(He3,n) Reaction at 25 MeV

Abstract

The (${}_{}{}^3{}_{}{}^{}\mathrm{He},n$) reaction has been studied on targets of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{58,60,62}{}_{}{}^{}\mathrm{Ni}$ at an incident energy of 25 MeV. The observed resolution of the neutron time-of-flight spectrometer used in this work was about 1%. Differential cross sections were obtained for the resolvable final states over the angular range of 0-40° (L). The angular distributions were compared with the predictions of a simple, one-step, two-nucleon-transfer model. In this formalism the diproton stripped from ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is transferred to the target retaining its ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ relative motion. The shapes of the angular distributions were unique for a given $l$ transfer and were, in most cases, generally reproduced by the calculations. For $0^{+}$ targets the $J^{\pi }$ of many final states could be assigned. Comparison of experimental with theoretical relative magnitudes permitted assignment of dominant shell-model configurations. To first approximation the relative transition strengths to final states in ${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{30}{}_{}{}^{}\mathrm{S}$, and ${}_{}{}^{60}{}_{}{}^{}\mathrm{Zn}$ were consistent with the assumption of two particles coupled to an effectively "closed core."