Search for isomeric transitions in fission products around mass number 150

Abstract

Abstract.A β-gated γ-ray and internal conversion electron measurement system for identifying isomers has been installed to the isotope separator on-line at the Kyoto University Research Reactor. On-line measurements for mass number A = 93 nuclides clearly showed that it had sufficient ability to distinguish isomeric transitions from those following β-decay. Using this equipment, an isomeric state in 148 Pr was successfully observed at 76.8 keV, and one in 151 Pr at 35.1 keV. We also found a candidate of an isomeric transition in an A = 150 nuclide produced by the thermal neutron-induced fission of 235 U.