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Agenda
for the parallel workshop sessions in Dark Matter – Candidates and Searches.
All links marked with a⇓ can be used to show/hide the abstracts and presentations.
Click here to show/hide all presentations and abstracts and here for a print version.
You may also download the compact program booklet (PDF, 1.9 MB)
and an abstract booklet (PDF, 0.4 MB).
As long as authors provided us with PDF versions of their slides, the corresponding downloads are available on this page.
Monday – Sep 5, 2011
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14:30 – 16:10 |
Dark Matter W1 – Searches with neutrinos and gamma rays
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Parallel Session (Festsaal) – Chair:
Pasquale Serpico
14:30
(15' + 5')
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Conservative upper limits on WIMP annihilation cross section from Fermi-LAT γ-rays⇓
slides
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Fiorenza Donato (Torino University)
The spectrum of an isotropic extragalactic gamma-ray background (EGB) has been measured by the Fermi-LAT telescope at high latitudes. Two new models for the EGB are derived from the subtraction of unresolved point sources and extragalactic diffuse processes, which could explain from 30% to 70% of the Fermi-LAT EGB. Within the hypothesis that the two residual EGBs are entirely due to the annihilation of dark matter (DM) particles in the Galactic halo, we obtain stringent upper limits on their annihilation cross section. Severe bounds on a possible Sommerfeld enhancement are set as well. Finally, we consider models for DM annihilation depending on the inverse of the velocity and associate the EGBs to photons arising from the annihilation of DM in primordial halos.
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14:50
(15' + 5')
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Spectral cutoffs in indirect dark matter searches⇓
slides
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Christoph Weniger (Max-Planck-Institut für Physik, München)
Indirect searches for dark matter annihilation or decay products in the cosmic-ray spectrum are plagued by the question of how to disentangle a dark matter signal from the omnipresent astrophysical background. One of the practically background-free `smoking gun' signatures for dark matter would be the observation of a sharp cutoff in the gamma-ray energy spectrum. Such a feature is generically produced in many dark matter models by internal Bremsstrahlung, and it can be treated in a similar manner as the traditionally looked-for gamma-ray lines. In this talk, we will discuss prospects for seeing such features with present and future gamma-ray telescopes. We will concentrate on Air Cherenkov Telescopes and comment on the Fermi LAT.
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15:10
(15' + 5')
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Determining WIMP properties with neutrinos in IceCube/DeepCore⇓
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Chitta Ranjan Das (Centro de Física Teórica de Partículas)
Cosmological and astrophysical observations provide increasing evidence of the existence of dark matter in our Universe. One of the favored candidates is a weakly interacting massive particle (WIMP). WIMP particles can be captured by the Sun, accumulate in the core, annihilate, and produce high energy neutrinos either directly or by subsequent decays of SM particles. These neutrinos can be a striking dark matter signature in IceCube/DeepCore neutrino telescope. We investigate the prospects for indirect WIMP dark matter detection in IceCube/DeepCore and its capabilities to determine some dark matter properties, as mass, cross section and the branching ratios of the various annihilation channels.
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15:30
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Downward going tau neutrinos and dark matter⇓
slides
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Viviana Niro (University of Torino and INFN/Torino)
We discuss the possibility of detecting Dark Matter using the
downward going tau neutrinos in Cherenkov detectors.
We include in our analysis the problem of misidentified muons
and electrons and show how this technical limitation influences
the Dark Matter discovery potential with downward going tau neutrinos.
Considering different Dark Matter masses and annihilation
channels, we calculate the limits on the Dark Matter flux from the Sun
that could be set by future Cherenkov detectors with specific
detection efficiencies.
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15:50
(15' + 5')
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Indirect searches for gravitino dark matter⇓
slides
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Michael Grefe (DESY)
The gravitino in models with a small R-parity violation is a well-motivated dark matter candidate that is leading to a cosmological scenario consistent with big bang nucleosynthesis and thermal leptogenesis. Its lifetime is sufficiently long since its decays are suppressed by the Planck-scale as well as the small R-parity violating parameter. We want to discuss the signals in different cosmic ray species coming from the decay of gravitino dark matter, namely gamma rays, positrons, antiprotons, antideuterons and neutrinos. Comparison to cosmic ray data can be used to constrain the parameters of the model and to predict fluxes for other cosmic ray channels.
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16:50 – 18:30 |
Dark Matter W2 – Directional and indirect + 0νbb experiments
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Parallel Session (Festsaal) – Chair:
Elisa Resconi
16:50
(12' + 3')
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Searches for dark matter with the IceCube detector⇓
slides
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Matthias Danninger (Stockholm University)
Construction of the IceCube neutrino observatory was recently completed, including the full DeepCore sub-array, a low-energy extension of the IceCube neutrino observatory.
We present recent results from the searches of dark matter candidates with IceCube, performed with the 22-and 40-string configurations using the Sun and the Galactic Center and Halo as possible dark matter sources.
We also report on the search for dark matter annihilations with the IceCube neutrino detector in the 79-string configuration. Furthermore, a formalism for quickly and directly comparing event-level IceCube data with arbitrary annihilation spectra in detailed model scans is presented. We show an application of this formalism to both model exclusion and parameter estimation in models of supersymmetry.
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17:05
(12' + 3')
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Indirect search for dark matter with the ANTARES neutrino telescope⇓
slides
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Vincent Bertin (CPPM)
The ANTARES Collaboration is operating the largest water Cherenkov neutrino telescope in the Northern hemisphere installed in the Mediterranean Sea offshore France. One major goal of ANTARES is the search for neutrinos produced in self-annihilation of Dark Matter particles, for instance in the direction of the Sun or the Galactic Centre.
First results on the search for Dark Matter annihilations in the Sun with the data recorded in 2007 and 2008 are presented, as well as sensitivity studies on Dark Matter searches with the full ANTARES detector and the future large undersea cubic-kilometre neutrino telescope studied by the KM3NeT consortium. A comparison with respect to predictions on neutrino fluxes from Dark Matter annihilations in the framework of CMSSM and UED models will be presented.
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17:20
(12' + 3')
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Recent progress from the DMTPC directional dark matter search⇓
slides
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Asher Kaboth (MIT)
The DMTPC directional dark matter detection experiment is a low-pressure CF4 gas time projection chamber, instrumented with charge and scintillation photon readout. This detector design strategy emphasizes reconstruction of WIMP-induced nuclear recoil tracks, in order to determine the direction of incident dark matter particles. Directional detection has the potential to make a definitive observation of dark matter using the unique angular signature of the dark matter wind, which is distinct from all known backgrounds. This talk will review the experimental technique and current status of DMTPC.
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17:35
(12' + 3')
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NEWAGE—direction-sensitive dark matter search experiment⇓
slides
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Kiseki Nakamura (Kyoto University)
NEWAGE is a direction-sensitive WIMP(weakly interacting massive particle) search experiment using a gaseous detector. Our 3-dimensional tracking device is based on a micro-patterned gaseous detector(MPGD). After our first underground measurement at Kamioka (PLB686(2010)11), we made several detector updates to improve the sensitivities.
One of the main improvements was lowering the energy threshold by decreasing the gas pressure. Energy threshold of a direction-sensitive gaseous detector is limited by the track length. With lower pressure gas, track length will be longer and energy threshold will be lower. We optimized the detector operation with CF4 gas at 76 torr, which is one half of the previous pressure. We report on the detector performance and the result of underground measurements.
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17:50
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Directional detection of dark matter with MIMAC⇓
slides
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Julien Billard (LPSC Grenoble)
Directional detection of galactic Dark Matter is a promising search strategy to identify genuine WIMP events amongst background ones. Indeed, using a dedicated statistical analysis, data of forthcoming directional detectors could lead either to a competitive exclusion or to a conclusive discovery, depending on the value of the WIMP-nucleon cross section. Constraints on both the WIMP properties and the WIMP velocity distribution may also be deduced. MIMAC is a project of directional detection of Dark Matter using a matrix of micro-tpc chambers with a 3D reconstruction of recoil tracks thanks to the use of pixelized micromegas.
I will then present several aspects of the MIMAC project: phenomenological studies, 3D track reconstruction analysis and some experimental results.
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18:05
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Dark matter sensitivities of the MAJORANA DEMONSTRATOR⇓
slides
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Graham Giovanetti (UNC-Chapel Hill, TUNL)
The MAJORANA DEMONSTRATOR is an array of natural and enriched high purity germanium detectors that will search for the neutrinoless double-beta decay of Germanium-76 and perform a search for WIMPs with masses below 10 GeV. To achieve a background rate in the neutrinoless double-beta decay region of interest of 1 count/keV/t/y, the DEMONSTRATOR utilizes a number of background reduction strategies, including a time-correlated event cut for 68Ge that requires a sub-keV energy threshold. This low energy threshold allows the DEMONSTRATOR to extend its physics reach to include a search for light WIMPs. I will discuss the detector systems and data analysis techniques required to achieve sub-keV thresholds as well as present the projected dark matter sensitivities of the MAJORANA DEMONSTRATOR.
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Tuesday – Sep 6, 2011
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14:30 – 16:10 |
Dark Matter W3 – Direct Detection and light WIMPs
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Parallel Session (Festsaal) – Chair:
Klaus Eitel
14:30
(12' + 3')
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CoGeNT-4: Prospects for an expanded search for light-mass WIMPs⇓
slides
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John Orrell (Pacific Northwest National Laboratory)
The CoGeNT experiment located at the Soudan Underground Laboratory has reported an excess of events below an electron scattering equivalent of 1 keV. This result may be interpreted alternatively as either an unidentified background contribution or a signature of light-mass (5-10 GeV/c2) weakly interacting massive particle (WIMP) dark matter. The initial CoGeNT results were produced using a single 440 gram high-purity germanium radiation detector operated at liquid nitrogen temperature. To further test these unexpected results, an expanded CoGeNT-4 experimental design is under development. The shield design concept is presented and the science impact of a four-detector experiment is explored.
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14:45
(12' + 3')
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Construction and commissioning of the China Jinping underground laboratory and the CDEX-TEXONO experiment⇓
slides
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Henry Wong (Academia Sinica)
Tsinghua University collaborating with the Ertan Hydropower Development Company of China began construction of the China Jinping Underground Laboratory (CJPL) in July 2009. CJPL is located in a traffic tunnel with about 2400 m of rock overburden and low ambient radioactivity background. CJPL was inaugurated on Dec. 12, 2010. The Phase-I laboratory has about 4000 m3 of space. As the first experiment project, the CDEX-TEXONO collaboration will perform a direct dark matter search with sub-keV PCGe detector array, starting from kg-scale experiment with projected upgrades to ton-scale target in the future. Two detectors with 20-g and 1000-g target mass are currently data taking at CJPL. The status and latest results will be presented.
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15:00
(12' + 3')
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An ionisation-only analysis of XENON10 data⇓
slides
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Peter Sorensen (Lawrence Livermore National Laboratory)
I will discuss a novel analysis technique applicable to liquid xenon detectors, in which only the ionisation signal is used. Despite the resulting loss of incident particle type discrimination, the results obtained from application to 12.5 live days of dark matter search obtained by the XENON10 experiment explores interesting regions of parameter space. The motivation for the technique is an increased sensitivity to light mass WIMPs, and the XENON10 result offers the best sensitivity in the 5-10 GeV particle mass range. The technique is expected to be applicable to larger xenon detectors such as XENON100 and LUX, with a commensurate increase in sensitivity.
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15:15
(12' + 3')
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Likelihood approach to XENON dark matter results⇓
slides
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Eilam Gross (Weizmann Institute of Science)
Many experiments that aim at the direct detection of Dark Matter are able to distinguish a dominant background from the expected feeble signals, based on some measured discrimination parameter. We develop a statistical model for such experiments using the Profile Likelihood ratio as a test statistic in a frequentist approach. We take data from calibrations as control measurements for signal and background. Systematic detector uncertainties, such as uncertainties in the energy scale, as well as astrophysical uncertainties, are included in the model. The statistical model can be used to either set an exclusion limit or to make a discovery claim, and the results are derived with a proper treatment of statistical and systematic uncertainties. We apply the model to the XENON100 experiment.
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15:30
(12' + 3')
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Bayes and present dark matter direct search status⇓
slides
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Chiara Arina (RWTH Aachen)
Recently there has been a huge activity in the dark matter direct detection field, with the report of an excess from CoGeNT
and Cresst, the two events in the CDMS-II along with the annual modulated signal of DAMA/Libra and the strong exclusion bound
from Xenon100. We analyse these results within the framework of bayesian inference. Indeed bayesian methods are well suited for marginalizing over the experimental systematics and the background. We present the result for
spin-independent interaction on nucleus with particular attention to the low dark matter mass region and the compatibility between experiments. In the same vein we also investigate the impact of astrophysical uncertainties on the WIMP preferred parameter space within the class of isotropic dark matter velocity distribution.
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15:45
(12' + 3')
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Light neutralino dark matter⇓
slides
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Nicolao Fornengo (University of Torino and INFN/Torino)
We examine the status of light neutralinos in an effective MSSM at the electroweak scale. We discuss these models in the light of dark matter direct detection and show that they fit quite well the DAMA/LIBRA annual modulation data, together with the preliminary results of CDMS, CoGeNT and CRESST, should these data, which hint at excesses of events over the expected backgrounds, be interpreted as authentic signals of dark matter. The analysis is implemented by the new measurements at the Tevatron, B-factories and LHC which might potentially provide significant constraints on the MSSM model. We examine in detail all these new data and show that the neutralino mass has a lower bound of 7-8 GeV, with interesting correlations with the other parameters of the model.
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16:50 – 18:30 |
Dark Matter W4 – Searches with charged cosmic rays
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Parallel Session (Festsaal) – Chair:
Dieter Horns
16:50
(15' + 5')
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Combined LEP/Tevatron/XENON100 analysis to determine the nature of DM⇓
slides
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Yann Mambrini (LPT Orsay, Universite Paris XI)
We will present how one can exclude light leptophylic (hadrophobic) and heavy hadrophylic (leptophobic) dark matter by combining the recent Tevatron/LEP and XENON analysis.
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17:10
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Discriminating dark matter in cosmic rays: The role of electron dipole anisotropy⇓
slides
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Enrico Borriello (DESY & University of Naples)
Indirect searches of particle Dark Matter (DM) with high energy Cosmic Rays (CR) are affected by large uncertainties, coming both from the DM side and from poor understanding of the astrophysical backgrounds. I will discuss such uncertainties in the light of the well known experimental data provided by PAMELA, Fermi and HESS.
I will also show that, on the contrary, the DM intrinsic degree of anisotropy in the arrival directions of high energy CR electrons and positrons does not suffer from these unknowns and can therefore be used as a tool to distinguish Dark Matter from astrophysical contributions to the electron and positron Cosmic Ray fluxes.
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17:30
(15' + 5')
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Galactic synchrotron emission from astrophysical electrons⇓
slides
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Roberto Alfredo Lineros Rodriguez (IFIC (U.Valencia/CSIC))
The interaction between the galactic magnetic field and the non-thermal population of electrons is responsible for a large part of the radio sky from 10 MHz up to several GHz. This population is mostly composed of electrons with primary and secondary origin. Cosmic ray propagation models describe their evolution in space and energy, and allow to study the impact on the radio sky in intensity and morphology at different frequencies. We consider different propagation models and test their compatibility with available radio maps. We find models highly consistent with B/C data, the local electron flux and synchrotron emission observations. The resulting constraints on propagation models would significantly improve indirect dark matter searches in these channels and in antiprotons.
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17:50
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Dark matter synchrotron emission and radio observations⇓
slides
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Marco Taoso (IFIC Valencia)
We compute the synchrotron emission induced by electrons produced by DM annihilations in galactic and extragalactic DM halos.
The signal is compared with observations in a large range of frequencies, ranging from tens of MHz up to few hundreds of GHz.
We set constraints on the DM mass and annihilation cross-section and highlight the impact of astrophysical uncertainties.
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18:10
(15' + 5')
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Antiproton constraints on light dark matter candidates⇓
slides
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Julien Lavalle (CNRS - LUPM)
I will discuss the cosmic-ray antiproton constraints on light dark matter candidates, showing that they can be very strong if dark matter annihilates into quarks or into singlet-like (pseudo-)scalar particles.
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Wednesday – Sep 7, 2011
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14:30 – 16:10 |
Dark Matter W5 – Direct Detection with bolometers
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Parallel Session (Festsaal) – Chair:
Laura Baudis
14:30
(12' + 3')
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Background discrimination in new iZIP detectors at SuperCDMS⇓
slides
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Silvia Scorza (Southern Methodist University)
The SuperCDMS is a direct dark matter search experiment in the Soudan Underground Laboratory (Minnesota, USA). Cryogenic germanium detectors are used to identify eventual rare nuclear recoils induced by elastic scattering of WIMPs from our Galactic halo.
The detectors measure phonon and ionization signals, simultaneously allowing an event by event discrimination between the electronic recoils, tracers of electromagnetic background, and the nuclear ones originated by neutrons and WIMPs.To further increase the discrimination background power, novel detectors with a special interleaved electrode scheme have been tested and installed. I will present the background rejection performances achieved, giving the resulting improvement in the sensitivity of the experiment for spin-independent WIMPs.
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14:45
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Backgrounds of the EDELWEISS-II dark matter experiment⇓
slides
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Pia Loaiza (Laboratoire Souterrain de Modane)
The EDELWEISS-II dark matter experiment searches for WIMP interactions using cryogenic germanium detectors.
The potential sources of background in the WIMP search region has been investigated using calibration data, measured background outside the nuclear-recoil band and Monte Carlo simulations. Three potential sources were considered: gamma-rays, surface events and neutron scattering. We present the studies leading to the background estimates for the WIMP search using a 4 kg array of Ge detectors with interleaved electrodes, with emphasis on surface events and gamma rays
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15:00
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Neutron background simulation for the CRESST-II experiment⇓
slides
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Stephan Scholl (Kepler Center for Astro and Particle Physics, Physikalisches Institut der Universität Tübingen)
Neutron induced nuclear recoils provide an important background for
all direct dark matter searches. If events are observed
experimentally in the region of interest (ROI), the question
arises if these can be explained by neutrons. The results of a GEANT4
simulation of the known neutron sources for the CRESST-II experiment
are presented in this work. Apart from the experimental total rate of
nuclear recoils, two independent checks with the predicted results
from the simulation are made: The multi-detector module approach of
the CRESST-II experiment allows the comparison of the observed
multiplicities of detector hit events to the simulated
ones. Additionally, the agreement of distribution of events in the
plane of deposited energy and lightyield to simulated results is
tested.
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15:15
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Scintillating bolometers for fast neutron spectroscopy in rare events searches⇓
slides
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Maria Martinez (IAS Orsay)
Neutrons are a relevant background in rare events physics. Detectors based on fast neutron-induced nuclear reactions are commonly used for fast neutron spectroscopy. In this subject, scintillating bolometers provide an excellent energy resolution and particle discrimination by the simultaneous measurement of the heat and emitted light. Our group has constructed several 6Li and 10B based massive scintillating bolometers (LiF, Li6Eu(BO3)3, Li6Gd(BO3)3), with energy resolutions ranging from 16 to 200 keV. First results of a 32 gr 6LiF scintillating bolometer enriched at 95% in 6Li operated at 20 mK are presented. The use of this material in a multi-target cryogenic dark matter experiment, like EURECA, would allow monitoring the neutron flux incident in the detector during the data-taking.
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15:30
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Dark matter search with 1t of cryogenic detectors: EURECA⇓
slides
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Gilles Gerbier (CEA Saclay - IRFU/SPP)
EURECA (European Underground Rare Event Calorimeter Array) is the European tonne-scale, cryogenic dark matter search project. It is based on cryogenic technology with powerful event type recognition through phonon-ionisation (EDELWEISS) and phonon-scintillation (CRESST/ROSEBUD) detection. The aim is to explore scalar cross sections down to the 10-46 cm2 region. A major advantage of EURECA is its multi-element dark matter target, a key component for WIMP identification. We report on the current status of the design of the experiment, its future prospects and the collaborative work with a similar project in the US led by the SuperCDMS collaboration.
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15:45
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Measurements of neutron fluxes in the LSM underground laboratory⇓
slides
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Klaus Eitel (Karlsruhe Institute of Technology (KIT))
Neutron background is a prime factor potentially limiting the sensitivity of rare event searches, especially Dark Matter experiments. The neutron flux in an underground lab such as LSM at 4800mwe overburden can be separated into ambient neutrons from (α,n) reactions and rare but energetic muon-induced neutrons where data on neutron yields are scarce. We report on recent measurements of fast, thermal and muon-induced neutrons performed in LSM with various detection systems (He-3, Gd-loaded scint.), on the reliability of modelling mu-induced neutrons and implications for existing and the planned DM searches.
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16:50 – 18:35 |
Dark Matter W6 – Direct Detection: Bubbles, NaI and CsI
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Parallel Session (Festsaal) – Chair:
Josef Jochum
16:50
(12' + 3')
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Recent results from the SIMPLE dark matter search⇓
slides
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Miguel Felizardo da Costa (Instituto Tecnológico e Nuclear)
We present the results of the recent Phase II SIMPLE search effort, comprising two stages each of ~14 kgd exposure of 15 Superheated Droplet Detectors with ~0.2 kg active mass and recoil energy threshold of 8 keV. In the second stage, the neutron shielding was increased to reduce the on-detector rate to ~0.25 evt/kgd. Combined with an improved nucleation efficiency and analysis of the detector pressure evolution during the measurements, the results yield improved results in the phase space of both spin -dependent and -independent WIMP interactions.
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17:05
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Searching for dark matter with COUPP⇓
slides
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Hugh Lippincott (Fermilab)
COUPP is an experimental campaign with the goal of detecting dark matter in the form of Weakly Interacting Massive Particles (WIMPs) using continuously sensitive bubble chambers, operated under mildly superheated conditions. Recoils of dark matter particles off the target nuclei in the chamber would produce single, isolated bubbles, which are detectable both optically and acoustically. Under normal operating conditions, the detector has an energy threshold for nuclear recoils of approximately 10 keV but is insensitive to electron recoils, which typically constitute the background in dark matter searches. Nuclear recoils can be discriminated from alpha decays in the target liquid with the acoustic signal produced by the bubbles, which show excess power at high frequencies for alpha events.
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17:20
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Spin-dependent dark matter searches with PICASSO⇓
slides
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Viktor Zacek (Université de Montréal)
PICASSO at SNOLAB searches for spin-dependent WIMP interactions on 19-F using the superheated droplet technique. This technique is based on the bubble chamber principle, where phase transitions in superheated liquids can be triggered by WIMP induced nuclear recoils. The physics of the detection process allows a highly efficient suppression of backgrounds from cosmic muons, gamma- and beta-rays. In this talk we will discuss recent progress in PICASSO and its present sensitivity for spin-dependent WIMP searches. We will also describe an important new background suppression mechanism, which allows also a powerful discrimination of alpha particle induced events. Finally we will discuss future, larger scale applications of this technique at the scale of 100 kg and more.
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17:35
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Recent result from KIMS⇓
slides
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Sun Kee Kim (Seoul National University)
The KIMS collaboration has carried out an experimental search for Weakly Interacting Massive Parricle using CsI(Tl) crystal detectors at Yangyang underground laboratory. We present recent KIMS result with 100 kg CsI(Tl) crystal array.
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17:50
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Update on the ANAIS experiment and first results at the new Canfranc Underground Laboratory Facilities with the ANAIS-0 prototype.⇓
slides
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Clara Cuesta (University of Zaragoza)
ANAIS (Annual modulation with NaI Scintillators) is a project aiming to set up, at the new facilities of the Canfranc Underground Laboratory a large scale NaI(Tl) experiment to explore the DAMA/LIBRA annual modulation positive result using the same target and technique. For this purpose, new ultrapure NaI(Tl) detectors are being developed: NaI powder is being purified in order to reduce K-40 bulk content and Ultra Low Background photomultipliers are being tested. In the meanwhile, a 9.6 kg NaI(Tl) crystal (ANAIS 0 prototype) has been installed at the new LSC facilities. The background model at low and high energy for this prototype will be presented and compared to the available experimental data. Different event populations contributing to the low energy spectrum will be analysed.
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18:05
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DM-Ice: A direct detection experiment for dark matter at the South Pole⇓
slides
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Reina Maruyama (University of Wisconsin)
DM-Ice, a direct detection dark matter experiment to be deployed at the South Pole, will be described. This experiment will use roughly 250 kg of low-background NaI detectors to search for the DAMA/LIBRA annual modulation in the southern hemisphere where many of the environmental backgrounds associated with seasonal variations present in experiments in the northern hemisphere are either reversed in phase or absent altogether. A 15-kg prototype was deployed in December 2010 at the South Pole at the depth of ~2200 m.w.e. as a feasibility study: it is now taking data. I will report on the status of the prototype and the plans for the full-scale experiment.
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18:20
(12' + 3')
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Technical aspects in dark matter investigations⇓
slides
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Riccardo Cerulli (INFN-LNGS)
Some technical aspects in Dark Matter investigations will
be discussed both on the experimental and the theoretical sides.
Some implications will be presented.
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Thursday – Sep 8, 2011
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14:30 – 16:10 |
Dark Matter W7 – Model building; Collider searches
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Parallel Session (Festsaal) – Chair:
Nicolao Fornengo
14:30
(15' + 5')
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Electroweak lights from DM annihilations⇓
slides
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Andrea De Simone (EPFL)
The energy spectra of Standard Model particles originated from dark matter annihilations can be significantly altered by the inclusion of electroweak gauge boson radiation from the final state. A situation where this effect is particularly important is when a Majorana dark matter particle annihilates into two light fermions. This process is in p-wave and hence suppressed by the small value of the relative velocity of the annihilating particles. The inclusion of electroweak radiation eludes this suppression and opens up a potentially sizeable s-wave contribution to the annihilation cross section. I will describe this effect in detail and discuss its impact on the fluxes of stable particles resulting from the dark matter annihilations, which are relevant for dark matter indirect searches. I will also comment on the effective field theory approach, pointing out that the opening of the s-wave is missed at the level of dimension-six operators and only encoded by higher orders.
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14:50
(15' + 5')
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Light neutralino in the MSSM: A playground for dark matter, flavor physics and collider experiments⇓
slides
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Toshihiko Ota (Max-Planck-Institut für Physik)
We investigate the constraints to the light neutralino dark matter scenario in the minimal supersymmetric standard model from available experimental observations such as decays of B and K meson, relic dark matter abundance, and the search for neutralino and Higgs production at colliders. We find that two regions of the MSSM parameter space fulfill all the constraints: a fine-tuned strip with large tan beta where the lightest neutralino can be as light as 8 GeV, and a low tan beta region providing a neutralino mass larger than 16 GeV. The large tan beta strip, which can be compatible with recently reported signals from direct detection experiments, can be fully tested by some low-energy observables and Higgs bosons searches at the LHC within the upcoming months.
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15:10
(15' + 5')
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keV sterile neutrino dark matter and neutrino model building⇓
slides
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Alexander Merle (Royal Institute of Technology (KTH))
When thinking about dark matter, one always has the typical WIMP with a mass of a few 100 GeV in mind. In this talk, we will argue that another valid possibility is to have sterile neutrinos at the keV scale ("warm dark matter"), which can yield the correct dark matter abundance when, e.g., produced non-thermally. The crucial advantage of this framework is that we need some type of right-handed neutrino to explain neutrino masses, which suggests an interesting connection of the Dark Matter problem to particle physics model building. We will explain these connections and present the most interesting models on the market.
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15:30
(15' + 5')
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Direct detection of hot dark matter including light sterile neutrinos⇓
slides
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Zhi-zhong Xing (Institute of High Energy Physics)
The relic neutrinos of the big bang, whose masses lie in the sub-eV range, may constitute hot dark matter in the Universe. Although their temperature is extremely low today, they can be detected by means of the thresholdless reaction νe + 3H → 3He + e. If sub-eV sterile neutrinos exist, they can also leave a distinct imprint on the electron energy spectrum in this capture process. We examine possible signals of hot active and sterile neutrino dark matter against the corresponding beta-decay background. We also look at the possibility of capturing hot antineutrino dark matter on EC-decaying 163Ho nuclei in a calorimetric experiment. This kind of direct detection of hot dark matter might be feasible in the future.
Y. F. Li and Z. Z. Xing: Phys. Lett. B 692 (2010) 261; 698 (2011) 430
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15:50
(15' + 5')
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Accurate estimate of the relic density and the kinetic decoupling in non-thermal dark matter models⇓
slides
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Giorgio Arcadi (S.I.S.S.A)
We reconsider non thermal dark matter production mechanisms in a systematic way, focusing on scenarios with long-lived states decaying into DM. We analize the connection of these scenarios with anomalies in cosmic rays detected by Pamela and Fermi and then, concentrating on Supersymmetry, we study the impact of non-thermal production into LHC phenomenology. We finally examine a rather predictive model, the G2-MSSM, also relaxing some of the standard assumptions usually implemented in the solution of the Boltzamann equation for the dark matter component. As a byproduct we develop here a formalism to compute the kinetic decoupling temperature in case of coannihilating particles, which can be applied also to other particle physics frameworks, also within standard cosmological scenarios.
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16:50 – 18:35 |
Dark Matter W8 – Direct Detection: liquid noble gases
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Parallel Session (Festsaal) – Chair:
Jean-Côme Lanfranchi
16:50
(12' + 3')
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The XMASS 800kg experiment⇓
slides
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Jing Liu (Institute for the Physics and Mathematics of the Universe, University of Tokyo)
The XMASS 800kg detector, aiming primarily at direct dark matter search, is currently under commissioning at the Kamioka Underground Observatory, Japan. The construction and performance of the detector are briefly reviewed.
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17:05
(12' + 3')
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Dark matter search at SNOLAB with DEAP-3600⇓
slides
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Mark Boulay (Queen's University)
The DEAP-3600 experiment will search for dark matter particle interactions on liquid argon at SNOLAB, located 2 km underground in Sudbury, Canada. The detector is currently under construction, and will contain a 3600 kg liquid argon target in an acrylic sphere surrounded by photomultiplier tubes for detection of scintillation light, with a target sensitivity to spin-independent scattering on nucleons of 10^{-46} cm^2. Significant background reduction studies, including pulse-shape discrimination of beta/gamma events, and studies of radon and surface contamination reduction have been carried out with a prototype liquid argon detector at SNOLAB. The status of the experiment and of background reduction studies will be presented.
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17:20
(12' + 3')
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Status of the LUX dark matter search⇓
slides
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Carter Hall (University of Maryland)
At 350 kg of target material, the LUX experiment is expected to be one of the most sensitive dark matter searches ever performed. LUX is a dual-phase liquid xenon TPC, and it is designed to detect WIMP dark matter through its interactions with the atomic nuclei in the sensitive volume. Radioactive backgrounds are suppressed by passive and active shielding, by nuclear recoil discrimination, and by a careful materials screening program. LUX is currently being commissioned in a surface facility at the Sanford Lab in Lead, South Dakota (formerly the Homestake mine), and it is on track to be installed underground in December of 2011. We review here the construction of the detector, the current status of the commissioning operations, and the projected sensitivity and of the final experiment.
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17:35
(12' + 3')
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Recent progress from the MiniCLEAN dark matter experiment⇓
slides
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Jocelyn Monroe (MIT)
The MiniCLEAN dark matter direct detection experiment is a single-phase liquid argon detector, instrumented with photomultiplier tubes to observe scintillation light from a 150kg fiducial mass. This detector design strategy emphasizes scalability to target masses of order 10 tons or more. The projected light yield is >5 photo-electrons per keV, which allows pulse shape discrimination to separate the electron background from a WIMP-induced nuclear recoil signal. MiniCLEAN is also designed for a liquid neon target which, in the event of a positive signal in argon, will enable an independent verification of backgrounds and provide a unique test of the expected A2 dependence of the WIMP interaction rate. This talk will review the experimental technique and current status of MiniCLEAN.
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17:50
(12' + 3')
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Measurements of the low-energy response of liquid xenon⇓
slides
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Aaron Manalaysay (University of Zurich)
The field of dark matter detection has seen important contributions in recent years from experiments using liquid xenon. These searches usually focus on detecting an excess rate of nuclear recoils, as generic expectations about WIMP properties predict these as their dominant interaction mode. However, signals from electronic recoils can also be considered for an examination if one is to perform a fully model-independent search, as has been emphasized by the DAMA collaboration. Liquid xenon is expected to have sensitivity for electronic recoils down to sub-keV energies, but no calibration has been made for energies below 9.4keV. I present a recent calibration of a small liquid xenon chamber using low-angle Compton scatters at energies never before calibrated, and discuss results.
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18:05
(12' + 3')
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Study of nuclear recoils in liquid argon⇓
slides
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Christian Regenfus (University of Zürich/CERN)
In the framework of direct dark matter detection with cryogenic liquid argon targets we are setting up a neutron scattering experiment in our laboratory at CERN. Monoenergetic neutrons from dd-fusion are collimated onto a small liquid argon cell and tagged by organic scintillators. Presently the cell is operated in single-phase mode (zero electric field) to study scintillation yields of nuclear recoils as well as light pulse shapes. At a later stage we plan to add an electric field and to extract the ionisation charge (dual phase) to determine field and energy dependences in liquid argon of both, the light and the charge yields, at working points relevant for dark matter searches. The experimental setup and first results will be presented and discussed.
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18:20
(12' + 3')
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DARWIN: dark matter WIMP search with noble liquids⇓
slides
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Laura Baudis (University of Zurich)
DARWIN (DARk matter WImp search with Noble liquids) is a design study towards the realization of a ton to multi-ton scale dark matter facility in Europe, based on the liquid argon and liquid xenon time projection chamber technique. Approved by ASPERA in late 2009, DARWIN brings together several European and US groups working on the existing XENON, WARP and ArDM experiments with the goal of providing a technical design report for the realization of the facility in three years from now. I will present the status and goals of DARWIN, as well as initial results from R&D studies.
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