Search for neutrinos from the Sun using the reactionGa71(νe,e−)71Ge

Abstract

A radiochemical ${}_{}{}^{71}{}_{}{}^{}\mathrm{-}_{}^{71}{}_{}{}^{}$Ge experiment using 30 tons of gallium to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory in the U.S.S.R. Assuming that the extraction efficiency for ${}_{}{}^{71}{}_{}{}^{}\mathrm{Ge}$ atoms produced by solar neutrinos is the same as from natural Ge carrier, we observed the capture rate to be ${20}_{\mathrm{-}20}^{+15\mathrm{}}$(stat)±32(syst) solar neutrino units (SNU), resulting in a limit of less than 79 SNU (90% C.L.). This is to be compared with 132 SNU predicted by the standard solar model.