Systematic study of fusion barrier characteristics within the relativistic mean-field formalism

Abstract

Background: Heavy-ion fusion reactions play a crucial role in various aspects of nuclear physics and astrophysics. The nuclear interaction potential and hence the fusion barrier formed between the interacting nuclei are the keys to understanding the complex fusion process dynamics. Thus, a theoretical investigation of fusion barrier characteristics which includes the relativistic effects is of paramount significance. Purpose: This work intends to explore the fusion barrier characteristics of different target-projectile combinations within the relativistic mean-field (RMF) formalism. The M3Y nucleon-nucleon (NN) potential is compared with the relativistic R3Y and density dependent R3Y (DDR3Y) NN potentials within the double folding approach. A systematic study is carried out to study the effect of different RMF density distributions and effective NN interactions on the fusion and/or capture cross-section of twenty-four (24 nos) target-projectile combinations leading to heavy and superheavy nuclei (SHN). Methods: The density distributions of interacting nuclei and the microscopic R3Y NN interaction are obtained from relativistic mean-field (RMF) formalism for non-linear NL1, NL3, TM1, and relativistic-Hartree-Bogoliubov (RHB) approach for DDME2 parameter sets. The medium independent relativistic R3Y, the density dependent DDR3Y, and widely adopted M3Y NN potential are used to obtain the nuclear interaction potential within the double folding approach. The densities for the projectiles and targets are obtained from the relativistic mean-field approaches. The fusion and/or capture cross-section for the different reaction systems is calculated using the well-known -summed Wong model. Results: The barrier height and position of 24 heavy-ion reaction systems are obtained for different nuclear density distributions and effective NN interaction potentials. We have considered the lighter mass projectile and heavier mass target combinations for synthesizing exotic drip-line nuclei, including the super-heavy nuclei (SHN). These reactions include the even-even 48 Ca+ 154 Sm, 48 Ca+ 238 U, 48 Ca+ 248 Cm, 26 Mg+ 248 Cm; even-odd 46 K+ 181 Ta; odd-odd 31 Al+ 197 Au and 39 K+ 181 Ta and also seventeen other systems for the synthesis of SHN Z=120. The comparison of fusion and/or capture cross-section obtained from the -summed Wong model is made with the available experimental data. Conclusions: The phenomenological M3Y NN potential is observed to give higher barrier heights than the relativistic R3Y NN potential for all the reaction systems. The comparison of results obtained from different relativistic parameter sets shows that the densities from NL1 and TM1 parameter sets give the lowest and highest barrier heights for all the systems under study. The density dependant DDR3Y NN potential is obtained within the Relativistic-Hartree-Bogoliubov approach for the DDME2 parameter set. We observed higher barrier heights and lower cross-sections for DDR3Y NN potential as compared to density-independent R3Y NN potentials obtained for con...