Nuclear-Reaction Studies in the Strontium Isotopes: Neutron Particle-Hole States inSr88and theSr87(d,p)Sr88Reaction

The levels of ${\mathrm{Sr}}^{88}$ have been studied with the ${\mathrm{Sr}}^{87}\mathrm{}(d,p)\mathrm{}{\mathrm{Sr}}^{88}$ reaction at a bombarding energy of 7.5 MeV using the MIT-ONR Van de Graaff generator and multiple-gap spectrograph. Seventy-three levels below 8.516-MeV excitation were observed, 32 of which displayed direct-stripping angular distributions. A distorted-wave Born-approximation analysis for the latter transitions was performed, and the values of the transferred orbital angular momentum $l_n$ and spectroscopic strengths $\frac{\mathrm{}(2J+1)\mathrm{}{S}_{l_n,j}}{(2\mathrm{}{J}_0+1)}$ were extracted. Sum-rule strengths were subsequently calculated and compared with shell-model limits. Locations of neutron particle-hole state multiplets were determined and compared with a simple model involving single-particle neutron states, determined from the ${\mathrm{Sr}}^{88}\mathrm{}(d,p)\mathrm{}{\mathrm{Sr}}^{89}$ reaction, weakly coupled to a single $1g_{\frac{9}{2}}$ hole in the major $N=50\mathrm{}$ shell. A comparison of the data is made with the previously known level structure of ${\mathrm{Sr}}^{88}$.