Evolution from quasivibrational to quasirotational structure in Tm155 and yrast 27/2− to

Abstract

Excited states in 155 Tm have been populated via the reaction 144 Sm( 16 O, p4n) 155 Tm at a beam energy of 118 MeV. The ground-state band has been extended and a new side band of the ground-state band is identified. E-GOS curves and potential energy surface calculations are employed to discuss the structure evolution of the ground-state band. The newly observed side band in 155 Tm is discussed based on the spin/energy systematics. In particular, the phenomenon of seniority inversion is proposed in 155 Tm, and a systematic study of this phenomenon in the A ≈ 150 mass region is performed.

General properties of terminating bands in the A = 110 and A = 160 mass regions

“…Another classic region to investigate band termination is the transitional nuclei near A ∼ 160 with around ten valence nucleons outside the 146 Gd closed core, which lies between the closed-core 146 Gd nucleus at one end and the well-deformed rotators at the other (N = 92). Some rotational bands in this region indicate band irregularities at high spin states, which are associated with weak collectivity and shape transition [13][14][15].…”