High spin band structure in 139Nd

Abstract

High-spin states in 139Nd nucleus have been reinvestigated with the reaction 128Te (16O, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2 ħ. At the low spin states, the yrast collective structure built on the vh11/2−1 multiplet shows a transitional shape with γ ≈ 32° according to calculations of the triaxial rotor-plus-particle model. Three collective oblate bands with γ ∼ −60° at the high spin states were identified for the first time. A band crossing is observed around ħω ∼0.4 MeV in one oblate band based on the 25/2− level.