85Kr and 39Ar background in GENIUS

GENIUS is a proposal for a large scale detector of rare events like double beta decay, cold dark matter and low-energy solar neutrinos in real time. The idea of GENIUS is to operate a large amount of ``naked'' Ge detectors in liquid nitrogen, with the aim of reducing the background down to a level of 10^(-3) counts/kg keV y. In this work we investigate the contribution to the background of GENIUS coming from argon (39Ar) and krypton (85Kr) contamination in the liquid nitrogen.Comment: In press, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment (2003

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