, 85748 Garching (Germany); Collaboration: CRESST-Collaboration

    2015-07-01

    The direct dark matter search experiment CRESST uses scintillating CaWO{sub 4} single crystals as targets for possible WIMP recoils. A particle interaction in the crystal produces phonons as well as scintillation light. As the light signal is dependent on the kind of interacting particle, e{sup -}-recoils and α-decays mainly originating from intrinsic impurities of the crystal can be discriminated from nuclear recoils (e.g. due to possible WIMP scatterings). To achieve the best possible discrimination a high light output and a high radiopurity of the crystals are crucial. Since 2011 CaWO{sub 4} crystals are grown in the crystal lab of TU Munich. In this way we can directly influence the growth parameters and find a method to improve light output and radiopurity which is required by CRESST and the future tonne-scale multi-material experiment EURECA. In this talk we will discuss the investigated radiopurity of the raw materials WO{sub 3} and CaCO{sub 3} as well as of TUM-grown crystals which are currently taking data in CRESST II Phase 2.

  8. Meta Search Engines.

    Science.gov (United States)

    Garman, Nancy

    1999-01-01

    Describes common options and features to consider in evaluating which meta search engine will best meet a searcher's needs. Discusses number and names of engines searched; other sources and specialty engines; search queries; other search options; and results options. (AEF)

  9. Development of a Low Background Environment for the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Da Silva, Angela Jane [British Columbia U.

    1996-01-01

    A major problem currently facing astrophysics and cosmology is the question of dark matter. Although there is little doubt about the existence of dark matter, there is considerable uncertainty about the abundance and nature of this matter. One possibility is that dark matter consists of weakly interacting massive particles (WIMPs), such as the lightest stable particle in supersymmetry models. Direct detection experiments look for nuclear recoils from WIMPs scattering in a detector. The first generation of direct detection experiments were ultimately limited by radioactive backgrounds. The Cryogenic Dark Matter Search (CDMS) is a direct detection experiment based on novel particle detectors operated at millikelvin temperatures that provide intrinsic background rejection. This capability, however, is not 100% effective. Therefore a low background environment is essential to the experiment. To create such an environment, all possible background sources have been extensively studied both by measuring the background contribution from muons, photons and neutrons and by performing detailed Monte Carlo simulations of the photon and neutron backgrounds. The results of this investigation, as discussed in this thesis, have influenced all aspects of the CDMS experiment. The initial site for the CDMS experiment is the Stanford Underground Facility. The relatively high muon flux at this site due to its shallow depth was balanced against the convenience of a local site with the unlimited access necessary for operating a complicated cryogenic system and developing new detector technology. The cryostat used to house the detectors was designed to accommodate the extensive shielding necessary to reduce the ambient backgrounds to acceptable levels and to minimize the amount of radioactive contamination near the detectors. Simulations and measurements of the local backgrounds led to a layered shield design that consists primarily of plastic scintillators to veto muons, lead and copper

  10. A search for non-baryonic dark matter using an ionisation bolometer in the edelweiss experiment; Recherche de matiere sombre non-baryonique au moyen d`un bolometre a ionisation dans le cadre de l`experience edelweiss

    Energy Technology Data Exchange (ETDEWEB)

    Di Stefano, Ph [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. d` Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l` Instrumentation Associee; [Paris-11 Univ., 91 - Orsay (France)

    1998-09-24

    The EDELWEISS experiment is an underground direct-detection search for hypothetical supersymmetric WIMPs that might solve the problem of dark matter. We have employed a cryogenic 70 g germanium ionisation bolometer, in which a WIMP would scatter elastically off a nucleus, creating both a heat and an ionisation signal. To offset the various electronic noises present in our necessarily small signals, we have s applied an optimal filtering technique in the frequency domain. This allows us to reach resolutions of 1.2 keV FWHM at 122 keV on north channels. It also provides good separation right down to low energies between the expected signal of nuclear recoils, and the photonic background of electron recoils which ionize more for a given energy. Calibration data show that we are able to reject 99.7 % of this background, while keeping 95% of the signal. However, our 1.17 kg.days of data searching for WIMPs show a third population encroaching on the expected signal. This is probably due to low energy photons or electrons interacting in the outer layers of the crystal, where charges are incompletely collected. Nevertheless, by trading off half of the conserved signal, we still manage to reject 98.5 % of the background. Thus the raw rate of 40 evts/d/kg/keV yields a conservative 90 % upper limit on the signal of 0.6 evts/d/kg/keV. This represents nearly a three orders of magnitude improvement for EDELWEISS, and puts the predicted supersymmetric phase space within two orders of magnitude. (author) 196 refs.

  11. Search for dark photons using data from CRESST-II Phase 2

    Science.gov (United States)

    Gütlein, A.; Angloher, G.; Bento, A.; Bucci, C.; Canonica, L.; Defay, X.; Erb, A.; Feilitzsch, F. v.; Ferreiro Iachellini, N.; Gorla, P.; Hauff, D.; Jochum, J.; Kiefer, M.; Kluck, H.; Kraus, H.; Lanfranchi, J.-C.; Loebell, J.; Mancuso, M.; Münster, A.; Pagliarone, C.; Petricca, F.; Potzel, W.; Pröbst, F.; Puig, R.; Reindl, F.; Schäffner, K.; Schieck, J.; Schönert, S.; Seidel, W.; Stahlberg, M.; Stodolsky, L.; Strandhagen, C.; Strauss, R.; Tanzke, A.; Trinh Thi, H. H.; Türkoǧlu, C.; Uffinger, M.; Ulrich, A.; Usherov, I.; Wawoczny, S.; Willers, M.; Wüstrich, M.; Zöller, A.

    2017-09-01

    Understanding the nature and origin of dark matter is one of the most important challenges for modern particle physics. During the previous decade the sensitivities of direct dark matter searches have improved by several orders of magnitude. These experiments focus their work mainly on the search for dark-matter particles interacting with nuclei (e.g. Weakly Interacting Massive Particles, WIMPs). However, there exists a large variety of different candidates for dark-matter particles. One of these candidates, the so-called dark photon, is a long-lived vector boson with a kinetic mixing to the standard-model photon. In this work we present the preliminary results of our search for dark photons. Using data from the direct dark matter search CRESST-II Phase 2 we can improve the existing constraints for the kinetic mixing for dark-photon masses between 0.3 and 0.5 keV/c2. In addition, we also present projected sensitivities for the next phases of the CRESST-III experiment showing great potential to improve the sensitivity for dark-photon masses below 1 keV.

  12. Optimization of the energy resolution and of the radioactive background rejection for ionization-heat detectors equipped with thermometric thin films for the direct WIMPs detection; Optimisation du pouvoir de resolution et du rejet du fond radioactif de detecteurs ionisation-chaleur equipes de couches minces thermometriques pour la detection directe de WIMPS

    Energy Technology Data Exchange (ETDEWEB)

    Dolgorouky, Y.W.

    2008-09-15

    The EDELWEISS experiment aims at the direct detection of WIMPs as possible candidates for dark matter. It uses heat-and-ionization detectors that can discriminate these particles from the radioactive background. To date, this method is limited by events with incomplete charge collection that occur just beneath the detectors electrodes. In order to identify and reject these undesirable events, we have developed detectors equipped with thin films used both as thermometers - and hence sensitive to the transient athermal regime - and as electrodes for the charge collection. This thesis focuses on the optimization of such thin films regarding surface events rejection and on the modelling of the physical processes enabling this identification. The optimization must both maximize the fiducial volume and conserve an energy resolution such that the recoil energy threshold is of the order of 30 keV. Our work explores four generations of detectors each of which corresponds to successive evolutions in their conception. In all cases, the electrode-thermometer is an amorphous Anderson insulator NbSi thin film polarized by two interleaved comb-shaped niobium electrodes. In spite of constant progress in the successive detectors performances, the latest generation does not display the performances required for the EDELWEISS II experiment. Our work has shown the difficulty of the transient thermal signal modelling due to the complex contribution of the charge collection. This works has lead to new ideas regarding the detectors configuration, so that the athermal regime can be optimized to enhance both the rejection capability and the resolution. (author)

  13. Searches for Particle Dark Matter with gamma-rays.

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    In this contribution I review the present status and discuss some prospects for indirect detection of dark matter with gamma-rays. Thanks to the Fermi Large Area Telescope, searches in gamma-rays have reached sensitivities that allow to probe the most interesting parameter space of the weakly interacting massive particles (WIMP) paradigm. This gain in sensitivity is naturally accompanied by a number of detection claims or indications, the most recent being the claim of a line feature at a dark matter particle mass of ∼ 130 GeV at the Galactic Centre, a claim which requires confirmation from the Fermi-LAT collaboration and other experiments, for example HESS II or the planned Gamma-400 satellite. Predictions for the next generation air Cherenkov telescope, Cherenkov Telescope Array (CTA), together with forecasts on future Fermi-LAT constraints arrive at the exciting possibility that the cosmological benchmark cross-section could be probed from masses of a few GeV to a few TeV. Consequently, non-detection wou...

  14. EDELWEISS-II, direct Dark Matter search experiment: first data analysis and results

    International Nuclear Information System (INIS)

    Scorza, Silvia

    2009-01-01

    One of the greatest mysteries of the universe that, for the present, puzzles the mind of most astronomers, cosmologists and physicists is the question: 'What makes up our universe?'. This is due to how a certain substance named Dark Matter came under speculation. It is believed this enigmatic substance, of type unknown, accounts for almost three-quarters of the cosmos within the universe, could be the answer to several questions raised by the models of the expanding universe astronomers have created, and even decide the fate of the expansion of the universe. There is strong observational evidence for the dominance of non-baryonic Dark Matter (DM) over baryonic matter in the universe. Such evidence comes from many independent observations over different length scales. The most stringent constraint on the abundance of DM comes from the analysis of the Cosmic Microwave Background (CMB) anisotropies. In particular, the WMAP (Wilkinson Microwave Anisotropy Probe) experiment restricts the abundance of matter and the abundance of baryonic matter in good agreement with predictions from Big Bang Nucleosynthesis. It is commonly believed that such a non-baryonic component could consist of new, as yet undiscovered, particles, usually referred to as WIMPs (Weakly Interacting Massive Particles). Some extensions of the standard model (SM) of particle physics predict the existence of particles that would be excellent DM candidates. In particular great attention has been dedicated to candidates arising in supersymmetric theories: the Lightest Supersymmetric Particle (LSP). In the most supersymmetric scenarios, the so-called neutralino seems to be a natural candidate, being stable in theories with conservation of R-parity and having masses and cross sections of typical WIMPs. The EDELWEISS collaboration is a direct dark matter search experiment, aiming to detect directly a WIMP interaction in a target material, high purity germanium crystal working at cryogenic temperatures. It

  15. Search for cold and hot dark matter with the Heidelberg-Moscow experiment, HDMS, GENIUS and GENIUS-TF

    International Nuclear Information System (INIS)

    Klapdor-Kleingrothaus, H.V.; Dietz, A.; Krivosheina, I.V.

    2003-01-01

    The recent result from the Heidelberg-Moscow double beta experiment allows neutrinos still to play an important role as hot dark matter in the Universe. HDMS has started in 2001 its search for cold dark matter (WIMPS), with a HPGe crystal of enriched 73 Ge. Concerning hot dark matter, GENIUS will improve the present accuracy for the (effective) neutrino mass. At the same time GENIUS will extend the range of sensitivity in an unprecedented way to cover a wide range of the parameter space of SUSY parameters for neutralinos as cold dark matter. A GENIUS Test Facility in the Gran Sasso has been approved in 2001 and will come into operation by end of 2002. Finally some comments are given to some criticism of the result presented elsewhere

  16. A search for annual and daily modulations of dark matter with NaI scintillators at Canfranc

    International Nuclear Information System (INIS)

    Sarsa, M.L.; Morales, A.; Morales, J.; Garcia, E.; Ortiz de Solorzano, A.; Puimedon, J.; Saenz, C.; Salinas, A.; Villar, J.A.

    1996-01-01

    A search for cold dark matter has been carried out at the Canfranc Underground Laboratory with a set of three sodium iodide scintillators of 10.7 kg each, during two years of data taking. The results, corresponding to an exposure of 4613.6 kg day are presented in the form of exclusion plots σ(m) for spin-independent and spin-dependent WIMP-matter interactions, by conventionally comparing the observed rate with the expected signal. Distinctive features of the CDM signal, like annual and daily modulations have been looked for in, respectively, 1342.85 kg day and 2769.6 kg day of data. The non observance of such modulations have been used to draw stringer exclusion plots than those derived from the previous, conventional method. (orig.)

  17. Phonon Sensor Dynamics for Cryogenic Dark Matter Search Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yen, Jeffrey [Stanford Univ., CA (United States)

    2015-01-01

    Understanding the quasiparticle diffusion process inside sputtered aluminum (Al thin films (~ 0.1-1 μm is critical for the Cryogenic Dark Matter Search (CDMS experiment to further optimize its detectors to directly search for dark matter. An initial study with Al films was undertaken by our group ~ 20 years ago, but some important questions were not answered at the time. This thesis can be considered a continuation of that critical study. The CDMS experiment utilizes high purity silicon and germanium crystals to simultaneously measure ionization and phonons created by particle interactions. In addition to describing some of the rich physics involved in simultaneously detecting ionization and phonons with a CDMS detector, this thesis focuses on the detailed physics of the phonon sensors themselves, which are patterned onto CDMS detector surfaces. CDMS detectors use thin sputtered Al films to collect phonon energy when it propagates to the surfaces of the detector crystals. The phonon energy breaks Cooper pairs and creates quasiparticles (qps). These qps diffuse until they get trapped in an proximitized “overlap” region where lower-Tc tungsten films connect to the Al film. These tungsten films are the transition edge sensors (W-TESs CDMS uses to readout phonon signals. We performed a wide range of experiments using several sets of test devices designed and fabricated specifically for this work. The devices were used mostly to study quasiparticle (qp transport in Al films and qp transmission through Al/W interfaces. The results of this work are being used to optimize the design of detectors for SuperCDMS SNOLAB. This thesis is intended for CDMS collaborators who are interested in knowing more about the detailed fundamentals of how our phonon sensors work so they can take full advantage of their benefits. However, this work can also be read by general readers who are interested in particle detection using TES technology. This thesis contains eight chapters. The

  18. Search for an Annual Modulation in a p-Type Point Contact Germanium Dark Matter Detector

    Energy Technology Data Exchange (ETDEWEB)

    Aalseth, Craig E.; Barbeau, Phil; Colaresi, J.; Collar, J. I.; Diaz Leon, J.; Fast, James E.; Fields, N.; Hossbach, Todd W.; Keillor, Martin E.; Kephart, Jeremy D.; Knecht, A.; Marino, Michael G.; Miley, Harry S.; Miller, M. L.; Orrell, John L.; Radford, D. C.; Wilkerson, J.; Yocum, K. M.

    2011-09-01

    Fifteen months of cumulative CoGeNT data are examined for indications of an annual modulation, a predicted signature of Weakly Interacting Massive Particle (WIMP) interactions. Presently available data support the presence of a modulated component of unknown origin, with parameters prima facie compatible with a galactic halo composed of light-mass WIMPs.

  19. Identification of radiopure titanium for the LZ dark matter experiment and future rare event searches

    Science.gov (United States)

    Akerib, D. S.; Akerlof, C. W.; Akimov, D. Yu.; Alsum, S. K.; Araújo, H. M.; Arnquist, I. J.; Arthurs, M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Balashov, S.; Barry, M. J.; Belle, J.; Beltrame, P.; Benson, T.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boast, K. E.; Bolozdynya, A.; Boxer, B.; Bramante, R.; Brás, P.; Buckley, J. H.; Bugaev, V. V.; Bunker, R.; Burdin, S.; Busenitz, J. K.; Carels, C.; Carlsmith, D. L.; Carlson, B.; Carmona-Benitez, M. C.; Chan, C.; Cherwinka, J. J.; Chiller, A. A.; Chiller, C.; Cottle, A.; Coughlen, R.; Craddock, W. W.; Currie, A.; Dahl, C. E.; Davison, T. J. R.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Edberg, T. K.; Edwards, W. R.; Emmet, W. T.; Faham, C. H.; Fiorucci, S.; Fruth, T.; Gaitskell, R. J.; Gantos, N. J.; Gehman, V. M.; Gerhard, R. M.; Ghag, C.; Gilchriese, M. G. D.; Gomber, B.; Hall, C. R.; Hans, S.; Hanzel, K.; Haselschwardt, S. J.; Hertel, S. A.; Hillbrand, S.; Hjemfelt, C.; Hoff, M. D.; Holbrook, B.; Holtom, E.; Hoppe, E. W.; Hor, J. Y.-K.; Horn, M.; Huang, D. Q.; Hurteau, T. W.; Ignarra, C. M.; Jacobsen, R. G.; Ji, W.; Kaboth, A.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Khazov, A.; Khromov, A. V.; Konovalov, A. M.; Korolkova, E. V.; Koyuncu, M.; Kraus, H.; Krebs, H. J.; Kudryavtsev, V. A.; Kumpan, A. V.; Kyre, S.; Lee, C.; Lee, H. S.; Lee, J.; Leonard, D. S.; Leonard, R.; Lesko, K. T.; Levy, C.; Liao, F.-T.; Lin, J.; Lindote, A.; Linehan, R. E.; Lippincott, W. H.; Liu, X.; Lopes, M. I.; Lopez Paredes, B.; Lorenzon, W.; Luitz, S.; Majewski, P.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Markley, D. J.; Martin, T. J.; Marzioni, M. F.; McConnell, C. T.; McKinsey, D. N.; Mei, D.-M.; Meng, Y.; Miller, E. H.; Mizrachi, E.; Mock, J.; Monzani, M. E.; Morad, J. A.; Mount, B. J.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; Nikkel, J. A.; O'Dell, J.; O'Sullivan, K.; Olcina, I.; Olevitch, M. A.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Piepke, A.; Powell, S.; Preece, R. M.; Pushkin, K.; Ratcliff, B. N.; Reichenbacher, J.; Reichhart, L.; Rhyne, C. A.; Richards, A.; Rodrigues, J. P.; Rose, H. J.; Rosero, R.; Rossiter, P.; Saba, J. S.; Sarychev, M.; Schnee, R. W.; Schubnell, M.; Scovell, P. R.; Shaw, S.; Shutt, T. A.; Silva, C.; Skarpaas, K.; Skulski, W.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Sosnovtsev, V. V.; Stancu, I.; Stark, M. R.; Stephenson, S.; Stiegler, T. M.; Stifter, K.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Temples, D.; Terman, P. A.; Thomas, K. J.; Thomson, J. A.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Tomás, A.; Tope, T. E.; Tripathi, M.; Tvrznikova, L.; Va'Vra, J.; Vacheret, A.; van der Grinten, M. G. D.; Verbus, J. R.; Vuosalo, C. O.; Waldron, W. L.; Wang, R.; Watson, R.; Webb, R. C.; Wei, W.-Z.; While, M.; White, D. T.; Whitis, T. J.; Wisniewski, W. J.; Witherell, M. S.; Wolfs, F. L. H.; Woodward, D.; Worm, S.; Xu, J.; Yeh, M.; Yin, J.; Zhang, C.; Lux-Zeplin (LZ) Collaboration

    2017-11-01

    The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a detector containing a total of 10 tonnes of liquid xenon within a double-vessel cryostat. The large mass and proximity of the cryostat to the active detector volume demand the use of material with extremely low intrinsic radioactivity. We report on the radioassay campaign conducted to identify suitable metals, the determination of factors limiting radiopure production, and the selection of titanium for construction of the LZ cryostat and other detector components. This titanium has been measured with activities of 238Ue < 1.6 mBq/kg, 238Ul < 0.09 mBq/kg, 232The = 0.28 ± 0.03 mBq/kg, 232Thl = 0.25 ± 0.02 mBq/kg, 40K < 0.54 mBq/kg, and 60Co < 0.02 mBq/kg (68% CL). Such low intrinsic activities, which are some of the lowest ever reported for titanium, enable its use for future dark matter and other rare event searches. Monte Carlo simulations have been performed to assess the expected background contribution from the LZ cryostat with this radioactivity. In 1,000 days of WIMP search exposure of a 5.6-tonne fiducial mass, the cryostat will contribute only a mean background of 0.160 ± 0.001(stat) ± 0.030(sys) counts.

  20. How doctors search

    DEFF Research Database (Denmark)

    Lykke, Marianne; Price, Susan; Delcambre, Lois

    2012-01-01

    Professional, workplace searching is different from general searching, because it is typically limited to specific facets and targeted to a single answer. We have developed the semantic component (SC) model, which is a search feature that allows searchers to structure and specify the search to co...

  1. Sound Search Engine Concept

    DEFF Research Database (Denmark)

    2006-01-01

    Sound search is provided by the major search engines, however, indexing is text based, not sound based. We will establish a dedicated sound search services with based on sound feature indexing. The current demo shows the concept of the sound search engine. The first engine will be realased June...

  2. Web Search Engines

    OpenAIRE

    Rajashekar, TB

    1998-01-01

    The World Wide Web is emerging as an all-in-one information source. Tools for searching Web-based information include search engines, subject directories and meta search tools. We take a look at key features of these tools and suggest practical hints for effective Web searching.

  3. submitter Searches at LEP

    CERN Document Server

    Kawagoe, Kiyotomo

    2001-01-01

    Searches for new particles and new physics were extensively performed at LEP. Although no evidence for new particle/physics was discovered, the null results set very stringent limits to theories beyond the standard model. In this paper, searches at LEP and anomalies observed in the searches are presented. Future prospect of searches at the new energy frontier machines is also discussed.

  4. Search for lightly ionizing particles using CDMS-II data and fabrication of CDMS detectors with improved homogeneity in properties

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Kunj Bihari [Texas A & M Univ., College Station, TX (United States)

    2013-12-01

    Fundamental particles are always observed to carry charges which are integral multiples of one-third charge of electron, e/3. While this is a well established experimental fact, the theoretical understanding for the charge quantization phenomenon is lacking. On the other hand, there exist numerous theoretical models that naturally allow for existence of particles with fractional electromagnetic charge. These particles, if existing, hint towards existence of physics beyond the standard model. Multiple high energy, optical, cosmological and astrophysical considerations restrict the allowable mass-charge parameter space for these fractional charges. Still, a huge unexplored region remains. The Cryogenic Dark Matter Search (CDMS-II), located at Soudan mines in northern Minnesota, employs germanium and silicon crystals to perform direct searches for a leading candidate to dark matter called Weakly Interacting Massive Particles (WIMPs). Alternately, the low detection threshold allows search for fractional electromagnetic-charged particles, or Lightly Ionizing Particles (LIPs), moving at relativistic speed. Background rejection is obtained by requiring that the magnitude and location of energy deposited in each detector be consistent with corresponding \\signatures" resulting from the passage of a fractionally charged particle. In this dissertation, the CDMS-II data is analyzed to search for LIPs, with an expected background of 0.078 0.078 events. No candidate events are observed, allowing exclusion of new parameter space for charges between e/6 and e/200.

  5. Myanmar Language Search Engine

    OpenAIRE

    Pann Yu Mon; Yoshiki Mikami

    2011-01-01

    With the enormous growth of the World Wide Web, search engines play a critical role in retrieving information from the borderless Web. Although many search engines are available for the major languages, but they are not much proficient for the less computerized languages including Myanmar. The main reason is that those search engines are not considering the specific features of those languages. A search engine which capable of searching the Web documents written in those languages is highly n...

  6. Ordered Consumer Search

    OpenAIRE

    Armstrong, Mark

    2016-01-01

    The paper discusses situations in which consumers search through their options in a deliberate order, in contrast to more familiar models with random search. Topics include: network effects (consumers may be better off following the same search order as other consumers); the use of price and non-price advertising to direct search; the impact of consumers starting a new search with their previous supplier; the incentive sellers have to merge or co-locate with other sellers; and the incentive a...

  7. The Search Performance Evaluation and Prediction in Exploratory Search

    OpenAIRE

    LIU, FEI

    2016-01-01

    The exploratory search for complex search tasks requires an effective search behavior model to evaluate and predict user search performance. Few studies have investigated the relationship between user search behavior and search performance in exploratory search. This research adopts a mixed approach combining search system development, user search experiment, search query log analysis, and multivariate regression analysis to resolve the knowledge gap. Through this study, it is shown that expl...

  8. Direct dark matter search by annual modulation in XMASS-I

    Directory of Open Access Journals (Sweden)

    K. Abe

    2016-08-01

    Full Text Available A search for dark matter was conducted by looking for an annual modulation signal due to the Earth's rotation around the Sun using XMASS, a single phase liquid xenon detector. The data used for this analysis was 359.2 live days times 832 kg of exposure accumulated between November 2013 and March 2015. When we assume Weakly Interacting Massive Particle (WIMP dark matter elastically scattering on the target nuclei, the exclusion upper limit of the WIMP–nucleon cross section 4.3×10−41 cm2 at 8 GeV/c2 was obtained and we exclude almost all the DAMA/LIBRA allowed region in the 6 to 16 GeV/c2 range at ∼10−40 cm2. The result of a simple modulation analysis, without assuming any specific dark matter model but including electron/γ events, showed a slight negative amplitude. The p-values obtained with two independent analyses are 0.014 and 0.068 for null hypothesis, respectively. We obtained 90% C.L. upper bounds that can be used to test various models. This is the first extensive annual modulation search probing this region with an exposure comparable to DAMA/LIBRA.

  9. Sapphire scintillation tests for cryogenic detectors in the Edelweiss dark matter search

    Energy Technology Data Exchange (ETDEWEB)

    Luca, M

    2007-07-15

    Identifying the matter in the universe is one of the main challenges of modern cosmology and astrophysics. An important part of this matter seems to be made of non-baryonic particles. Edelweiss is a direct dark matter search using cryogenic germanium bolometers in order to look for particles that interact very weakly with the ordinary matter, generically known as WIMPs (weakly interacting massive particles). An important challenge for Edelweiss is the radioactive background and one of the ways to identify it is to use a larger variety of target crystals. Sapphire is a light target which can be complementary to the germanium crystals already in use. Spectroscopic characterization studies have been performed using different sapphire samples in order to find the optimum doping concentration for good low temperature scintillation. Ti doped crystals with weak Ti concentrations have been used for systematic X ray excitation tests both at room temperature and down to 30 K. The tests have shown that the best Ti concentration for optimum room temperature scintillation is 100 ppm and 50 ppm at T = 45 K. All concentrations have been checked by optical absorption and fluorescence. After having shown that sapphire had interesting characteristics for building heat-scintillation detectors, we have tested if using a sapphire detector was feasible within a dark matter search. During the first commissioning tests of Edelweiss-II, we have proved the compatibility between a sapphire heat scintillation detector and the experimental setup. (author)

  10. Current and future searches for dark matter

    International Nuclear Information System (INIS)

    Bauer, Daniel A.

    2005-01-01

    Recent experimental data confirms that approximately one quarter of the universe consists of cold dark matter. Particle theories provide natural candidates for this dark matter in the form of either Axions or Weakly Interacting Massive Particles (WIMPs). A growing body of experiments is aimed at direct or indirect detection of particle dark matter. I summarize the current status of these experiments and offer projections of their future sensitivity

  11. Large Neighborhood Search

    DEFF Research Database (Denmark)

    Pisinger, David; Røpke, Stefan

    2010-01-01

    Heuristics based on large neighborhood search have recently shown outstanding results in solving various transportation and scheduling problems. Large neighborhood search methods explore a complex neighborhood by use of heuristics. Using large neighborhoods makes it possible to find better...... candidate solutions in each iteration and hence traverse a more promising search path. Starting from the large neighborhood search method,we give an overview of very large scale neighborhood search methods and discuss recent variants and extensions like variable depth search and adaptive large neighborhood...

  12. Search for neutral leptons

    International Nuclear Information System (INIS)

    Perl, M.L.

    1984-12-01

    At present we know of three kinds of neutral leptons: the electron neutrino, the muon neutrino, and the tau neutrino. This paper reviews the search for additional neutral leptons. The method and significance of a search depends upon the model used for the neutral lepton being sought. Some models for the properties and decay modes of proposed neutral leptons are described. Past and present searches are reviewed. The limits obtained by some completed searches are given, and the methods of searches in progress are described. Future searches are discussed. 41 references

  13. A search for gamma-ray imprints of annihilating dark matter in the galaxy, and the astrophysical implications of ultra-light fundamental vector bosons

    International Nuclear Information System (INIS)

    Zechlin, Hannes-Sebastian

    2013-12-01

    Standard Model extensions imply new elementary particles that can lead to specific astrophysical signatures. In particular, weakly interacting massive particles (WIMPs) can constitute the unknown non-luminous cold dark matter, which contributes approximately 84% to the matter content of the Universe. Annihilation or decay of WIMPs may lead to high-energy gamma-rays. In this thesis, new methods of searching for gamma-ray signals from annihilating dark matter are developed and applied. Moreover, astrophysical imprints of new ultra-light hidden U(1) gauge bosons in radio data are investigated. Hierarchical structure formation predicts a variety of smaller bound dark matter sub-halos in Milky-Way-like galactic hosts. It is shown that the Fermi-LAT is sufficiently sensitive for detecting up to a few nearby dark matter subhalos in terms of faint gamma-ray sources with a moderate angular extent. Searches in the first and second Fermi-LAT source catalogs reveal about ten candidate sources each. To discriminate the source candidates from conventional astrophysical objects, an analysis for spectral, spatial, positional, and temporal gamma-ray properties using 3.5 years of Fermi-LAT data is carried out. In addition, a multi-wavelength analysis of archival data or follow-up observations in the radio, infrared, optical, UV, X-ray, high-energy, and very-high energy gamma-ray bands is carried out. The broad-band spectra of all promising candidates are compatible with AGN, in particular high-energy peaked BL-Lac type objects (HBLs). Dark matter annihilation can contribute to the small-scale angular anisotropy spectrum of the diffuse gamma-ray background (DGB). The detection capabilities of currently operating imaging atmospheric Cherenkov telescopes and the planned Cherenkov Telescope Array (CTA) are studied. With CTA, a relative gamma-ray contribution from annihilating dark matter of 10% to the extragalactic DGB can be resolved via angular anisotropies. In terms of the dark

  14. First search for a dark matter annual modulation signal with NaI(Tl) in the Southern Hemisphere by DM-Ice17

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa de Souza, E.; Cherwinka, J.; Cole, A.; Ezeribe, A. C.; Grant, D.; Halzen, F.; Heeger, K. M.; Hsu, L.; Hubbard, A. J. F.; Jo, J. H.; Karle, A.; Kauer, M.; Kudryavtsev, V. A.; Lim, K. E.; Macdonald, C.; Maruyama, R. H.; Mouton, F.; Paling, S. M.; Pettus, W.; Pierpoint, Z. P.; Reilly, B. N.; Robinson, M.; Rogers, F. R.; Sandstrom, P.; Scarff, A.; Spooner, N. J. C.; Telfer, S.; Yang, L.

    2017-02-28

    The first search for a dark matter annual modulation signal with NaI(Tl) target material in the Southern Hemisphere conducted with the DM-Ice17 experiment is presented. DM-Ice17 consists of 17 kg of NaI(Tl) scintillating crystal under 2200 m.w.e. overburden of Antarctic glacial ice. The analysis presented here utilizes a 60.8 kg yr exposure. While unable to exclude the signal reported by DAMA/LIBRA, the DM-Ice17 data are consistent with no modulation in the energy range of 4-20 keV, providing the strongest limits on WIMP candidates from a direct detection experiment located in the Southern Hemisphere. Additionally, the successful deployment and stable operation of 17 kg of NaI(Tl) crystal over 3.5 years establishes the South Pole ice as a viable location for future underground, low-background experiments.

  15. Cube search, revisited

    Science.gov (United States)

    Zhang, Xuetao; Huang, Jie; Yigit-Elliott, Serap; Rosenholtz, Ruth

    2015-01-01

    Observers can quickly search among shaded cubes for one lit from a unique direction. However, replace the cubes with similar 2-D patterns that do not appear to have a 3-D shape, and search difficulty increases. These results have challenged models of visual search and attention. We demonstrate that cube search displays differ from those with “equivalent” 2-D search items in terms of the informativeness of fairly low-level image statistics. This informativeness predicts peripheral discriminability of target-present from target-absent patches, which in turn predicts visual search performance, across a wide range of conditions. Comparing model performance on a number of classic search tasks, cube search does not appear unexpectedly easy. Easy cube search, per se, does not provide evidence for preattentive computation of 3-D scene properties. However, search asymmetries derived from rotating and/or flipping the cube search displays cannot be explained by the information in our current set of image statistics. This may merely suggest a need to modify the model's set of 2-D image statistics. Alternatively, it may be difficult cube search that provides evidence for preattentive computation of 3-D scene properties. By attributing 2-D luminance variations to a shaded 3-D shape, 3-D scene understanding may slow search for 2-D features of the target. PMID:25780063

  16. Carrier Transport and Related Effects in Detectors of the Cryogenic Dark Matter Search

    Energy Technology Data Exchange (ETDEWEB)

    Sundqvist, Kyle Michael [Univ. of California, Berkeley, CA (United States)

    2012-01-01

    The Cryogenic Dark Matter Search (CDMS) is searching for weakly-interacting massive particles (WIMPS), which could explain the dark matter problem in cosmology and particle physics. By simultaneously measuring signals from deposited charge and the energy in nonequilibrium phonons created by particle interactions in intrinsic germanium crystals at a temperature of 40 mK, a signature response for each event is produced. This response, combined with phonon pulse-shape information, allows CDMS to actively discriminate candidate WIMP interactions with nuclei from electromagnetic radioactive background which interacts with electrons. The challenges associated with these techniques are unique. Carrier scattering is dominated by the spontaneous emission of Luke-Neganov phonons due to zeropoint fluctuations of the lattice ions. Drift fields are maintained at only a few V/cm, else these emitted phonons would dominate the phonons of the original interaction. The dominant systematic issues with CDMS detectors are due to the effects of space charge accumulation. It has been an open question how space charge accrues, and by which of several potential recombination and ionization processes. In this work, we have simulated the transport of electrons and holes in germanium under CDMS conditions. We have implemented both a traditional Monte Carlo technique based on carrier energy, followed later by a novel Monte Carlo algorithm with scattering rates defined and sampled by vector momentum. This vector-based method provides for a full anisotropic simulation of carrier transport including free-fight acceleration with an anisotropic mass, and anisotropic scattering rates. With knowledge of steady state carrier dynamics as a function of applied field, the results of our Monte Carlo simulations allow us to make a wide variety of predictions for energy dependent processes for both electrons and holes. Such processes include carrier capture by charged impurities, neutral impurities, static

  17. Professional and Regulatory Search

    Science.gov (United States)

    Professional and Regulatory search are designed for people who use EPA web resources to do their job. You will be searching collections where information that is not relevant to Environmental and Regulatory professionals.

  18. Search on Rugged Landscapes

    DEFF Research Database (Denmark)

    Billinger, Stephan; Stieglitz, Nils; Schumacher, Terry

    2014-01-01

    This paper presents findings from a laboratory experiment on human decision-making in a complex combinatorial task. We find strong evidence for a behavioral model of adaptive search. Success narrows down search to the neighborhood of the status quo, while failure promotes gradually more explorative...... for local improvements too early. We derive stylized decision rules that generate the search behavior observed in the experiment and discuss the implications of our findings for individual decision-making and organizational search....

  19. Integrated vs. Federated Search

    DEFF Research Database (Denmark)

    Løvschall, Kasper

    2009-01-01

    Oplæg om forskelle og ligheder mellem integrated og federated search i bibliotekskontekst. Holdt ved temadag om "Integrated Search - samsøgning i alle kilder" på Danmarks Biblioteksskole den 22. januar 2009.......Oplæg om forskelle og ligheder mellem integrated og federated search i bibliotekskontekst. Holdt ved temadag om "Integrated Search - samsøgning i alle kilder" på Danmarks Biblioteksskole den 22. januar 2009....

  20. Searches for dark matter self-annihilation signals from dwarf spheroidal galaxies and the Fornax galaxy cluster with imaging air Cherenkov telescopes

    International Nuclear Information System (INIS)

    Opitz, Bjoern Helmut Bastian

    2014-06-01

    Many astronomical observations indicate that dark matter pervades the universe and dominates the formation and dynamics of cosmic structures. Weakly interacting massive particles (WIMPs) with masses in the GeV to TeV range form a popular class of dark matter candidates. WIMP self-annihilation may lead to the production of γ-rays in the very high energy regime above 100 GeV, which is observable with imaging air Cherenkov telescopes (IACTs). For this thesis, observations of dwarf spheroidal galaxies (dSph) and the Fornax galaxy cluster with the Cherenkov telescope systems H.E.S.S., MAGIC and VERITAS were used to search for γ-ray signals of dark matter annihilations. The work consists of two parts: First, a likelihood-based statistical technique was introduced to combine published results of dSph observations with the different IACTs. The technique also accounts for uncertainties on the ''J factors'', which quantify the dark matter content of the dwarf galaxies. Secondly, H.E.S.S. observations of the Fornax cluster were analyzed. In this case, a collection of dark matter halo models was used for the J factor computation. In addition, possible signal enhancements from halo substructures were considered. None of the searches yielded a significant γ-ray signal. Therefore, the results were used to place upper limits on the thermally averaged dark matter self-annihilation cross-section left angle σν right angle. Different models for the final state of the annihilation process were considered. The cross-section limits range from left angle σν right angle UL ∝10 -19 cm 3 s -1 to left angle σν right angle UL ∝10 -25 cm 3 s -1 for dark matter particles masses between 100 GeV and 100 TeV. Some of the diverse model uncertainties causing this wide range of left angle σν right angle UL values were analyzed.

  1. Mapping online consumer search

    NARCIS (Netherlands)

    Bronnenberg, B.J.; Kim, J.; Albuquerque, P.

    2011-01-01

    The authors propose a new method to visualize browsing behavior in so-called product search maps. Manufacturers can use these maps to understand how consumers search for competing products before choice, including how information acquisition and product search are organized along brands, product

  2. The Information Search

    Science.gov (United States)

    Doraiswamy, Uma

    2011-01-01

    This paper in the form of story discusses a college student's information search process. In this story we see Kuhlthau's information search process: initiation, selection, exploration, formulation, collection, and presentation. Katie is a student who goes in search of information for her class research paper. Katie's class readings, her interest…

  3. Keyword Search in Databases

    CERN Document Server

    Yu, Jeffrey Xu; Chang, Lijun

    2009-01-01

    It has become highly desirable to provide users with flexible ways to query/search information over databases as simple as keyword search like Google search. This book surveys the recent developments on keyword search over databases, and focuses on finding structural information among objects in a database using a set of keywords. Such structural information to be returned can be either trees or subgraphs representing how the objects, that contain the required keywords, are interconnected in a relational database or in an XML database. The structural keyword search is completely different from

  4. A Search for Weakly Interacting Particles with the Cryogenic Dark Matter Search Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Bruch, Tobias [Univ. of Zurich (Switzerland)

    2010-01-01

    Dark matter particles cannot only be detected directly in laboratories, but also indirectly by their annihilation products. Previous predictions of the neutrino flux from WIMP annihilation in the Earth and the Sun have assumed that galactic dark matter is distributed according to the SHM. Although the dark disc has a local density comparable to the dark halo, its higher phase space density at low velocities greatly enhances capture rates in the Sun and Earth. For typical dark disc properties, the resulting muon flux from the Earth is increased by three orders of magnitude over the SHM, while for the Sun the increase is one order of magnitude. This significantly increases the prospects of neutrino telescopes to fix or constrain parameters in WIMP models. The flux from the Earth is extremely sensitive to the detailed properties of the dark disc, while the flux from the Sun is more robust.

  5. University Students' Online Information Searching Strategies in Different Search Contexts

    Science.gov (United States)

    Tsai, Meng-Jung; Liang, Jyh-Chong; Hou, Huei-Tse; Tsai, Chin-Chung

    2012-01-01

    This study investigates the role of search context played in university students' online information searching strategies. A total of 304 university students in Taiwan were surveyed with questionnaires in which two search contexts were defined as searching for learning, and searching for daily life information. Students' online search strategies…

  6. [Advanced online search techniques and dedicated search engines for physicians].

    Science.gov (United States)

    Nahum, Yoav

    2008-02-01

    In recent years search engines have become an essential tool in the work of physicians. This article will review advanced search techniques from the world of information specialists, as well as some advanced search engine operators that may help physicians improve their online search capabilities, and maximize the yield of their searches. This article also reviews popular dedicated scientific and biomedical literature search engines.

  7. Adaptive Large Neighbourhood Search

    DEFF Research Database (Denmark)

    Røpke, Stefan

    Large neighborhood search is a metaheuristic that has gained popularity in recent years. The heuristic repeatedly moves from solution to solution by first partially destroying the solution and then repairing it. The best solution observed during this search is presented as the final solution....... This tutorial introduces the large neighborhood search metaheuristic and the variant adaptive large neighborhood search that dynamically tunes parameters of the heuristic while it is running. Both heuristics belong to a broader class of heuristics that are searching a solution space using very large...... neighborhoods. The tutorial also present applications of the adaptive large neighborhood search, mostly related to vehicle routing problems for which the heuristic has been extremely successful. We discuss how the heuristic can be parallelized and thereby take advantage of modern desktop computers...

  8. Supporting Book Search

    DEFF Research Database (Denmark)

    Bogers, Toine; Petras, Vivien

    2017-01-01

    of information needs. In this paper, we present a large-scale empirical comparison of the effectiveness of book metadata elements for searching complex information needs. Using a test collection of over 2 million book records and over 330 real-world book search requests, we perform a highly controlled and in......-depth analysis of topical metadata, comparing controlled vocabularies with social tags. Tags perform better overall in this setting, but controlled vocabulary terms provide complementary information, which will improve a search. We analyze potential underlying factors that contribute to search performance......, such as the relevance aspect(s) mentioned in a request or the type of book. In addition, we investigate the possible causes of search failure. We conclude that neither tags nor controlled vocabularies are wholly suited to handling the complex information needs in book search, which means that different approaches...

  9. A search for particle dark matter using cryogenic germanium and silicon detectors in the one- and two- tower runs of CDMS-II at Soudan

    International Nuclear Information System (INIS)

    Ogburn, Reuben Walter IV

    2008-01-01

    Images of the Bullet Cluster of galaxies in visible light, X-rays, and through gravitational lensing confirm that most of the matter in the universe is not composed of any known form of matter. The combined evidence from the dynamics of galaxies and clusters of galaxies, the cosmic microwave background, big bang nucleosynthesis, and other observations indicates that 80% of the universe's matter is dark, nearly collisionless, and cold. The identify of the dar, matter remains unknown, but weakly interacting massive particles (WIMPs) are a very good candidate. They are a natural part of many supersymmetric extensions to the standard model, and could be produced as a nonrelativistic, thermal relic in the early universe with about the right density to account for the missing mass. The dark matter of a galaxy should exist as a spherical or ellipsoidal cloud, called a 'halo' because it extends well past the edge of the visible galaxy. The Cryogenic Dark Matter Search (CDMS) seeks to directly detect interactions between WIMPs in the Milky Way's galactic dark matter halo using crystals of germanium and silicon. Our Z-sensitive ionization and phonon ('ZIP') detectors simultaneously measure both phonons and ionization produced by particle interactions. In order to find very rare, low-energy WIMP interactions, they must identify and reject background events caused by environmental radioactivity, radioactive contaminants on the detector,s and cosmic rays. In particular, sophisticated analysis of the timing of phonon signals is needed to eliminate signals caused by beta decays at the detector surfaces. This thesis presents the firs two dark matter data sets from the deep underground experimental site at the Soudan Underground Laboratory in Minnesota. These are known as 'Run 118', with six detectors (1 kg Ge, 65.2 live days before cuts) and 'Run 119', with twelve detectors (1.5 kg Ge, 74.5 live days before cuts). They have analyzed all data from the two runs together in a single

  10. ElasticSearch cookbook

    CERN Document Server

    Paro, Alberto

    2013-01-01

    Written in an engaging, easy-to-follow style, the recipes will help you to extend the capabilities of ElasticSearch to manage your data effectively.If you are a developer who implements ElasticSearch in your web applications, manage data, or have decided to start using ElasticSearch, this book is ideal for you. This book assumes that you've got working knowledge of JSON and Java

  11. Mastering ElasticSearch

    CERN Document Server

    Kuc, Rafal

    2013-01-01

    A practical tutorial that covers the difficult design, implementation, and management of search solutions.Mastering ElasticSearch is aimed at to intermediate users who want to extend their knowledge about ElasticSearch. The topics that are described in the book are detailed, but we assume that you already know the basics, like the query DSL or data indexing. Advanced users will also find this book useful, as the examples are getting deep into the internals where it is needed.

  12. Search engine optimization

    OpenAIRE

    Marolt, Klemen

    2013-01-01

    Search engine optimization techniques, often shortened to “SEO,” should lead to first positions in organic search results. Some optimization techniques do not change over time, yet still form the basis for SEO. However, as the Internet and web design evolves dynamically, new optimization techniques flourish and flop. Thus, we looked at the most important factors that can help to improve positioning in search results. It is important to emphasize that none of the techniques can guarantee high ...

  13. Mobile Search and Advertising

    OpenAIRE

    Lovitskii, Vladimir; McCaffery, Colin; Thrasher, Michael; Traynor, David; Wright, Peter

    2009-01-01

    Mobile advertising is a rapidly growing sector providing brands and marketing agencies the opportunity to connect with consumers beyond traditional and digital media and instead communicate directly on their mobile phones. Mobile advertising will be intrinsically linked with mobile search, which has transported from the internet to the mobile and is identified as an area of potential growth. The result of mobile searching show that as a general rule such search result exceed 1...

  14. Search and Disrupt

    DEFF Research Database (Denmark)

    Ørding Olsen, Anders

    . However, incumbent sources engaged in capability reconfiguration to accommodate disruption improve search efforts in disruptive technologies. The paper concludes that the value of external sources is contingent on more than their knowledge. Specifically, interdependence of sources in search gives rise...... to influence from individual strategic interests on the outcomes. More generally, this points to the need for understanding the two-way influence of sources, rather than viewing external search as one-way knowledge accessing....

  15. Delaying information search

    Directory of Open Access Journals (Sweden)

    Yaniv Shani

    2012-11-01

    Full Text Available In three studies, we examined factors that may temporarily attenuate information search. People are generally curious and dislike uncertainty, which typically encourages them to look for relevant information. Despite these strong forces that promote information search, people sometimes deliberately delay obtaining valuable information. We find they may do so when they are concerned that the information might interfere with future pleasurable activities. Interestingly, the decision to search or to postpone searching for information is influenced not only by the value and importance of the information itself but also by well-being maintenance goals related to possible detrimental effects that negative knowledge may have on unrelated future plans.

  16. Google Power Search

    CERN Document Server

    Spencer, Stephan

    2011-01-01

    Behind Google's deceptively simple interface is immense power for both market and competitive research-if you know how to use it well. Sure, basic searches are easy, but complex searches require specialized skills. This concise book takes you through the full range of Google's powerful search-refinement features, so you can quickly find the specific information you need. Learn techniques ranging from simple Boolean logic to URL parameters and other advanced tools, and see how they're applied to real-world market research examples. Incorporate advanced search operators such as filetype:, intit

  17. Optimization of partial search

    International Nuclear Information System (INIS)

    Korepin, Vladimir E

    2005-01-01

    A quantum Grover search algorithm can find a target item in a database faster than any classical algorithm. One can trade accuracy for speed and find a part of the database (a block) containing the target item even faster; this is partial search. A partial search algorithm was recently suggested by Grover and Radhakrishnan. Here we optimize it. Efficiency of the search algorithm is measured by the number of queries to the oracle. The author suggests a new version of the Grover-Radhakrishnan algorithm which uses a minimal number of such queries. The algorithm can run on the same hardware that is used for the usual Grover algorithm. (letter to the editor)

  18. Search for an Annual Modulation in a p-Type Point Contact Germanium Dark Matter Detector

    Energy Technology Data Exchange (ETDEWEB)

    Barbeau, P.S. [University of Chicago; Collar, J.I. [University of Chicago; Fields, N. [University of Chicago; Hossbach, T.W. [Pacific Northwest National Laboratory (PNNL); Aalseth, C.E. [Pacific Northwest National Laboratory (PNNL); Fast, James E. [Pacific Northwest National Laboratory (PNNL); Keillor, M. [Pacific Northwest National Laboratory (PNNL); Kephart, J.D. [Pacific Northwest National Laboratory (PNNL); Miley, H.S. [Pacific Northwest National Laboratory (PNNL); Orrell, John L. [Pacific Northwest National Laboratory (PNNL); Colaresi, James F. [Canberra Industries, Inc., Meriden, CT; Yocum, K. Michael [Canberra Industries, Inc., Meriden, CT; Leon, J. Diaz [University of Washington, Ctr Expt Nucle Phys & Astrophys; Knecht, A. [University of Washington, Ctr Expt Nucle Phys & Astrophys; Marino, M. G. [University of Washington, Ctr Expt Nucle Phys & Astrophys; Miller, M. L. [University of Washington, Ctr Expt Nucle Phys & Astrophys; Radford, David C [ORNL; Wilkerson, John F [University of North Carolina, Chapel Hill

    2011-01-01

    Fifteen months of cumulative CoGeNT data are examined for indications of an annual modulation, a predicted signature of weakly interacting massive particle (WIMP) interactions. Presently available data support the presence of a modulated component of unknown origin, with parameters prima facie compatible with a galactic halo composed of light-mass WIMPs. Unoptimized estimators yield a statistical significance for a modulation of {approx}2.8{sigma}, limited by the short exposure.

  19. Results from the 1 tonne*year Dark Matter Search with XENON1T

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    Weakly Interacting Massive Particles (WIMPs) are an excellent candidate for the mysterious Dark Matter in the Universe. The XENON1T experiment at LNGS is the world’s largest and most sensitive experiment for the direct detection of WIMPs via nuclear recoils. Details of the experiment and of the achieved unprecedented low background conditions will be covered and new results from a record exposure of 1 tonne x year will be presented for the first time.

  20. Citation Searching: Search Smarter & Find More

    Science.gov (United States)

    Hammond, Chelsea C.; Brown, Stephanie Willen

    2008-01-01

    The staff at University of Connecticut are participating in Elsevier's Student Ambassador Program (SAmP) in which graduate students train their peers on "citation searching" research using Scopus and Web of Science, two tremendous citation databases. They are in the fourth semester of these training programs, and they are wildly successful: They…

  1. Constructing Effective Search Strategies for Electronic Searching.

    Science.gov (United States)

    Flanagan, Lynn; Parente, Sharon Campbell

    Electronic databases have grown tremendously in both number and popularity since their development during the 1960s. Access to electronic databases in academic libraries was originally offered primarily through mediated search services by trained librarians; however, the advent of CD-ROM and end-user interfaces for online databases has shifted the…

  2. Search for annihilating dark matter in the Sun with 3 years of IceCube data

    Energy Technology Data Exchange (ETDEWEB)

    Aartsen, M.G.; Hill, G.C.; Robertson, S.; Wallace, A.; Whelan, B.J. [University of Adelaide, Department of Physics, Adelaide (Australia); Ackermann, M.; Bernardini, E.; Blot, S.; Bretz, H.P.; Franckowiak, A.; Jacobi, E.; Karg, T.; Kintscher, T.; Kunwar, S.; Nahnhauer, R.; Satalecka, K.; Spiering, C.; Stasik, A.; Strotjohann, N.L.; Terliuk, A.; Usner, M.; Santen, J. van [DESY, Zeuthen (Germany); Adams, J. [University of Canterbury, Department of Physics and Astronomy, Private Bag 4800, Christchurch (New Zealand); Aguilar, J.A.; Ansseau, I.; Heereman, D.; Meagher, K.; Meures, T.; O' Murchadha, A.; Pinat, E.; Raab, C. [Universite Libre de Bruxelles, Science Faculty CP230, Brussels (Belgium); Ahlers, M.; Braun, J.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Fahey, S.; Feintzeig, J.; Ghorbani, K.; Gladstone, L.; Griffith, Z.; Halzen, F.; Hanson, K.; Jero, K.; Karle, A.; Kauer, M.; Kelley, J.L.; Kheirandish, A.; Krueger, C.; Mancina, S.; McNally, F.; Merino, G.; Sabbatini, L.; Tobin, M.N.; Tosi, D.; Vandenbroucke, J.; Van Rossem, M.; Wandkowsky, N.; Wendt, C.; Westerhoff, S.; Wille, L.; Xu, D.L. [University of Wisconsin, Department of Physics and Wisconsin IceCube Particle Astrophysics Center, Madison, WI (United States); Ahrens, M.; Bohm, C.; Dumm, J.P.; Finley, C.; Flis, S.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M. [Stockholm University, Department of Physics, Oskar Klein Centre, Stockholm (Sweden); Altmann, D.; Anton, G.; Gluesenkamp, T.; Katz, U.; Kittler, T.; Tselengidou, M. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erlangen (Germany); Andeen, K. [Marquette University, Department of Physics, Milwaukee, WI (United States); Anderson, T.; Dunkman, M.; Eller, P.; Huang, F.; Keivani, A.; Lanfranchi, J.L.; Pankova, D.V.; Quinnan, M.; Tesic, G.; Weiss, M.J. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Archinger, M.; Baum, V.; Boeser, S.; Pino Rosendo, E. del; Lorenzo, V. di; Eberhardt, B.; Ehrhardt, T.; Foesig, C.C.; Koepke, L.; Krueckl, G.; Peiffer, P.; Sandroos, J.; Steuer, A.; Wiebe, K. [University of Mainz, Institute of Physics, Mainz (Germany); Argueelles, C.; Axani, S.; Collin, G.H.; Conrad, J.M.; Jones, B.J.P.; Moulai, M. [Massachusetts Institute of Technology, Department of Physics, Cambridge, MA (United States); Auffenberg, J.; Bissok, M.; Glauch, T.; Haack, C.; Hansmann, T.; Konietz, R.; Leuermann, M.; Penek, Oe.; Raedel, L.; Reimann, R.; Rongen, M.; Schoenen, S.; Schumacher, L.; Stettner, J.; Vehring, M.; Vogel, E.; Wallraff, M.; Wickmann, S.; Wiebusch, C.H. [RWTH Aachen University, III. Physikalisches Institut, Aachen (Germany); Bai, X. [South Dakota School of Mines and Technology, Physics Department, Rapid City, SD (United States); Barwick, S.W.; Yodh, G. [University of California, Department of Physics and Astronomy, Irvine, CA (United States); Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K. [University of California, Department of Physics, Berkeley, CA (United States); Beatty, J.J. [Ohio State University, Department of Physics and Center for Cosmology and Astro-Particle Physics, Columbus, OH (United States); Ohio State University, Department of Astronomy, Columbus, OH (United States); Becker Tjus, J.; Bos, F.; Eichmann, B.; Kroll, M.; Mandelartz, M.; Schoeneberg, S.; Tenholt, F. [Ruhr-Universitaet Bochum, Fakultaet fuer Physik and Astronomie, Bochum (Germany); Becker, K.H.; Bindig, D.; Helbing, K.; Hickford, S.; Hoffmann, R.; Kopper, S.; Lauber, F.; Naumann, U.; Obertacke Pollmann, A.; Soldin, D. [University of Wuppertal, Department of Physics, Wuppertal (Germany); BenZvi, S.; Cross, R. [University of Rochester, Department of Physics and Astronomy, Rochester, NY (United States); Berley, D.; Blaufuss, E.; Cheung, E.; Felde, J.; Friedman, E.; Hellauer, R.; Hoffman, K.D.; Maunu, R.; Olivas, A.; Schmidt, T.; Song, M.; Sullivan, G.W. [University of Maryland, Department of Physics, College Park, MD (United States); Bernhard, A.; Coenders, S.; Huber, M.; Krings, K.; Resconi, E.; Turcati, A. [Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Besson, D.Z. [University of Kansas, Department of Physics and Astronomy, Lawrence, KS (United States); Binder, G.; Gerhardt, L.; Klein, S.R.; Miarecki, S.; Palczewski, T.; Tatar, J. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Boerner, M.; Fuchs, T.; Meier, M.; Menne, T.; Pieloth, D.; Rhode, W.; Ruhe, T.; Sandrock, A.; Schlunder, P. [TU Dortmund University, Department of Physics, Dortmund (Germany); Bose, D.; Dujmovic, H.; In, S.; Jeong, M.; Kang, W.; Kim, J.; Kim, M.; Rott, C. [Sungkyunkwan University, Department of Physics, Suwon (Korea, Republic of); Collaboration: IceCube Collaboration; and others

    2017-03-15

    We present results from an analysis looking for dark matter annihilation in the Sun with the IceCube neutrino telescope. Gravitationally trapped dark matter in the Sun's core can annihilate into Standard Model particles making the Sun a source of GeV neutrinos. IceCube is able to detect neutrinos with energies >100 GeV while its low-energy infill array DeepCore extends this to >10 GeV. This analysis uses data gathered in the austral winters between May 2011 and May 2014, corresponding to 532 days of live time when the Sun, being below the horizon, is a source of up-going neutrino events, easiest to discriminate against the dominant background of atmospheric muons. The sensitivity is a factor of two to four better than previous searches due to additional statistics and improved analysis methods involving better background rejection and reconstructions. The resultant upper limits on the spin-dependent dark matter-proton scattering cross section reach down to 1.46 x 10{sup -5} pb for a dark matter particle of mass 500 GeV annihilating exclusively into τ{sup +}τ{sup -} particles. These are currently the most stringent limits on the spin-dependent dark matter-proton scattering cross section for WIMP masses above 50 GeV. (orig.)

  3. Search for dark matter annihilation in the Galactic Center with IceCube-79

    International Nuclear Information System (INIS)

    Aartsen, M.G.; Hill, G.C.; Robertson, S.; Whelan, B.J.; Abraham, K.; Bernhard, A.; Coenders, S.; Gross, A.; Holzapfel, K.; Huber, M.; Jurkovic, M.; Krings, K.; Resconi, E.; Veenkamp, J.; Ackermann, M.; Berghaus, P.; Bernardini, E.; Bretz, H.P.; Cruz Silva, A.H.; Gluesenkamp, T.; Gora, D.; Jacobi, E.; Kaminsky, B.; Karg, T.; Middell, E.; Mohrmann, L.; Nahnhauer, R.; Schoenwald, A.; Shanidze, R.; Spiering, C.; Stasik, A.; Stoessl, A.; Strotjohann, N.L.; Terliuk, A.; Usner, M.; Yanez, J.P.; Adams, J.; Brown, A.M.; Aguilar, J.A.; Heereman, D.; Meagher, K.; Meures, T.; O'Murchadha, A.; Pinat, E.; Ahlers, M.; Arguelles, C.; Beiser, E.; BenZvi, S.; Braun, J.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Fadiran, O.; Fahey, S.; Feintzeig, J.; Ghorbani, K.; Gladstone, L.; Halzen, F.; Hanson, K.; Hoshina, K.; Jero, K.; Karle, A.; Kelley, J.L.; Kheirandish, A.; McNally, F.; Merino, G.; Middlemas, E.; Morse, R.; Richter, S.; Sabbatini, L.; Tobin, M.N.; Tosi, D.; Vandenbroucke, J.; Van Santen, J.; Wandkowsky, N.; Weaver, C.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wille, L.; Ahrens, M.; Bohm, C.; Dumm, J.P.; Finley, C.; Flis, S.; Hulth, P.O.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M.; Altmann, D.; Classen, L.; Kappes, A.; Tselengidou, M.; Anderson, T.; Arlen, T.C.; Dunkman, M.; Eagan, R.; Groh, J.C.; Huang, F.; Keivani, A.; Lanfranchi, J.L.; Quinnan, M.; Smith, M.W.E.; Stanisha, N.A.; Tesic, G.; Archinger, M.; Baum, V.; Boeser, S.; Eberhardt, B.; Ehrhardt, T.; Koepke, L.; Kroll, G.; Luenemann, J.; Sander, H.G.; Schatto, K.; Wiebe, K.; Auffenberg, J.; Bissok, M.; Blumenthal, J.; Glagla, M.; Gier, D.; Gretskov, P.; Haack, C.; Hansmann, B.; Hellwig, D.; Kemp, J.; Konietz, R.; Koob, A.; Leuermann, M.; Leuner, J.; Paul, L.; Puetz, J.; Raedel, L.; Reimann, R.; Rongen, M.; Schimp, M.; Schoenen, S.; Schukraft, A.; Stahlberg, M.; Vehring, M.; Wallraff, M.; Wichary, C.; Wiebusch, C.H.; Bai, X.; Barwick, S.W.; Yodh, G.; Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K.; Beatty, J.J.; Becker Tjus, J.; Bos, F.; Eichmann, B.; Fedynitch, A.; Kroll, M.; Saba, S.M.; Schoeneberg, S.; Becker, K.H.; Bindig, D.; Fischer-Wasels, T.; Helbing, K.; Hickford, S.; Hoffmann, R.; Klaes, J.; Kopper, S.; Naumann, U.; Obertacke, A.; Omairat, A.; Posselt, J.; Soldin, D.; Berley, D.; Blaufuss, E.; Cheung, E.; Christy, B.; Felde, J.; Hellauer, R.; Hoffman, K.D.; Huelsnitz, W.; Maunu, R.; Olivas, A.; Redl, P.; Schmidt, T.; Sullivan, G.W.; Wissing, H.; Besson, D.Z.; Binder, G.; Gerhardt, L.; Ha, C.; Klein, S.R.; Miarecki, S.; Boersma, D.J.; Botner, O.; Euler, S.; Hallgren, A.

    2015-01-01

    The Milky Way is expected to be embedded in a halo of dark matter particles, with the highest density in the central region, and decreasing density with the halo-centric radius. Dark matter might be indirectly detectable at Earth through a flux of stable particles generated in dark matter annihilations and peaked in the direction of the Galactic Center. We present a search for an excess flux of muon (anti-) neutrinos from dark matter annihilation in the Galactic Center using the cubic-kilometer-sized IceCube neutrino detector at the South Pole. There, the Galactic Center is always seen above the horizon. Thus, new and dedicated veto techniques against atmospheric muons are required to make the southern hemisphere accessible for IceCube. We used 319.7 live-days of data from IceCube operating in its 79-string configuration during 2010 and 2011. No neutrino excess was found and the final result is compatible with the background. We present upper limits on the self-annihilation cross-section, left angle σ A right angle, for WIMP masses ranging from 30 GeV up to 10 TeV, assuming cuspy (NFW) and flat-cored (Burkert) dark matter halo profiles, reaching down to ≅ 4 . 10 -24 cm 3 s -1 , and ≅ 2.6 . 10 -23 cm 3 s -1 for the νanti ν channel, respectively. (orig.)

  4. Search for black matter through the detection of gravitational micro-lenses in differential photometry

    International Nuclear Information System (INIS)

    Le Guillou, L.

    2003-09-01

    The nature of dark matter is an open question. The search for gravitational microlensing effects is an interesting tool because this effect is strongly dependent on the mass of objects whether they are luminous or not, however this detection method is only sensitive to compact forms of dark matter (MACHOS - massive astronomical halo compact objects), and as a consequence no-baryonic matter like neutrinos or WIMPS (weakly interacting massive particles) can not be detected this way. In the first chapter the author reviews the plausible candidates to black matter. The use of the microlensing effect as a probe of the galactic halo is presented in the second chapter. The third chapter is dedicated to the series of experiments worldwide that focus on the detection of MACHOS. In the fourth chapter the author shows how the DIA (difference image analysis) method may be promising in the study of gravitational microlensing effects. The main part of this work has been the use of the DIA method to process five-year data set collected by the Eros experiment in the small Magellanic cloud (SMC). The data processing line and the results are presented in the fifth and sixth chapters. The results are consistent with previous results given by Eros and they confirm the disparity of the durations of micro-lenses detected in the large and small Magellanic clouds. (A.C.)

  5. Search for dark matter annihilation in the Galactic Center with IceCube-79

    Energy Technology Data Exchange (ETDEWEB)

    Aartsen, M.G.; Hill, G.C.; Robertson, S.; Whelan, B.J. [University of Adelaide, School of Chemistry and Physics, Adelaide, SA (Australia); Abraham, K.; Bernhard, A.; Coenders, S.; Gross, A.; Holzapfel, K.; Huber, M.; Jurkovic, M.; Krings, K.; Resconi, E.; Veenkamp, J. [Technische Universitaet Muenchen, Garching (Germany); Ackermann, M.; Berghaus, P.; Bernardini, E.; Bretz, H.P.; Cruz Silva, A.H.; Gluesenkamp, T.; Gora, D.; Jacobi, E.; Kaminsky, B.; Karg, T.; Middell, E.; Mohrmann, L.; Nahnhauer, R.; Schoenwald, A.; Shanidze, R.; Spiering, C.; Stasik, A.; Stoessl, A.; Strotjohann, N.L.; Terliuk, A.; Usner, M.; Yanez, J.P. [DESY, Zeuthen (Germany); Adams, J.; Brown, A.M. [University of Canterbury, Department of Physics and Astronomy, Private Bag 4800, Christchurch (New Zealand); Aguilar, J.A.; Heereman, D.; Meagher, K.; Meures, T.; O' Murchadha, A.; Pinat, E. [Universite Libre de Bruxelles, Science Faculty CP230, Brussels (Belgium); Ahlers, M.; Arguelles, C.; Beiser, E.; BenZvi, S.; Braun, J.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Fadiran, O.; Fahey, S.; Feintzeig, J.; Ghorbani, K.; Gladstone, L.; Halzen, F.; Hanson, K.; Hoshina, K.; Jero, K.; Karle, A.; Kelley, J.L.; Kheirandish, A.; McNally, F.; Merino, G.; Middlemas, E.; Morse, R.; Richter, S.; Sabbatini, L.; Tobin, M.N.; Tosi, D.; Vandenbroucke, J.; Van Santen, J.; Wandkowsky, N.; Weaver, C.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wille, L. [Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Department of Physics, Madison, WI (United States); Ahrens, M.; Bohm, C.; Dumm, J.P.; Finley, C.; Flis, S.; Hulth, P.O.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M. [Oskar Klein Centre, Stockholm University, Department of Physics, Stockholm (Sweden); Altmann, D.; Classen, L.; Kappes, A.; Tselengidou, M. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erlangen (Germany); Anderson, T.; Arlen, T.C.; Dunkman, M.; Eagan, R.; Groh, J.C.; Huang, F.; Keivani, A.; Lanfranchi, J.L.; Quinnan, M.; Smith, M.W.E.; Stanisha, N.A.; Tesic, G. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Archinger, M.; Baum, V.; Boeser, S.; Eberhardt, B.; Ehrhardt, T.; Koepke, L.; Kroll, G.; Luenemann, J.; Sander, H.G.; Schatto, K.; Wiebe, K. [University of Mainz, Institute of Physics, Mainz (Germany); Auffenberg, J.; Bissok, M.; Blumenthal, J.; Glagla, M.; Gier, D.; Gretskov, P.; Haack, C.; Hansmann, B.; Hellwig, D.; Kemp, J.; Konietz, R.; Koob, A.; Leuermann, M.; Leuner, J.; Paul, L.; Puetz, J.; Raedel, L.; Reimann, R.; Rongen, M.; Schimp, M.; Schoenen, S.; Schukraft, A.; Stahlberg, M.; Vehring, M.; Wallraff, M.; Wichary, C.; Wiebusch, C.H. [RWTH Aachen University, III. Physikalisches Institut, Aachen (Germany); Bai, X. [South Dakota School of Mines and Technology, Physics Department, Rapid City, SD (United States); Barwick, S.W.; Yodh, G. [University of California, Department of Physics and Astronomy, Irvine, CA (United States); Bay, R.; Filimonov, K.; Price, P.B.; Woschnagg, K. [University of California, Department of Physics, Berkeley, CA (United States); Beatty, J.J. [Ohio State University, Department of Physics and Center for Cosmology and Astro-Particle Physics, Columbus, OH (United States); Ohio State University, Department of Astronomy, Columbus, OH (United States); Becker Tjus, J.; Bos, F.; Eichmann, B.; Fedynitch, A.; Kroll, M.; Saba, S.M.; Schoeneberg, S. [Ruhr-Universitaet Bochum, Fakultaet fuer Physik and Astronomie, Bochum (Germany); Becker, K.H.; Bindig, D.; Fischer-Wasels, T.; Helbing, K.; Hickford, S.; Hoffmann, R.; Klaes, J.; Kopper, S.; Naumann, U.; Obertacke, A.; Omairat, A.; Posselt, J.; Soldin, D. [University of Wuppertal, Department of Physics, Wuppertal (Germany); Berley, D.; Blaufuss, E.; Cheung, E.; Christy, B.; Felde, J.; Hellauer, R.; Hoffman, K.D.; Huelsnitz, W.; Maunu, R.; Olivas, A.; Redl, P.; Schmidt, T.; Sullivan, G.W.; Wissing, H. [University of Maryland, Department of Physics, College Park, MD (United States); Besson, D.Z. [University of Kansas, Department of Physics and Astronomy, Lawrence, KS (United States); Binder, G.; Gerhardt, L.; Ha, C.; Klein, S.R.; Miarecki, S. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Boersma, D.J.; Botner, O.; Euler, S.; Hallgren, A.; Collaboration: IceCube Collaboration; and others

    2015-10-15

    The Milky Way is expected to be embedded in a halo of dark matter particles, with the highest density in the central region, and decreasing density with the halo-centric radius. Dark matter might be indirectly detectable at Earth through a flux of stable particles generated in dark matter annihilations and peaked in the direction of the Galactic Center. We present a search for an excess flux of muon (anti-) neutrinos from dark matter annihilation in the Galactic Center using the cubic-kilometer-sized IceCube neutrino detector at the South Pole. There, the Galactic Center is always seen above the horizon. Thus, new and dedicated veto techniques against atmospheric muons are required to make the southern hemisphere accessible for IceCube. We used 319.7 live-days of data from IceCube operating in its 79-string configuration during 2010 and 2011. No neutrino excess was found and the final result is compatible with the background. We present upper limits on the self-annihilation cross-section, left angle σ{sub A} right angle, for WIMP masses ranging from 30 GeV up to 10 TeV, assuming cuspy (NFW) and flat-cored (Burkert) dark matter halo profiles, reaching down to ≅ 4 . 10{sup -24} cm{sup 3}s{sup -1}, and ≅ 2.6 . 10{sup -23} cm{sup 3}s{sup -1} for the νanti ν channel, respectively. (orig.)

  6. INTERFACING GOOGLE SEARCH ENGINE TO CAPTURE USER WEB SEARCH BEHAVIOR

    OpenAIRE

    Fadhilah Mat Yamin; T. Ramayah

    2013-01-01

    The behaviour of the searcher when using the search engine especially during the query formulation is crucial. Search engines capture users’ activities in the search log, which is stored at the search engine server. Due to the difficulty of obtaining this search log, this paper proposed and develops an interface framework to interface a Google search engine. This interface will capture users’ queries before redirect them to Google. The analysis of the search log will show that users are utili...

  7. Vertical Search Engines

    OpenAIRE

    Curran, Kevin; Mc Glinchey, Jude

    2017-01-01

    This paper outlines the growth in popularity of vertical search engines, their origins, the differences between them and well-known broad based search engines such as Google and Yahoo. We also discuss their use in business-to-business, their marketing and advertising costs, what the revenue streams are and who uses them.

  8. African Environment: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  9. Mathematics Connection: Advanced Search

    African Journals Online (AJOL)

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  10. Supporting complex search tasks

    DEFF Research Database (Denmark)

    Gäde, Maria; Hall, Mark; Huurdeman, Hugo

    2015-01-01

    , is fragmented at best. The workshop addressed the many open research questions: What are the obvious use cases and applications of complex search? What are essential features of work tasks and search tasks to take into account? And how do these evolve over time? With a multitude of information, varying from...

  11. Innovation: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  12. Human memory search

    NARCIS (Netherlands)

    Davelaar, E.J.; Raaijmakers, J.G.W.; Hills, T.T.; Robbins, T.W.; Todd, P.M.

    2012-01-01

    The importance of understanding human memory search is hard to exaggerate: we build and live our lives based on what whe remember. This chapter explores the characteristics of memory search, with special emphasis on the use of retrieval cues. We introduce the dependent measures that are obtained

  13. Zede Journal: Advanced Search

    African Journals Online (AJOL)

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  14. Searches for Supersymmetry

    CERN Document Server

    Ventura, Andrea; The ATLAS collaboration

    2017-01-01

    New and recent results on Supersymmetry searches are shown for the ATLAS and the CMS experiments. Analyses with about 36 fb$^{-1}$ are considered for searches concerning light squarks and gluinos, direct pair production of 3$^{rd}$ generation squarks, electroweak production of charginos, neutralinos, sleptons, R-parity violating scenarios and long-lived particles.

  15. Searches for Supersymmetry

    CERN Document Server

    Ventura, Andrea; The ATLAS collaboration

    2017-01-01

    New and recents results on Supersymmetry searches are shown for the ATLAS and the CMS experiments. Analyses with about 36 fb^-1 are considered for searches concerning light squarks and gluinos, direct pair production of 3rd generation squarks, electroweak production of charginos, neutralinos, sleptons, R-parity violating scenarios and long-lived particles.

  16. Philosophical Papers: Advanced Search

    African Journals Online (AJOL)

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  17. Kiswahili: Advanced Search

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  18. Sciences & Nature: Advanced Search

    African Journals Online (AJOL)

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  19. Vulture News: Advanced Search

    African Journals Online (AJOL)

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  20. Agronomie Africaine: Advanced Search

    African Journals Online (AJOL)

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  1. Distributed Deep Web Search

    NARCIS (Netherlands)

    Tjin-Kam-Jet, Kien

    2013-01-01

    The World Wide Web contains billions of documents (and counting); hence, it is likely that some document will contain the answer or content you are searching for. While major search engines like Bing and Google often manage to return relevant results to your query, there are plenty of situations in

  2. ElasticSearch cookbook

    CERN Document Server

    Paro, Alberto

    2015-01-01

    If you are a developer who implements ElasticSearch in your web applications and want to sharpen your understanding of the core elements and applications, this is the book for you. It is assumed that you've got working knowledge of JSON and, if you want to extend ElasticSearch, of Java and related technologies.

  3. Africa Insight: Advanced Search

    African Journals Online (AJOL)

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  4. Critical Arts: Advanced Search

    African Journals Online (AJOL)

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  5. Ergonomics SA: Advanced Search

    African Journals Online (AJOL)

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  6. Kenya Veterinarian: Advanced Search

    African Journals Online (AJOL)

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  7. Counsellor (The): Advanced Search

    African Journals Online (AJOL)

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  8. Search for a planet

    International Nuclear Information System (INIS)

    Tokovinin, A.A.

    1986-01-01

    The problem of search for star planets is discussed in a popular form. Two methods of search for planets are considered: astrometric and spectral. Both methods complement one another. An assumption is made that potential possessors of planets are in the first place yellow and red dwarfs with slow axial rotation. These stars are the most numerous representatives of Galaxy population

  9. Nigerian Libraries: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  10. Search of associative memory.

    NARCIS (Netherlands)

    Raaijmakers, J.G.W.; Shiffrin, R.M.

    1981-01-01

    Describes search of associative memory (SAM), a general theory of retrieval from long-term memory that combines features of associative network models and random search models. It posits cue-dependent probabilistic sampling and recovery from an associative network, but the network is specified as a

  11. African Zoology: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  12. Fractional charge search

    International Nuclear Information System (INIS)

    Innes, W.; Klein, S.; Perl, M.; Price, J.C.

    1982-06-01

    A device to search for fractional charge in matter is described. The sample is coupled to a low-noise amplifier by a periodically varying capacitor and the resulting signal is synchronously detected. The varying capacitor is constructed as a rapidly spinning wheel. Samples of any material in volumes of up to 0.05 ml may be searched in less than an hour

  13. Intermittent search strategies

    Science.gov (United States)

    Bénichou, O.; Loverdo, C.; Moreau, M.; Voituriez, R.

    2011-01-01

    This review examines intermittent target search strategies, which combine phases of slow motion, allowing the searcher to detect the target, and phases of fast motion during which targets cannot be detected. It is first shown that intermittent search strategies are actually widely observed at various scales. At the macroscopic scale, this is, for example, the case of animals looking for food; at the microscopic scale, intermittent transport patterns are involved in a reaction pathway of DNA-binding proteins as well as in intracellular transport. Second, generic stochastic models are introduced, which show that intermittent strategies are efficient strategies that enable the minimization of search time. This suggests that the intrinsic efficiency of intermittent search strategies could justify their frequent observation in nature. Last, beyond these modeling aspects, it is proposed that intermittent strategies could also be used in a broader context to design and accelerate search processes.

  14. Tales from the Field: Search Strategies Applied in Web Searching

    Directory of Open Access Journals (Sweden)

    Soohyung Joo

    2010-08-01

    Full Text Available In their web search processes users apply multiple types of search strategies, which consist of different search tactics. This paper identifies eight types of information search strategies with associated cases based on sequences of search tactics during the information search process. Thirty-one participants representing the general public were recruited for this study. Search logs and verbal protocols offered rich data for the identification of different types of search strategies. Based on the findings, the authors further discuss how to enhance web-based information retrieval (IR systems to support each type of search strategy.

  15. The Cryogenic Dark Matter Search (CDMS)

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.D., Jr. [UC, Berkeley

    1996-01-01

    A substantial body of observational evidence indicates that the universe contains much more material than we observe directly via photons of any wavelength. The existence of this "missing" mass or "dark" matter is inferred by its gravitational effects on the luminous material. Accepting the existence of dark matter has profoundly shaken our understanding in most areas of cosmology. If it exists at the lowest densities measured it is hard to understand in detail the creation of the elements in the early universe. If moderate density values are correct, then we have trouble understanding how the universe came to have so much structure on large scales. If the largest densities are correct, then dark matter is not ordinary matter, but must be something exotic like a new fundamental particle. We would like to measure the properties of the dark matter directly. Supposing that the dark matter consists of a WIMP, that was in thermal equilibrium in the early universe, we have built an experiment to detect dark matter directly by elastic scattering with germanium or silicon nuclei. Our detectors are large (~ 200 g) calorimeters that can discriminate between interactions with the electrons, due to background photons and beta particles, and interactions with the nuclei, due to WIMPs and background neutrons. The detectors operate at low temperatures (~ 20 mK) in a specially constructed cryostat. To reduce the rate of background events to a manageable level, the detectors and cryostat have been constructed out of selected materials and properly shielded. This dissertation discusses the properties of the hypothetical WIMPs, the detectors, cryostat, and shielding system, and finally, the analysis methods.new fundamental particle, a

  16. How Users Search the Library from a Single Search Box

    Science.gov (United States)

    Lown, Cory; Sierra, Tito; Boyer, Josh

    2013-01-01

    Academic libraries are turning increasingly to unified search solutions to simplify search and discovery of library resources. Unfortunately, very little research has been published on library user search behavior in single search box environments. This study examines how users search a large public university library using a prominent, single…

  17. Search For Dark Matter Produced in Association With a Bottom-Quark In Proton-Proton Collision at $\\sqrt{s} = $ 8 TeV With the CMS Experiment

    CERN Document Server

    AUTHOR|(CDS)2088829; Wan Abdullah, Wan Ahmad Tajuddin Bin

    Dark Matter is a hypothetical particle proposed to explain the missing matter discovered from the cosmological observation. The motivation of Dark Matter is overwhelming, however those studies mainly deduced from gravitational interaction which does little to understand the underlying structure of the particle. On the other hand, the WIMP Miracle motivating dark matter production at weak scale, implying the possibility of detecting dark matter in LHC. Assuming Dark Matter is the only new particle accessible in LHC, it is expected to be pair produced in association with a Standard Model particles which can be inferred from the Transverse Missing Energy. Search for dark matter in monojet final state is a dominant channel in placing model-independent constrains on a set of effective operators coupling Dark Matter to Standard Model particle. However in the case of effective operators generated by the exchange of heavy scalar mediator, the inclusive Monojet channel is weakened due to the light quark suppression. A...

  18. Composite Differential Search Algorithm

    Directory of Open Access Journals (Sweden)

    Bo Liu

    2014-01-01

    Full Text Available Differential search algorithm (DS is a relatively new evolutionary algorithm inspired by the Brownian-like random-walk movement which is used by an organism to migrate. It has been verified to be more effective than ABC, JDE, JADE, SADE, EPSDE, GSA, PSO2011, and CMA-ES. In this paper, we propose four improved solution search algorithms, namely “DS/rand/1,” “DS/rand/2,” “DS/current to rand/1,” and “DS/current to rand/2” to search the new space and enhance the convergence rate for the global optimization problem. In order to verify the performance of different solution search methods, 23 benchmark functions are employed. Experimental results indicate that the proposed algorithm performs better than, or at least comparable to, the original algorithm when considering the quality of the solution obtained. However, these schemes cannot still achieve the best solution for all functions. In order to further enhance the convergence rate and the diversity of the algorithm, a composite differential search algorithm (CDS is proposed in this paper. This new algorithm combines three new proposed search schemes including “DS/rand/1,” “DS/rand/2,” and “DS/current to rand/1” with three control parameters using a random method to generate the offspring. Experiment results show that CDS has a faster convergence rate and better search ability based on the 23 benchmark functions.

  19. Skewed Binary Search Trees

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Moruz, Gabriel

    2006-01-01

    It is well-known that to minimize the number of comparisons a binary search tree should be perfectly balanced. Previous work has shown that a dominating factor over the running time for a search is the number of cache faults performed, and that an appropriate memory layout of a binary search tree...... can reduce the number of cache faults by several hundred percent. Motivated by the fact that during a search branching to the left or right at a node does not necessarily have the same cost, e.g. because of branch prediction schemes, we in this paper study the class of skewed binary search trees....... For all nodes in a skewed binary search tree the ratio between the size of the left subtree and the size of the tree is a fixed constant (a ratio of 1/2 gives perfect balanced trees). In this paper we present an experimental study of various memory layouts of static skewed binary search trees, where each...

  20. Magnetic monopole search experiments

    International Nuclear Information System (INIS)

    Stone, J.L.

    1986-01-01

    Experimental searches for the elusive magnetic monopole have extended over 50 years -- ever since Dirac showed that the existence of isolated magnetic charges could account for the observation of quantized electric charge. Early searches for Dirac's monopole were hampered since there was no indication of the expected monopole mass, velocity, or origin in the theory. Consequently, numerous experiments searched more or less blindly for relativistic low mass monopoles in the cosmic rays and in particle collisions at high energy accelerators. In this paper, the author reviews briefly the monopole properties which are relevant for their detection and summarize current experimental efforts using induction, ionization/excitation, and catalysis techniques

  1. Exotic searches at lep

    International Nuclear Information System (INIS)

    Seager, P.

    2001-01-01

    The search for exotic processes at LEP is presented. The Standard Model Higgs has as yet not been observed. This provides freedom to search for processes beyond the Standard Model and even beyond the minimal version of the supersymmetric extension to the Standard Model. This paper outlines the searches for charged Higgs bosons, fermiophobic Higgs bosons, invisibly decaying Higgs bosons, technicolor, leptoquarks, unstable heavy leptons and excited leptons. The results presented are those from the LEP collaborations using data taken up to a centre-of-mass energy of √s = 202 GeV. (author)

  2. Searching low and high

    DEFF Research Database (Denmark)

    Laursen, Keld; Salter, Ammon

    2003-01-01

    AbstractThis paper examines the factors that influence whether firms draw from universities in theirinnovative activities. The link between the universities and industrial innovation, and the role ofdifferent search strategies in influencing the propensity of firms to use universities is explored.......The results suggest that firms who adopt `open' search strategies and invest in R&D are morelikely than other firms to draw from universities, indicating that managerial choice matters inshaping the propensity of firms to draw from universities.Key words: University-industry links, innovation, external search...

  3. Modified harmony search

    Science.gov (United States)

    Mohamed, Najihah; Lutfi Amri Ramli, Ahmad; Majid, Ahmad Abd; Piah, Abd Rahni Mt

    2017-09-01

    A metaheuristic algorithm, called Harmony Search is quite highly applied in optimizing parameters in many areas. HS is a derivative-free real parameter optimization algorithm, and draws an inspiration from the musical improvisation process of searching for a perfect state of harmony. Propose in this paper Modified Harmony Search for solving optimization problems, which employs a concept from genetic algorithm method and particle swarm optimization for generating new solution vectors that enhances the performance of HS algorithm. The performances of MHS and HS are investigated on ten benchmark optimization problems in order to make a comparison to reflect the efficiency of the MHS in terms of final accuracy, convergence speed and robustness.

  4. ElasticSearch server

    CERN Document Server

    Rogozinski, Marek

    2014-01-01

    This book is a detailed, practical, hands-on guide packed with real-life scenarios and examples which will show you how to implement an ElasticSearch search engine on your own websites.If you are a web developer or a user who wants to learn more about ElasticSearch, then this is the book for you. You do not need to know anything about ElastiSeach, Java, or Apache Lucene in order to use this book, though basic knowledge about databases and queries is required.

  5. Simulations of the muon-induced neutron background of the EDELWEISS-II experiment for Dark Matter search

    International Nuclear Information System (INIS)

    Horn, O.M.

    2007-01-01

    In modern astroparticle physics and cosmology, the nature of Dark Matter is one of the central problems. Particle Dark Matter in form of WIMPs is favoured among many proposed candidates. The EDELWEISS direct Dark Matter search uses Germanium bolometers to detect these particles by nuclear recoils. Here, the use of two signal channels on an event-by-event basis, namely the heat and ionisation signal, enables the detectors to discriminate between electron and nuclear recoils. This technique leaves neutrons in the underground laboratory as the main background for the experiment. Besides (α,n) reactions of natural radioactivity, neutrons are produced in electromagnetic and hadronic showers induced by cosmic ray muons in the surrounding rock and shielding material of the Germanium crystals. To reach high sensitivities, the EDELWEISS-II experiment, as well as other direct Dark Matter searches, has to efficiently suppress this neutron background. The present work is devoted to study the muon-induced neutron flux in the underground laboratory LSM and the interaction rate within the Germanium crystals by using the Monte Carlo simulation toolkit Geant4. To ensure reliable results, the implemented physics in the toolkit regarding neutron production is tested in a benchmark geometry and results are compared to experimental data and other simulation codes. Also, the specific energy and angular distribution of the muon flux in the underground laboratory as a consequence of the asymmetric mountain overburden is implemented. A good agreement of the simulated muon flux is shown in a comparison to preliminary experimental data obtained with the EDELWEISS-II muon veto system. Furthermore, within a detailed geometry of the experimental setup, the muon-induced background rate of nuclear recoils in the bolometers is simulated. Coincidences of recoil events in the Germanium with an energy deposit of the muoninduced shower in the plastic scintillators of the veto system are studied to

  6. Simulations of the muon-induced neutron background of the EDELWEISS-II experiment for Dark Matter search

    Energy Technology Data Exchange (ETDEWEB)

    Horn, O M

    2007-12-21

    In modern astroparticle physics and cosmology, the nature of Dark Matter is one of the central problems. Particle Dark Matter in form of WIMPs is favoured among many proposed candidates. The EDELWEISS direct Dark Matter search uses Germanium bolometers to detect these particles by nuclear recoils. Here, the use of two signal channels on an event-by-event basis, namely the heat and ionisation signal, enables the detectors to discriminate between electron and nuclear recoils. This technique leaves neutrons in the underground laboratory as the main background for the experiment. Besides ({alpha},n) reactions of natural radioactivity, neutrons are produced in electromagnetic and hadronic showers induced by cosmic ray muons in the surrounding rock and shielding material of the Germanium crystals. To reach high sensitivities, the EDELWEISS-II experiment, as well as other direct Dark Matter searches, has to efficiently suppress this neutron background. The present work is devoted to study the muon-induced neutron flux in the underground laboratory LSM and the interaction rate within the Germanium crystals by using the Monte Carlo simulation toolkit Geant4. To ensure reliable results, the implemented physics in the toolkit regarding neutron production is tested in a benchmark geometry and results are compared to experimental data and other simulation codes. Also, the specific energy and angular distribution of the muon flux in the underground laboratory as a consequence of the asymmetric mountain overburden is implemented. A good agreement of the simulated muon flux is shown in a comparison to preliminary experimental data obtained with the EDELWEISS-II muon veto system. Furthermore, within a detailed geometry of the experimental setup, the muon-induced background rate of nuclear recoils in the bolometers is simulated. Coincidences of recoil events in the Germanium with an energy deposit of the muoninduced shower in the plastic scintillators of the veto system are studied

  7. Beyond MEDLINE for literature searches.

    Science.gov (United States)

    Conn, Vicki S; Isaramalai, Sang-arun; Rath, Sabyasachi; Jantarakupt, Peeranuch; Wadhawan, Rohini; Dash, Yashodhara

    2003-01-01

    To describe strategies for a comprehensive literature search. MEDLINE searches result in limited numbers of studies that are often biased toward statistically significant findings. Diversified search strategies are needed. Empirical evidence about the recall and precision of diverse search strategies is presented. Challenges and strengths of each search strategy are identified. Search strategies vary in recall and precision. Often sensitivity and specificity are inversely related. Valuable search strategies include examination of multiple diverse computerized databases, ancestry searches, citation index searches, examination of research registries, journal hand searching, contact with the "invisible college," examination of abstracts, Internet searches, and contact with sources of synthesized information. Extending searches beyond MEDLINE enables researchers to conduct more systematic comprehensive searches.

  8. Custom Search Engines: Tools & Tips

    Science.gov (United States)

    Notess, Greg R.

    2008-01-01

    Few have the resources to build a Google or Yahoo! from scratch. Yet anyone can build a search engine based on a subset of the large search engines' databases. Use Google Custom Search Engine or Yahoo! Search Builder or any of the other similar programs to create a vertical search engine targeting sites of interest to users. The basic steps to…

  9. Searching with Quantum Computers

    OpenAIRE

    Grover, Lov K.

    2000-01-01

    This article introduces quantum computation by analogy with probabilistic computation. A basic description of the quantum search algorithm is given by representing the algorithm as a C program in a novel way.

  10. Searches at LEP

    CERN Document Server

    Junk, Tom

    2000-01-01

    Searches have been conducted for a broad range of new phenomena by the four experiments ALEPH, DELPHI, L3, and OPAL, at LEP2. Each experiment contributes approximately 150 pb-1 of e+e- annihilation data with a mean sqrt(s) of 205.9 GeV in 2000 to these searches (data prepared for the September 5 LEPC meeting). The statistical procedure for setting limits and evaluating the significance of excesses observed in the data is reviewed. Search results are presented for the Standard Model Higgs boson, the neutral Higgs bosons in the MSSM, charged Higgs bosons, invisibly decaying Higgs bosons produced by Higgs-strahlung, and fermiophobic Higgs bosons. Search results are briefly summarized for gauginos, stops, and staus. The photon recoil spectrum is checked for hints of new physics.

  11. Automated search for supernovae

    International Nuclear Information System (INIS)

    Kare, J.T.

    1984-01-01

    This thesis describes the design, development, and testing of a search system for supernovae, based on the use of current computer and detector technology. This search uses a computer-controlled telescope and charge coupled device (CCD) detector to collect images of hundreds of galaxies per night of observation, and a dedicated minicomputer to process these images in real time. The system is now collecting test images of up to several hundred fields per night, with a sensitivity corresponding to a limiting magnitude (visual) of 17. At full speed and sensitivity, the search will examine some 6000 galaxies every three nights, with a limiting magnitude of 18 or fainter, yielding roughly two supernovae per week (assuming one supernova per galaxy per 50 years) at 5 to 50 percent of maximum light. An additional 500 nearby galaxies will be searched every night, to locate about 10 supernovae per year at one or two percent of maximum light, within hours of the initial explosion

  12. Automated search for supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Kare, J.T.

    1984-11-15

    This thesis describes the design, development, and testing of a search system for supernovae, based on the use of current computer and detector technology. This search uses a computer-controlled telescope and charge coupled device (CCD) detector to collect images of hundreds of galaxies per night of observation, and a dedicated minicomputer to process these images in real time. The system is now collecting test images of up to several hundred fields per night, with a sensitivity corresponding to a limiting magnitude (visual) of 17. At full speed and sensitivity, the search will examine some 6000 galaxies every three nights, with a limiting magnitude of 18 or fainter, yielding roughly two supernovae per week (assuming one supernova per galaxy per 50 years) at 5 to 50 percent of maximum light. An additional 500 nearby galaxies will be searched every night, to locate about 10 supernovae per year at one or two percent of maximum light, within hours of the initial explosion.

  13. Fuzzing and Vulnerabilities Search

    OpenAIRE

    Stanislav Evgenyevich Kirillov; Nikolai Petrovich Lavrentiev

    2013-01-01

    Fuzzing for vulnerabilities can be very effective if we know the input data format. This work contains description of network message format recovery algorithm and the usage of restored data model in fuzzing and vulnerabilities search.

  14. Fuzzing and Vulnerabilities Search

    Directory of Open Access Journals (Sweden)

    Stanislav Evgenyevich Kirillov

    2013-02-01

    Full Text Available Fuzzing for vulnerabilities can be very effective if we know the input data format. This work contains description of network message format recovery algorithm and the usage of restored data model in fuzzing and vulnerabilities search.

  15. Chemical Search Web Utility

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Chemical Search Web Utility is an intuitive web application that allows the public to easily find the chemical that they are interested in using, and which...

  16. Searches for new physics

    International Nuclear Information System (INIS)

    Ellis, J.; Pauss, F.

    1989-01-01

    The CERN p bar p Collider has been the first accelerator to operate in a completely new energy domain, reaching center-of-mass energies an order of magnitude larger than those previously available with the intersecting Storage Rings (ISR) at CERN, or with the Positron-Electron Tandem Ring Accelerator (PETRA) at DESY and the Positron-Electron Project (PEP) at SLAC. Naturally there has been great interest in the searches for new physics in this virgin territory. Theorists have approached these searches from either or both of two rival points of view. Either they have had an a priori prejudice as to what new physics should be searched for, and what its signatures should be, or they have tried to interpret a posteriori some experimental observations. The basic building-blocks of new physics in the 100 GeV energy domain are jets j, charged leptons l, photons γ, and missing transverse energy E T . Therefore searches have been conducted in channels which are combinations of these elements. It also shows some of the main a priori theoretical prejudices which can be explored in each of these channels. The layout of the rest of this paper is as follows. There are sections discussing each of the major prejudices: the Standard Model supersymmetry; extra gauge degrees of freedom; composite models; and other possibilities. Each of these sections contains a description of the motivations and characteristics of the new physics to be searched for, followed by a review of the searches made up to now at the CERN p bar p Collider. Finally, it summarizes the lessons to be learnt so far from searches for new physics at the CERN p bar p Collider, and previews some of the prospects for the next rounds of collider searches at CERN and FNAL

  17. Spatial Search, Position Papers

    OpenAIRE

    Center for Spatial Studies, UCSB

    2014-01-01

    The Spatial Search specialist meeting in Santa Barbara (December 2014) brought together 35 academic and industry representatives from computational, geospatial, and cognitive sciences with interest in focused discussions on the development of an interdisciplinary research agenda to advance spatial search from scientific and engineering viewpoints. The position papers from participants represent the shared expertise that guided discussions and the formulation of research questions about proces...

  18. Search and imperative programming

    OpenAIRE

    Apt, Krzysztof; Schaerf, A.

    1996-01-01

    textabstractWe augment the expressive power of imperative programming in order to make it a more attractive vehicle for problems that involve search.The proposed additions are limited yet powerful and are inspired by the logic programming paradigm.We illustrate their use by presenting solutions to a number of classical problems, including the straight search problem, the knapsack problem, and the 8 queens problem. These solutions are substantially simpler than their counterparts written in th...

  19. Status of gluonium searches

    International Nuclear Information System (INIS)

    Heusch, C.A.; California Univ., Santa Cruz, CA

    1991-01-01

    Quantum chromodynamics predicts the existence of quarkless mesons. The search for these hadrons has been ingenious and persevering. A review is presented of the current status of research that considers all model-dependent theoretical prejudice when searching for specific states. Early hints for candidate states have been investigated in the light of recent data, mostly from the Mark III Collaboration, in radiative charmonium decay. No 'smoking-gun' candidate stands out. (R.P.) 25 refs., 20 figs., 2 tabs

  20. Monopole searches at ISABELLE

    International Nuclear Information System (INIS)

    Giacomelli, G.; Thorndike, A.

    1975-01-01

    A discussion is given which supports the continuance of the search for magnetic monopoles at ISABELLE, based on the following assumptions: (1) by 1982 monopoles have not been found; (2) this indicates that, if they exist, they are very massive; (3) other monopole properties are as they are usually assumed to be. An experiment to search for dense tracks is described, an outline is given of a monopole collector for induced current detection, and some discussion is given of the multigamma approach

  1. Global OpenSearch

    Science.gov (United States)

    Newman, D. J.; Mitchell, A. E.

    2015-12-01

    At AGU 2014, NASA EOSDIS demonstrated a case-study of an OpenSearch framework for Earth science data discovery. That framework leverages the IDN and CWIC OpenSearch API implementations to provide seamless discovery of data through the 'two-step' discovery process as outlined by the Federation for Earth Sciences (ESIP) OpenSearch Best Practices. But how would an Earth Scientist leverage this framework and what are the benefits? Using a client that understands the OpenSearch specification and, for further clarity, the various best practices and extensions, a scientist can discovery a plethora of data not normally accessible either by traditional methods (NASA Earth Data Search, Reverb, etc) or direct methods (going to the source of the data) We will demonstrate, via the CWICSmart web client, how an earth scientist can access regional data on a regional phenomena in a uniform and aggregated manner. We will demonstrate how an earth scientist can 'globalize' their discovery. You want to find local data on 'sea surface temperature of the Indian Ocean'? We can help you with that. 'European meteorological data'? Yes. 'Brazilian rainforest satellite imagery'? That too. CWIC allows you to get earth science data in a uniform fashion from a large number of disparate, world-wide agencies. This is what we mean by Global OpenSearch.

  2. Search Tips: MedlinePlus

    Science.gov (United States)

    ... of this page: https://medlineplus.gov/searchtips.html Search Tips To use the sharing features on this page, please enable JavaScript. How do I search MedlinePlus? The search box appears at the top ...

  3. Axion Searches, Old and New

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    Outline of the lecture: Constraints from laboratory searches and astrophysics, axion cosmology, the cavity detector of dark matter axions, solar axion searches, laser experiments, a telescope search, macroscopic forces mediated by axions.

  4. SEARCHES FOR SUPERSYMMETRY IN ATLAS

    CERN Document Server

    Xu, Da; The ATLAS collaboration

    2017-01-01

    A wide range of supersymmetric searches are presented. All searches are based on the proton- proton collision dataset collected by the ATLAS experiment during the 2015 and 2016 (before summer) run with a center-of-mass energy of 13 TeV, corresponding to an integrated lumi- nosity of 36.1 (36.7) fb-1. The searches are categorized into inclusive gluino and squark search, third generation search, electroweak search, prompt RPV search and long-lived par- ticle search. No evidence of new physics is observed. The results are intepreted in various models and expressed in terms of limits on the masses of new particles.

  5. US Cosmic Visions: New Ideas in Dark Matter 2017 : Community Report

    Energy Technology Data Exchange (ETDEWEB)

    Feng, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fox, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dawson, W. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ammons, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Axelrod, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chapline, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Drlica-Wagner, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Golovich, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schneider, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-05-08

    This white paper summarizes the workshop “U.S. Cosmic Visions: New Ideas in Dark Matter” held at University of Maryland from March 23-25. The flagships of the US Dark Matter search program are the G2 experiments ADMX, LZ, and SuperCDMS, which will cover well-motivated axion and WIMP dark matter over a range of masses. The workshop assumes that a complete exploration of this parameter space remains the highest priority of the dark matter community, and focuses instead on the science case for additional new small-scale projects in dark matter science that complement the G2 program (and other ongoing projects worldwide). It therefore concentrates on exploring distinct, well-motivated parameter space that will not be covered by the existing program; on surveying ideas for such projects (i.e. projects costing ~$10M or less); and on placing these ideas in a global context. The workshop included over 100 presentations of new ideas, proposals and recent science and R&D results from the US and international scientific community.

  6. Market Dominance and Search Quality in the Search Engine Market

    NARCIS (Netherlands)

    Lianos, I.; Motchenkova, E.I.

    2013-01-01

    We analyze a search engine market from a law and economics perspective and incorporate the choice of quality-improving innovations by a search engine platform in a two-sided model of Internet search engine. In the proposed framework, we first discuss the legal issues the search engine market raises

  7. SearchResultFinder: federated search made easy

    NARCIS (Netherlands)

    Trieschnigg, Rudolf Berend; Tjin-Kam-Jet, Kien; Hiemstra, Djoerd

    Building a federated search engine based on a large number existing web search engines is a challenge: implementing the programming interface (API) for each search engine is an exacting and time-consuming job. In this demonstration we present SearchResultFinder, a browser plugin which speeds up

  8. Children's Search Engines from an Information Search Process Perspective.

    Science.gov (United States)

    Broch, Elana

    2000-01-01

    Describes cognitive and affective characteristics of children and teenagers that may affect their Web searching behavior. Reviews literature on children's searching in online public access catalogs (OPACs) and using digital libraries. Profiles two Web search engines. Discusses some of the difficulties children have searching the Web, in the…

  9. Mastering Search Analytics Measuring SEO, SEM and Site Search

    CERN Document Server

    Chaters, Brent

    2011-01-01

    Many companies still approach Search Engine Optimization (SEO) and paid search as separate initiatives. This in-depth guide shows you how to use these programs as part of a comprehensive strategy-not just to improve your site's search rankings, but to attract the right people and increase your conversion rate. Learn how to measure, test, analyze, and interpret all of your search data with a wide array of analytic tools. Gain the knowledge you need to determine the strategy's return on investment. Ideal for search specialists, webmasters, and search marketing managers, Mastering Search Analyt

  10. Search for glueballs

    Energy Technology Data Exchange (ETDEWEB)

    Toki, W. [Colorado State Univ., Ft. Collins, CO (United States). Dept. of Physics

    1997-06-01

    In these Summer School lectures, the author reviews the results of recent glueball searches. He begins with a brief review of glueball phenomenology and meson spectroscopy, including a discussion of resonance behavior. The results on the f{sub o}(1500) and f{sub J}(1700) resonances from proton-antiproton experiments and radiative J/{Psi} decays are discussed. Finally, {pi}{pi} and {eta}{pi} studies from D{sub s} decays and exotic meson searches are reviewed. 46 refs., 40 figs.

  11. Upgrading Enterprise Search

    Energy Technology Data Exchange (ETDEWEB)

    McDunn, R

    2005-04-28

    This presentation will describe the process we went through this past year to upgrade our enterprise search tool from a very old version of Inktomi to the latest version of Verity Ultraseek. We started with requirements gathering and then compared requirements against several available products to determine which product to choose. After purchasing the product, we worked through several defined phases of implementation and customization, with initial rollout late January 2004. Finally, we will show you where we are today and describe future search plans.

  12. SUSY Searches at ATLAS

    CERN Document Server

    Mamuzic, Judita; The ATLAS collaboration

    2017-01-01

    Supersymmetry (SUSY) is considered one of the best motivated extensions of the Standard Model. It postulates a fundamental symmetry between fermions and bosons, and introduces a set of new supersymmetric particles at the electroweak scale. It addresses the hierarchy and naturalness problem, gives a solution to the gauge coupling unification, and offers a cold dark matter candidate. Different aspects of SUSY searches, using strong, electroweak, third generation production, and R-parity violation and long lived particles are being studied at the LHC. An overview of most recent SUSY searches results using the 13 TeV ATLAS RUN2 data will be presented.

  13. Quark search conference

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    In spite of (or perhaps because of) the present doctrine of total quark confinement held by the majority of particle theorists, experimental searches for free fractional charge and other anomalous stable particles in ordinary matter have been increasing in number during recent years, using a range of techniques of increasing sophistication and sensitivity. As a result, researchers in this area had a conference to themselves in June. About 40 participants and 150 observers gathered at San Francisco State University to report progress and discuss future plans, with representatives present from almost every group involved in quark searches

  14. Searching for supersymmetry scalelessly

    Energy Technology Data Exchange (ETDEWEB)

    Schlaffer, M. [DESY, Hamburg (Germany); Weizmann Institute of Science, Department of Particle Physics and Astrophysics, Rehovot (Israel); Spannowsky, M. [Durham University, Department of Physics, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Weiler, A. [Technische Universitaet Muenchen, Physik Department T75, Garching (Germany)

    2016-08-15

    In this paper we propose a scale invariant search strategy for hadronic top or bottom plus missing energy final states. We present a method which shows flat efficiencies and background rejection factors over broad ranges of parameters and masses. The resulting search can easily be recast into a limit on alternative models. We show the strength of the method in a natural SUSY setup where stop and sbottom squarks are pair produced and decay into hadronically decaying top quarks or bottom quarks and higgsinos. (orig.)

  15. Search Parameter Optimization for Discrete, Bayesian, and Continuous Search Algorithms

    Science.gov (United States)

    2017-09-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS SEARCH PARAMETER OPTIMIZATION FOR DISCRETE , BAYESIAN, AND CONTINUOUS SEARCH ALGORITHMS by...to 09-22-2017 4. TITLE AND SUBTITLE SEARCH PARAMETER OPTIMIZATION FOR DISCRETE , BAYESIAN, AND CON- TINUOUS SEARCH ALGORITHMS 5. FUNDING NUMBERS 6...simple search and rescue acts to prosecuting aerial/surface/submersible targets on mission. This research looks at varying the known discrete and

  16. The Evolution of Web Searching.

    Science.gov (United States)

    Green, David

    2000-01-01

    Explores the interrelation between Web publishing and information retrieval technologies and lists new approaches to Web indexing and searching. Highlights include Web directories; search engines; portalisation; Internet service providers; browser providers; meta search engines; popularity based analysis; natural language searching; links-based…

  17. Prices and heterogeneous search costs

    NARCIS (Netherlands)

    Luis Moraga-Gonzalez, Jose; Sandor, Zsolt; Wildenbeest, Matthijs R.

    2017-01-01

    We study price formation in a model of consumer search for differentiated products in which consumers have heterogeneous search costs. We provide conditions under which a pure-strategy symmetric Nash equilibrium exists and is unique. Search costs affect two margins-the intensive search margin (or

  18. Complete local search with memory

    NARCIS (Netherlands)

    Ghosh, D.; Sierksma, G.

    2000-01-01

    Neighborhood search heuristics like local search and its variants are some of the most popular approaches to solve discrete optimization problems of moderate to large size. Apart from tabu search, most of these heuristics are memoryless. In this paper we introduce a new neighborhood search heuristic

  19. Online Patent Searching: The Realities.

    Science.gov (United States)

    Kaback, Stuart M.

    1983-01-01

    Considers patent subject searching capabilities of major online databases, noting patent claims, "deep-indexed" files, test searches, retrieval of related references, multi-database searching, improvements needed in indexing of chemical structures, full text searching, improvements needed in handling numerical data, and augmenting a…

  20. Self-learning search engines

    NARCIS (Netherlands)

    Schuth, A.

    2015-01-01

    How does a search engine such as Google know which search results to display? There are many competing algorithms that generate search results, but which one works best? We developed a new probabilistic method for quickly comparing large numbers of search algorithms by examining the results users

  1. Standardization of Keyword Search Mode

    Science.gov (United States)

    Su, Di

    2010-01-01

    In spite of its popularity, keyword search mode has not been standardized. Though information professionals are quick to adapt to various presentations of keyword search mode, novice end-users may find keyword search confusing. This article compares keyword search mode in some major reference databases and calls for standardization. (Contains 3…

  2. Two-singlet model for light cold dark matter

    International Nuclear Information System (INIS)

    Abada, Abdessamad; Ghaffor, Djamal; Nasri, Salah

    2011-01-01

    We extend the standard model by adding two gauge-singlet Z 2 -symmetric scalar fields that interact with visible matter only through the Higgs particle. One is a stable dark matter WIMP, and the other one undergoes a spontaneous breaking of the symmetry that opens new channels for the dark matter annihilation, hence lowering the mass of the WIMP. We study the effects of the observed dark matter relic abundance on the WIMP annihilation cross section and find that in most regions of the parameters' space, light dark matter is viable. We also compare the elastic-scattering cross section of our dark matter candidate off a nucleus with existing (CDMSII and XENON100) and projected (SuperCDMS and XENON1T) experimental exclusion bounds. We find that most of the allowed mass range for light dark matter will be probed by the projected sensitivity of the XENON1T experiment.

  3. Biased Predecessor Search

    DEFF Research Database (Denmark)

    Bose, Prosenjit; Fagerberg, Rolf; Howat, John

    2016-01-01

    We consider the problem of performing predecessor searches in a bounded universe while achieving query times that depend on the distribution of queries. We obtain several data structures with various properties: in particular, we give data structures that achieve expected query times logarithmic...

  4. Biased predecessor search

    DEFF Research Database (Denmark)

    Bose, Prosenjit; Fagerberg, Rolf; Howat, John

    2014-01-01

    We consider the problem of performing predecessor searches in a bounded universe while achieving query times that depend on the distribution of queries. We obtain several data structures with various properties: in particular, we give data structures that achieve expected query times logarithmic...

  5. Quantum Search and Beyond

    Science.gov (United States)

    2008-07-02

    mechanics leads to non-local paradoxical effects (physicists sometimes call this "spooky action at a distance"). Spatial searching is the problem where...resource of EPR pairs, and that they use the states |0L〉 = |00〉+ |11〉 (|1L〉 = |00〉 − |11〉) to encode a logical zero (one). Note that each of them can set

  6. In Search of Insight.

    Science.gov (United States)

    Kaplan, Craig A.; Simon, Herbert A.

    1990-01-01

    Attaining the insight needed to solve the Mutilated Checkerboard problem, which requires discovery of an effective problem representation (EPR), is described. Performance on insight problems can be predicted from the availability of generators and constraints in the search for an EPR. Data for 23 undergraduates were analyzed. (TJH)

  7. ChemSearch Journal

    African Journals Online (AJOL)

    Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. Journal Homepage Image. Chemsearch Journal is a peer – reviewed journal that publishes original research work, scientific papers and technical reports in all the field of Chemistry (pure science, agriculture, environmental science, ...

  8. Google Search Mastery Basics

    Science.gov (United States)

    Hill, Paul; MacArthur, Stacey; Read, Nick

    2014-01-01

    Effective Internet search skills are essential with the continually increasing amount of information available on the Web. Extension personnel are required to find information to answer client questions and to conduct research on programs. Unfortunately, many lack the skills necessary to effectively navigate the Internet and locate needed…

  9. Search for intervalmodels

    DEFF Research Database (Denmark)

    Høskuldsson, Agnar

    1996-01-01

    Methods are presented that carry out sorting of data according to some criteria, and investigate the possibilities of finding intervals that give separate models relative to the given data. The methods presented are more reliable than related clustering methods, because the search is carried out...

  10. Pentaquark searches with ALICE

    CERN Document Server

    Bobulska, Dana

    2016-01-01

    In this report we present the results of the data analysis for searching for possible invariant mass signals from pentaquarks in the ALICE data. Analysis was based on filtered data from real p-Pb events at psNN=5.02 TeV collected in 2013. The motivation for this project was the recent discovery of pentaquark states by the LHCb collaboration (c ¯ cuud resonance P+ c ) [1]. The search for similar not yet observed pentaquarks is an interesting research topic [2]. In this analysis we searched for a s ¯ suud pentaquark resonance P+ s and its possible decay channel to f meson and proton. The ALICE detector is well suited for the search of certain candidates thanks to its low material budget and strong PID capabilities. Additionally we might expect the production of such particles in ALICE as in heavy-ion and proton-ion collisions the thermal models describes well the particle yields and ratios [3]. Therefore it is reasonable to expect other species of hadrons, including also possible pentaquarks, to be produced w...

  11. Searching for Movies

    DEFF Research Database (Denmark)

    Bogers, Toine

    2015-01-01

    Despite a surge in popularity of work on casual leisure search, some leisure domains are still relatively underrepresented. Movies are good example of such a domain, which is peculiar given the popularity of movie-centered websites and discovery services such as IMDB, RottenTomatoes, and Netflix...

  12. SUSY Search at LHC

    CERN Document Server

    Xu, Da; The ATLAS collaboration

    2018-01-01

    Despite the absence of experimental evidence, weak scale supersymmetry remains one of the best motivated and studied Standard Model extensions. This talk gives an overview of the most recent SUSY searches in ATLAS and CMS experiments using 13 TeV ATLAS Run2 data.

  13. Search and Recommendation

    DEFF Research Database (Denmark)

    Bogers, Toine

    2014-01-01

    In just a little over half a century, the field of information retrieval has experienced spectacular growth and success, with IR applications such as search engines becoming a billion-dollar industry in the past decades. Recommender systems have seen an even more meteoric rise to success with wide...

  14. Search and imperative programming

    NARCIS (Netherlands)

    K.R. Apt (Krzysztof); A. Schaerf

    1996-01-01

    textabstractWe augment the expressive power of imperative programming in order to make it a more attractive vehicle for problems that involve search.The proposed additions are limited yet powerful and are inspired by the logic programming paradigm.We illustrate their use by presenting solutions to a

  15. THE SEARCH FOR CLUES

    OpenAIRE

    Landy Gobes

    2010-01-01

    This article is the keynote address given at the 4th International Integrative Psychotherapy Association Conference in Lake Bled, Slovenia. The author describes her journey in therapy and her experiences as a client searching for clues and unraveling what was “missing”.

  16. Excited lepton search

    International Nuclear Information System (INIS)

    Behrend, H.J.; Buerger, J.; Criegee, L.; Fenner, H.; Field, J.H.; Franke, G.; Fuster, J.; Holler, Y.; Meyer, J.; Schroeder, V.; Sindt, H.; Timm, U.; Winter, G.G.; Zimmermann, W.; Bussey, P.J.; Campbell, A.J.; Dainton, J.B.; Hendry, D.; McCurrach, G.; Scarr, J.M.; Skillicorn, I.O.; Smith, K.M.; Blobel, V.; Poppe, M.; Spitzer, H.; Boer, W. de; Buschhorn, G.; Christiansen, W.; Grindhammer, G.; Gunderson, B.; Kiesling, C.; Kotthaus, R.; Kroha, H.; Lueers, D.; Oberlack, H.; Sack, B.; Schacht, P.; Shooshtari, G.; Wiedenmann, W.; Cordier, A.; Davier, M.; Fournier, D.; Gaillard, M.; Grivaz, J.F.; Haissinski, J.; Janot, P.; Journe, V.; Le Diberder, F.; Ros, E.; Spadafora, A.; Veillet, J.J.; Aleksan, R.; Cozzika, G.; Ducros, Y.; Jarry, P.; Lavagne, Y.; Ould Saada, F.; Pamela, J.; Pierre, F.; Zacek, J.; Alexander, G.; Bella, G.; Gnat, Y.; Grunhaus, J.

    1986-02-01

    Using the CELLO detector at PETRA we have searched for excited leptons by studying e + e - interactions which yield p + p - γγ, l + l - γ and γγ final states, where l = 3, μ or τ. We observe good agreement with QED and set new limits on e*, μ*, and τ* production. (orig.)

  17. The Pulsar Search Collaboratory

    Science.gov (United States)

    Rosen, R.; Heatherly, S.; McLaughlin, M. A.; Kondratiev, V. I.; Boyles, J. R.; Wilson, M.; Lorimer, D. R.; Lynch, R.; Ransom, S.

    2010-01-01

    The Pulsar Search Collaboratory (PSC) (NSF #0737641) is a joint project between the National Radio Astronomy Observatory and West Virginia University designed to interest high school students in science, technology, engineering, and mathematics related career paths by helping them to conduct authentic scientific research. The 3 year PSC program,…

  18. Entity associations for search

    NARCIS (Netherlands)

    Reinanda, R.

    2017-01-01

    In this thesis, we investigate the broad problem of computing entity associations for search. Specifically, we consider three types of entity association: entity-entity, entity-document, and entity-aspect associations. We touch upon various domains, starting with specific domains such as the

  19. Flexible digital library search

    NARCIS (Netherlands)

    Windhouwer, M.; Schmidt, A.; Zwol, van R.; Petkovic, M.; Blok, H.E.; Dahanayake, A.; Gerhardt, W.

    2003-01-01

    In this chapter the development of a specialised search engine for a digital library is described. The proposed system architecture consists of three levels: the conceptual, the logical and the physical level. The conceptual level schema enables by its exposure of a domain specific schema

  20. Measuring Personalization of Web Search

    DEFF Research Database (Denmark)

    Hannak, Aniko; Sapiezynski, Piotr; Kakhki, Arash Molavi

    2013-01-01

    are simply unable to access information that the search engines’ algorithm decidesis irrelevant. Despitetheseconcerns, there has been little quantification of the extent of personalization in Web search today, or the user attributes that cause it. In light of this situation, we make three contributions...... as a result of searching with a logged in account and the IP address of the searching user. Our results are a first step towards understanding the extent and effects of personalization on Web search engines today....

  1. Results from the Cryogenic Dark Matter Search Using a Chi Squared Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sander, Joel [UC, Santa Barbara

    2007-12-01

    Most of the mass-energy density of the universe remains undetected and is only understood through its affects on visible, baryonic matter. The visible, baryonic matter accounts for only about half of a percent of the universe's total mass-energy budget, while the remainder of the mass-energy of the universe remains dark or undetected. About a quarter of the dark mass-energy density of the universe is comprised of massive particles that do not interact via the strong or electromagnetic forces. If these particles interact via the weak force, they are termed weakly interacting massive particles or WIMPs, and their interactions with baryonic matter could be detectable. The CDMS II experiment attempts to detect WIMP interactions in the Soudan Underground Laboratory using germanium detectors and silicon detectors. A WIMP can interact a with detector nuclei causing the nuclei to recoil. A nuclear recoil is distinguished from background electron recoils by comparing the deposited ionization and phonon energies. Electron recoils occurring near detector surfaces are more difficult to reject. This thesis describes the results of a χ2 analysis designed to reject events occurring near detector surfaces. Because no WIMP signal was observed, separate limits using the germanium and silicon detectors are set on the WIMP cross section under standard astrophysical assumptions.

  2. Search features of digital libraries

    Directory of Open Access Journals (Sweden)

    Alastair G. Smith

    2000-01-01

    Full Text Available Traditional on-line search services such as Dialog, DataStar and Lexis provide a wide range of search features (boolean and proximity operators, truncation, etc. This paper discusses the use of these features for effective searching, and argues that these features are required, regardless of advances in search engine technology. The literature on on-line searching is reviewed, identifying features that searchers find desirable for effective searching. A selective survey of current digital libraries available on the Web was undertaken, identifying which search features are present. The survey indicates that current digital libraries do not implement a wide range of search features. For instance: under half of the examples included controlled vocabulary, under half had proximity searching, only one enabled browsing of term indexes, and none of the digital libraries enable searchers to refine an initial search. Suggestions are made for enhancing the search effectiveness of digital libraries, for instance by: providing a full range of search operators, enabling browsing of search terms, enhancement of records with controlled vocabulary, enabling the refining of initial searches, etc.

  3. Berkeley automated supernova search

    Energy Technology Data Exchange (ETDEWEB)

    Kare, J.T.; Pennypacker, C.R.; Muller, R.A.; Mast, T.S.; Crawford, F.S.; Burns, M.S.

    1981-01-01

    The Berkeley automated supernova search employs a computer controlled 36-inch telescope and charge coupled device (CCD) detector to image 2500 galaxies per night. A dedicated minicomputer compares each galaxy image with stored reference data to identify supernovae in real time. The threshold for detection is m/sub v/ = 18.8. We plan to monitor roughly 500 galaxies in Virgo and closer every night, and an additional 6000 galaxies out to 70 Mpc on a three night cycle. This should yield very early detection of several supernovae per year for detailed study, and reliable premaximum detection of roughly 100 supernovae per year for statistical studies. The search should be operational in mid-1982.

  4. Searching for Lorentz violation

    International Nuclear Information System (INIS)

    Allen, Roland E.; Yokoo, Seiichirou

    2004-01-01

    Astrophysical, terrestrial, and space-based searches for Lorentz violation are very briefly reviewed. Such searches are motivated by the fact that all superunified theories (and other theories that attempt to include quantum gravity) have some potential for observable violations of Lorentz invariance. Another motivation is the exquisite sensitivity of certain well-designed experiments and observations to particular forms of Lorentz violation. We also review some new predictions of a specific Lorentz-violating theory: If a fundamental energy m-bar c2 in this theory lies below the usual GZK cutoff E GZK , the cutoff is shifted to infinite energy; i.e., it no longer exists. On the other hand, if m-bar c2 lies above E GZK , there is a high-energy branch of the fermion dispersion relation which provides an alternative mechanism for super-GZK cosmic-ray protons

  5. Berkeley automated supernova search

    International Nuclear Information System (INIS)

    Kare, J.T.; Pennypacker, C.R.; Muller, R.A.; Mast, T.S.

    1981-01-01

    The Berkeley automated supernova search employs a computer controlled 36-inch telescope and charge coupled device (CCD) detector to image 2500 galaxies per night. A dedicated minicomputer compares each galaxy image with stored reference data to identify supernovae in real time. The threshold for detection is m/sub v/ = 18.8. We plan to monitor roughly 500 galaxies in Virgo and closer every night, and an additional 6000 galaxies out to 70 Mpc on a three night cycle. This should yield very early detection of several supernovae per year for detailed study, and reliable premaximum detection of roughly 100 supernovae per year for statistical studies. The search should be operational in mid-1982

  6. Search for Hidden Particles

    CERN Multimedia

    Solovev, V

    The SHiP Experiment is a new general-purpose fixed target facility at the SPS to search for hidden particles as predicted by a very large number of recently elaborated models of Hidden Sectors which are capable of accommodating dark matter, neutrino oscillations, and the origin of the full baryon asymmetry in the Universe. Specifically, the experiment is aimed at searching for very weakly interacting long lived particles including Heavy Neutral Leptons - right-handed partners of the active neutrinos; light supersymmetric particles - sgoldstinos, etc.; scalar, axion and vector portals to the hidden sector. The high intensity of the SPS and in particular the large production of charm mesons with the 400 GeV beam allow accessing a wide variety of light long-lived exotic particles of such models and of SUSY. Moreover, the facility is ideally suited to study the interactions of tau neutrinos.

  7. Exotics searches in ATLAS

    CERN Document Server

    Wang, Renjie; The ATLAS collaboration

    2017-01-01

    Many theories beyond the Standard Model predict new physics accessible by the LHC. The ATLAS experiment all have rigorous search programs ongoing with the aim to find indications for new physics involving state of the art analysis techniques. This talk reports on new results obtained using the pp collision data sample collected in 2015 and 2016 at the LHC with a centre-of-mass energy of 13 TeV.

  8. Optimal intermittent search strategies

    International Nuclear Information System (INIS)

    Rojo, F; Budde, C E; Wio, H S

    2009-01-01

    We study the search kinetics of a single fixed target by a set of searchers performing an intermittent random walk, jumping between different internal states. Exploiting concepts of multi-state and continuous-time random walks we have calculated the survival probability of a target up to time t, and have 'optimized' (minimized) it with regard to the transition probability among internal states. Our model shows that intermittent strategies always improve target detection, even for simple diffusion states of motion

  9. Search Analytics for Your Site

    CERN Document Server

    Rosenfeld, Louis

    2011-01-01

    Any organization that has a searchable web site or intranet is sitting on top of hugely valuable and usually under-exploited data: logs that capture what users are searching for, how often each query was searched, and how many results each query retrieved. Search queries are gold: they are real data that show us exactly what users are searching for in their own words. This book shows you how to use search analytics to carry on a conversation with your customers: listen to and understand their needs, and improve your content, navigation and search performance to meet those needs.

  10. evaluating search effectiveness of some selected search engines

    African Journals Online (AJOL)

    Precision, relative recall and response time were considered for this ... a total of 24 search queries were sampled based on information queries, .... searching process and results, although there are other ... Q3.2 Software prototype model.

  11. Diphoton searches in ATLAS

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00213273; The ATLAS collaboration

    2016-01-01

    Searches for new resonances decaying into two photons in the ATLAS experiment at the LHC are described. The analysis is based on $pp$ collision data corresponding to an integrated luminosity of 3.2 fb$^{-1}$ at $\\sqrt{s}$ = 13 TeV recorded in 2015. Two different searches are performed, one targeted for a spin-2 particle, using Randall-Sundrum graviton states as a benchmark model, and one optimized for a spin-0 particle. The most significant deviation from the background predictions is observed at a diphoton invariant mass around 750 GeV with local significances of 3.6 and 3.9 standard deviations in the searches optimized for a spin-2 and spin-0 particle, respectively. The global significances are estimated to be 1.8 and 2.0 standard deviations. The consistency between the data collected at 13 TeV and 8 TeV is also evaluated. Limits on the production cross-section for the two benchmark resonances are reported.

  12. Search for fractional charge

    International Nuclear Information System (INIS)

    Turner, R.E.

    1984-01-01

    A search was made for fractional charges of the form Z plus two-thirds e, where Z is an integer. It was assumed that the charges exist in natural form bound with other fractional charges in neutral molecules. It was further assumed that these neutral molecules are present in air. Two concentration schemes were employed. One sample was derived from the waste gases from a xenon distillation plant. This assumes that high mass, low vapor pressure components of air are concentrated along with the xenon. The second sample involved ionizing air, allowing a brief recombination period, and then collecting residual ions on the surface of titanium discs. Both samples were analyzed at the University of Rochester in a system using a tandem Van de Graff to accelerate particles through an essentially electrostatic beam handling system. The detector system employed both a Time of Flight and an energy-sensitive gas ionization detector. In the most sensitive mode of analysis, a gas absorber was inserted in the beam path to block the intense background. The presence of an absorber limited the search to highly penetrating particles. Effectively, this limited the search to particles with low Z and masses greater than roughly fifty GeV. The final sensitivities attained were on the order of 1 x 10 -20 for the ionized air sample and 1 x 10 -21 for the gas sample. A discussion of the caveats that could reduce the actual level of sensitivity is included

  13. MINOS Sterile Neutrino Search

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, David Jason [Univ. College London, Bloomsbury (United Kingdom)

    2009-02-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline accelerator neutrino experiment designed to measure properties of neutrino oscillation. Using a high intensity muon neutrino beam, produced by the Neutrinos at Main Injector (NuMI) complex at Fermilab, MINOS makes two measurements of neutrino interactions. The first measurement is made using the Near Detector situated at Fermilab and the second is made using the Far Detector located in the Soudan Underground laboratory in northern Minnesota. The primary goal of MINOS is to verify, and measure the properties of, neutrino oscillation between the two detectors using the v μ→ Vτ transition. A complementary measurement can be made to search for the existence of sterile neutrinos; an oft theorized, but experimentally unvalidated particle. The following thesis will show the results of a sterile neutrino search using MINOS RunI and RunII data totaling ~2.5 x 1020 protons on target. Due to the theoretical nature of sterile neutrinos, complete formalism that covers transition probabilities for the three known active states with the addition of a sterile state is also presented.

  14. Accelerated Profile HMM Searches.

    Directory of Open Access Journals (Sweden)

    Sean R Eddy

    2011-10-01

    Full Text Available Profile hidden Markov models (profile HMMs and probabilistic inference methods have made important contributions to the theory of sequence database homology search. However, practical use of profile HMM methods has been hindered by the computational expense of existing software implementations. Here I describe an acceleration heuristic for profile HMMs, the "multiple segment Viterbi" (MSV algorithm. The MSV algorithm computes an optimal sum of multiple ungapped local alignment segments using a striped vector-parallel approach previously described for fast Smith/Waterman alignment. MSV scores follow the same statistical distribution as gapped optimal local alignment scores, allowing rapid evaluation of significance of an MSV score and thus facilitating its use as a heuristic filter. I also describe a 20-fold acceleration of the standard profile HMM Forward/Backward algorithms using a method I call "sparse rescaling". These methods are assembled in a pipeline in which high-scoring MSV hits are passed on for reanalysis with the full HMM Forward/Backward algorithm. This accelerated pipeline is implemented in the freely available HMMER3 software package. Performance benchmarks show that the use of the heuristic MSV filter sacrifices negligible sensitivity compared to unaccelerated profile HMM searches. HMMER3 is substantially more sensitive and 100- to 1000-fold faster than HMMER2. HMMER3 is now about as fast as BLAST for protein searches.

  15. Search costs and efficiency : Do unemployed workers search enough?

    NARCIS (Netherlands)

    Gautier, Pieter A.; Moraga González, José; Wolthoff, Ronald P.

    Many labor market policies affect the marginal benefits and costs of job search. The impact and desirability of such policies depend on the distribution of search costs. In this paper, we provide an equilibrium framework for identifying the distribution of search costs and we apply it to the Dutch

  16. Subject search study. Final report

    International Nuclear Information System (INIS)

    Todeschini, C.

    1995-01-01

    The study gathered information on how users search the database of the International Nuclear Information System (INIS), using indicators such as Subject categories, Controlled terms, Subject headings, Free-text words, combinations of the above. Users participated from the Australian, French, Russian and Spanish INIS Centres, that have different national languages. Participants, both intermediaries and end users, replied to a questionnaire and executed search queries. The INIS Secretariat at the IAEA also participated. A protocol of all search strategies used in actual searches in the database was kept. The thought process for Russian and Spanish users is predominantly non-English and also the actual initial search formulation is predominantly non-English among Russian and Spanish users while it tends to be more in English among French users. A total of 1002 searches were executed by the five INIS centres including the IAEA. The search protocols indicate the following search behaviour: 1) free text words represent about 40% of search points on an average query; 2) descriptors used as search keys have the widest range as percentage of search points, from a low of 25% to a high of 48%; 3) search keys consisting of free text that coincides with a descriptor account for about 15% of search points; 4) Subject Categories are not used in many searches; 5) free text words are present as search points in about 80% of all searches; 6) controlled terms (descriptors) are used very extensively and appear in about 90% of all searches; 7) Subject Headings were used in only a few percent of searches. From the results of the study one can conclude that there is a greater reluctance on the part of non-native English speakers in initiating their searches by using free text word searches. Also: Subject Categories are little used in searching the database; both free text terms and controlled terms are the predominant types of search keys used, whereby the controlled terms are used more

  17. Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Amole, C.; Ardid, M.; Asner, David M.; Baxter, D.; Behnke, E.; Bhattacharjee, P. S.; Borsodi, H.; Bou-Cabo, M.; Brice, S. J.; Broemmelsiek, D.; Clark, K.; Collar, J. I.; Cooper, P. S.; Crisler, M.; Dahl, C. E.; Daley, S.; Das, Madhusmita; Debris, F.; Dhungana, N.; Farine, J.; Felis, I.; Filgas, R.; Fines-Neuschild, M.; Girard, Francoise; Giroux, G.; Hai, M.; Hall, Jeter C.; Harris, O.; Jackson, C. M.; Jin, M.; Krauss, C. B.; Lafreniere, M.; Laurin, M.; Lawson, I.; Levine, I.; Lippincott, W. H.; Mann, E.; Martin, J. P.; Maurya, D.; Mitra, Pitam; Neilson, R.; Noble, A. J.; Plante, A.; Podviianiuk, R. B.; Priya, S.; Robinson, A. E.; Ruschman, M.; Scallon, O.; Seth, S.; Sonnenschein, Andrew; Starinski, N.; Stekl, I.; Vazquez-Jauregui, E.; Wells, J.; Wichoski, U.; Zacek, V.; Zhang, J.

    2015-06-12

    New data are reported from the operation of a 2-liter C3F8 bubble chamber in the 2100 meter deep SNOLAB underground laboratory, with a total exposure of 211.5 kg-days at four different recoil energy thresholds ranging from 3.2 keV to 8.1 keV. These data show that C3F8 provides excellent electron recoil and alpha rejection capabilities at very low thresholds, including the rst observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with signicant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.

  18. Switching strategies to optimize search

    International Nuclear Information System (INIS)

    Shlesinger, Michael F

    2016-01-01

    Search strategies are explored when the search time is fixed, success is probabilistic and the estimate for success can diminish with time if there is not a successful result. Under the time constraint the problem is to find the optimal time to switch a search strategy or search location. Several variables are taken into account, including cost, gain, rate of success if a target is present and the probability that a target is present. (paper: interdisciplinary statistical mechanics)

  19. Search Engines for Tomorrow's Scholars

    Science.gov (United States)

    Fagan, Jody Condit

    2011-01-01

    Today's scholars face an outstanding array of choices when choosing search tools: Google Scholar, discipline-specific abstracts and index databases, library discovery tools, and more recently, Microsoft's re-launch of their academic search tool, now dubbed Microsoft Academic Search. What are these tools' strengths for the emerging needs of…

  20. Undergraduate Students' Information Search Practices

    Science.gov (United States)

    Nikolopoulou, Kleopatra; Gialamas, Vasilis

    2011-01-01

    This paper investigates undergraduate students' information search practices. The subjects were 250 undergraduate students from two university departments in Greece, and a questionnaire was used to document their search practices. The results showed that the Web was the primary information system searched in order to find information for…

  1. Dark Matter Searches at LHC

    CERN Document Server

    Terashi, Koji; The ATLAS collaboration

    2017-01-01

    This talk will present dark matter searches at the LHC in the PIC2017 conference. The main emphasis is placed on the direct dark matter searches while the interpretation of searches for SUSY and invisible Higgs signals for the dark matter is also presented.

  2. Search for scalar muons

    International Nuclear Information System (INIS)

    Bartel, W.; Becker, L.; Bowdery, C.; Cords, D.; Felst, R.; Haidt, D.; Knies, G.; Krehbiel, H.; Meinke, R.; Naroska, B.; Olsson, J.; Steffen, P.; Junge, H.; Schmidt, D.; Laurikainen, P.; Dietrich, G.; Hagemann, J.; Heinzelmann, G.; Kado, H.; Kleinwort, C.; Kuhlen, M.; Meier, K.; Petersen, A.; Ramcke, R.; Schneekloth, U.; Weber, G.; Allison, J.; Baines, J.; Ball, A.H.; Barlow, R.J.; Chrin, J.; Duerdoth, I.P.; Greenshaw, T.; Hill, P.; Loebinger, F.K.; Macbeth, A.A.; McCann, H.; Mills, H.E.; Murphy, P.G.; Stephens, K.; Warming, P.; Glasser, R.G.; Sechi-Zorn, B.; Skard, J.A.J.; Wagner, S.R.; Zorn, G.T.; Cartwright, S.L.; Clarke, D.; Marshall, R.; Middleton, R.P.; Whittaker, J.B.; Kawamoto, T.; Kobayashi, T.; Mashimo, T.; Minowa, M.; Takeda, H.; Takeshita, T.; Yamada, S.

    1984-12-01

    The supersymmetric partner of the muon was searched for in a systematic way. No candidate was found and 95% CL limits on its mass were given for different cases. If it is stable, the limit is 20.9 GeV/c 2 . If it decays into a muon and an invisible low mass particle, the limit is 20.3 GeV/c 2 . If it decays into a muon and an unstable neutral particle which decays further into a photon and an invisible massless particles, the limit is 19.2 GeV/c 2 . (orig.)

  3. Search for black holes

    International Nuclear Information System (INIS)

    Cherepashchuk, Anatolii M

    2003-01-01

    Methods and results of searching for stellar mass black holes in binary systems and for supermassive black holes in galactic nuclei of different types are described. As of now (June 2002), a total of 100 black hole candidates are known. All the necessary conditions Einstein's General Relativity imposes on the observational properties of black holes are satisfied for candidate objects available, thus further assuring the existence of black holes in the Universe. Prospects for obtaining sufficient criteria for reliably distinguishing candidate black holes from real black holes are discussed. (reviews of topical problems)

  4. Search for scalar mesons

    International Nuclear Information System (INIS)

    Pennington, M.R.

    1989-01-01

    The search for I = 0 0 ++ mesons is described. The crucial role played by the states in the 1 GeV region is highlighted. An analysis program that with unimpeachable data would produce definitive results on these is outlined and shown with present data to provide prima facie evidence for dynamics beyond that of the quark model. The authors briefly speculate on the current status of the lowest mass scalar mesons and discuss how experiment can resolve the unanswered issues. 30 references, 6 figures, 1 table

  5. A New Search for $ \

    CERN Multimedia

    Dore, U; Kodama, K; Ushida, N; Loverre, P F

    2002-01-01

    % WA95\\\\ \\\\ The question whether neutrino flavours mix at some level - and the related question whether neutrinos have non-zero mass - is one of the remaining great challenges of experimental physics. Neutrinos from supernovae, from the sun, from the earth's atmosphere, from nuclear reactors and from radioactive decays are currently under study; in this frame, experiments using accelerators play a privileged role because the well known neutrino source properties allow high precision measurements and background control.\\\\ \\\\The main goal of the CHORUS experiment is to search for neutrino oscillations in the $\

  6. ATLAS Exotic Searches

    CERN Document Server

    Bousson, Nicolas

    2012-01-01

    Thanks to the outstanding performance of the Large Hadron Collider (LHC) that delivered more than 2 fb^-1 of proton-proton collision data at center-of-mass energy of 7 TeV, the ATLAS experiment has been able to explore a wide range of exotic models trying to address the questions unanswered by the Standard Model of particle physics. Searches for leptoquarks, new heavy quarks, vector-like quarks, black holes, hidden valley and contact interactions are reviewed in these proceedings.

  7. Pentaquark Searches at Jlab

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Patrizia

    2007-01-01

    Since LEPS collaboration reported the first evidence for a S=+1 baryon resonance in early 2003 with a mass of 1.54 GeV, dubbed Θ+, more than ten experiments have confirmed this exotic state, among these two carried out at Jefferson Laboratory. At the same time, there are a number of experiments, mostly at high energies, that report null results. To try to clarify this situation, during the past year, The CLAS Collaboration at Jefferson Laboratory has undertaken a second generation high-statistics experimental program to search for exotics baryons. Here the preliminary results from these experiments are reported.

  8. Higgs Searches at DØ

    Science.gov (United States)

    Owen, Mark

    2009-09-01

    The Higgs boson is essential to achieve electroweak symmetry breaking in the Standard Model. Results on searches for the Higgs boson using data collected in pbar p collisions at √ s = 1.96 {TeV} with the DØ detector at the Fermilab Teva-tron collider are presented. The data, corresponding to integrated luminosities between 1 fb-1 and 2 fb-1 show no excess above the expected backgrounds and as such upper limits on the production cross section of Higgs bosons are set at the 95% confidence level.

  9. Optimal intermittent search strategies

    Energy Technology Data Exchange (ETDEWEB)

    Rojo, F; Budde, C E [FaMAF, Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina); Wio, H S [Instituto de Fisica de Cantabria, Universidad de Cantabria and CSIC E-39005 Santander (Spain)

    2009-03-27

    We study the search kinetics of a single fixed target by a set of searchers performing an intermittent random walk, jumping between different internal states. Exploiting concepts of multi-state and continuous-time random walks we have calculated the survival probability of a target up to time t, and have 'optimized' (minimized) it with regard to the transition probability among internal states. Our model shows that intermittent strategies always improve target detection, even for simple diffusion states of motion.

  10. Learning about Job Search

    DEFF Research Database (Denmark)

    Altmann, Steffen; Falk, Armin; Jäger, Simon

    strategies and the consequences of unemployment, and motivated them to actively look for new employment. We study the causal impact of the brochure by comparing labor market outcomes of treated and untreated job seekers in administrative data containing comprehensive information on individuals’ employment...... findings indicate that targeted information provision can be a highly effective policy tool in the labor market.......We conduct a large-scale field experiment in the German labor market to investigate how information provision affects job seekers’ employment prospects and labor market outcomes. Individuals assigned to the treatment group of our experiment received a brochure that informed them about job search...

  11. Search Engine Optimization

    CERN Document Server

    Davis, Harold

    2006-01-01

    SEO--short for Search Engine Optimization--is the art, craft, and science of driving web traffic to web sites. Web traffic is food, drink, and oxygen--in short, life itself--to any web-based business. Whether your web site depends on broad, general traffic, or high-quality, targeted traffic, this PDF has the tools and information you need to draw more traffic to your site. You'll learn how to effectively use PageRank (and Google itself); how to get listed, get links, and get syndicated; and much more. The field of SEO is expanding into all the possible ways of promoting web traffic. This

  12. Search Databases and Statistics

    DEFF Research Database (Denmark)

    Refsgaard, Jan C; Munk, Stephanie; Jensen, Lars J

    2016-01-01

    having strengths and weaknesses that must be considered for the individual needs. These are reviewed in this chapter. Equally critical for generating highly confident output datasets is the application of sound statistical criteria to limit the inclusion of incorrect peptide identifications from database...... searches. Additionally, careful filtering and use of appropriate statistical tests on the output datasets affects the quality of all downstream analyses and interpretation of the data. Our considerations and general practices on these aspects of phosphoproteomics data processing are presented here....

  13. Searching for uranium

    International Nuclear Information System (INIS)

    Spaargaren, F.A.

    1988-01-01

    In the not-so-distant past, the search for uranium usually followed a conceptual approach in which an unexplored terrain was selected because of its presumed similarities with one that is known to contain one or more deposits. A description, in general terms, is given of the methodology adopted during the different stages of the exploration programme, up to the point of a discovery. Three case histories prove that, in order to reach this point, a certain amount of improvisation and luck is usually required. (author)

  14. Searching for dark matter

    Science.gov (United States)

    Mateo, Mario

    1994-01-01

    Three teams of astronomers believe they have independently found evidence for dark matter in our galaxy. A brief history of the search for dark matter is presented. The use of microlensing-event observation for spotting dark matter is described. The equipment required to observe microlensing events and three groups working on dark matter detection are discussed. The three groups are the Massive Compact Halo Objects (MACHO) Project team, the Experience de Recherche d'Objets Sombres (EROS) team, and the Optical Gravitational Lensing Experiment (OGLE) team. The first apparent detections of microlensing events by the three teams are briefly reported.

  15. Dark Matter Searches

    International Nuclear Information System (INIS)

    Moriyama, Shigetaka

    2008-01-01

    Recent cosmological as well as historical observations of rotational curves of galaxies strongly suggest the existence of dark matter. It is also widely believed that dark matter consists of unknown elementary particles. However, astrophysical observations based on gravitational effects alone do not provide sufficient information on the properties of dark matter. In this study, the status of dark matter searches is investigated by observing high-energy neutrinos from the sun and the earth and by observing nuclear recoils in laboratory targets. The successful detection of dark matter by these methods facilitates systematic studies of its properties. Finally, the XMASS experiment, which is due to start at the Kamioka Observatory, is introduced

  16. Pentaquark Searches at JLab

    International Nuclear Information System (INIS)

    Rossi, P.

    2007-01-01

    Since LEPS collaboration reported the first evidence for a S=+1 baryon resonance in early 2003 with a mass of 1.54 GeV, dubbed Θ + , more than ten experiments have confirmed this exotic state, among these two carried out at Jefferson Laboratory. At the same time, there are a number of experiments, mostly at high energies, that report null results. To try to clarify this situation, during the past year, The CLAS Collaboration at Jefferson Laboratory has undertaken a second generation high-statistics experimental program to search for exotics baryons. Here the preliminary results from these experiments are reported

  17. A search for gamma-ray imprints of annihilating dark matter in the galaxy, and the astrophysical implications of ultra-light fundamental vector bosons

    Energy Technology Data Exchange (ETDEWEB)

    Zechlin, Hannes-Sebastian

    2013-12-15

    Standard Model extensions imply new elementary particles that can lead to specific astrophysical signatures. In particular, weakly interacting massive particles (WIMPs) can constitute the unknown non-luminous cold dark matter, which contributes approximately 84% to the matter content of the Universe. Annihilation or decay of WIMPs may lead to high-energy gamma-rays. In this thesis, new methods of searching for gamma-ray signals from annihilating dark matter are developed and applied. Moreover, astrophysical imprints of new ultra-light hidden U(1) gauge bosons in radio data are investigated. Hierarchical structure formation predicts a variety of smaller bound dark matter sub-halos in Milky-Way-like galactic hosts. It is shown that the Fermi-LAT is sufficiently sensitive for detecting up to a few nearby dark matter subhalos in terms of faint gamma-ray sources with a moderate angular extent. Searches in the first and second Fermi-LAT source catalogs reveal about ten candidate sources each. To discriminate the source candidates from conventional astrophysical objects, an analysis for spectral, spatial, positional, and temporal gamma-ray properties using 3.5 years of Fermi-LAT data is carried out. In addition, a multi-wavelength analysis of archival data or follow-up observations in the radio, infrared, optical, UV, X-ray, high-energy, and very-high energy gamma-ray bands is carried out. The broad-band spectra of all promising candidates are compatible with AGN, in particular high-energy peaked BL-Lac type objects (HBLs). Dark matter annihilation can contribute to the small-scale angular anisotropy spectrum of the diffuse gamma-ray background (DGB). The detection capabilities of currently operating imaging atmospheric Cherenkov telescopes and the planned Cherenkov Telescope Array (CTA) are studied. With CTA, a relative gamma-ray contribution from annihilating dark matter of 10% to the extragalactic DGB can be resolved via angular anisotropies. In terms of the dark

  18. Multimedia Search Engines : Concept, Performance, and Types

    OpenAIRE

    Sayed Rabeh Sayed

    2005-01-01

    A Research about multimedia search engines, it starts with definition of search engines at general and multimedia search engines, then explains how they work, and divided them into: Video search engines, Images search engines, and Audio search engines. Finally, it reviews a samples to multimedia search engines.

  19. Heuristic Search Theory and Applications

    CERN Document Server

    Edelkamp, Stefan

    2011-01-01

    Search has been vital to artificial intelligence from the very beginning as a core technique in problem solving. The authors present a thorough overview of heuristic search with a balance of discussion between theoretical analysis and efficient implementation and application to real-world problems. Current developments in search such as pattern databases and search with efficient use of external memory and parallel processing units on main boards and graphics cards are detailed. Heuristic search as a problem solving tool is demonstrated in applications for puzzle solving, game playing, constra

  20. Search For Trapped Antihydrogen

    CERN Document Server

    Andresen, Gorm B.; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D.; Bray, Crystal C.; Butler, Eoin; Cesar, Claudio L.; Chapman, Steven; Charlton, Michael; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C.; Gill, David R.; Hangst, Jeffrey S.; Hardy, Walter N.; Hayano, Ryugo S.; Hayden, Michael E.; Humphries, Andrew J.; Hydomako, Richard; Jonsell, Svante; Jorgensen, Lars V.; Kurchaninov, Lenoid; Lambo, Ricardo; Madsen, Niels; Menary, Scott; Nolan, Paul; Olchanski, Konstantin; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Nasr, Sarah Seif El; Silveira, Daniel M.; So, Chukman; Storey, James W.; Thompson, Robert I.; van der Werf, Dirk P.; Wilding, Dean; Wurtele, Jonathan S.; Yamazaki, Yasunori

    2011-01-01

    We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consist...

  1. Searching for heavy leptons

    International Nuclear Information System (INIS)

    Perl, M.L.

    1979-11-01

    This frankly speculative paper discusses ways in which leptons heavier than the tau (if they exist) might be found. The status of the tau is briefly reviewed, and methods for searching for sequential charged leptons beyond the tau and other charged leptons at PEP, PETRA, and CESR are sketched. Charged leptons with mass greater than 20 GeV/c 2 might be found at proton accelerators in hadron-hadron, photon-hadron, or ν-hadron collisions. Unstable, neutral heavy leptons might have unique, conserved lepton number or nonunique lepton number. The most difficult leptons to detect are stable neutral heavy leptons; nevertheless, a possible detection method is suggested. The obvious solution to seeking the postulated leptons is an e + e - colliding beam storage ring with c.m. energy = several hundred GeV. Until such a machine is built, one can employ Z 0 → L + + L - ; the use of R/sub Z 0 / and GAMMA/sub Z 0 / in this connection is discussed. If heavier Z 0 's exist, the heavy lepton search can be extended to higher energies. Another solution for producing these leptons involves the use of clashing e + e - linear accelerators. Characteristics of storage rings are compared with those of clashing linacs; a general description is given of the proposed SLAC Linac-Collider, along with the physics that could be done at such a machine. 6 figures

  2. Stability of cascade search

    Energy Technology Data Exchange (ETDEWEB)

    Fomenko, Tatiana N [M. V. Lomonosov Moscow State University, Faculty of Computational Mathematics and Cybernetics, Moscow (Russian Federation)

    2010-10-22

    We find sufficient conditions on a searching multi-cascade for a modification of the set of limit points of the cascade that satisfy an assessing inequality for the distance from each of these points to the initial point to be small, provided that the modifications of the initial point and the initial set-valued functionals or maps used to construct the multi-cascade are small. Using this result, we prove the stability (in the above sense) of the cascade search for the set of common pre-images of a closed subspace under the action of n set-valued maps, n{>=}1 (in particular, for the set of common roots of these maps and for the set of their coincidences). For n=2 we obtain generalizations of some results of A. V. Arutyunov; the very statement of the problem comes from a recent paper of his devoted to the study of the stability of the subset of coincidences of a Lipschitz map and a covering map.

  3. One visual search, many memory searches: An eye-tracking investigation of hybrid search.

    Science.gov (United States)

    Drew, Trafton; Boettcher, Sage E P; Wolfe, Jeremy M

    2017-09-01

    Suppose you go to the supermarket with a shopping list of 10 items held in memory. Your shopping expedition can be seen as a combination of visual search and memory search. This is known as "hybrid search." There is a growing interest in understanding how hybrid search tasks are accomplished. We used eye tracking to examine how manipulating the number of possible targets (the memory set size [MSS]) changes how observers (Os) search. We found that dwell time on each distractor increased with MSS, suggesting a memory search was being executed each time a new distractor was fixated. Meanwhile, although the rate of refixation increased with MSS, it was not nearly enough to suggest a strategy that involves repeatedly searching visual space for subgroups of the target set. These data provide a clear demonstration that hybrid search tasks are carried out via a "one visual search, many memory searches" heuristic in which Os examine items in the visual array once with a very low rate of refixations. For each item selected, Os activate a memory search that produces logarithmic response time increases with increased MSS. Furthermore, the percentage of distractors fixated was strongly modulated by the MSS: More items in the MSS led to a higher percentage of fixated distractors. Searching for more potential targets appears to significantly alter how Os approach the task, ultimately resulting in more eye movements and longer response times.

  4. Policy implications for familial searching.

    Science.gov (United States)

    Kim, Joyce; Mammo, Danny; Siegel, Marni B; Katsanis, Sara H

    2011-11-01

    In the United States, several states have made policy decisions regarding whether and how to use familial searching of the Combined DNA Index System (CODIS) database in criminal investigations. Familial searching pushes DNA typing beyond merely identifying individuals to detecting genetic relatedness, an application previously reserved for missing persons identifications and custody battles. The intentional search of CODIS for partial matches to an item of evidence offers law enforcement agencies a powerful tool for developing investigative leads, apprehending criminals, revitalizing cold cases and exonerating wrongfully convicted individuals. As familial searching involves a range of logistical, social, ethical and legal considerations, states are now grappling with policy options for implementing familial searching to balance crime fighting with its potential impact on society. When developing policies for familial searching, legislators should take into account the impact of familial searching on select populations and the need to minimize personal intrusion on relatives of individuals in the DNA database. This review describes the approaches used to narrow a suspect pool from a partial match search of CODIS and summarizes the economic, ethical, logistical and political challenges of implementing familial searching. We examine particular US state policies and the policy options adopted to address these issues. The aim of this review is to provide objective background information on the controversial approach of familial searching to inform policy decisions in this area. Herein we highlight key policy options and recommendations regarding effective utilization of familial searching that minimize harm to and afford maximum protection of US citizens.

  5. Development of CDMS-II Surface Event Rejection Techniques and Their Extensions to Lower Energy Thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Hofer, Thomas James [Univ. of Minnesota, Minneapolis, MN (United States)

    2014-12-01

    The CDMS-II phase of the Cryogenic Dark Matter Search, a dark matter direct-detection experiment, was operated at the Soudan Underground Laboratory from 2003 to 2008. The full payload consisted of 30 ZIP detectors, totaling approximately 1.1 kg of Si and 4.8 kg of Ge, operated at temperatures of 50 mK. The ZIP detectors read out both ionization and phonon pulses from scatters within the crystals; channel segmentation and analysis of pulse timing parameters allowed e ective ducialization of the crystal volumes and background rejection su cient to set world-leading limits at the times of their publications. A full re-analysis of the CDMS-II data was motivated by an improvement in the event reconstruction algorithms which improved the resolution of ionization energy and timing information. The Ge data were re-analyzed using three distinct background-rejection techniques; the Si data from runs 125 - 128 were analyzed for the rst time using the most successful of the techniques from the Ge re-analysis. The results of these analyses prompted a novel \\mid-threshold" analysis, wherein energy thresholds were lowered but background rejection using phonon timing information was still maintained. This technique proved to have signi cant discrimination power, maintaining adequate signal acceptance and minimizing background leakage. The primary background for CDMS-II analyses comes from surface events, whose poor ionization collection make them di cult to distinguish from true nuclear recoil events. The novel detector technology of SuperCDMS, the successor to CDMS-II, uses interleaved electrodes to achieve full ionization collection for events occurring at the top and bottom detector surfaces. This, along with dual-sided ionization and phonon instrumentation, allows for excellent ducialization and relegates the surface-event rejection techniques of CDMS-II to a secondary level of background discrimination. Current and future SuperCDMS results hold great promise for mid- to low

  6. Search for new physics in final states with a high energy electron and large missing transverse energy

    Energy Technology Data Exchange (ETDEWEB)

    Schuh, Natascha

    2017-01-13

    The most successful and comprehensive theory describing the microcosm is the Standard Model of particle physics (SM). It comprises all known elementary particles and describes in high precision the basic processes of three of the four fundamental interactions. But still, not all experimental observations and theoretical challenges are covered. Many models exist that take the SM as a good approximation of natural phenomena in already discovered energy regions, but extend it in various ways. The Large Hadron Collider (LHC) provides the opportunity to look into these high energy regions using proton-proton collisions at significantly higher center-of-mass energies than previous experiments. This dissertation searches for physics beyond the SM especially in final states with one highly energetic electron (respectively positron) and large missing transverse energy. With the data set recorded in 2012 by the ATLAS detector, a large multi-purpose detector making use of the LHC, the spectrum of the related combined transverse mass can be measured up to the TeV scale. To find any evidence to the existence of new physics beyond the SM, it was searched for significant deviations between the observed data and the expectations due to SM processes. Unfortunately, no significant excess could be observed and exclusion limits in the context of three different new physics scenarios are provided. Besides a so-called Sequential Standard Model (SSM) predicting additional vector gauge bosons, also the possible existence of (charged) chiral bosons is analyzed. Also inferences about dark matter candidates called ''weakly interacting massive particles (WIMP)'' are drawn. With the aid of a Bayesian ansatz, the observed (expected) exclusion limit on the boson pole mass is set to 3.13 TeV(3.13 TeV) for a SSM W' boson and to 3.08 TeV(3.08 TeV) for charged chiral W{sup *} bosons (at 95% C.L.).

  7. Search for double beta decay processes of {sup 124}Xe with XENON100 and XENON1T

    Energy Technology Data Exchange (ETDEWEB)

    Fieguth, Alexander [IKP, Westfaelische-Wilhelms-Universitaet Muenster (Germany)

    2016-07-01

    Driven by the search for dark matter particles the XENON dark matter project recently installed its next stage multi-ton experiment XENON1T at the LNGS, which will probe the spin-indpendent-WIMP-Nucleon cross section down to 2.10{sup -47} cm{sup 2}. Besides its main purpose different particle physics topics can be addressed by the taken data. One example are the double beta decay processes of natural isotope {sup 124}Xe. This isotope is expected to decay via two-neutrino double electron capture (2νECEC) and due to its high Q-value of 2864 keV additionally through 2νβ{sup +}β{sup +}. Since these processes have not been detected so far, there is only a lower limit the respective half-life (e.g. > 4.7.10{sup 21} yr for 2νECEC). A detection of the 2νECEC is possible using XENON1T data by looking for its clear signature of secondary X-rays or Auger electrons and at least new lower half-life limits for all other decay channels can be obtained. While these processes are expected from standard model physics, a detection of a decay without neutrinos (e.g 0νECEC) would hint towards beyond the standard model physics and could derive conclusions on the neutrino mass. Until XENON1T is taking data, the search for all processes can be tested in the recorded data of its predecessor XENON100.

  8. Beyond the search surface: visual search and attentional engagement.

    Science.gov (United States)

    Duncan, J; Humphreys, G

    1992-05-01

    Treisman (1991) described a series of visual search studies testing feature integration theory against an alternative (Duncan & Humphreys, 1989) in which feature and conjunction search are basically similar. Here the latter account is noted to have 2 distinct levels: (a) a summary of search findings in terms of stimulus similarities, and (b) a theory of how visual attention is brought to bear on relevant objects. Working at the 1st level, Treisman found that even when similarities were calibrated and controlled, conjunction search was much harder than feature search. The theory, however, can only really be tested at the 2nd level, because the 1st is an approximation. An account of the findings is developed at the 2nd level, based on the 2 processes of input-template matching and spreading suppression. New data show that, when both of these factors are controlled, feature and conjunction search are equally difficult. Possibilities for unification of the alternative views are considered.

  9. Higgs searches with CMS

    CERN Multimedia

    CERN. Geneva

    2011-01-01

    The excellent performances of the LHC in the 2011 run are setting the grounds for the final chase of the Higgs boson. The CMS experiment is recording high quality data that are being thoroughly scrutinized. Several decay channels are investigated to probe the entire possible Higgs mass spectrum, from 110 to 600 GeV/c^2. The study of the first 1.5/fb of collected data places already tight limits and excludes large fractions of the Higgs mass range, leaving however still open the search in the theoretically favored low mass region. In this seminar we will report on the diverse CMS analyses that yield to such results describing the experimental challenges that each had to meet.

  10. Open Search Environments: The Free Alternative to Commercial Search Services

    Directory of Open Access Journals (Sweden)

    Adrian O'Riordan

    2014-06-01

    Full Text Available Open search systems present a free and less restricted alternative to commercial search services. This paper explores the space of open search technology looking in particular at the issue of interoperability. A description of current protocols and formats for engineering open search applications is presented. The suitability of these technologies and issues around their adoption and operation are discussed. This open search approach is especially proving a fitting choice in applications involving the harvesting of resources and information integration. Principal among the technological solutions are OpenSearch and SRU. OpenSearch and SRU implement a federated model to enable existing and new search engines and search clients communicate. Applications and instances where Opensearch and SRU can be combined are presented. Other relevant technologies such as OpenURL, Apache Solr, and OAI-PMH are also discussed. The deployment of these freely licensed open standards in digital library applications is now a genuine alternative to commercial or proprietary systems.

  11. The search for dark matter in xenon: Innovative calibration strategies and novel search channels

    Science.gov (United States)

    Reichard, Shayne Edward

    The direct detection dark matter experiment XENON1T became operational in early 2016, heralding the era of tonne-scale dark matter detectors. Direct detection experiments typically search for elastic scatters of dark matter particles off target nuclei. XENON1T's larger xenon target provides the advantage of stronger dark matter signals and lower background rates compared to its predecessors, XENON10 and XENON100; but, at the same time, calibration of the detector's response to backgrounds with traditional external sources becomes exceedingly more difficult. A 220Rn source is deployed on the XENON100 dark matter detector in order to address the challenges in calibration of tonne-scale liquid noble element detectors. I show that the subsequent 212Pb beta emission can be used for low-energy electronic recoil calibration in searches for dark matter. The isotope spreads throughout the entire active region of the detector, and its activity naturally decays below background level within a week after the source is closed. I find no increase in the activity of the troublesome 222Rn background after calibration. Alpha emitters are also distributed throughout the detector and facilitate calibration of its response to 222Rn. Using the delayed coincidence of 220Rn/216Po, I map for the first time the convective motion of particles in the XENON100 detector. Additionally, I make a competitive measurement of the half-life of 212Po, t1/2=293.9+/-(1.0)stat+/-(0.6)ns. In contrast to the elastic scattering of dark matter particles off nuclei, I explore inelastic scattering where the nucleus is excited to a low-lying state of 10-100 keV, with a subsequent prompt de-excitation. I use the inelastic structure factors for the odd-mass xenon isotopes based on state-of-the-art large-scale shell-model calculations with chiral effective field theory WIMP-nucleon currents, finding that the inelastic channel is comparable to or can dominate the elastic channel for momentum transfers around 150 Me

  12. Search 3.0: Present, Personal, Precise

    Science.gov (United States)

    Spivack, Nova

    The next generation of Web search is already beginning to emerge. With it we will see several shifts in the way people search, and the way major search engines provide search functionality to consumers.

  13. A Search Model of Discouragement

    DEFF Research Database (Denmark)

    Rosholm, Michael; Toomet, Ott

    Discouragement is a process occurring during an unemployment spell. As the spell prolongs, an individual gradually realises that the returns to search can no longer outweigh search costs, and hence she may eventually leave the labour force. This is analysed theoretically in a framework...... of unemployed search. We construct a search model, which is stationary from the point of view of the individual, but which has nonstationary features. Namely, the unemployed worker is occasionally hit by shocks leading to a decline in job offer arrival rates. These shocks can be due to stigmatisation...... or to psychological consequences of unemployement affecting search effectiveness. This model enables us to analyse the issue of discouragement, as the returns to search will gradually decline. Even so, the model is actually stationary from the point of view of the individual, which implies that many interesting...

  14. Clinician search behaviors may be influenced by search engine design.

    Science.gov (United States)

    Lau, Annie Y S; Coiera, Enrico; Zrimec, Tatjana; Compton, Paul

    2010-06-30

    Searching the Web for documents using information retrieval systems plays an important part in clinicians' practice of evidence-based medicine. While much research focuses on the design of methods to retrieve documents, there has been little examination of the way different search engine capabilities influence clinician search behaviors. Previous studies have shown that use of task-based search engines allows for faster searches with no loss of decision accuracy compared with resource-based engines. We hypothesized that changes in search behaviors may explain these differences. In all, 75 clinicians (44 doctors and 31 clinical nurse consultants) were randomized to use either a resource-based or a task-based version of a clinical information retrieval system to answer questions about 8 clinical scenarios in a controlled setting in a university computer laboratory. Clinicians using the resource-based system could select 1 of 6 resources, such as PubMed; clinicians using the task-based system could select 1 of 6 clinical tasks, such as diagnosis. Clinicians in both systems could reformulate search queries. System logs unobtrusively capturing clinicians' interactions with the systems were coded and analyzed for clinicians' search actions and query reformulation strategies. The most frequent search action of clinicians using the resource-based system was to explore a new resource with the same query, that is, these clinicians exhibited a "breadth-first" search behaviour. Of 1398 search actions, clinicians using the resource-based system conducted 401 (28.7%, 95% confidence interval [CI] 26.37-31.11) in this way. In contrast, the majority of clinicians using the task-based system exhibited a "depth-first" search behavior in which they reformulated query keywords while keeping to the same task profiles. Of 585 search actions conducted by clinicians using the task-based system, 379 (64.8%, 95% CI 60.83-68.55) were conducted in this way. This study provides evidence that

  15. LHCb Exotica and Higgs searches

    CERN Multimedia

    Lucchesi, Donatella

    2016-01-01

    The unique phase space coverage and features of the LHCb detector at the LHC makes it an ideal environment to probe complementary New Physics parameter regions. In particular, recently developed jet tagging algorithms are ideal for searches involving $b$ and $c$ jets. This poster will review different jet-related exotica searches together with the efforts in the search for a Higgs boson decaying to a pair of heavy quarks.

  16. Guided Search for Triple Conjunctions

    OpenAIRE

    Nordfang, Maria; Wolfe, Jeremy M

    2014-01-01

    A key tenet of Feature Integration Theory and related theories such as Guided Search (GS) is that the binding of basic features requires attention. This would seem to predict that conjunctions of features of objects that have not been attended should not influence search. However, Found (1998) reported that an irrelevant feature (size) improved the efficiency of search for a color × orientation conjunction if it was correlated with the other two features across the display compared to the cas...

  17. Policy implications for familial searching

    OpenAIRE

    Kim, Joyce; Mammo, Danny; Siegel, Marni B; Katsanis, Sara H

    2011-01-01

    Abstract In the United States, several states have made policy decisions regarding whether and how to use familial searching of the Combined DNA Index System (CODIS) database in criminal investigations. Familial searching pushes DNA typing beyond merely identifying individuals to detecting genetic relatedness, an application previously reserved for missing persons identifications and custody battles. The intentional search of CODIS for partial matches to an item of evidence offers law enforce...

  18. Dark Matter Searches at ATLAS

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    The astrophysical evidence of dark matter provides some of the most compelling clues to the nature of physics beyond the Standard Model. From these clues, ATLAS has developed a broad and systematic search program for dark matter production in LHC collisions. These searches are now entering their prime, with the LHC now colliding protons at the increased 13 TeV centre-of-mass energy and set to deliver much larger datasets than ever before. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

  19. Searching for the productivity slowdown

    OpenAIRE

    Steiner, Viktor

    1990-01-01

    Searching for the productivity slowdown : some surprising findings from West- German manufacturing / by Gebhard Flaig and Viktor Steiner. - Augsburg, 1990. - 29 S. - (Volkswirtschaftliche Diskussionsreihe ; 45)

  20. Searching and Archiving : Exploring Online Search Behaviors of Researchers

    NARCIS (Netherlands)

    Vyas, Dhaval; de Groot, S.; van der Veer, Gerrit C.; Dainoff, Marvin J.

    2007-01-01

    Searching for relevant peer-reviewed material is an integral part of corporate and academic researchers. Researchers collect huge amount of information over the years and sometimes struggle organizing it. Based on a study with 30 academic researchers, we explore, in combination, different searching

  1. 29 CFR 4050.4 - Diligent search.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false Diligent search. 4050.4 Section 4050.4 Labor Regulations... § 4050.4 Diligent search. (a) Search required. A diligent search must be made for each missing... § 4050.6. (b) Diligence. A search is a diligent search only if the search— (1) Begins not more than 6...

  2. The search for the top quark

    International Nuclear Information System (INIS)

    Barbaro-Galtieri, A.

    1989-03-01

    This paper discusses the following topics: top search in the near future, general remarks, top search at HERA, searching for the top quarks at the Z 0 machines, finding the top at Lep II, top search in UA2, top search in UA1, and top search at CDF. 58 refs., 38 figs

  3. Multitasking Web Searching and Implications for Design.

    Science.gov (United States)

    Ozmutlu, Seda; Ozmutlu, H. C.; Spink, Amanda

    2003-01-01

    Findings from a study of users' multitasking searches on Web search engines include: multitasking searches are a noticeable user behavior; multitasking search sessions are longer than regular search sessions in terms of queries per session and duration; both Excite and AlltheWeb.com users search for about three topics per multitasking session and…

  4. Search for interstellar methane

    International Nuclear Information System (INIS)

    Knacke, R.F.; Kim, Y.H.; Noll, K.S.; Geballe, T.R.

    1990-01-01

    Researchers searched for interstellar methane in the spectra of infrared sources embedded in molecular clouds. New observations of several lines of the P and R branches of the nu 3 band of CH4 near 3.3 microns give column densities in the range N less than 1(-2) times 10 to the minus 16th power cm(-2). Resulting abundance ratios are (CH4)/(CO) less than 3.3 times 10 to the minus 2nd power toward GL961 in NGC 2244 and less than 2.4 times 10 to the minus 3rd power toward GL989 in the NGC 2264 molecular cloud. The limits, and those determined in earlier observations of BN in Orion and GL490, suggest that there is little methane in molecular clouds. The result agrees with predictions of chemical models. Exceptions could occur in clouds where oxygen may be depleted, for example by H2O freezing on grains. The present observations probably did not sample such regions

  5. New particle searches

    International Nuclear Information System (INIS)

    Derrick, M.

    1985-01-01

    The Standard Model is a remarkable result of decades of work in particle physics, but it is clearly an incomplete representation of the world. Exploring possibilities beyond the Standard Model is a major preoccupation of both theorists and experimentalists. Despite the many suggestions that are extant about the missing links within the Standard Model as well as extensions beyond it, no hard experimental evidence exists. In particular, in more than five years of experimentation both at PETRA and PEP no new particles have been found that would indicate new physics. Several reasons are possible for these negative results: the particles may be too heavy; the experiments may not be looking in the proper way; the cross sections may be too small or finally the particles may not exist. A continuing PEP program, at high luminosity will ensure that the second and third reason continue to be addressed. The higher energy e + e - storage rings such as TRISTAN and LEP will extend the mass limits. High mass particles can also be produced at the CERN collider and soon with the Tevatron collider. A concise summary of the mass limits from the PETRA experiments has been given in a recent Mark J publication. The results shown provide a convenient yardstick against which to measure future search experiments

  6. Visual Representation Determines Search Difficulty: Explaining Visual Search Asymmetries

    Directory of Open Access Journals (Sweden)

    Neil eBruce

    2011-07-01

    Full Text Available In visual search experiments there exist a variety of experimental paradigms in which a symmetric set of experimental conditions yields asymmetric corresponding task performance. There are a variety of examples of this that currently lack a satisfactory explanation. In this paper, we demonstrate that distinct classes of asymmetries may be explained by virtue of a few simple conditions that are consistent with current thinking surrounding computational modeling of visual search and coding in the primate brain. This includes a detailed look at the role that stimulus familiarity plays in the determination of search performance. Overall, we demonstrate that all of these asymmetries have a common origin, namely, they are a consequence of the encoding that appears in the visual cortex. The analysis associated with these cases yields insight into the problem of visual search in general and predictions of novel search asymmetries.

  7. Development and Performance of Detectors for the Cryogenic Dark Matter Search Experiment with an Increased Sensitivity Based on a Maximum Likelihood Analysis of Beta Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Driscoll, Donald D [Case Western Reserve Univ., Cleveland, OH (United States)

    2004-05-01

    The Cryogenic Dark Matter Search (CDMS) uses cryogenically-cooled detectors made of germanium and silicon in an attempt to detect dark matter in the form of Weakly-Interacting Massive Particles (WIMPs). The expected interaction rate of these particles is on the order of 1/kg/day, far below the 200/kg/day expected rate of background interactions after passive shielding and an active cosmic ray muon veto. Our detectors are instrumented to make a simultaneous measurement of both the ionization energy and thermal energy deposited by the interaction of a particle with the crystal substrate. A comparison of these two quantities allows for the rejection of a background of electromagnetically-interacting particles at a level of better than 99.9%. The dominant remaining background at a depth of ~ 11 m below the surface comes from fast neutrons produced by cosmic ray muons interacting in the rock surrounding the experiment. Contamination of our detectors by a beta emitter can add an unknown source of unrejected background. In the energy range of interest for a WIMP study, electrons will have a short penetration depth and preferentially interact near the surface. Some of the ionization signal can be lost to the charge contacts there and a decreased ionization signal relative to the thermal signal will cause a background event which interacts at the surface to be misidentified as a signal event. We can use information about the shape of the thermal signal pulse to discriminate against these surface events. Using a subset of our calibration set which contains a large fraction of electron events, we can characterize the expected behavior of surface events and construct a cut to remove them from our candidate signal events. This thesis describes the development of the 6 detectors (4 x 250 g Ge and 2 x 100 g Si) used in the 2001-2002 CDMS data run at the Stanford Underground Facility with a total of 119 livedays of data. The preliminary results presented are based on the first use

  8. Search for black matter through the detection of gravitational micro-lenses in differential photometry; Recherche de matiere noire galactique par detection de microlentilles gravitationnelles en photometrie differentielle

    Energy Technology Data Exchange (ETDEWEB)

    Le Guillou, L

    2003-09-01

    The nature of dark matter is an open question. The search for gravitational microlensing effects is an interesting tool because this effect is strongly dependent on the mass of objects whether they are luminous or not, however this detection method is only sensitive to compact forms of dark matter (MACHOS - massive astronomical halo compact objects), and as a consequence no-baryonic matter like neutrinos or WIMPS (weakly interacting massive particles) can not be detected this way. In the first chapter the author reviews the plausible candidates to black matter. The use of the microlensing effect as a probe of the galactic halo is presented in the second chapter. The third chapter is dedicated to the series of experiments worldwide that focus on the detection of MACHOS. In the fourth chapter the author shows how the DIA (difference image analysis) method may be promising in the study of gravitational microlensing effects. The main part of this work has been the use of the DIA method to process five-year data set collected by the Eros experiment in the small Magellanic cloud (SMC). The data processing line and the results are presented in the fifth and sixth chapters. The results are consistent with previous results given by Eros and they confirm the disparity of the durations of micro-lenses detected in the large and small Magellanic clouds. (A.C.)

  9. Dark matter search with the HDMS-experiment and the GENIUS project

    International Nuclear Information System (INIS)

    Baudis, L.; Hellmig, J.; Klapdor-Kleingrothaus, H.V.; Ramachers, Y.; Strecker, H.

    1999-01-01

    We present a new Germanium Dark Matter Experiment. It consists of two HPGe-Detectors which are run in a unique configuration. The anticoincidence between the two detectors will further reduce the background that we achieve now in the Heidelberg-Moscow-Experiment and will allow to improve WIMP cross section limits to a level comparable to planned cryogenic experiments. This should also allow to test recently claimed positive evidence for dark matter by the DAMA experiment. We show first detector performances from the test period in the Heidelberg Low Level Laboratory and give a preliminary estimation for the background reduction efficiency. The HDMS experiment in being built up now in the Gran Sasso Underground Laboratory and will start taking data by the end of this year. For a substantial improvement of the WIMP-nucleon cross section limits, future dark matter experiments will have to be either massive direction-sensitive detectors or massive ton-scale detectors with almost zero background. A proposal for a high mass (1 ton) Ge experiment with a much further reduced background is the Heidelberg GENIUS experiment. GENIUS will be able to give a WIMP limit of the order 0.02 counts/day/kg and additionally to look for the annual modulation WIMP-signature by using raw data without subtraction

  10. Zimbabwe Science News: Advanced Search

    African Journals Online (AJOL)

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  11. Agro-Science: Advanced Search

    African Journals Online (AJOL)

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  12. Online Searching at 9600 Baud.

    Science.gov (United States)

    Scott, Ralph Lee; Scott, Nancy Sue Schell

    1991-01-01

    Discusses online searching with the new 9600 baud rate and describes test searches on the BRS, Data-Star, LEXIS, and Dow Jones databases through three packet-switching networks: US Sprint, MEADNET, and TYMNET. Hardware and software are described, data communications equipment standards are discussed, and the impact of higher baud rates on pricing…

  13. IMTU Medical Journal: Advanced Search

    African Journals Online (AJOL)

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  14. Mizan Law Review: Advanced Search

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  15. Ethiopian Veterinary Journal: Advanced Search

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  16. Health SA Gesondheid: Advanced Search

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  17. Malawi Medical Journal: Advanced Search

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  18. Ethiopian Pharmaceutical Journal: Advanced Search

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  19. Nigerian Food Journal: Advanced Search

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  20. Scientific Medical Journal: Advanced Search

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  1. Visual search deficits in amblyopia.

    Science.gov (United States)

    Tsirlin, Inna; Colpa, Linda; Goltz, Herbert C; Wong, Agnes M F

    2018-04-01

    Amblyopia is a neurodevelopmental disorder defined as a reduction in visual acuity that cannot be corrected by optical means. It has been associated with low-level deficits. However, research has demonstrated a link between amblyopia and visual attention deficits in counting, tracking, and identifying objects. Visual search is a useful tool for assessing visual attention but has not been well studied in amblyopia. Here, we assessed the extent of visual search deficits in amblyopia using feature and conjunction search tasks. We compared the performance of participants with amblyopia (n = 10) to those of controls (n = 12) on both feature and conjunction search tasks using Gabor patch stimuli, varying spatial bandwidth and orientation. To account for the low-level deficits inherent in amblyopia, we measured individual contrast and crowding thresholds and monitored eye movements. The display elements were then presented at suprathreshold levels to ensure that visibility was equalized across groups. There was no performance difference between groups on feature search, indicating that our experimental design controlled successfully for low-level amblyopia deficits. In contrast, during conjunction search, median reaction times and reaction time slopes were significantly larger in participants with amblyopia compared with controls. Amblyopia differentially affects performance on conjunction visual search, a more difficult task that requires feature binding and possibly the involvement of higher-level attention processes. Deficits in visual search may affect day-to-day functioning in people with amblyopia.

  2. Next-Gen Search Engines

    Science.gov (United States)

    Gupta, Amardeep

    2005-01-01

    Current search engines--even the constantly surprising Google--seem unable to leap the next big barrier in search: the trillions of bytes of dynamically generated data created by individual web sites around the world, or what some researchers call the "deep web." The challenge now is not information overload, but information overlook.…

  3. Personalization in professional academic search

    NARCIS (Netherlands)

    Verberne, S.; Sappelli, M.; Sørensen, D.R.; Kraaij, W.

    2013-01-01

    In this paper, we investigated how academic search can profit from personalization by incorporating query history and background knowledge in the ranking of the results. We implemented both techniques in a language modelling framework, using the Indri search engine. For our experiments, we used the

  4. Tanzania Medical Journal: Advanced Search

    African Journals Online (AJOL)

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  5. Kioo cha Lugha: Advanced Search

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  6. Zimbabwe Veterinary Journal: Advanced Search

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  7. Nigerian Music Review: Advanced Search

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  8. Semantic Search of Web Services

    Science.gov (United States)

    Hao, Ke

    2013-01-01

    This dissertation addresses semantic search of Web services using natural language processing. We first survey various existing approaches, focusing on the fact that the expensive costs of current semantic annotation frameworks result in limited use of semantic search for large scale applications. We then propose a vector space model based service…

  9. Tanzania Dental Journal: Advanced Search

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  10. Continuing Medical Education: Advanced Search

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  11. Ghana Mining Journal: Advanced Search

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  12. Thought and Practice: Advanced Search

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  13. Search Our Site With Google

    African Journals Online (AJOL)

    Search Our Site With Google. Journal Home > Search Our Site With Google. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

  14. Law, Democracy & Development: Advanced Search

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  15. African Research Review: Advanced Search

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  16. Open Veterinary Journal: Advanced Search

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  17. Searches for supersymmetry at CMS

    Energy Technology Data Exchange (ETDEWEB)

    Collaboration: F. Giordano on behalf of the CMS Collaboration

    2017-11-15

    Among the most promising prospects for a theory of physics beyond the standard model is supersymmetry. In this talk, the latest results from the CMS experiment at the LHC on searches for supersymmetry produced through strong production and electroweak production channels are presented using 20/fb of data from the 8 TeV LHC run, with particular focus on gluino and stop searches.

  18. Perspectives in Education: Advanced Search

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  19. Discovery and Innovation: Advanced Search

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  20. Tropical Freshwater Biology: Advanced Search

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  1. Nigerian Medical Journal: Advanced Search

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  2. Tanzania Veterinary Journal: Advanced Search

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  3. Nigeria Agricultural Journal: Advanced Search

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  4. Evaluating aggregated search using interleaving

    NARCIS (Netherlands)

    Chuklin, A.; Schuth, A.; Hofmann, K.; Serdyukov, P.; de Rijke, M.

    2013-01-01

    A result page of a modern web search engine is often much more complicated than a simple list of "ten blue links." In particular, a search engine may combine results from different sources (e.g., Web, News, and Images), and display these as grouped results to provide a better user experience. Such a

  5. XML and Better Web Searching.

    Science.gov (United States)

    Jackson, Joe; Gilstrap, Donald L.

    1999-01-01

    Addresses the implications of the new Web metalanguage XML for searching on the World Wide Web and considers the future of XML on the Web. Compared to HTML, XML is more concerned with structure of data than documents, and these data structures should prove conducive to precise, context rich searching. (Author/LRW)

  6. Nigerian Dental Journal: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  7. Madagascar Conservation & Development: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  8. ChemSearch Journal: Submissions

    African Journals Online (AJOL)

    AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING ... SCOPE: ChemSearch Journal is a peer-reviewed journal that publishes ... Authors whose papers have been accepted for publication will be notified in writing. ... The literature cited must be discussed to show the relationships between the ...

  9. Nigerian Medical Practitioner: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  10. Gender and Behaviour: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  11. Humanities Review Journal: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  12. Searching for What I Want

    DEFF Research Database (Denmark)

    Liu, Fei; Xiao, Bo Sophia; Lim, Eric

    2016-01-01

    Inefficiencies associated with online information search are amplifying in the current era of big data. Despite growing scholarly interest in studying Internet users’ information search behaviour, there is a paucity of theory-guided investigation in this regard. In this paper, we draw on the theory...

  13. Searching Algorithm Using Bayesian Updates

    Science.gov (United States)

    Caudle, Kyle

    2010-01-01

    In late October 1967, the USS Scorpion was lost at sea, somewhere between the Azores and Norfolk Virginia. Dr. Craven of the U.S. Navy's Special Projects Division is credited with using Bayesian Search Theory to locate the submarine. Bayesian Search Theory is a straightforward and interesting application of Bayes' theorem which involves searching…

  14. Ghana Library Journal: Advanced Search

    African Journals Online (AJOL)

    Search tips: Search terms are case-insensitive; Common words are ignored; By default only articles containing all terms in the query are returned (i.e., AND is implied); Combine multiple words with OR to find articles containing either term; e.g., education OR research; Use parentheses to create more complex queries; e.g., ...

  15. Diversity, intent, and aggregated search

    NARCIS (Netherlands)

    de Rijke, M.

    2014-01-01

    Diversity, intent and aggregated search are three core retrieval concepts that receive significant attention. In search result diversification one typically considers the relevance of a document in light of other retrieved documents. The goal is to identify the probable "aspects" of an ambiguous

  16. Searching for Roots / Pierre Gervasoni

    Index Scriptorium Estoniae

    Gervasoni, Pierre

    1997-01-01

    Uuest heliplaadist "Searching for Roots. Eduard Tubin: Symphonie no 11; Arvo Pärt: Nekrolog-Symphonie no 1; Erkki-Sven Tüür: Searching for Roots - Insula deserta - Zeitraum; Orchestre philharmonique royal de Stockholm, Paavo Järvi (direction)" Virgin Classics 5 45212 2 (distribue par EMI)

  17. Search for unstable photinos

    International Nuclear Information System (INIS)

    Mayer, P.

    1987-04-01

    We have searched in e + e - -annihilation for the photino, the partner of the photon, which is predicted by supersymmetry. Photinos can be pair produced in e + e - annihilation by the exchange of a scalar electron, the partner of the electron. It was assumed that the photino is unstable and decays in a photon and a lighter supersymmetric particle. This second particle leaves the detector unobserved. In the final state one sees then two photons with missing energy and missing momentum. The data were taken with the detector CELLO at the e + e - storage ring PETRA at DESY, Hamburg. The CMS energy was between 38.3 GeV and 46.8 GeV, the total luminosity was 38.3 pb -1 . The liquid argon lead calorimeter of CELLO, the most important part for this analysis, is specialised for the measurement of electromagnetic showers. It has a good space resolution and covers 96% of the solid angle of 4π. We have selected events with 2 photons in the central calorimeter, both with an energy of more than 2 GeV. The high background due to cosmic showers was reduced by accepting only events which were correlated to the time of the e + e - annihilation. Also the direction of the showers had to point to the interaction point. The applied cuts accepted the expected events with a probability P≅0.3. No event was found which was compatible with the production of unstable photinos. One can give limits on the mass of the photino, which depend on the mass of the scalar electron and on the decay path of the photino. In the simplest case, if all photinos decay at the interaction point, photinos with masses below 21 GeV are excluded (with a mass of the scalar electron below 40 GeV). (orig.) [de

  18. Searching for Suicide Information on Web Search Engines in Chinese

    Directory of Open Access Journals (Sweden)

    Yen-Feng Lee

    2017-01-01

    Full Text Available Introduction: Recently, suicide prevention has been an important public health issue. However, with the growing access to information in cyberspace, the harmful information is easily accessible online. To investigate the accessibility of potentially harmful suicide-related information on the internet, we discuss the following issue about searching suicide information on the internet to draw attention to it. Methods: We use five search engines (Google, Yahoo, Bing, Yam, and Sina and four suicide-related search queries (suicide, how to suicide, suicide methods, and want to die in traditional Chinese in April 2016. We classified the first thirty linkages of the search results on each search engine by a psychiatric doctor into suicide prevention, pro-suicide, neutral, unrelated to suicide, or error websites. Results: Among the total 352 unique websites generated, the suicide prevention websites were the most frequent among the search results (37.8%, followed by websites unrelated to suicide (25.9% and neutral websites (23.0%. However, pro-suicide websites were still easily accessible (9.7%. Besides, compared with the USA and China, the search engine originating in Taiwan had the lowest accessibility to pro-suicide information. The results of ANOVA showed a significant difference between the groups, F = 8.772, P < 0.001. Conclusions: This study results suggest a need for further restrictions and regulations of pro-suicide information on the internet. Providing more supportive information online may be an effective plan for suicidal prevention.

  19. Evidence-based Medicine Search: a customizable federated search engine.

    Science.gov (United States)

    Bracke, Paul J; Howse, David K; Keim, Samuel M

    2008-04-01

    This paper reports on the development of a tool by the Arizona Health Sciences Library (AHSL) for searching clinical evidence that can be customized for different user groups. The AHSL provides services to the University of Arizona's (UA's) health sciences programs and to the University Medical Center. Librarians at AHSL collaborated with UA College of Medicine faculty to create an innovative search engine, Evidence-based Medicine (EBM) Search, that provides users with a simple search interface to EBM resources and presents results organized according to an evidence pyramid. EBM Search was developed with a web-based configuration component that allows the tool to be customized for different specialties. Informal and anecdotal feedback from physicians indicates that EBM Search is a useful tool with potential in teaching evidence-based decision making. While formal evaluation is still being planned, a tool such as EBM Search, which can be configured for specific user populations, may help lower barriers to information resources in an academic health sciences center.

  20. Hybrid keyword search auctions

    KAUST Repository

    Goel, Ashish; Munagala, Kamesh

    2009-01-01

    Search auctions have become a dominant source of revenue generation on the Internet. Such auctions have typically used per-click bidding and pricing. We propose the use of hybrid auctions where an advertiser can make a per-impression as well as a per-click bid, and the auctioneer then chooses one of the two as the pricing mechanism. We assume that the advertiser and the auctioneer both have separate beliefs (called priors) on the click-probability of an advertisement. We first prove that the hybrid auction is truthful, assuming that the advertisers are risk-neutral. We then show that this auction is superior to the existing per-click auction in multiple ways: 1. We show that risk-seeking advertisers will choose only a per-impression bid whereas risk-averse advertisers will choose only a per-click bid, and argue that both kind of advertisers arise naturally. Hence, the ability to bid in a hybrid fashion is important to account for the risk characteristics of the advertisers. 2. For obscure keywords, the auctioneer is unlikely to have a very sharp prior on the click-probabilities. In such situations, we show that having the extra information from the advertisers in the form of a per-impression bid can result in significantly higher revenue. 3. An advertiser who believes that its click-probability is much higher than the auctioneer's estimate can use per-impression bids to correct the auctioneer's prior without incurring any extra cost. 4. The hybrid auction can allow the advertiser and auctioneer to implement complex dynamic programming strategies to deal with the uncertainty in the click-probability using the same basic auction. The per-click and per-impression bidding schemes can only be used to implement two extreme cases of these strategies. As Internet commerce matures, we need more sophisticated pricing models to exploit all the information held by each of the participants. We believe that hybrid auctions could be an important step in this direction. The hybrid