Fragmentation of IsovectorM8Strength inNi58

Abstract

Form factors were measured for transitions to levels at 7.937, 8.808, 10.19, 11.24, and 12.50 MeV and identified as $M8\mathrm{}$ and assigned $J^{\pi }=8^{-}$. The interpretation is given that the one-particle, one-hole component of these levels is dominantly ($g_{\frac{9}{2}}{f_{\frac{7}{2}}}^{-1\mathrm{}}$) and composes most of the observable $M8\mathrm{}$ strength, which is, however, only about 22% of simple shell-model predictions.