Detailed spectroscopy and IBFFM interpretation of the odd-odd nuclei 132Pr and 130Pr

Abstract

High-spin rotational structures in the odd-odd nuclei 130,132Pr have been studied via the 104Pd + 32S reaction at 160 MeV. Several states below the previously reported negative- and positive-parity states have been established through the observation of low-energy transitions, leading to new spin assignments for all observed levels. The bands based on the πh 11 2 ⊗ vg 7 2 and πh 11 2 ⊗ vh 11 2 configurations have been extended at much higher spins. Detailed interacting boson-fermion-fermion model calculations have been performed for the two nuclei, which reveal the complex structure of the new observed low-lying states. The change from inverted to normal signature at high spin and the staggering pattern of all observed bands are well reproduced, being explained by the interplay between a new term introduced in the boson quadrupole operator and the residual quadrupole-quadrupole interaction.