Nuclear Structure Of Neutron-Rich N=83 Isotones By Cf-252 Fission At Gammasphere

Structure of neutron-rich N = 83 isotones was studied with Cf-252 source and Gammasphere. High spin level schemes of Ba-139 (Z = 56) and Te-135 (Z = 52) were proposed, and those of Xe-137 (Z = 54) and I-136(Z = 53) were extended. Spins, parities and configurations are tentatively assigned to the levels. Rich spectroscopic information characteristic of spherical shell model excitations and enhanced E3 cascade were observed in Te-135, Xe-137 and I-136, and resemblance between Sn-132 and Pb-208 region was observed in the isotones. But 139Ba exhibits different structure which is interpreted by the difference between particle-particle and particle-hole excitations. Based on a detailed measurement of a regular band consisting of intense M1 and very weak crossover E2 high-lying in Te-135, the band is interpreted as a magnetic rotation band.