Lifetime and Angular Distribution Measurements from theP31(p, γ)S32Reaction

Abstract

The $^{31}\mathrm{P}(p, \ensuremath{\gamma})^{32}\mathrm{S}$ reaction has been studied at several resonances with a 20-${\mathrm{cm}}^{3}$ Ge(Li) detector. A level at 6.664 MeV has been populated which may be the same as one found at 6.671 MeV from (${\mathrm{He}}^{3}$, $d$) experiments. This state is found to branch almost equally to the states at 3.775 and 2.230 MeV. Measured branching ratios for the first six excited states are in agreement with earlier work except for a ground-state transition for the 5.006-MeV level which supports an odd-parity assignment for this state. New branching ratios are assigned for the levels at 5.544 and 6.673 MeV. Doppler-shift lifetime measurements for the states at 3.775, 4.280, 4.694, 5.006, 5.410, 5.544, 6.226, and 6.623 MeV are consistent with other measurements. The lifetime of the level at 6.664 MeV is found to be ${0.054}_{\ensuremath{-}0.009}^{0.013}$ psec. An upper limit of 0.01 psec is set for the mean life of the 7.952-MeV level. Angular distributions have been measured with the Ge(Li) detector for the 1.248- and 1.438-MeV resonances. Spins deduced from combining these results with the lifetime measurements confirm previous assignments for levels at 6.623, 6.226, and 5.410 MeV. The spin of the 4.459-MeV level is limited to 3 or 4, consistent with other recent work and with the hypothesis of Goswami et al. that this is the ${4}^{+}$ level of a rotational band based on the ${0}^{+}$ ground state. Mixing ratios are given for a number of transitions.