Band crossing observed in neutron-rich Pd isotopes via spontaneous fission ofCf252

Abstract
High spin excited states in neutron-rich nuclei Pd112,114,116 have been investigated by measuring prompt γ rays emitted from a Cf252 spontaneous fission source. Two different measurements were performed. First, γ-γ coincidence data, necessary to determine the decay schemes, were obtained by using an array of 20 Compton-suppressed Ge detectors. Second, Z identification and the enhancement of a desired neutron channel were carried out using a x-n-γ multiplicity spectrometer. Ground state bands have been extended to Jπ=10+ for Pd112, and Jπ=12+ for Pd114 and Pd116. Band crossings were observed in all three isotopes. It was found from cranked shell model calculations that these backbends are due to the alignment of two g9/2 protons. The measured energy levels were also compared with predictions of the interacting boson model.