Novel features of nuclear spectra of light mass Os isotopes

Abstract

The (N=88-108) light mass Os isotopes exhibit level spectra different from the heavier (N > 108) isotopes. The spectral pattern, for ground, β- and γ- bands is illustrated empirically, and analyzed in terms of the collective rotation vibration model and the algebraic sd Interacting Boson Model IBM-1. The variation of the spectral features with neutron number N has been linked to the odd-A neighbors and to the occupation of the underlying Nilsson orbits. The quadrupole β vibration produces the axially symmetric shape of light mass Os isotopes, in contrast to the main role of the asymmetry parameter γ in the heavier Os isotopes. The energy level spectra, and the inter band B(E2) ratios in IBM-1 reproduce the shape variation from spherical to the X(5) symmetry status, and to the prolate deformed rotor, as in experiment. This reveals the interesting physics of the rotation vibration model by high lighting the special features of the light mass 164−184Os isotopes. The detailed band structure and their variation with neutron number N of the Os isotopes is presented empirically and in IBM-1.