مقالات رزومه دکتر هادی صبری

In this study, the statistical correlation of the electric quadrupole transition probabilities in the spherical nuclei is investigated. To this aim, the spherical even-even nuclei in the 100 < A < 126 mass region are selected and the electric quadrupole transition rates of different levels in the ground band are determined by the interacting boson model in the U(5) dynamical limit. A non-parametric kernel density estimation method is used in the framework of nearest neighbor spacing distribution of random matrix theory to consider the statistical correlation of these quadrupole transition rates. Also, the Kullback-Leibler divergence is used to describe the regular or chaotic behavior of the considered sequences. The results show the correlation of the electric quadrupole transition probabilities between different levels of the ground band. Also, the correlation increased for such transitions that the angular momentum of the initial state of quadrupole transitions increased.

The electric quadrupole transition probabilities of 98-104Ru isotopic chain are investigated in the both shell and interacting boson models frameworks. The OXBASH code for shell model and the SU(1,1)-affine infinite dimensional algebra for interacting boson model are used to determine the quadrupole transition rates. Also, the dependence of calculation accuracy and the effective charges to quadrupole deformation and experimental half-lives are considered and the quadrupole moments are computed for these nuclei. The shell model make exact results for such nuclei which are located near the closed shell and also verified the existence of closed sub-shell at N=58 neutron number. On the other hand, the interacting boson model make more exact results for nuclei which have signatures of deformation and also the quadrupole intra-band transition rates. The results suggest a shape coexistence in the 102Ru nucleus.

In this paper, the Hamiltonian of Bohr-Mottelson model was solved to determine the energy levels and also energy surfaces of 190Hg nucleus in the Z(5) critical point. The Morse and Harmonic oscillator potentials are used for radial and angular parts of Hamiltonian, respectively. The asymptotic iteration method is used to solve radial equation and the constants of model are extracted in comparison with experimental data. The results are compared with the predictions of previous studies which solved Bohr-Hamiltonian in this critical point with using infinite well potential for radial part and also the predictions of O(6) dynamical limit of interacting boson model. Significant improvements are yield with using Morse potential in determination of energy levels of excited energy bands. Also, the results of this potential show more corresponding with the predictions of O(6) dynamical model.

The aim of this paper is to calculate the effective quadruple deformation of different levels in the Nd isotopic chain in the framework of the boson interaction model. For this purpose, by labeling the selected states in the form of the dynamic limit of U(5), the expectation value of the quadruple interaction operator is calculated and the quadruple shape invariant and the Effective quadruple deformation of levels are obtained and compared to the corresponding experimental values, the effective boson charge for each isotope has been determined. The results show the existence of overlap in the values of the effective quadruple deformation of 0_3^+ and 2_1^+ levels in this isotopic chain. Also, a certain relationship is observed between the effective quadruple deformation values and the effective Boson charge and the spacing of the levels. The existence of this dependence for the Nd isotopic chain and the overlap of quantities can be reported as signs of shape coexistence in (_60^140)Nd and (_60^142)Nd and (_60^146)Nd isotopes.

In this paper, the spectral statistics of prolatedeformed nuclei are investigated by using random matrix theory. To this aim, we used both available experimental data and also the energy levels of ground, beta, and gamma bands of 51 deformed even-even nuclei, which are determined via partial SU(3) dynamical symmetry limit of interacting boson model. The results verified the ability of the considered models in the restoration of experimental data and also the displacement of beta and gamma energy bands. Also, the dependence of the statistical situation of energy levels is considered to the mass of nuclei, spins, half-lives of the ground state, bands of energy, and different configurations of excited bands of energies. The results suggested obvious differences in the spectral situation of the levels in different rotational bands and also different mass regions. Also, the displacement of levels and the lower energy of  state in comparison with level reduce the correlation of levels in spectral statistics.

In this paper, the 180-188Hg isotopic chain is studied in the transitional region between the prolate and oblate shapes. To this aim, we have used a two parametric transitional Hamiltonian in the interacting boson model. With using Catastrophe theory in combination with coherent state formalism, we have determined the energy surfaces in this transitional region. The results of this study for energy levels and quadrupole transition probabilities are in the satisfactory agreement with experimental counterparts. Also the results for the control parameter of transitional Hamiltonian and the variation of energy surfaces propose a first order phase transition in this isotopic chain and suggest 188Hg nucleus as the best candidate for the O(6) dynamical symmetry limit or Z(5) critical point symmetry.

In this paper, we have considered the energy levels and energy surfaces of nuclei located between the spherical and the gamma soft shapes. We have used a three levels spd-interacting boson model which are defined in the affine SU(1,1) algebra to describe both positive and negative parity states. The energy surfaces of 100-106Ru isotopes are determined via catastrophe theory and coherent states formalism in the U(5)-SO(9) transitional region of interacting boson model. The agreement between the theoretical prediction of model and the most recent experimental counterparts is acceptable. Also, the variation of the energy surface’s shapes suggest a second order shape phase transition in this isotopic chain. The values of the control parameters and also the shape of energy surfaces suggest 100Ru as the best candidate for the critical point of this transitional region.

In this paper, we have studied the spectral statistics of 101 even-even nuclei in the nearest neighbor spacing distribution framework. Sequences are prepared by using all the latest experimental data for 2 levels of considered nuclei in the 40 ≥ A≥198 mass region. The maximum likelihood estimation technique has been used to extract the Berry-Robnik distribution’s parameter which explores the regular or chaotic behavior of considered sequences. Sequences are classified as their mass, quadrupole deformation parameter, the energy ratio and the shell model configuration for the last protons and neutrons of all nuclei. Our results suggest a regular dynamics for these even mass nuclei. Also, the regularity is increased for light nuclei vis-a-vis heavier ones and also the deformed nuclei vis-a-vis spherical ones. Our results show a deviation of chaotic dynamics when the spins of proton levels are decreased or the spins of neutron levels are increased.

In this paper، we have considered the energy spectra and quadruple transition probabilities of even-even Er isotopes via partial dynamical symmetry in interacting boson model framework. The advantage of using interactions with a partial dynamical symmetry is that they can be introduced، in a controlled manner، without destroying results previously obtained with a dynamical symmetry for a segment of the spectrum. Partial dynamical SU (3) symmetry has an accurate description for nuclei which exhibit rotational deformed structure because of removing undesired degeneracies from energy spectrum of them. The agreement with the most recent experimental counterparts is acceptable. Also، there are some suggestions about the reduction of uncertainty with increasing the neutron number and quadrupole deformation parameter.

Using experimental data، the Nearest Neighbor Spacing Distribution (NNSD) function for both stable and radioactive nuclei was directly calculated by kernel density estimation (KDE) method and the distance between the obtained function and regular and chaotic limits was determined using Kullback-Leibeller Divergence (KLD) method. The results show that stable nuclei have more regular spectra than radioactive nuclei and nuclei with alpha decay have more irregular spectra than other nuclei. This indicates that stable nuclei have a more symmetrical structure than radioactive nuclei.