C. S. Han

NEGATIVE-PARITY STATES OF N = 88 ISOTONES IN THE INTERACTING BOSON APPROXIMATION

Abstract The negative-parity states of N =88 isotones are studied systematically in terms of the interacting boson approximation A mass-independent effective interacting boson hamiltonian reproduced energy levels very well. Unified E1 and E3 transition operators are found. The effect of p bosons on the energy spectra and electromagnetic transitions is discussed.

IBA calculations on the even-even Pt isotopes

Abstract By performing least-squares-fit calculations on the energy spectra of the even-even 186–196 Pt isotopes, the IBA model I and the IBA model II are compared on an equal footing. It is found that both model I and model II can fit energy spectra and absolute B (E2) transition rates reasonably well. Model II shows a distinct improvement in the energy spectra of β-bands of heavier nuclei in the isotope series. It is suggested that for regions far from the closed shells model I may be used to simulate model II as a useful phenomenological probing tool.

CALCULATION OF ENERGY-SPECTRA IN N = 28 NUCLEI

Energy spectra of the nuclei for N=28, 22<or=Z<or=26 are calculated within the framework of the shell model by using a two-range central-plus-tensor potential proposed by Schiffer (1976). An inert 48Ca core is assumed. Calculations are made in several basic vector spaces. Good isospin is included for the case of one proton excitation.

Multichannel nucleon-α and α-α interactions

The nucleon-alpha and alpha-alpha interactions are obtained for the multichannel case in which the internal structure of the alpha particle is approximately represented by a two-state system. In this model the nucleon-alpha and alpha-alpha interactions are represented by l-dependent 2*2 and 3*3 matrices respectively. The corresponding Schrodinger equations are diagonalized by a unitary transformation to obtain exact expressions for the total cross section and the phase shift in terms of the potential parameters which are determined from the low-energy two-body scattering data.The nucleon-alpha and alpha-alpha interactions are obtained for the multichannel case in which the internal structure of the alpha particle is approximately represented by a two-state system. In this model the nucleon-alpha and alpha-alpha interactions are represented by l-dependent 2 x 2 and 3 x 3 matrices respectively. The corresponding Schrodinger equations are diagonalized by a unitary transformation to obtain exact expressions for the total cross section and the phase shift in terms of the potential parameters which are determined from the low-energy two-body scattering data.

Multichannel nucleon-alpha and alpha-alpha interactions?

The nucleon-alpha and alpha-alpha interactions are obtained for the multichannel case in which the internal structure of the alpha particle is approximately represented by a two-state system. In this model the nucleon-alpha and alpha-alpha interactions are represented by l-dependent 2*2 and 3*3 matrices respectively. The corresponding Schrodinger equations are diagonalized by a unitary transformation to obtain exact expressions for the total cross section and the phase shift in terms of the potential parameters which are determined from the low-energy two-body scattering data.The nucleon-alpha and alpha-alpha interactions are obtained for the multichannel case in which the internal structure of the alpha particle is approximately represented by a two-state system. In this model the nucleon-alpha and alpha-alpha interactions are represented by l-dependent 2 x 2 and 3 x 3 matrices respectively. The corresponding Schrodinger equations are diagonalized by a unitary transformation to obtain exact expressions for the total cross section and the phase shift in terms of the potential parameters which are determined from the low-energy two-body scattering data.

THE IBA STUDY AND THE EFFECTIVE BOSON CALCULATION FOR ER ISOTOPES

Abstract The structure of even-even Er isotopes with neutron number 86 ⩽ N ⩽ 96 are studied within the framework of the IBA model. We first perform a traditional IBA calculation by taking Z = 64 and N = 82 as a closed shell. The agreements between the calculated and the observed energy levels are not good even when a g-boson is included in the calculation. This means that Z = 64 and N = 82 is not a good closed shell. In order to take into account the partially closed effects near Z = 64, a smooth variation of the effective boson numbers are assumed. The energy levels and B (E2) values of the above nuclei are calculated. It is found that the agreements between the theoretical and observed data are much better in the model of the effective boson consideration.

Effective interactions and energy spectra for N=28, 29 and 30 nuclei

A two-range central-plus-tensor potential is assumed for the effective nucleon-nucleon interactions in the shell-model calculation of N=28, 29 and 30 isotopes. A model space of (f72/n-1, (3/2, p12/, f5/2)) is assumed for the proton configuration of N=28 nuclei. The correct isospin wavefunctions proposed by Osnes (1970) are considered. For N=29 and 30 nuclei, the protons are restricted to the 1f7/2 orbit, and the valence neutrons are allowed to distribute in the 2p3/2, 2p1/2 and 1f5/2 shells. Energy level spectra for N=28, 29 and 30 nuclei are calculated in a Talmi-type calculation. The calculated results are in good agreement with the experimental observations.