Isospin asymmetry dependence of theαspectroscopic factor for heavy nuclei

Abstract

Both the valence nucleons (holes) and the isospin asymmetry dependencies of the preformation probability of an α-cluster inside parents radioactive nuclei are investigated. The calculations are employed in the framework of the density-dependent cluster model of an α-decay process for the even-even spherical parents nuclei with protons number around the closed shell Z 0 = 82 and neutrons number around the closed shells Z 0 = 82 and Z 0 = 126. The microscopic α-daughter nuclear interaction potential is calculated in the framework of the Hamiltonian energy density approach based on the SLy4 Skyrme-like effective interaction. Also, the calculations based on the realistic effective M3Y-Paris nucleon-nucleon force have been used to confirm the results. The calculations then proceed to find the assault frequency and the α penetration probability within the WKB approximation. The half-lives of the different mentioned α decays are then determined and have been used in turn to find the α spectroscopic factor. We found that the spectroscopic factor increases with increasing the isospin asymmetry of the parent nuclei if they have valence protons and neutrons. When the parent nuclei have neutron or proton holes in addition to the valence protons or neutrons, then the spectroscopic factor is found to decrease with increasing isospin asymmetry. The obtained results show also that the deduced spectroscopic factors follow individual linear behaviors as a function of the multiplication of the valence proton (N p ) and neutron (N n ) numbers. These linear dependencies are correlated with the closed shells core (Z 0 , N 0 ). The same individual linear behaviors are obtained as a function of the multiplication of N p N n and the isospin asymmetry parameter, N p N n I . Moreover, the whole deduced spectroscopic factors are found to exhibit a nearly general linear trend with the function N p N n /(Z 0 + N 0 ).

Systematic study of α decay of nuclei around the Z=82, N=126 shell closures within the cluster-formation model and proximity potential 1977 formalism

“…In 1928, the phenomenon of α decay for nuclei was independently explained by Gurney and Condon [1] and Gamow [2] using the quantum tunnel theory. Since then, α decay has long been perceived as one of the most powerful tools to investigate unstable nuclei, neutron-deficient nuclei and superheavy nuclei, and has been an active area of research of nuclear physics [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Preformation probability inside α emitters having different ground state spin-parity than their daughters

“…Other factors are the released energy and the penetration probability. The uncertainties pertaining to the obtained values of the -cluster preformation probability, or the  spectroscopic factor [1,2,3], in the different studies [4,5,6,7,8] make it one of the open problems. The accurate determination of the preformation probability would help in estimating the half-life times of the superheavy elements, suggested to synthesize in future, against their α decay modes.…”

“…Also, the α particle formation probabilities are deduced using the universal decay law method based on the R-matrix [6]. Furthermore, it can be extracted from its explicit relation to the experimental half-life time [2,3,12] and the calculated decay width.…”

Systematics of nucleon density distributions and neutron skin of nuclei

“…The nuclear energy density functional is optimized to provide an adequate approximation of the total energy and the local nuclear local. The SLy4 parameterization of the Skyrme-like force is widely used in different nuclear studies such as the nuclear structure [36,37,38], the nuclear reactions [39,40,41] as well as the decay processes of heavy nuclei [42,43,44]. One of the advantages of the Skyrme force is that it gives simple analytic expressions which are easy to handle with straight forward calculations.…”