| A large variety of shapes may be observed in Sr and Zr nuclei of the A = 100 region when the number of neutrons increases from N = 58 to N = 64. The lighter isotopes are rather spherical. It is also well established that three shapes co-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 isomer of half-life 1.4(2) microsecond was observed in $^{95}$Kr, the odd-odd $^{96}$Rb has been reinvestigated and a new high spin isomer observed in the even-even $^{98}$Zr. Beyond N = 60 nuclei, the neutron-rich Mo isotopes represent well deformed nuclei, but at the same time, the triaxial degree of freedom plays an important role. We have re-investigated the odd $^{105}$Mo and $^{107}$Mo and found that odd and even Mo in the neutron range N = 62-66 have comparable quadrupole and triaxial deformation. These nuclei were studied by means of prompt $\gamma$-ray spectroscopy of the spontaneous fission of $^{248}$Cm using the EUROGAM 2 Ge array and/or measurements of microsecond isomers produced by fission of $^{239,241}$Pu with thermal neutrons at the ILL (Grenoble). |
Récupérer au format
