SIGNAL TO BACKGROUND RATIO OF THE GEOCHEMICAL TL-205 SOLAR-NEUTRINO EXPERIMENT

The neutrino capture rate of Tl-205 and the effect of neutrino oscilla tions in matter are discussed. The contributions of natural radioactiv ity, stopped negative muons and fast muons to the background of the ge ochemical Tl-205 experiment is estimated. The production of radioisoto pes in the lead region induced by cosmic ray muons was investigated at the high energy muon channel(M2) of CERN. Results and conclusions of experiments with 120, 200 and 280 GeV muons are presented. It is found that the background contribution of cosmic ray muons is significantly higher than expected by former estimations and restricts the feasibil ity of the Tl-205 solar neutrino experiment.