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

Lifetimes of high-spin states in the N = 50 nucleus Rh-95 were measured using the recoil-distance Doppler-shift technique. The nuclei were produced via the reaction Ni-58(Ca-40,3p) at 145 MeV beam energy and the gamma radiation was detected in six EUROBALL cluster detectors. Reduced transition probabilities for seventeen gamma 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 Ni-68 core. The results indicate that all observed states with 27/2 less than or equal to I less than or equal to 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 nu(g(9/2))(-1)nu(d(5/2)) neutron part of the wavefunctions, (C) 1998 Elsevier Science B.V.