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XENON research group at the University of Zurich
XENON is a direct dark matter detection experiment using liquid xenon as the detector medium. The goal is to detect the small charge and light signal after a dark matter particle interacts with a xenon nucleus. The first module (XENON10) has been successfully operated at the Gran Sasso Undeground Laboratory (LNGS), in dark matter search mode from August 2006 to February 2007. The second module (XENON100) is currently under commissioning at LNGS and will start taking science data by summer 2008. The third phase (XENON1t) is under study.

XENON100:
The pictures show the XENON100 detector during its installation, the top and bottom PMT arrays, as well as the closed detector in its shield:











XENON10:
The picture shows the XENON10 detector in its low-background shield. Note the difference to XENON100, for which the cables, feed-throughs and cryo-cooler have been moved outside the shield.



First results on spin-independent WIMP-nucleon interactions have been published in 2008 (Phys. Rev. Lett. 100, 2008). No dark matter candidates have been detected, and the sensitivity to WIMP-nucleon cross sections extends to about 4x10-8pb (4x10-44cm2) at a WIMP mass of 30 GeV/c2. The figure below shows the excluded region in the WIMP cross section-WIMP mass parameter space (region above the red curve), along with the CDMS-II 2005 results (blue curve), and predictions from the constrained MSSM (filled regions).





Our group is involved in PMT testing, calibration and operations at LNGS, in the construction of various detector and shield hardware components, in material screening with a high-purity Ge spectrometer, in data processing and analysis, in Monte Carlo simulations of the expected gamma, alpha and neutron backgrounds, in the WIMP analysis for spin-dependent and spin-independent interactions, as well as in the design, construction and Monte Carlo simulations for the next phase. We are leading the collaboration wide Monte Carlo Working Group.

To measure the ionization and scintillation yield of nuclear recoils at low energies we have built a small dual-phase xenon chamber, which we will operate in a neutron beam. The picture below shows the inner chamber, made of teflon and stainless steel grids.



Our group operates a 2 kg high-purity Ge (HPGe) spectrometer at LNGS, to screen the detector and shield components for their U/Th/K/Co content. The results were used to construct a full background model of XENON10, XENON100, and are guiding the construction of the next phase, Xenon1t. The pictures show the HPGe detector during its installation, as well as the final setup.



We are conducting Geant4 Monte Carlo simulation to predict the XENON100/XENON10 internal and external backgrounds at LNGS, as well as gamma calibration source simulations. Pictures of the XENON100 and XENON10 geometries are shown below.


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XENON in the news:

Discover Magazine ranks XENON100 as one of the 6 most important experiments in the world.
Physics Today Nature
Resonaances Particle Theory Blog