Tests of microscopic calculations of multiple band structures and large deformations in 68Ge and 72Se.

Abstract

High-spin states in $^{68}\mathrm{Ge}$ and $^{72}\mathrm{Se}$ have been studied by in-beam, gamma-ray spectroscopy. In $^{68}\mathrm{Ge}$ the three known bands beginning at ${8}^{+}$ are found to exhibit crossing transitions and other new positive-parity bands are discovered to feed into them. In $^{72}\mathrm{Se}$ only a single positive-parity yrast band is seen to high spin. Detailed, more realistic microscopic model calculations have been carried out for $^{68}\mathrm{Ge}$ and $^{72}\mathrm{Se}$. There is striking agreement between the calculations and the new data for $^{68}\mathrm{Ge}$, including a predicted new band with superdeformation, \ensuremath{\beta}\ensuremath{\sim}0.42. The calculations for $^{72}\mathrm{Se}$ predict similar multiple band structures that are not seen experimentally.