Abstract:In this study, we determined the most appropriate Hamiltonian that is needed for present calculations of nuclei in the A ∼ = 80 region by the view of interacting boson model (IBM-2). Using the best-fitted values of parameters in the Hamiltonian, we have calculated energy levels and B(E2) values for a number of transitions in some doubly even Se nuclei. The results were compared with the previous experimental and theoretical data and it is observed that they are in good agreement. The calculations have been extended to Se isotopes with A < 76 for which some B(E2) values are still not known.

The interacting boson model (IBM) has been widely used for describing the quadrupole collective states of the medium-heavy nuclei and no distinction is made between proton and neutron variables when the first version of the model is applied. However, the neutrons' and protons' degrees of freedom are described explicitly in the second version of the model (IBM-2). Moreover, the microscopic foundations certainly state that it is very important to describe the proton and neutron variables explicitly and this is also the generalized definition of the second version of the IBA model (IBM-2 model). So, triaxiality can be described explicitly through the introduction of cubic terms in the boson operators. Using the best-fitted values of parameters in the Hamiltonian of the IBM-2, we have calculated energy levels and B(E2) values for a number of transitions in 122,124,126,128,130,132,134Xe. The results were compared with the previous experimental and theoretical data and it has been observed that they are in good agreement. Many B(E2) values that are still not known so far are stated and the set of parameters used in these calculations is the best approximation that has been carried out so far. It has also turned out that the IBA and Bohr–Mottelson Hamiltonian with Davidson potential are fairly reliable models for the calculation of spectra in the entire set of 122,124,126,128,130,132,134Xe isotopes.

In this study, we determined the most appropriate Hamiltonian that is needed for present calculations of nuclei in the A≅130 region by the view of projection of IBM-2 parameters onto IBM-1. The interacting boson model has been widely used for describing the quadrupole collective states of the medium heavy nuclei and no distinction is made between proton and neutron variables when the first version of the model (IBM-1) is applied. So, triaxiality can be described explicitly, through the introduction of cubic terms in the boson operators. However, the microscopic foundations state certainly that it is very important to describe the proton and neutron variables explicitly. This is also a generalized definition of the second version of the IBA-model (IBM-2 model). Using the best-fitted values of parameters in the Hamiltonian of the IBM-2, we have calculated energy levels and B(E2) values for a number of transitions in 144,146,148,150,152,154Nd. The results were compared with the previous experimental and theoretical data and it is observed that they are in good agreement. Many B(E2) values that are still not known so far are stated and the set of parameters used in these calculations is the best approximation that has been carried out so far. It has turned out that the interacting boson approximation (IBA) is fairly reliable for the calculation of spectra in the entire set of 144,146,148,150,152,154Nd isotopes.

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