Description of shape coexistence in Zr96 based on the quadrupole-collective Bohr Hamiltonian

Abstract

© 2019 American Physical Society. Experimental data on Zr96 indicate coexisting spherical and deformed structures with small mixing amplitudes. Although a possible geometrical description of such a shape coexistence is implied in the contemporary discussion, it does not exist yet for Zr96. The observed properties of the low-lying collective states of Zr96 based on the geometrical collective model are investigated. The quadrupole-collective Bohr Hamiltonian with the potential having two minima, spherical and deformed, is applied. Good agreement with the experimental data on the excitation energies, B(E2), and B(M1) reduced transition probabilities is obtained. It is shown that the low-energy structure of Zr96 can be described in a satisfactory way within the geometrical collective model with a potential function supporting shape coexistence without other restrictions of its shape. However, the excitation energy of the 22+ state can be reproduced only if the rotation inertia coefficient is taken to be 5 times smaller than the vibrational one in the region of the deformed well. It is shown also that shell effects are important for the description of B(M1;22+→21+). An indication of the influence of the pairing vibrational mode on the 02+→01+ transition is obtained.