158 research outputs found
Direct Dark Matter Searches with CDMS and XENON
The Cryogenic Dark Matter Search (CDMS) and XENON experiments aim to directly
detect dark matter in the form of weakly interacting massive particles (WIMPs)
via their elastic scattering on the target nuclei. The experiments use
different techniques to suppress background event rates to the minimum, and at
the same time, to achieve a high WIMP detection rate. The operation of
cryogenic Ge and Si crystals of the CDMS-II experiment in the Soudan mine
yielded the most stringent spin-independent WIMP-nucleon cross-section
(~10^{-43} cm^2) at a WIMP mass of 60 GeV/c^2. The two-phase xenon detector of
the XENON10 experiment is currently taking data in the Gran Sasso underground
lab and promising preliminary results were recently reported. Both experiments
are expected to increase their WIMP sensitivity by a one order of magnitude in
the scheduled science runs for 2007.Comment: appears in the proceedings of the 36th COSPAR Scientific Assembly in
Beijing, July 200
The neutron background of the XENON100 dark matter experiment
TheXENON100 experiment, installed underground at the LaboratoriNazionali del Gran Sasso, aims to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering off xenon nuclei. This paper presents a study on the nuclear recoil background of the experiment, taking into account neutron backgrounds from (alpha, n) reactions and spontaneous fission due to natural radioactivity in the detector and shield materials, as well as muon-induced neutrons. Based on MonteCarlo simulations and using measured radioactive contaminations of all detector components, we predict the nuclear recoil backgrounds for the WIMP search results published by theXENON100 experiment in 2011 and 2012, 0.11(-0.04)(+0.08) events and 0.17(-0.07)(+0.12) events, respectively, and conclude that they do not limit the sensitivity of the experiment
ArDM: a ton-scale liquid Argon experiment for direct detection of Dark Matter in the Universe
The ArDM project aims at developing and operating large noble liquid
detectors to search for direct evidence of Weakly Interacting Massive Particle
(WIMP) as Dark Matter in the Universe. The initial goal is to design, assemble
and operate a 1 ton liquid Argon prototype to demonstrate the
feasibility of a ton-scale experiment with the required performance to
efficiently detect and sufficiently discriminate backgrounds for a successful
WIMP detection. Our design addresses the possibility to detect independently
ionization and scintillation signals. In this paper, we describe this goal and
the conceptual design of the detector.Comment: 5 pages, 3 figures, Talk given at IXth international conference on
Topics in Astroparticle and Underground Physics (TAUP05), Zaragoza, (Spain
222Rn emanation measurements for the XENON1T experiment
The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the 222Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a 222Rn activity concentration of 10μBq/kg in 3.2t of xenon. The knowledge of the distribution of the 222Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the 222Rn activity concentration in XENON1T. The final 222Rn activity concentration of (4.5±0.1)μBq/kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment
Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T
We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3×10−42  cm2 at 30  GeV/c2 and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator
Gamma Ray Spectroscopy with Scintillation Light in Liquid Xenon
Scintillation light from gamma ray irradiation in liquid xenon is detected by
two Hamamatsu R9288 photomultiplier tubes (PMTs) immersed in the liquid. UV
light reflector material, PTFE, is used to optimize the light collection
efficiency. The detector gives a high light yield of 6 photoelectron per keV
(pe/keV), which allows efficient detection of the 122 keV gamma-ray line from
Co-57, with a measured energy resolution of (8.8+/-0.6)% (sigma). The best
achievable energy resolution, by removing the instrumental fluctuations, from
liquid xenon scintillation light is estimated to be around 6-8% (sigma) for
gamma-ray with energy between 662 keV and 122 keV
Sneutrino cold dark matter, a new analysis: relic abundance and detection rates
We perform a new and updated analysis of sneutrinos as dark matter
candidates, in different classes of supersymmetric models. We extend previous
analyses by studying sneutrino phenomenology for full variations of the
supersymmetric parameters which define the various models. We first revisit the
standard Minimal Supersymmetric Standard Model, concluding that sneutrinos are
marginally compatible with existing experimental bounds, including direct
detection, provided they compose a subdominant component of dark matter. We
then study supersymmetric models with the inclusion of right-handed fields and
lepton-number violating terms. Simple versions of the lepton-number-violating
models do not lead to phenomenology different from the standard case when the
neutrino mass bounds are properly included. On the contrary, models with
right-handed fields are perfectly viable: they predict sneutrinos which are
compatible with the current direct detection sensitivities, both as subdominant
and dominant dark matter components. We also study the indirect detection
signals for such successful models: predictions for antiproton, antideuteron
and gamma-ray fluxes are provided and compared with existing and future
experimental sensitivities. The neutrino flux from the center of the Earth is
also analyzed.Comment: 72 pages, 50 figures. The version on the archive has low-resolution
figures. The paper with high resolution figures may be found through
http://www.to.infn.it/~arina/papers or
http://www.to.infn.it/~fornengo/Research/paperlist.htm
Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 Data
We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 yr, from January 2010 to January 2014. A profile likelihood method, which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events. There is a weak modulation signature at a period of day in the low energy region of (2.0–5.8) keV in the single scatter event sample, with a global significance of 1.9; however, no other more significant modulation is observed. The significance of an annual modulation signature drops from 2.8, from a previous analysis of a subset of this data, to 1.8 with all data combined. Single scatter events in the low energy region are thus used to exclude the DAMA/LIBRA annual modulation as being due to dark matter electron interactions via axial vector coupling at 5.7
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