Nuclear Structure studies of Microsecond Isomers near A = 100

摘要

A large variety of shapes may be observed in Sr and Zr nuclei of the A = 100region when the number of neutrons increases from N = 58 to N = 64. Thelighter isotopes are rather spherical. It is also well established that three shapesco-exist in the transitional odd-A, N = 59, Sr and Zr nuclei. For N > 59,strongly deformed axially symmetric bands are observed. Recently, a new iso-mer of half-life 1.4(2) ss was observed in 95Kr, the odd-odd 96Rb has beenreinvestigated and a new high spin isomer observed in the even-even 98Zr.Beyond N = 60 nuclei, the neutron-rich Mo isotopes represent well deformednuclei, but at the same time, the triaxial degree of freedom plays an importantrole. We have re-investigated the odd '°5Mo and 107Mo and found that oddand even Mo in the neutron range N = 62-66 have comparable quadrupoleand triaxial deformation. These nuclei were studied by means of prompt ry-rayspectroscopy of the spontaneous fission of 248Cm using the EUROGAM 2 Gearray and/or measurements of /is isomers produced by fission of 239'241Pu withthermal neutrons at the ILL (Grenoble).