Search

High spin states in the odd–odd nucleus 122Cs have been studied by in-beam γ-ray spectroscopy with a 107Ag(19F,1p3n) fusion-evaporation reaction at a beam energy of 85 MeV. A previously known πh11/2 ⊗ νh11/2 yrast band was confirmed and its spin I was re-examined. A ΔI = 2 band was identified, which together with another known ΔI = 2 band forms a side band of the πh11/2 ⊗ νh11/2 yrast band. The two observed πh11/2 ⊗ νh11/2 bands are proposed as a pair of chiral doublet bands in 122Cs based on a systematic comparison with those in the neighbouring odd–odd Cs isotopes, as well as the relativistic mean field and the triaxial particle-rotor-model calculations.

High-spin states in 122Ba have been investigated in the 107Ag(19F, 4n) reaction by in-beam γ-ray spectroscopic methods. The ground-state band has been observed with spin up to 20 and a negative-parity band is identified with spin state up to 19. A band-crossing in the yrast band is observed at a rotational frequency of ω≈ 0.36 MeV and, in accordance with cranked shell model calculations, is interpreted as arising from the alignment of two h11/2 protons. Strong E1 transitions between the negative-parity and the yrast bands have been observed, which are proposed as possible evidence for octupole correlations.

Levels in the neutron-rich 104Mo nucleus have been investigated by observing prompt γ-rays from the spontaneous fission of 252Cf with the Gammasphere detector array. The ground-state band, the one-phone and the two-phone γ-vibrational bands as well as a quasiparticle band have been confirmed and expanded with spin up to 14. Other two side bands probably built on new quasiparticle states are identified. The possible configurations for the quasiparticle bands are discussed. Two of the quasiparticle bands show larger moments of inertia and may have pair-free characteristics. The levels of the ground-state band, the one-phonon γ-band and the two-phonon γ-band calculated from a general collective model are in close agreement with the experimental data. PACS: 21. 10. Re, 23. 20. Lv, 27. 60. +j, 25. 85. Ca

High spin states in 137Ce have been studied by using the heavy-ion induced reaction 124Sn(18O, 5n) carried out at China Institute of Atomic Energy. Partial level scheme with spin up to (43/2-), including a high spin collective rotational band observed for the first time, has been established. The collective band shows the properties similar to those oblate bands with ? ~ -60? in neighboring nuclei and probably originates from the five quasi-particle configuration ?s1/2 ? [?h11/2]2 ? ?g7/2 ? ?h11/2. The characteristics of this oblate band have been discussed.

High spin states in neutron-rich odd-N 145Ba nucleus have been investigated from study of prompt γ-rays in spontaneous fission of 252Cf. The alternating parity bands are identified indicating octupole deformation with simplex quantum number s = -i. The ground state band shows signature splitting and inversion at low spin. These collective band structures exhibit the competition and co-existence between symmetric and asymmetric shapes.

High spin states in 138Ce have been investigated following heavy-ion induced reactions carried out at the China Institute of Atomic Energy, Beijing. Two collective rotational bands were established for the first time. These two bands show oblate deformation with γ = -60° and probably originate from the four quasiparticle configurations πg7/2 ⊗ πh11/2 ⊗ νh11/2 ⊗ νd3/2 and πg7/2 ⊗ πh11/2 ⊗ [νh11/2]2, respectively. These oblate bands exhibit strong M 1 transitions, no signature splitting and different moments of inertia from those of prolate bands.

The levels in neutron-rich odd-A 107,109Ru nuclei have been investigated by using γ-γ- and γ-γ-γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from ν(d5/2 + g7/2) quasiparticle configurations and the negative parity bands are from νh11/2 orbital.