Neutron pickup strength in 87Sr from the (p

Abstract

Differential cross section and analyzing power angular distributions have been obtained for the $^{87}(\mathit{p}\ensuremath{\rightarrow}$,d${)}^{86}$Sr reaction in two measurements using different magnetic spectrometers at incident proton energies of 94.2 and 91.8 MeV. Typical energy resolutions of 70 and 40 keV, respectively, were achieved. Optical-model parameters were obtained by fitting the elastic scattering data measured to laboratory angles of 90\ifmmode^\circ\else\textdegree\fi{} for protons at 94.2 MeV and to 120\ifmmode^\circ\else\textdegree\fi{} for deuterons at 88.0 MeV. Standard exact finite range distorted-wave Born approximation calculations using these optical-model parameters failed to describe the experimental data, while the adiabatic approximation improved the description to some extent. Orbital and total angular momenta, l and j, of the picked-up neutron were extracted from the angular distributions of the differential cross section and analyzing power for all the residual states observed. The rms radius of the 1${g}_{9/2}$ neutron orbital, obtained from magnetic electron scattering, was used in the extraction of strength for this orbital, while rms radii from Hartree-Fock calculations were used for the 2${p}_{1/2}$, 2${p}_{3/2}$, 1${f}_{5/2}$, and 1${f}_{7/2}$ orbitals. The observed 1${g}_{9/2}$ strength, spread over 20 states up to 5.4-MeV excitation, indicates a depletion of about 43% compared to simple shell-model expectations. Similarly, the observed 1${f}_{5/2}$ strength, spread over 17 states, indicates a depletion of about 32%. The weighted summed spectroscopic strength for the 1${g}_{9/2}$ orbital, deduced from the present study, is lower than that obtained from magnetic electron scattering.