High-spin bandcrossing in 129Ba

doi:10.1016/0375-9474(92)90080-4

Nuclear Physics A

Volume 548, Issue 1, 5 October 1992, Pages 131-158

https://doi.org/10.1016/0375-9474(92)90080-4 Get rights and content

Abstract

The high-spin structure of ¹²⁹Ba was investigated via in-beam γ-ray spectroscopy allowing many new transitions to be placed in the level scheme. Two isometric states with lifetimes of τ = 23 (2) ns (182 keV level) and 68 (2) ns (2463 keV level) were identified. A high-K 3-quasineutron configuration $[72^{+} [404]⊗ 72^{−} [523]⊗ 92^{−} [514]]$ is proposed for the latter. A discussion of the high-spin structure and the deformation driving effects in ¹²⁹Ba is presented in terms of the cranked shell model. The conclusion reached is that the alignment gains are dominated by $h_{112}$ proton pairs.

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Diversity of shapes and rotations in the γ-soft 130Ba nucleus: First observation of a t-band in the A = 130 mass region
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Several new bands have been identified in ¹³⁰Ba, among which there is one with band-head spin $8^{+}$ . Its properties are in agreement with the Fermi-aligned $ν h_{11 / 2}^{2}$ , $7 / 2^{-} [523] \otimes 9 / 2^{-} [514]$ Nilsson configuration. This is the first observation of a two-quasiparticle t-band in the $A = 130$ mass region. The t-band is fed by a dipole band involving two additional $h_{11 / 2}$ protons. The odd-spin partners of the proton and neutron S-bands and the ground-state band at high spins are also newly identified. The observed bands are discussed using several theoretical models, total Routhians surfaces (TRS), tilted axis cranking (TAC), particle rotor model (PRM) and projected shell model (PSM), which strongly suggest the coexistence of prolate and oblate shapes polarized by rotation aligned two-proton and two-neutron configurations, as well as prolate collective rotations around axes with different orientations. With the new results, ¹³⁰Ba presents one of the best and most complete sets of collective excitations that a γ-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the $A = 130$ mass region.
Fabrication of 121Sb isotopic targets for the study of nuclear high spin features
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Isotopic ¹²¹Sb targets with ¹⁹⁷Au backing have been prepared by Physical Vapor Deposition (PVD) method using the diffusion pump based coating unit at target laboratory, Inter University Accelerator Centre (IUAC), New Delhi, India. The target thickness was measured by stylus profilo-meter and the purity of the targets was investigated by Energy Dispersive X-ray Analysis (EDXA). One of these targets has been used in an experiment which was performed at IUAC for nuclear structure study through fusion evaporation reaction. The excitation function of the ¹²¹Sb(¹²C, $y x n γ$ ) reaction has been performed for energies 58 to 70 MeV in steps of 4 MeV. The experimental results were compared with the calculations of statistical models : PACE4 and CASCADE. The methods adopted to achieve best quality foils and good deposition efficiency are reported in this paper.
Anomalous magnetic moment at Ba in Au
2015, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
The Time differential perturbed angular distribution $(TDPAD)$ technique is employed to measure the local susceptibility at the recoil implanted Ba ions in Au following the nuclear reaction ¹²⁰Sn(¹²C, 3nγ)¹²⁹Ba. We have observed first time the local paramagnetic susceptibility of 5.26(18) at Ba ions comparable to 4f-ions in any non-ferromagnetic metal at room temperature which seems to be related to the electronic s–d and s–f transfer at positive lattice pressure.
Nuclear Data Sheets for A = 129
2014, Nuclear Data Sheets
The experimental nuclear spectroscopic data for known nuclides of mass number 129 (Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm) have been evaluated and presented together with adopted properties for levels and γ rays. This evaluation represents a revision of the previous one 18 years ago by Y. Tendow (1996Te01). Extensive new data have become available for many nuclides in the intervening years, although, no data are available for excited states in ¹²⁹Pm and ¹²⁹Sm, and for ¹²⁹Ag and ¹²⁹Cd, only limited information is available for the g.s. and isomers. The decay schemes of ¹²⁹Ag, ¹²⁹Pm and ¹²⁹Sm are unknown, and those for ¹²⁹Cd, ¹²⁹In, ¹²⁹Ce, ¹²⁹Pr and ¹²⁹Nd are incomplete. Many γ rays and extended level schemes have been reported for the ground state and isomer decays of ¹²⁹Ba to ¹²⁹Cs, yet the adopted set of intensities in this evaluation originate from a brief paper in an annual laboratory report. There remain several unplaced gamma rays, coupled with ambiguity about division of intensities amongst the two activities of ¹²⁹Ba with nearly the same half-lives. Isomerism is expected in ¹²⁹Pr, but there is no confirmed identification. Low-lying level structure in ¹²⁹Nd, including identification of a possible third long-lived isomer in this nuclide, remains uncertain.
The spin-parity assignments of (5/2+) for the ground state and (7/2−) for an isomer at 107.6 keV in ¹²⁹Ce are assigned based on strong support from systematics and band configurations, yet this result is in contradiction with the quadrupole interaction hyperfine structure measurement which favors 9/2− over 7/2− for the isomer, consequently 7/2+ for the ground state. Direct measurements of spins of ground state and isomer of ¹²⁹Ce are needed to settle this issue. Confirmed spins and parities of the ground state and isomer of ¹²⁹La are also lacking. Assignments in this work are mainly based on systematics of $h_{11 / 2}$ decoupled structures. A direct measurement of ground state spin of ¹²⁹La will also be desirable.
Recommended data presented in this work supersede those in previous NDS evaluations of A=129 nuclides published by 1996Te01, 1983Ha46 and 1972Ho55.
Single particle excitations in 129Ba from a (→d, t) reaction study
1998, Nuclear Physics A
The ¹³⁰Ba( $d, t)$ ¹²⁹Ba reaction was studied with 25 MeV deuterons and excellent energy resolution. About 50 excited states have been observed up to E_x = 2.0 MeV and for 42 of them transferred ℓ values and/or J^π values were assigned on the basis of the measured angular distributions and asymmetries. The level scheme of ¹²⁹Ba, the neutron pickup strength distribution and the known electromagnetic decay scheme are compared with results of calculations with the interacting boson-fermion model. These simple multi-shell IBFM-1 calculations describe well the main features of the experimental data.
Nuclear data sheets for A=129
1996, Nuclear Data Sheets
Abstract:The 1983 evaluation of A = 129 (83Ha46) has been updated using experimental decay and reaction data received by the cutoff date noted below.
Cutoff Date:All data available before December 31, 1995, have been considered for inclusion in this evaluation.
General Policies and Organization of Material:See the January issue of Nuclear Data Sheets.
Acknowledgments:The author would like to thank the staff of the Nuclear Data Center, Japan Atomic Energy Research Institute, for their support. The many useful comments and suggetions by the reviewer and Editor-in-Chief, are gratefully appreciated. I also thank T. Tamura for his helpful comments, and Y. Kidachi for her aid in the preparation of this evaluation.

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¹: Permanent address: II Physikalisches Institut, Universität Göttingen, D-3400 Götingen, Germany

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Nuclear Physics A

Abstract

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Cited by (27)

Diversity of shapes and rotations in the γ-soft <sup>130</sup>Ba nucleus: First observation of a t-band in the A = 130 mass region

Fabrication of <sup>121</sup>Sb isotopic targets for the study of nuclear high spin features

Anomalous magnetic moment at Ba in Au

Nuclear Data Sheets for A = 129

Single particle excitations in <sup>129</sup>Ba from a (<sup>→</sup>d, t) reaction study

Nuclear data sheets for A=129