The use of argon as a detection and shielding medium for neutrino and dark matter experiments has made the precise knowledge of the cross section for neutron capture on argon an important design and ...operational parameter. Since previous measurements were averaged over thermal spectra and have significant disagreements, a differential measurement has been performed using a time-of-flight neutron beam and a ∼4π gamma spectrometer. A fit to the differential cross section from 0.015–0.15 eV, assuming a 1/v energy dependence, yields σ2200=673±26(stat)±59(sys) mb.
The XENON100 dark matter experiment Aprile, E.; Arisaka, K.; Arneodo, F. ...
Astroparticle physics,
April 2012, 2012-4-00, 20120401, Volume:
35, Issue:
9
Journal Article
Peer reviewed
Open access
► XENON100 is currently one of the most sensitive experiments to detect WIMP dark matter. ► Detector design and active/passive shielding reduce the radioactive background level. ► The event vertex of ...an interaction is reconstructed with a few mm precision. ► All position dependent signal corrections are presented in the paper. ► An energy scale exploiting the light-charge anti-correlation leads to an energy resolution competitive with NaI(Tl) crystals.
The XENON100 dark matter experiment uses liquid xenon (LXe) in a time projection chamber (TPC) to search for xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper we present a detailed description of the detector design and present performance results, as established during the commissioning phase and during the first science runs.
The active target of XENON100 contains 62kg of LXe, surrounded by an LXe veto of 99kg, both instrumented with photomultiplier tubes (PMTs) operating inside the liquid or in xenon gas. The LXe target and veto are contained in a low-radioactivity stainless steel vessel, embedded in a passive radiation shield and is installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. The experiment has recently published results from a 100 live-days dark matter search. The ultimate design goal of XENON100 is to achieve a spin-independent WIMP-nucleon scattering cross section sensitivity of σ=2×10−45cm2 for a 100GeV/c2 WIMP.
The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso in Italy, is designed to search for dark matter weakly interacting massive particles (WIMPs) scattering off 62 kg of ...liquid xenon in an ultralow background dual-phase time projection chamber. In this Letter, we present first dark matter results from the analysis of 11.17 live days of nonblind data, acquired in October and November 2009. In the selected fiducial target of 40 kg, and within the predefined signal region, we observe no events and hence exclude spin-independent WIMP-nucleon elastic scattering cross sections above 3.4 × 10⁻⁴⁴ cm² for 55 GeV/c² WIMPs at 90% confidence level. Below 20 GeV/c², this result constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.
Dark matter and double beta decay experiments require extremely low radioactivity within the detector materials. For this purpose, the University of California, Los Angeles and Hamamatsu Photonics ...have developed the QUartz Photon Intensifying Detector (Q
upid), an ultra-low background photodetector based on the Hybrid Avalanche Photo Diode (HAPD) and entirely made of ultraclean synthetic fused silica. In this work we present the basic concept of the Q
upid and the testing measurements on Q
upids from the first production line.
Screening of radioactivity at the Gator facility in the Laboratori Nazionali del Gran Sasso has shown that the Q
upids safely fulfill the low radioactive contamination requirements for the next generation zero background experiments set by Monte Carlo simulations.
The quantum efficiency of the Q
upid at room temperature is
>
30
% at the xenon scintillation wavelength. At −100
°C, the Q
upid shows a leakage current smaller than 1
nA and a global gain of 10
5. In these conditions, the photocathode and the anode show
>
95
%
linearity up to
1
μ
A
for the cathode and 3
mA for the anode. The photocathode and collection efficiency are uniform to 80% over the entire surface. In parallel with single photon counting capabilities, the Q
upids have a good timing response: 1.8 ±0.1
ns rise time, 2.5 ±0.2
ns fall time, 4.20 ±0.05
ns (FWHM) pulse width, and 160 ±30
ps (FWHM) transit time spread.
The Q
upids have also been tested in a liquid xenon environment, and scintillation light from
57Co and
210Po radioactive sources was observed.
► We propose a 3-stage DM and Iˆ1/2 observatory based on multi-ton LXe and LAr detectors. ► This work is a quantitative study of the topics in Astropart. Phys. 31 (2009) 63–74. ► WIMP cross-sections ...and masses could be measured with sensitivity of 10-47cm2. ► 0ν2β decay could be observed for 136Xe with sensitivity to half-lives 10E27–10E28y. ► The pp solar ν spectrum, and ν flux from a Galactic SN, could also be measured.
We study a three stage dark matter and neutrino observatory based on multi-ton two-phase liquid Xe and Ar detectors with sufficiently low backgrounds to be sensitive to WIMP dark matter interaction cross sections down to 10-47cm2, and to provide both identification and two independent measurements of the WIMP mass through the use of the two target elements in a 5:1 mass ratio, giving an expected similarity of event numbers. The same detection systems will also allow measurement of the pp solar neutrino spectrum, the neutrino flux and temperature from a Galactic supernova, and neutrinoless double beta decay of 136Xe to the lifetime level of 1027–1028y corresponding to the Majorana mass predicted from current neutrino oscillation data. The proposed scheme would be operated in three Generic stages G2, G3, G4, beginning with fiducial masses 1-ton Xe+5-ton Ar (G2), progressing to 10-ton Xe+50-ton Ar (G3) then, dependent on results and performance of the latter, expandable to 100-ton Xe+500-ton Ar (G4). This method of scale-up offers the advantage of utilizing the Ar vessel and ancillary systems of one stage for the Xe detector of the succeeding stage, requiring only one new detector vessel at each stage. Simulations show the feasibility of reducing or rejecting all external and internal background levels to a level <1 events per year for each succeeding mass level, by utilizing an increasing outer thickness of target material as self-shielding. The system would, with increasing mass scale, become increasingly sensitive to annual signal modulation, the agreement of Xe and Ar results confirming the Galactic origin of the signal. Dark matter sensitivities for spin-dependent and inelastic interactions are also included, and we conclude with a discussion of possible further gains from the use of Xe/Ar mixtures.
We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20 GeV/c^{2} using a target of low-radioactivity argon with a 6786.0 kg d ...exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. 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 event/keVee/kg/d 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}.
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