“Anomalous” signature splitting in the yrast band of the odd-odd 160Ho nucleus

doi:10.1016/0370-2693(84)91103-1

Physics Letters B

Volume 137, Issues 1–2, 22 March 1984, Pages 47-51

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Abstract

The (¹¹B, 5n) reaction has been used to study the yrast band in ¹⁶⁰Ho up to high spin states (I = 24). A careful analysis of the experimental odd-even staggering of the [i $132$ ]_n[h $112$ ]_p band reveals in “anomalous” signature splitting for this configuration. This effect is compatible with a small triaxial deformation γ = 5°.

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Nuclear Data Sheets for A=160
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The experimental results published before May 2021 from the various reaction and decay studies leading to nuclides of Z=59 to Z=75, ¹⁶⁰Pr, ¹⁶⁰Nd, ¹⁶⁰Pm, ¹⁶⁰Sm, ¹⁶⁰Eu, ¹⁶⁰Gd, ¹⁶⁰Tb, ¹⁶⁰Dy, ¹⁶⁰Ho, ¹⁶⁰Er, ¹⁶⁰Tm, ¹⁶⁰Yb, ¹⁶⁰Lu, ¹⁶⁰Hf, ¹⁶⁰Ta, ¹⁶⁰W, ¹⁶⁰Re in the A=160 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. This work is intended to supersede the previous evaluation of the A=160 nuclides by C.W.Reich (2005Re18), which was published in Nuclear Data Sheets 105, 557 (2005).
Projected shell model study of band spectra and electromagnetic properties of 160-164Ho
2015, Nuclear Physics A
The structure of observed rotational bands in ^160–164Ho isotopes have been studied by employing projected shell model approach. The theoretical results have been obtained for the band spectra, transition energies and electromagnetic quantities for the experimentally known bands in these isotopes. The theoretical results for band spectra and electromagnetic properties are found to be in reasonably good agreement with most of the observed ones.
Nuclear data sheets for A = 160
2005, Nuclear Data Sheets
The experimental results from the various reaction and decay studies leading to nuclides in the $A = 160$ mass chain have been reviewed. The elements included range from Sm ( $Z = 62$ ) through Re ( $Z = 75$ ). These data are summarized and presented, together with adopted level schemes and properties. This work is intended to supersede the previous evaluation of the $A = 160$ nuclides by this author (1996Re22), which was published in Nuclear Data Sheets 78, 547 (1996).
Three-quasiparticle rotational bands in 101Rh: IBFBPM description and signature inversion of the πg<inf>9/2</inf> orbital
2001, Nuclear Physics A
High- and intermediate-spin level structures of the ¹⁰¹Rh nucleus have been studied using the reaction ⁷⁰Zn+³⁶S at 130 MeV bombarding energy. γ-rays were detected with the EUROGAM II detector array. Three new ΔI=1 rotational bands have been observed in this nucleus. The deduced level scheme is compared with results of calculations using Interacting Boson–Fermion plus Broken Pair Model. The model calculations give a consistent description of the one- and three-quasiparticle states providing fair agreement between the observed and calculated level energies and branching ratios. Experimental Routhians of the new high-spin bands and the πg_9/2νh_11/2 bands in the neighbouring Rh and Ag nuclei have been found to exhibit signature inversion. This signature inversion can be interpreted qualitatively as the inversion of the two signatures of the proton g_9/2 orbital caused by triaxial nuclear shape with large positive γ parameter.
Band structures and proton-neutron interactions in 174Ta
1998, Nuclear Physics A
Six rotational bands in the odd-odd nucleus ¹⁷⁴Ta have been populated with the ¹⁶⁰Gd(¹⁹F,5n) reaction. High-spin states were identified using the NORDBALL array. Both signatures of the doubly decoupled $π 12^{−} [541] ⊗ ν 12^{−} [521]$ band and semi-decoupled $π 12^{−} [541] ⊗ ν 72^{−} [633]$ band are observed, in addition to the high-K couplings of the $π 92^{−} [514] ⊗ ν 72^{+} [633]$ , $π 92^{−} [514] ⊗ ν 52^{−} [512]$ , $π 72^{+} [404] ⊗ ν 72^{+} [633]$ , and $π 52^{+} [402] ⊗ ν 52^{−} [512]$ configurations. The signature splitting of the $π 12^{−} [541] ⊗ ν 72^{+} [633]$ band is inverted from the expected splitting, and this is interpreted as being due to a residual proton-neutron interaction. It is shown empirically that this interaction, together with deformation changes, can account for the increased crossing frequency associated with the alignment of $i_{132}$ neutrons in the $π 12^{−} [541]$ bands of odd-Z nuclei.
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1996, Nuclear Physics A
Excited states in ¹⁶⁰Ho, populated in the ¹⁵⁴Sm(¹¹B,5nγ) reaction, were investigated using Compton-suppressed Ge detectors. Four rotational bands were observed and their configurations assigned. The electromagnetic properties of the observed bands were studied and compared with model predictions. An increase of the $B(M1) B(E2)$ ratios in the yrast band for frequencies larger than 0.25 MeV is observed. This confirms an effect previously evinced in this and in other odd-odd nuclei of the rare-earth region. A systematic study of the signature inversion in odd-odd nuclei of the rare-earth region is presented. The variation of the inversion frequency for series of isotones and isotopes shows smooth trends.

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¹: Chercheur CNRS.

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Physics Letters B

Abstract

References (11)

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Nuclear Data Sheets for A=160

Projected shell model study of band spectra and electromagnetic properties of <sup>160-164</sup>Ho

Nuclear data sheets for A = 160

Three-quasiparticle rotational bands in <sup>101</sup>Rh: IBFBPM description and signature inversion of the πg<inf>9/2</inf> orbital

Band structures and proton-neutron interactions in <sup>174</sup>Ta

Collective excitations in <sup>160</sup>Ho and anomalous signature splitting phenomena in odd-odd nuclei