Feasibility of sup 81 Br(nu,e exp - ) sup 81 Kr Solar Neutrino Experiment

摘要

Several ingenious solutions have been offered for the solar neutrino problem - a defect in the solar model, the appearance of a new type of neutrino physics, the sun is no longer burning, etc. The range of these proffered solutions stresses the need for a new experiment to study the sun. The modern pulsed laser now makes possible a new solar neutrino test which examines an independent neutrino source in the sun. A recently proposed experiment would use the reaction sup 81 Br(nu,e exp - ) sup 81 Kr to measure the flux of exp 7 Be neutrinos from the sun. When sup 7 Be decays by electron capture to make sup 7 Li, a neutrino is emitted at 0.862 MeV and the flux of these on the earth is about 4 x 10 exp 9 cm exp -2 s exp -1 , according to the standard model. Therefore, an experiment based on sup 81 Br(nu,e exp - ) sup 81 Kr which is sensitive to these lower energy neutrinos would be of fundamental importance. To first order, the chlorine experiment detects the sup 8 B neutrinos while bromine detects the much more abundant sup 7 Be neutrino source. In practice, the proposed bromine experiment would be very similar to the chlorine radiochemical experiment, except that sup 81 Kr with a half-life of 2 x 10 exp 5 years cannot be counted by decay methods. With an experiment of about the same volume as the chlorine experiment (380 m exp 3 ) filled with CH sub 2 Br sub 2 , the model predicts about 2 atoms of sup 81 Kr per day. The bromine experiment depends entirely on the RIS method, implemented with pulsed lasers, for its success. 10 refs., 3 figs. (ERA citation 10:047471)