ELECTROMAGNETIC TRANSITION RATES IN 58NI

Lifetimes of 15 excited states in Ni58 and one in Ni62 have been measured using the Doppler-shift-attenuation method. The levels were excited via inelastic proton scattering at bombarding energies from 7 to 9 MeV. The Doppler shifts of decay rays were measured in a 30-cm3 Ge(Li) detector in coincidence with particles backscattered near 170°. Theoretical estimates of stopping powers were checked experimentally by Dopplershift-attenuation measurements; excellent agreement was found. The matrix elements extracted from the measured lifetimes are compared with shell-model and vibrational-model predictions. Agreement is, in general, poor. The theoretical analysis indicates that a state-dependent neutron effective charge must be taken into account, and that core excitations play an important role in the determination of transition probabilities. © 1969 The American Physical Society.