Interacting Boson Fermion Model Research Articles

SU(6) quadrupole phonon model for even and odd nuclei and the SU(3) limit

Analogous to the equivalence between the SU(6) quadrupole-phonon model (TQM) and the interacting boson model (IBM), the equivalence is pointed out for odd systems between the SU(6) particle quadrupole-phonon coupling model (PTQM) and the interacting boson-fermion model (IBFM). PTQM is formulated starting from the Dyson representation for the odd system. Different aspects of the SU(3) limit of TQM and PTQM are studied; the quadrupole-phonon block structure of rotational bands in even and odd nuclei and analytic expressions based on the coherent state; signature effects generated in PTQM; electromagnetic properties and correction factors for PTQM; overlaps of the PTQM analogs of Nilsson states with Coriolis-coupled Nilsson states and the relation to the rotational model representation.

A test of the interacting boson fermion model and its microscopic basis in transitional Tc and Ag nuclei

Parameters of the interacting boson fermion model obtained by fitting the model to the spectra of four nuclei in the 1g 9 2 shell have been compared with the values given by microscopic formulas taking into account the two-particle structure of the bosons.

Multilevel calculations in odd- A nuclei

The formalism of the Interacting Boson-Fermion Model (IBFM) permits the calculation of the low-lying spectra of odd-mass nuclei, including several single-particle degrees of freedom. Moreover, it allows one to treat cases in which the mixing of these separate degrees of freedom is not weak. We present here the application of this formalism to the study of the positive parity states in the transitional nucleus 131Xe, for which the 3 s 1 2 , 2 d 3 2 , 2 d 5 2 and 1 g 7 2 neutron levels play a major role.

Evidence of boson cut-off in the aligned [formula omitted] band in 79Rb

Electronic timing, recoil distance and DSA lifetime measurements were performed for the states of the decoupled g 9 2 proton band in 79Rb, up to 29 2 + , by means of the reactions 70Ge( 12C, p2n) and 63C( 19F, p2n). It was found that the B(E2) values of the higher in-band transitions are reduced with respect to the predictions of the rotational alignment model, but agree well with the interacting boson fermion model. This effect is attributed to the finite boson number N = 8 of the 78Kr core.

Band structure of odd-Arubidium isotopes in the interacting boson fermion model

Energy spectra and E2 matrix elements have been calculated by means of the interacting boson fermion model for /sup 79,81,83/Rb. A more schematic description obtained by assuming that the extra proton which is coupled to an even-even Kr core is in a pure g/sub 9/2/ particle state has been compared with calculations within a larger model space including the d/sub 5/2/ and g/sub 7/2/ particle states. We find that it is possible to achieve excellent agreement for both the schematic and the more detailed calculation as far as only level energies are concerned. However, the choice of the model space turns out to have a strong influence on the model parameters. Moreover, we find that B(E2) values differ considerably in both descriptions. We conclude that even if there is a large separation between shells, the mixing due to the strong core-particle quadrupole force does not allow for restricting the model space to a single j shell.