Gamow-Teller strength from the 76Se(n,p)76As reaction: Implications for the double beta decay of 76Ge

Cross sections have been measured up to 35 MeV excitation for the {sup 76}Se(n,p){sup 76}As reaction at five laboratory angles between 0{degree} and 15{degree}. 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 {sup 76}Ge(p,n){sup 76}As reaction to obtain an estimate of a lower limit for the lifetime of {sup 76}Ge for {beta}{beta} decay. The estimate is in qualitative agreement with the measured lifetime. {copyright} {ital 1997} {ital The American Physical Society}