Shell model calculation for theGa71(ν,e−)71Ge solar neutrino detector

Gamow-Teller allowed neutrino capture transitions between the ground state of ${}_{}{}^{71}{}_{}{}^{}\mathrm{Ga}$ and accessible excited states in ${}_{}{}^{71}{}_{}{}^{}\mathrm{Ge}$ are calculated in a model space of the 2p and 1f shells. The total (p,n) Gamow-Teller strength function is also calculated. The effects of model-space truncation are systematically investigated and detailed comparisons are made between calculated and experimental spectroscopic data for states in ${}_{}{}^{71}{}_{}{}^{}\mathrm{Ga}$ and ${}_{}{}^{71}{}_{}{}^{}\mathrm{Ge}$. The calculated effect of excited-state transitions is in good agreement with a previous phenomenological estimate (based upon beta decay measurements in the vicinity of mass 71) except for the higher energy ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrinos. For these rare high energy neutrinos, there is not yet sufficient experimental information to make a complete phenomenological estimate. The total cross section for ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrinos is calculated to be about ten times larger than the ground-state–to–ground-state capture rate. The overall uncertainty in the capture rate for a ${}_{}{}^{71}{}_{}{}^{}\mathrm{Ga}$ detector that is caused by excited state transitions is estimated to be about 5 percent for a standard solar model and about 1 percent for nonstandard models that are consistent with the ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ solar neutrino experiment.