Gamow-Teller strength distribution in 81Kr and the consequences for a 81Br solar neutrino detector

Neutron time-of-flight measurements have been performed on the 81 Br(p,n) 81 Kr reaction at E p = 190 and 200 MeV. Gamow-Teller transition strengths have been deduced for final 81 Kr states accessible through solar neutrino capture on 81 Br. For the standard solar model, 81 Br is most sensitive to 8 B neutrinos, not — as previously believed — 7 Be neutrinos.