Levels in 99Zr observed in the decay of 99Y

New investigation of the decay scheme of 99Y to 99Zr removes minor discrepancies between decay and prompt-fission data.The existence of a strongly coupled band on the 725-keV level postulated in an earlier beta-decay work is not confirmed. Calculations in the IBFM framework allow an alternative interpretation of the even-parity levels above 500 keV

β decay of odd-A As to Ge isotopes in the interacting boson-fermion model

The structure of odd-mass isotopes of As and Ge is described in the framework of the proton-neutron interacting boson-fermion model. The energy levels and the electromagnetic properties of 69, 71, 73As and 69, 71, 73Ge are calculated and compared with the experiment. The beta-decay rates from the As isotopes to the Ge isotopes are calculated. The calculated decays tend to be stronger than the observed ones. This may indicate a mixture of components outside the model space in the wave functions of actual nuclei. The effect of the higher-order terms in the decay operators seems small

β decay of the even-even 124Ba nucleus: A test for the interacting boson-fermion-fermion model

IBFFM is applied to β decay of 124Ba to 124Cs. The interacting boson-fermion-fermion model approach to β decay is applied to the decay from the even-even 124Ba to the odd-odd 124Cs nucleus. The theoretical results for energy levels, electromagnetic properties and β decay rates are compared with experimental data for 124Cs. The calculated β-decay rates demonstrate that the interacting boson approximation can be applied in the description of β decays from even-even to odd-odd nuclei

β decay of odd-A Cs isotopes in the interacting boson-fermion model

The structure of odd-mass isotopes of Cs and Xe is described in the framework of IBFM. The model provides a consistent description of beta decay from Cs to Xe nuclei of mass number A = 125, 127, and 129

Interacting boson-fermion model calculation of the level scheme and electromagnetic properties of 99Zr

A theoretical study of the 99Zr nucleus is presented. Energy levels, wave functions, and electromagnetic rates were calculated in the framework of the interacting boson-fermion model and are compared to the available data for low-lying states. In particular, we discuss the sensitivity of the g factor of the 3/2+1 state to the quenching of the spin gyromagnetic ratio and to the structure of the respective wave function

Interacting boson fermion-fermion model calculation of the h11/2h11/2 doublet bands in 134Pr

The interacting boson fermion-fermion model is employed in the analysis of the positive-parity doublet bands in 134Pr. It is shown that stable triaxial deformation gives rise to the experimentally observed crossing between the yrast and yrare bands built on the h11/2h11/2 configuration. The collective structure of the yrast band is basically built on the ground-state band of the triaxial core, whereas the collective structure of the yrare band is predominantly based on the band of the core. The mixing between the two bands increases with angular momentum. A constant energy spacing between the two lowest positive-parity bands is predicted in other odd-odd N = 75 nuclei with -soft potential energy surfaces

Role of collectivity in the structure of 120,122,124Sb nuclei

Energy spectra, spectroscopic factors and electromagnetic moments of the low-lying states of 120-124Sb have been calculated in the framework of the interacting boson-fermion-fermion model, and compared with the experimental values. It was found that the collectivity has a significant effect on the energy splitting of the multiplets. The dynamical boson-fermion interaction leads to a smoothing of the energy splitting, while the exchange interaction tends to cause a fourth order polynomial splitting in the E* versus J(J+1) plot. The smoothing of the energy splitting can be interpreted in a quasiparticle picture as the lengthening of the range of the p-n effective interaction. The collective and single particle effects have comparable contributions in the electromagnetic moments, and the single particle part of the transfer operator determines the spectroscopic factors

Shape coexistence in the odd-odd neutron-rich nucleus 98Y studied in the interacting boson model

Data on levels in 98Y have been investigated and interpreted using recently published information on band structure in this region. Calculation in the IBM framework suggests that the 1182 keV isomer is spherical 10- state with π g9/2 ν h11/2 configuration. This assignment implies that the 8.0 microsecond bandhead at 496 keV is a 4- state with highly probable π(422)5/2 ν(541)3/2 configuration. The level structure of 98Y is well reproduced by coupling the levels of its both spherical and deformed odd-A neighbors and the origin of the isomeric states is understood

Nuclear structure of 97Y in the interacting boson fermion plus broken pair model and the nature of the 3.523 MeV high-spin isomer

Nuclear structure of 97Y is described in the interacting boson fermion plus broken pair model, including quasiproton and quasiproton-two-quasineutron configurations in the basis states. In particular, the yrast bands and the decay of the 27/2- high-spin isomer are accounted for in this approach

Dynamic chirality in the interacting boson fermion-fermion model

The chiral interpretation of twin bands in odd-odd nuclei was investigated in the interacting boson fermion-fermion model. The analysis of the wave functions has shown that the possibility for angular momenta of the valence proton, neutron and core to find themselves in the favorable, almost orthogonal geometry is present, but not dominant. Such behavior is found to be similar in nuclei where both the level energies and the electromagnetic decay properties display the chiral pattern, as well as in those where only the level energies of the corresponding levels in the twin bands are close together. The difference in the structure of the two types of chiral candidates nuclei can be attributed to different β and γ fluctuations, induced by the exchange boson-fermion interaction of the interacting boson fermion-fermion model. In both cases the chirality is weak and dynamic