Particle-rotor model for doubly odd transitional nuclei of the Tl-region

Abstract

A model has been investigated describing a situation in which two noninteracting high-j Nilsson-BCS quasiparticles move in the deformed field of an axially and reflection symmetric rotor. According to the positions of the j-shells with respect to the proton and neutron Fermi surfaces structures of different character emerge referred to as semi-and doubly-decoupled. In particular, strongly Coriolis-distorted bands recently reported in doubly odd T1 nuclei are discussed. Also ~h9/2 bands in neighbouring odd mass TI isotopes are analysed on the same footing. It is shown that the pronounced odd even staggering of the transition energies can be understood as a specific quantal feature associated with the Coriolis interaction.

First observation of the excited states in the doubly odd nucleus118Cs identified throughγ-recoil coincidences

“…Once the valence particles are aligned, above the (vg0/2rhn/2)10-state, collective degrees of freedom are excited and a rotational AI=I band starts. The band exhibits an energy staggering which can be explained by the Coriolis interaction in the quasiparticlerotor model [3]. The crossover E2 transitions, forming a rotational-like band which starts from J~r=12-level and is observed up to spin 24-, confirms the collective character of this excitations.…”

“…At low excitation energy the proposed level scheme shows small M1 transitions connecting four members of the ugg/27rhu/2 multiplet. Small initial transition energies are indeed characteristic for doubly odd nuclei due to increasing alignment of the decoupled valence neutron [3]. Once the valence particles are aligned, above the (vg0/2rhn/2)10-state, collective degrees of freedom are excited and a rotational AI=I band starts.…”

“…23.20.Lv; 27.60.+J 7 Recent experimental studies of the doubly odd nuclei in the mass re,on with A--,120 and Z > 50 show evidence of a collective behaviour which is manifested by the presence of a AI=I negative parity high-spin bands based on the go/2| state with E2 crossover transitions [1,2]. The theoretical approach involving two quasiparticles plus rotational core can explain the features of such bands by assuming a configuration of a strongly coupled particle-hole and a decoupled particle based on g9/~ and htz/9, orbitals of proton or neutron character [3]. …”

Internal decay of the(10−)intruder state inTl184

“…The allocation of the states in the odd-odd thallium isotopes within each full multiplet will primarily depend on the specific proton-neutron residual interaction in these [j p ⊗ j n ]J π configurations. This has been thoroughly discussed by several authors [6,[29][30][31][32]. The two lowest states in Fig.…”

Isomeric cross section of theAu197(n,2n) reaction

“…The possible existence of a rotational band built on this intrinsic structure for doubly odd nuclei in this region is proposed in Refs. [46] and [47], and rotational bands based on high-j unique parity quasiparticle states (πh9/2, πh11/2, νi13/2) have been reported for Tl isotopes in Ref. [46] and other isotopes in the transitional region Os-Pb (references in Ref.…”