Bubble structure in magic nuclei

Abstract

The existence of bubble nuclei identified by the central depletion in nucleonic density is studied for the conventional magic N (Z) = 8, 20, 28, 40, 50, 82, 126 isotones (isotopes) and recently speculated magic N = 164, 184, 228 superheavy isotones. Many new bubble nuclei are predicted in all regions. Study of density profiles, form factor, single particle levels and depletion fraction (DF) across the periodic chart reveals that the central depletion is correlated to shell structure and occurs due to unoccupancy in s-orbit (2s, 3s, 4s) and inversion of (2s, 1d) and (3s, 1h) states in nuclei upto Z ≤ 82. Bubble effect in superheavy region is a signature of the interplay between the Coulomb and nn-interaction and depletion fraction (DF) is found to increase with Z (Coulomb repulsion) and decrease with isospin. Our results are consistent with the available data. The occupancy in s-state in 34 Si increases with temperature which appears to quench the bubble effect.

Neutron Skin, Central Depletion, Neutron–Proton Interaction Effects and 2pF Parameterization for Zr in Neutron Stars

“…It is obvious that the bubble structure for the Zr isotopes does not have a noticeable effect on NST. The isospin for the nuclei with constant Z configurations like the Zr isotopes and quantum shell effects may be investigated by new studies because the quantum shell effects strongly influence the bubble structure in lighter nuclei, contrary to heavy/superheavy nuclei, due to coherence between the strong attractive nucleon-nucleon force and the large repulsive Coulomb interaction [42]. To assess the ability of the employed SHF approach for the SkM* parameter, we have compared the binding energies of the Zr isotopes with those of experimental and theoretical results from FRDM, AME and RMFT [24][25][26] in Fig.…”

“…Notably, the variation in density is related to quantal effects which fill the single-particle levels near the Fermi energy. This situation leads to sensitivity in the depletion fraction to the quantal effects, and the s orbitals (l = 0) are exclusively a non-zero wave function at the center, whereas there is no contribution to density at the center in the non-zero l orbitals [42]. The detection of depletion fraction for the neutron density at the center of nuclei may be provided by bubble parameters:…”

Structural properties and α-decay chains of transfermium nuclei (101≤Z≤110)

“…The calculations in the relativistic mean-field approach [17,[54][55][56][57][58] have been carried out using the model Lagrangian density with nonlinear terms both for the σ and ω mesons along with NL3* parametrization [59]. The corresponding Dirac equations for nucleons and Klein-Gordon equations for mesons obtained with the mean-field approximation are solved by the expansion method on the widely used axially deformed Harmonic-Oscillator basis [60,61].…”

Collapse of N$=$28 magicity in exotic $^{40}$Mg -- Probe of deformed halo and 2n-radioactivity at Mg neutron drip-line

“…We use relativistic mean-field approach (RMF) [29][30][31][32][33][34][35][36][37][38] for the present study where the various parameterizations/variants of the RMF models have been used for the calculations. The first variant of RMF comprises of the following model Lagrangian density with nonlinear terms for the σ and ω mesons [36,[39][40][41];…”

“…The nucleus 40 Mg, with magic neutron number N=28, is the most neutron-rich isotope of Mg accessible experimentally [1]. The experimental observation of γ-ray transitions in 40 Mg [2] indicate that the structure of 40 Mg is different from the neighbouring isotopes 36,38 Mg in contrast to the theoretical expectations [2]. This could possibly be due to two weakly bound valence neutrons at the Fermi surface that may couple to the classically forbidden continuum where the nucleon binding is dominated by pairing correlations rather than the mean-field of core to form a halo [3].…”