Multi-quasi-particle states in 173Hf

Abstract

Rotational bands built on 1, 3 and 5 quasi-particle (qp) states in 173Hf have been populated to medium and high spins through the 160Gd(18O, 5n) reaction. The 1qp bands, previously identified as the 1 2-[521], 5 2-[512] and 7 2+[633] (mixed i 13 2) Nilsson configurations, have the first back-bend and show different alignment properties, possibly originating from deformation differences. The multi-particle states were identified from excitation energies, the properties of their associated band structures and decay patterns. The 3qp states are the previously known Kπ = 19 2+ and 23 2- isomeric states originating from the 7 2+[633] quasi-neutron coupled to 8-, 2-quasi-proton excitations and a Kπ=( 13 2+) state possibly containing the three lowest quasi-neutrons. A 5qp state with Kπ = ( 29 2-) was identified as the same three lowest lying quasi-neutrons coupled to the 8-, 2-quasi-proton excitation. The low excitation energies of these two related 3-and 5-quasi-particle states implies a reduced neutron pairing gap, which can be attributed to the effect of blocking. Show more