Falih H. Al-Khudair

Competition in rotation-alignment between high-j neutrons and protons in transfermium nuclei

The study of rotation-alignment of quasiparticles probes sensitively the properties of high-j intruder orbits. The distribution of very-high-7 orbits, which are consequences of the fundamental spin-orbit interaction, links with the important question of single-particle levels in superheavy nuclei. With the deformed single-particle states generated by the standard Nilsson potential, we perform Projected Shell Model calculations for transfermium nuclei where detailed spectroscopy experiments are currently possible. Specifically, we study the systematical behavior of rotation-alignment and associated band-crossing phenomenon in Cf, Fm, and No isotopes. Neutrons and protons from the high-7 orbits are found to compete strongly in rotation-alignment, which gives rise to testable effects. Observation of these effects will provide direct information on the single-particle states in the heaviest nuclear mass region.

γ-vibrational states in superheavy nuclei

Recent experimental advances have made it possible to study excited structure in superheavy nuclei. The observed states have often been interpreted as quasiparticle excitations. We show that in superheavy nuclei collective vibrations systematically appear as low-energy excitation modes. By using the microscopic Triaxial Projected Shell Model, we make a detailed prediction on {gamma}-vibrational states and their E2 transition probabilities to the ground state band in fermium and nobelium isotopes where active structure research is going on, and in {sup 270}Ds, the heaviest isotope where decay data have been obtained for the ground-state and for an isomeric state.

Isospin and symmetry structure in the f7/2 shell 44–48Ti isotopes

The interacting boson model 3 has been used to study the nuclear level structures and electromagnetic transition probabilities for Ti44-48 isotopes. This helps us to identify some low-lying mixed symmetry states. We have analysed the wavefunctions and given the symmetry labelling of the states. The analysis is consistent with the available data. The isospin excitation states with T > T-Z are also studied, and comparison with experimental data is given.

Isospin and F-spin symmetry structure in low-lying levels of 48,50Cr isotopes

The low-energy level structure and electromagnetic transitions of 48,50Cr nuclei have been studied using the interacting boson model with isospin (IBM-3). A sequence of isospin excitation bands with isospin T = Tz, Tz+1 and Tz+2 has been assigned and compared with available data. According to this study, the 2+3 and 2+2 states are the lowest mixed symmetry states in 48Cr and 50Cr, respectively. In particular, the present calculations suggest that a combination of isospin and F-spin excitation can explain the structure in these nuclei. The transition probabilities between the levels are analysed in terms of isoscalar and isovector decompositions which reveal the detailed nature of the energy levels. The results obtained are in good agreement with recent experimental data.

Detailed description of mixed symmetry states in Mo-94 using interacting boson model

We have investigated the low-lying collective states and electromagnetic transitions in Mo-94 within the framework of the interacting boson model. The influence of model parameters on the energy levels and electromagnetic properties has been investigated. The analysis of the obtained results and the parameter values predict that the 2(3)(+) state is the lowest mixed symmetry state with pure F = F-max in this nucleus. The calculated results predicate that the 2(5)(+) (two-Q-phonon) mixed symmetry state is closed to the J = 2(+) at 2.870 MeV in the experimental data, and the 2.965 MeV state is the lowest mixed symmetry with J = 3(+).

Low-lying states and isospin excitation in the Ge isotopes

The level structure of 64–70Ge isotopes has been studied within the framework of the interacting boson model-3 (IBM-3). The symmetry character in the proton and neutron degrees of freedom of the energy levels has been investigated. The isospin excitation states (T >Tz) have been assigned for the 64Ge (N = Z) nucleus. Some intruder states in these nuclei have been suggested. The calculated energy levels and transition probabilities are in good agreement with recent experimental data. The study indicates that the Ge isotopes are in transition from γ-unstable to vibrational.

Negative-Parity States and beta-decays in odd Ho and Dy Nuclei with A=151,153

We investigated the negative-parity states and electromagnetic transitions in

Properties of the 0{sub 2}{sup +} state and isospin excitation in the N=Z nucleus {sup 68}Se

^{151,153}\mathrm{Ho}

Triaxial interaction effect in the structure of 148?158Sm

and

Properties of the 0+(2) state and isospin excitation in the N=Z nucleus Se-68

^{151,153}\mathrm{Dy}