Systematic Nuclear Structure Studies of Z=53, 55 Isotopes

Nuclear structure studies of Z=53 iodine and Z=55 cesium nuclei have been carried out using γ-ray spectroscopic techniques with heavy-ion induced reactions. Experiments on odd-A I and Cs isotopes were carried out over the range N=62-76. These nuclei are particularity interesting both because they have collective quadrupole shapes whose potential energy surfaces are soft with respect to the triaxiality parameter γ and because they are relatively close to the Z=50 magic proton shell. A shell gap at Z=54 for collective oblate γ=+60o states result in important structure effects. Three specific topics examined are: A) coexistence of prolate and oblate nuclear shapes associated with the same single-quasi proton, B) rotational band termination by non-collective γ=+60o shapes, and C) rotational alignment properties as a function of neutron Fermi level and induced shape changes. 19 figs., 35 refs. (author)