Azam Kardan

The structures of yrast normal-deformed (ND) bands in Hf isotopes have been investigated using the unpaired cranked Nilsson-Strutinsky (CNS), and the paired cranked Nilsson-Strutinsky-Bogoliubov (CNSB) models. New optimized Nilsson parameters have been derived and used in the models to interpret the experimental data in Hf168-175 isotopes. The calculated kinematic moments of inertia, as well as the excitation energies of the yrast bands, have been compared with the experimental findings, and good agreements are observed. Configuration changes along the yrast lines have been traced by the aid of the CNS calculations. The calculated single-particle excitations shed more light on the nature of the crossings and successfully explain some features of the observed rotational bands which had not been clear before. © 2018 American Physical Society.

We have theoretically studied the potential barrier between triaxial superdeformed (TSD) and normal deformed (ND) wells in {161,163,167,168}Lu and {168}Hf nuclei within the framework of the cranked Nilsson-Strutinsky model. We show that the theoretical TSD-ND barrier has disappeared or is narrow or shallow where the experimental TSD-ND electromagnetic transitions are observed, while a theoretical high barrier is seen in nuclei excluding the experimental TSD-ND decay. Also, our calculations show that the barrier between TSD and ND wells decreases with increasing the neutron number. © The Author(s) 2017. Published by Oxford University Press on behalf of the Physical Society of Japan.

We have studied the Nilsson potential energies at different deformation parameters using a code based on the perturbative treatment. Special attention is given to the projection of a proton state at different deformations on the asymptotic basis functions. Our calculations show that the spin-orbit and the orbital angular momentum terms couple different asymptotic eigenstates, Nilsson Hamiltonian being hence not diagonal in these basis functions. Therefore, at least at deformations ε2≥4.4 IMAGE0.4, the asymptotic quantum numbers are not good quantum numbers. © 2017, Isfahan University of Technology. All rights reserved.

Effect of the nuclear hexacontatetrapole deformation on the rotational structure of 158Er is analyzed using the Cranked Nilsson-Strutinsky (CNS) approach. Our calculations show that it will lead to a decrease of the total energy of ∼ 700keV in the strongly deformed (SD) region and only a few keV in the triaxial superdeformed (TSD) region. Therefore, it is concluded that the effect of the hexacontatetrapole deformation is significant for SD shapes and essentially negligible for TSD shapes. © 2017 World Scientific Publishing Company.

The isomeric states 8− and 16+ in 178Hf are analyzed within the framework of unpaired Cranked Nilsson-Strutinsky (CNS) model including Strutinsky renormalization and the Lublin-Strasbourg Drop (LSD) and Finite Range Liquid Drop (FRLDM) liquid drop methods. Special attention is given to the potential energy surfaces to determine the deformation parameters in the ground and isomeric states. Our calculations show that the hexadecapole deformations in the isomeric states are somewhat larger than those in previous study. Also, the pairing correlation has no effects on the isomeric states shape, while has a significant effects on the excitation energies. © 2017, Editura Academiei Romane. All rights reserved.

Fission barrier of the heavy nucleus 250Cf is analyzed in a multi-dimensional deformation space. This space includes two quadrupole (ϵ2,γ) and three hexadecapole deformation (ϵ40,ϵ42,ϵ44) parameters. The analysis is performed within an unpaired macroscopic-microscopic approach. Special attention is given to the effects of the axial and non-axial hexadecapole deformation shapes. It is found that the inclusion of the nonaxial hexadecapole shapes does not change the fission barrier heights, so it should be sufficient to minimize the energy in only one degree of freedom in the hexadecapole space ϵ4. The role of hexadecapole deformation parameters is also discussed on the Lublin-Strasbourg drop (LSD) macroscopic and the Strutinsky shell energies. © 2016 World Scientific Publishing Company.

The nuclear potential energies of Lu isotopes with neutron number N = 90-98 up to high spins are computed within the framework of the unpaired cranked Nilsson-Strutinsky method. The potential and the macroscopic Lublin-Strasbourg drop (LSD) energy-surface diagrams are analyzed in terms of quadrupole deformation and triaxiality parameter. The shape evolution of these isotopes with respect to angular momentum, as well as the neutron number is studied. © 2016 World Scientific Publishing Company.

Selected high-spin bands in A = 120-170 nuclei are interpreted within the configuration-constrained Cranked Nilsson-Strutinsky formalism with pairing neglected (CNS) and with pairing included (CNSB). A few bands in Lu/Hf nuclei which have been interpreted as formed at large triaxial deformation are reinterpreted as rotational bands at small deformation approaching termination. The differences between the linked high-spin rotational bands in 125,126Xe are explored, suggesting that the bands in 126Xe terminate high above yrast at close to spherical shape.

High-spin states in 123I were populated in the reaction 80Se(48Ca,p4n)123I at a beam energy of 207 MeV and γ-ray coincidence events were measured using the Gammasphere spectrometer. Three weakly populated, high-spin rotational bands have been discovered with characteristics similar to those of the long collective bands recently observed in other nuclei of this mass region. Configuration assignments are proposed based on calculations within the framework of the cranked Nilsson-Strutinsky approach. ©2012 American Physical Society.
PUBLISHER: American Physical Society