Structure of excited bands in 162Tm and residual interactions

Abstract

The nucleus 162Tm has been populated by the 130Te( 37Cl,5n) reaction, and the γ-cascades detected with the NORDBALL array. Eight coupled rotational bands involving the proton orbitals, g 7 2 [404] 7 2 + , d 3 2 [411] 1 2 + , d 5 2 [402] 5 2 + , h 11 2 [523] 7 2 − and h 9 2 [541] 1 2 − and neutron orbitals i 13 2 [642] 5 2 + , h 9 2 [523] 5 2 − and f 7 2 [521] 3 2 − have been established in 162Tm, to spins varying from 18 to 47ℏ. Various phenomena which can be related to residual neutron-proton interactions are discussed. In particular, signature inversion in the π [541]1 2 − ⊗ ν [642]5 2 + bands based on the h 9 2 quasiproton and i 13 2 quasineutron, rewpectively, may be explained by a fairly large p-n interaction. In addition, interactions at the crossings of bands with constituent quasiparticles differing both in parity and signature have been extracted with strength of the order of a few (4–12) keV. Such interactions also require terms beyond the standard mean field description.