Study of solar neutrinos with the 600 t liquid argon ICARUS detector

The ICARUS time projection chamber can yield sound information on B-8 solar neutrinos. Owing to the high-energy resolution and the good capability of event reconstruction it can make a contribution to our understanding of neu trino intensities and their energy spectrum. Moreover. the MSW oscillation probability for sterile and active neutrinos can be well studied because bo th elastic scattering by electrons and absorption reaction on argon nuclei can be measured independently. Tho main problem in detecting the low-energy neutrino interactions arises from the environmental radioactivity. In the present work we study by Monte Carlo simulation the topology and the rates of the events, induced by neutrinos and background neutrons, in a 470 t (fi ducial mass) liquid-argon TPC detector. For neutrino interactions we use th e Standard solar model BP98 and the recent experimental confirmation of the shell model computation of absorption cross section. The noise is estimate d from new data on natural neutron background, collected in the hall C of t he Gran Sasso laboratory, It is confirmed that, with a relatively modest ne utron shielding and particular off-line event triggers, the weight of spuri ous events can be made to have little influence on the ICARUS solar neutrin o measurement. Indeed, we expect 6 (26) background events per year in the 2 12 (759) elastic scattering (absorption reaction) sample. (C) 2000 Elsevier Science B.V. All rights reserved.