30Si(3He,d)31P reaction at 25 MeV.

Abstract

The $^{30}\mathrm{Si}$${(}^{3}$He,d${)}^{31}$P reaction has been investigated at 25 MeV incident energy. About 80 levels were observed up to an excitation energy of 10 MeV by using a split-pole magnetic spectrograph. Most of the proton-unbound states were identified with resonance levels observed in proton capture reactions on $^{30}\mathrm{Si}$. Four levels were observed for the first time in a reaction which couples a proton to a $^{30}\mathrm{Si}$ core. Spectroscopic information has been obtained for about 60 levels through angular distribution measurements and distorted wave Born approximation analyses, with special treatment applied in the cases of the proton-unbound states. The spectroscopic factors of the proton-unbound states are in overall agreement with the spectroscopic factors which are deduced from the proton partial widths measured in resonant proton scattering experiments, but the proton partial width which is obtained in this work for the 7897 keV level is in disagreement with previous values from \ensuremath{\gamma}-ray resonant absorption measurements. The strengths of the l=0, 2, and 3 transfers are essentially concentrated into one level, each of isospin T=1/2 and T=3/2. In contrast the l=1,T=1/2, strength is distributed over many levels, especially in a cluster of six levels between 9.0 and 9.8 MeV. The sum rule for the 2${\mathit{p}}_{3/2}$,T=1/2, proton single-particle strength is exhausted, leading to a centroid energy of about 7.9 MeV for this configuration. Isospin assignments are discussed for some levels. The excitation energies and spectroscopic factors for even-parity states are compared with the results of a recent, complete sd-shell space, shell-model calculation.