Boson description of low-lying collective states inBa128

Abstract

The low-lying collective states in $^{128}\mathrm{Ba}$ are investigated microscopically by means of the boson expansion theory with the self-consistent effective interactions. Calculated level structures and electromagnetic properties are compared with the experimental data. Theoretical structures of the collective wave functions are illustrated in detail for ${0}_{1}^{+},\phantom{\rule{0.16em}{0ex}}{0}_{2}^{+},\phantom{\rule{0.16em}{0ex}}{0}_{3}^{+},\phantom{\rule{0.16em}{0ex}}{2}_{1}^{+},\phantom{\rule{0.16em}{0ex}}{2}_{2}^{+}$, and ${2}_{3}^{+}$ states. In the present results, the main contribution to the ${0}_{2}^{+}$ state of $^{128}\mathrm{Ba}$ comes from the three-phonon component, and the two-phonon component is rather dominant in the ${0}_{3}^{+}$ state. The description of the wave functions is compared to the results of the general collective model.