Empirical study of the shape evolution and shape coexistence in Zn, Ge and Se isotopes

The spectra of the isotopes of Zn, Ge and Se in the A=60–80 region of the nuclear landscape display interesting spectral variations with N and Z. At first we study these structures empirically. The state-wise deformation status of each isotope is deduced using the power index formula. The average value of the power index displays the variation with neutron number N. The linear plot of B(E2,01+→21+) versus [1/E(21+)] for a given Z gives further information on the spectral variation with N. The level energy spectra are used to study the role of the excited bands in the phase transitions and the possible shape co-existence. The common spectral features of the three isotopic chains and some unique features are pointed out from our study and the role of the Nilsson single particle orbits is discussed. A comparison with recent works for Ge and Se isotopes reveals the importance of our empirical studies vis-à-vis the high efficiency experiments and different theoretical interpretations of the shape changes with N and Z and spin.