Neutron Shell Structure inZr91andZr92by (d, p) and (α,He3) Reactions

Angular distributions from ∼12.5 to ∼45° were measured for ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}(d, p)$ and ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}(d, p)$ at 33.3 MeV. The resolution was about 25 keV. A number of doublets were resolved, and levels were found that had not been reported in previous neutron-transfer studies. ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}(\alpha , {}_{}{}^3{}_{}{}^{}\mathrm{He})$ and ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}(\alpha , {}_{}{}^3{}_{}{}^{}\mathrm{He})$ spectra with 55-keV resolution were obtained at 15 and 20° with 65.9-MeV $\alpha$ particles. The data are compared with distorted-wave predictions. The ($d, p$) spectroscopic factors agree with those from the ($\alpha$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$) reaction wherever comparisons are feasible. Sums of spectroscopic factors, centers of gravity, and second moments are presented for levels assigned to $d_{\frac{5}{2}}$, $s_{\frac{1}{2}}$, $d_{\frac{3}{2}}$, $g_{\frac{7}{2}}$, and $h_{\frac{11}{2}}$ configurations in each final nucleus. The sums are generally in agreement with the sum-rule predictions. The $h_{\frac{11}{2}}$ strength appears to be highly fragmented; in both nuclei, about 50% of the predicted strength was identified. The separations of the centers of gravity are similar for the two nuclei.