Deformation Effect on Proton Bubble Structure in N = 28 Isotones

Abstract

Purpose: To study the effect of nuclear deformation on proton bubble structure of N = 28 isotones and and compare it with the spherical limits. The reduction of depletion fraction due to deformation can be explained by studying the relative differences in the central densities.Methods: In this work, we have employed relativistic Hartree-Bogoliubov (RHB) model withdensity-dependent meson-exchange (DD-ME2) interaction and separable pairing interaction. We have performed axially constrained calculations to investigate the deformed proton bubble structure in 40Mg, 42Si, 44S, and 46Ar, isotones of N = 28 shell closure.Results: We have observed that the nuclear deformation play againsts the formation of bubble structure. In the spherical limits, the isotones of N = 28 shell closure have pronounced bubble structure with large value of depletion fraction. But, the increase in deformation leads to the disappearance of bubble structure. The internal densities in deformed nuclei are found to increase with deformation which can be related to the decrease in depletion fraction.Conclusion: By using RHB model, we have investigated the ground state and proton bubble structure of N = 28 isotones. In 44S, and 46Ar, the 2s1/21d3/2 states get inverted due to the weakning of spin-orbit strength. Due to strong dynamical correlations, arising from deformation, the central depletion of proton density is greatly affected in these isotones. The decrease in depletion fraction can be related to increase in the internal density due to deformation