出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Within the XENON program, we are operating a double-phase time-projection chamber (TPC) using liquid xenon (LXe) as target material. The current phase, XENON100 installed in the LNGS, is in science mode since the beginning of 2010, with a sensitivity goal of 2 ×10−45 cm2 for spin-independent WIMP-nucleon scattering. For the next step, we propose to build a detector with a total mass of 2.4 tons of LXe (1.2 fiducial): XENON1T. The goal is to reduce the background by two orders of magnitude with respect to XENON100, reaching a sensitivity of about 5×10−47 cm2. Therefore it is crucial to reduce the external backgrounds: gammas and neutrons from the ambient radioactivity and the most dangerousmuon-induced neutrons. A study of the shield and muon veto needed by the experiment has been carried on with a full Geant4 Monte Carlo simulation. To shield the experiment at LNGS we plan to build a water tank of 10 m diameter and 10 m height, instrumented with PMTs to act as a Cerenkov muon veto. The results of the simulation show that the gammas and neutrons from rock and concrete radioactivity are reduced at a completely negligible level, and the muon-induced neutrons contribute to mimic the WIMP’s signal with 0.07 events per year, which allows to reach the foreseen sensitivity of the experiment.
