Abstract
The XENON100 experiment is the second phase of the XENON direct Dark Matter search program. It consists of an ultra-low background double phase (liquid-gas) xenon filled time projection chamber with a total mass of 161 kg (62 in the target region and 99 in the active shield), installed at the Laboratori Nazionali del Gran Sasso (LNGS). Here the results from the 224.6 live days of data taken between March 2011 and April 2012 are reported. The experiment set one of the most stringent limits on the WIMP-nucleon spin-independent cross section to date (2 × 10−45 cm2 for a 55 Gev/c2 WIMP mass at 90 % confidence level) and the most stringent on the spin-dependent WIMP-neutron interaction (3.5 × 10−40 for a 45 GeV/c2 WIMP mass). With the same dataset, XENON100 excludes also solar axion coupling to electrons at gAe > 7.7 × 10−12 for a mass of mAxion <1 keV/c2 and galactic axion couplings by gAe > 1 × 10−12 at a mass range of mAxion = 5−10 keV/c2 (both 90 % C.L.). Moreover an absolute spectral comparison between simulated and measured nuclear recoil distributions of light and charge signals from a 241AmBe source demonstrates a high level of detector and systematics understanding. Finally, the third generation of the XENON experiments, XENON1T, is the first tonne scale direct WIMP search experiment currently under construction. The commissioning phase of XENON1T is expected to start in early 2015 followed, a few months after, by the first science run. The experiment will reach sensitivities on the WIMP-nucleon spin-independent cross section down to 2 ×10−47 cm2 after two years of data taking.
Highlights
An increasing number of astrophysical and astronomical observations points to the existence of a non luminous, non baryonic and cold matter component of the Universe, called Cold Dark Matter (CDM) [1,2,3]
The Dark Matter particles are still undetected, but they have to belong to a category beyond the Standard Model; the most appealing and interesting candidates are the so called Weakly Interactive Massive Particles (WIMPs) predicted by Supersymmetric theories (SUSY), models with extra dimensions and little Higgs models [4,5,6]
Different WIMP detection approaches are used in order to determine the characteristics of such particles: experiments at LHC will try to look for their appearance in the collisions; high energy astro-particle physics experiments are looking for WIMP annihilation signatures from the center of the Sun or from the center of the Galaxy and/or other places where the matter is quite dense whereas Dark Matter direct detection experiments are looking for the elastic scattering of WIMPs off the target nuclei
Summary
An increasing number of astrophysical and astronomical observations points to the existence of a non luminous, non baryonic and cold (i.e. non relativistic) matter component of the Universe, called Cold Dark Matter (CDM) [1,2,3]. The Dark Matter particles are still undetected, but they have to belong to a category beyond the Standard Model; the most appealing and interesting candidates are the so called Weakly Interactive Massive Particles (WIMPs) predicted by Supersymmetric theories (SUSY), models with extra dimensions and little Higgs models [4,5,6]. Among the latter category, the XENON project is one of the most promising: after the results of a first 10 kg scale prototype, XENON10 [7], the second generation experiment (XENON100, the results of which are presented here) has been running since 2009 and successfully achieved its initial aim of improving the sensitivity by a factor ∼ 50 with respect to XENON10. While XENON100 is still running, XENON1T is currently in advanced phase of construction at Laboratori Nazionali del Gran Sasso in Italy
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