Spectroscopy in the second potential well of 151Tb

Abstract

Using the EUROGAM array, seven excited superdeformed bands have been found in the nucleus 151Tb which offer the possibility to perform a complete spectroscopy of the second potential well in this nucleus. Three of these bands are interpreted as a single proton excitation whereas the four remaining ones suggest the promotion of the last neutron from high-N into low-N orbitals. Data for proton excited bands are compared with recent fully self consistent calculations and this shows large disagreement. Furthermore, if the signature partner of the yrast configuration has been most probably identified, a doubt remains on the observation of the signature partner of the first excited band which originated, a few years ago, the field of identical bands. From the systematic investigation of neutron excitations across the N = 86 shell gap, it turns out that the four other superdeformed bands in 151Tb exhibit the characteristic features of degenerate signature partners.