Gamow-Teller Strength from the 76Se(n,p)76As Reaction: Implication for the Double Beta Decay of 76Ge

Abstract

Cross sections have been measured up to 35 MeV excitation for the 76Se(n,p)76As reaction at five laboratory angles between 0� and 15�. The incident neutron energy was 198 MeV. The distribution of Gamow-Teller (GT) strength at excitation energies less than 10 MeV was deduced by carrying out a multipole decomposition of the data. The GT strength below 6 MeV excitation was found to be less than 0.9 units, in qualitative agreement with a quasiparticle random-phase approximation calculation. The present results have been compared with data from the 76Ge(p,n)76As reaction to obtain an estimate of a lower limit for the lifetime of 76Ge for ?? decay. The estimate is in qualitative agreement with the measured lifetime.