Isomer spectroscopy of 127Cd

The spin and configurational structure of excited states of 127 Cd, the two-proton and three-neutron hole neighbor of 132 Sn, has been studied. An isomeric state with a half-life of 17.5(3) μs was populated in the fragmentation of a 136 Xe beam on a 9 Be target at a beam energy of 750 MeV/u. Time distributions of the delayed γ transitions and γγ coincidence relations were exploited to construct a decay scheme. The observed yrast (19/2) + isomer is proposed to have dominant configurations of ν(h ―3 11/2 )π(g ―1 9/2 , p ―1 1/2 ), ν(h ―2 11/2 d ―1 3/2 )π(g ―2 9/2 ), and ν(h ―2 11/2 , s ―1 1/2 )π(g ―2 9/2 ) and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone 129 Sn. The new information provides input for the proton-neutron interaction and the evolution of neutron hole energies in nuclei around the doubly magic 132 Sn core.