1f72neutron hole strength inNi59with theNi60(p→, d)Ni59reaction at 94 MeV

Abstract

The $^{60}\mathrm{Ni}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{p}}, \mathrm{d})^{59}\mathrm{Ni}$ reaction has been studied with 94-MeV polarized protons. Angular distributions of the differential cross section and analyzing power have been measured for states in $^{59}\mathrm{Ni}$ up to an excitation energy of 4.8 MeV. A characteristic $j$ dependence of the ($\stackrel{\ensuremath{\rightarrow}}{\mathrm{p}}$, d) analyzing powers was observed for $l=1$ and $l=3$ transfers, which allowed reliable spin determinations to be made for hole states in $^{59}\mathrm{Ni}$. As a result, spins of $\frac{7}{{2}^{\ensuremath{-}}}$ were assigned to the levels at 2.63, 3.04, 3.73, 4.16, 4.23, 4.56, and 4.69 MeV in $^{59}\mathrm{Ni}$. Standard distorted-wave Born approximation calculations have been performed and their predictive power to describe the shape of the differential cross section and analyzing power angular distributions was tested as a function of the input parameters. No large discrepancies between calculated and experimental cross sections were found. Relative spectroscopic factors for the neutron pickup from the $1{f}_{\frac{7}{2}}$ orbital were extracted and compared to recent shell-model predictions. These shell-model calculations account quite well for the centroid of the observed $1{f}_{\frac{7}{2}}$ neutron hole distribution but fail to reproduce the strength distribution.