High-Resolution Proton Scattering onZr91and the Core-Excitation Model

The reactions ${\mathrm{Zr}}^{90}(p,p^{\prime }){\mathrm{Zr}}^{90}$ and ${\mathrm{Zr}}^{91}(p,p^{\prime }){\mathrm{Zr}}^{91}$ have been studied with 12.0-MeV protons. Proton spectra were measured with a broad-range magnetic spectrograph at six reaction angles between 30° and 90°, sufficient to distinguish between $L=2\mathrm{}$ and $L=3\mathrm{}$ transitions. The ${\mathrm{Zr}}^{91}$ spectrum is interpreted in terms of $d_{\frac{5}{2}}$, $s_{\frac{1}{2}}$, $d_{\frac{3}{2}}$, and $g_{\frac{7}{2}}$ neutron states coupling to the low-lying states of the ${\mathrm{Zr}}^{90}$ core. The predictions of the core-excitation model are compared in detail with the data for the multiplets formed by the $d_{\frac{5}{2}}$ neutron coupling to the 2+ and 3- states in the ${\mathrm{Zr}}^{90}$ core.