[en] In this mass region, both protons and neutrons can occupy the unique-parity h_11/2 intruder orbitals which play an important role in driving the nuclear shape. The proton Fermi surface lies in the lower part of the h_11/2 subshell, which favors prolate shape, whereas the neutron Fermi surface lies in the middle or upper part of the h_11/2 subshell, which favors oblate shape. Thus, a coexistence of different shapes is expected in these nuclei because of opposite shape-driving forces of protons and neutrons in h_11/2 orbitals. The nuclear electromagnetic moment measurements are crucial to give unambiguous information about the configuration and the shape of the nucleus. Two isomeric band heads are observed in ¹²⁹Ba i.e., I = 9/2^- (T_1/2 = 18ns) and I = 23/2⁺ (T_1/2 = 63ns). Both the rotational bands belong to high-j neutron configuration having different deformation driving forces

[en] The study of the decoupling effects in the even-even ¹²⁶Ba nucleus has been completed. The study of spins and parities of the even-odd ¹²⁹Ba nucleus was carried out in Grenoble, France. The measurement of linear polarization of gamma rays in these nuclei revealed anomalous negative parity bands. The negative parity levels in even-even light barium isotopes can be interpreted as coriolis decoupled two-quasiproton configurations in which the h/sub ¹¹/₂/ proton plays a prominent role. On the other hand, the negative parity levels in the even-odd light barium isotopes are strikingly different, and can be interpreted as due to the rotation-alignment coupling of h/sub ¹¹/₂/ neutron holes to the triaxial core. 1 table, 2 figures

[en] The even-even nuclei in the mass A = 130 region exhibit extreme softness to γ-deformation. The change in γ-deformation results in vulnerability to shape polarisation with the addition of an extra nucleon. The previous studies on odd-A Ba nuclei concluded that the quadrupole deformation decreased with increasing neutron number and the γ-deformation changed to a larger extent around ¹³³Ba nucleus. Here, We focus on one of the band in ¹²⁹₅₆ Ba nucleus. In present work, experimental B(M1)=B(E2) ratios were obtained for the previously identified h_11/2 band and compared with the theoretical calculations using the Donau formula. The B(M1)/B(E2) ratios are measured for previously identified h_11/2 band. The rotational limit formalism and the Danau formula are used to calculate the theoretical estimates with and without mixing having K = 9=2 & K = 11=2. The results are in agreement with changing value of γ-deformation

[en] The level structure of ¹²⁹Ba has been studied by the ¹²⁰Sn(¹²C,3nγ) reaction. A set of negative-parity levels based upon a 9/2^- state is interpreted in terms of the rotation-alignment coupling of hsub(11/2) neutron holes to the triaxial core. A new band structure built upon a 7/2⁺ state is also observed. It could be due to the coupling of a gsub(7/2) neutron hole to the triaxial core

[en] The structure of ¹²⁹Ba is investigated through the beta decay of ¹²⁹La, whose half-life is measured to be 11.6+-0.2m. The decay properties are studied by means of beta, gamma and conversion electron spectroscopy techniques. Many transitions are observed and a level scheme of ¹²⁹Ba with deduced Jsup(π) values is proposed. The total decay energy of ¹²⁹Ba is measured to be 3.72+-0.05 MeV, which is compared with predictions of mass formulae. Low-lying struture of ¹²⁹Ba is discussed in terms of collective models. (orig.)

[en] The transitional nuclei in the A∼130 mass region with few valence nucleons near shell closure offer to study rich variety of shapes and structures due to interplay of various multi quasiparticle excitations and the collective behavior of underlying core. Many experimental studies based on gamma-ray spectroscopy with heavy ion-induced reactions evidenced mainly high-spin level structures, an outstanding one being that due to the unique parity orbital h_11/2 both for protons and neutrons. The different deformation driving forces of the valence protons and neutrons occupying low and high Ω states of the h_11/2 intruder orbital leads to phenomenon of shape coexistence. With increasing angular momentum, the calculated potential energy surfaces, soft in the γ-degree of freedom, show two distinct minima corresponding to collective prolate and oblate shapes. One of the nuclear models first used to understand the experimental features observed was the particle-triaxial core model, whose application to the Ba isotopes revealed the importance of triaxial deformation in this nuclear region. A sensitive test of the model is the measurement of electromagnetic moments of nuclei. The knowledge of the static magnetic dipole moments is very important for elucidating the structure of coexisting shapes, as they are providing independent information on the underlying configurations. The present work is devoted to the investigation of the magnetic moments for two isomeric states with spin-parities 9/2^- ( τ_1/2 = 14ns) and 23/2⁺ (τ_1/2 = 47ns) in ¹²⁹Ba

No abstract available

[en] We have determined the isomeric ratios in ¹³⁰Ba(γ, n)^129m,gBa, ¹³²Ba(γ, n)^131m,gBa and ¹³⁴Ba(γ, n)^133m,gBa photonuclear reactions of natural barium induced by bremsstrahlungs with end-point energies in the giant dipole resonance region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured with spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray 1332 keV of ⁶⁰Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results were discussed and compared with those of other authors. (author)

[en] It is demonstrated that recent experimental results on high spin states of ^128,129Ba offer substantial new evidence for static octupole deformation in these nuclei. (orig.)

No abstract available