Multiquasiparticle states in the neutron-rich nucleus174Tm

Abstract

Deep inelastic and transfer reactions with an 820-MeV, 136 Xe beam and various ytterbium and lutetium targets have been employed to study high-spin structures in the neutron-rich thulium isotopes beyond 171 Tm. Results in the doubly odd nucleus, 174 Tm, include the identification of numerous new two-and four-quasiparticle intrinsic states including several isomers below 1 MeV, and the observation of the K π = 4 − ground state rotational band populated via direct decay from a τ = 153(10)-μs, K π = 14 − isomer at 2092 keV. The 398-keV, M1 transition linking the isomer and ground state band is abnormally fast for a highly forbidden, K = 10 decay. This relative enhancement is explained in terms of mixing of the 13 − level with the nearby 13 − member of a K π = 8 − rotational band, with an interaction strength of V ≈ 1.4 keV. Multiquasiparticle calculations are compared with the observed states.