Picosecond lifetime measurement of neutron core-excited states in the N = 50 nucleus 95Rh

Abstract

Lifetimes of high-spin states in the N = 50 nucleus 95Rh were measured using the recoil-distance Doppler-shift technique. The nuclei were produced via the reaction 58Ni( 40Ca,3p) at 145 MeV beam energy and the γ radiation was detected in six EUROBALL cluster detectors. Reduced transition probabilities for seventeen γ transitions and limits for nine further transitions were extracted and compared with the predictions of the spherical shell model based on the extended configuration space, ( 0f 5 2 , 1p 3 2 , 1p 1 2 , 0g 9 2 ) for protons and ( 0g 9 2 , 1d 5 2 ) for neutrons relative to a hypothetical 68Ni core. The results indicate that all observed states with 27 2 ⩽ I ⩽ 39 2 are built from a neutron g 9 2 → d 5 2 excitation across the N = 50 shell closure, coupled to up to five valence protons in different configurations. Evidence of stretched dipole cascades having large M1 strengths was found and explained by spin recoupling within the ν( g 9 2 ) −1ν( d 5 2 ) neutron part of the wavefunctions.