A neural network approach based on more input neurons to predict nuclear mass

The study of nuclear mass is very important, and the neural network(NN) approach can be used to improve the prediction of nuclear mass for various models. Considering the number of valence nucleons of protons and neutrons separately in the input quantity of the NN model, the root-mean-square deviation of binding energy between data from AME2016 and liquid drop model calculations for 2314 nuclei was reduced from 2.385 MeV to 0.203 MeV. In addition, some defects in the Weizs\"{a}cker-Skyrme(WS)-type model were repaired, which well reproduced the two neutron separation energy of the nucleus synthesized recently by RIKEN RI Beam Factory [Phys. Rev. Lett 125 (2020) 122501]. The masses of some of the new nucleus appearing in the latest atomic mass evaluation(AME2020) are also well reproduced. However, the results of neural network methods for predicting the description of regions far from known atomic nuclei need to be further improved The study shows that such a statistical model can be a possible tool for searching in systematic of nuclei beyond existing experimental data.

Shell Model Calculations for Some Properties of 29-34Mg Isotopes

The calculations of the shell model, based on the large basis, were carried out for studying the nuclear 29-34Mg structure. Binding energy, single neutron separation energy, neutron shell gap, two neutron separation energy, and reduced transition probability, are explained with the consideration of the contributions of the high-energy configurations beyond the model space of sd-shell. The wave functions for these nuclei are used from the model of the shell with the use of the USDA 2-body effective interaction. The OBDM elements are computed with the use of NuShellX@MSU shell model code that utilizes the formalism of proton-neutron.

Beta-decay studies for applied and basic nuclear physics

In this review we will present the results of recent $$\beta $$ β -decay studies using the total absorption technique that cover topics of interest for applications, nuclear structure and astrophysics. The decays studied were selected primarily because they have a large impact on the prediction of (a) the decay heat in reactors, important for the safety of present and future reactors and (b) the reactor electron anti-neutrino spectrum, of interest for particle/nuclear physics and reactor monitoring. For these studies the total absorption technique was chosen, since it is the only method that allows one to obtain $$\beta $$ β -decay probabilities free from a systematic error called the Pandemonium effect. The total absorption technique is based on the detection of the $$\gamma $$ γ cascades that follow the initial $$\beta $$ β decay. For this reason the technique requires the use of calorimeters with very high $$\gamma $$ γ detection efficiency. The measurements presented and discussed here were performed mainly at the IGISOL facility of the University of Jyväskylä (Finland) using isotopically pure beams provided by the JYFLTRAP Penning trap. Examples are presented to show that the results of our measurements on selected nuclei have had a large impact on predictions of both the decay heat and the anti-neutrino spectrum from reactors. Some of the cases involve $$\beta $$ β -delayed neutron emission thus one can study the competition between $$\gamma $$ γ - and neutron-emission from states above the neutron separation energy. The $$\gamma $$ γ -to-neutron emission ratios can be used to constrain neutron capture (n,$$\gamma $$ γ ) cross sections for unstable nuclei of interest in astrophysics. The information obtained from the measurements can also be used to test nuclear model predictions of half-lives and Pn values for decays of interest in astrophysical network calculations. These comparisons also provide insights into aspects of nuclear structure in particular regions of the nuclear chart.

Exploring the α-decay chain of 302122 within relativistic mean field formalism

The ground and first excited state structural properties like binding energy, charge radius, deformation parameter, pairing energy, and two-neutron separation energy for the isotopic chain of Z= 122 are analyzed. The axially deformed relativistic mean-field formalism with NL3* force parameter is used for the present analysis. Based on the analysis of binding energy per particle, chemical potential and single-particle spacing, we predict the isotopes of Z =122 with N = 180. 182 and 184 are the possible stable nuclei over the considered isotopic chain. The α-decay energies and the decay half-lives of ³⁰²122 chains are investigated using four different empirical formulae. The results of our calculations are compared with the available experimental data and Finite Range Droplet Model predictions. We also established a correlation for the decay energy with the half-lives for the considered α-decay chains for various empirical formulae.

A study of nuclear radii and neutron skin thickness of neutron-rich nuclei near the neutron drip line

We studied the charge radius ([Formula: see text]), neutron radius ([Formula: see text]), and neutron skin-thickness ([Formula: see text]) over a chain of isotopes from C to Zr with the stable region to the neutron drip line. Theoretical calculations are done with axially deformed self-consistent relativistic mean-field theory (RMF) and effective nonlinear NL3 and NL3* interactions. The theoretically estimated values are compared with available experimental data and a reasonable agreement is noted. We additionally assessed the two-neutron separation energy ([Formula: see text]) to mark the drip line nuclei of the considered isotopic series. In the reference of [Formula: see text], neutron magicity is also discussed. The calculated neutron radii are compared with empirical estimation made by [Formula: see text] to examine the abnormal trend of the radius for neutron drip line nuclei. In view to guide the long tails, the density distribution for some skin candidates is analyzed. Finally, neutron skin thickness is observed for the whole considered isotopic series.

Determination of single neutron spectroscopic factor of doubly shell closed, neutron shell closed and neutron-rich nuclei through (d,p) reaction

The spectroscopic factor (SF) of doubly-magic nuclei, neutron shell closed and neutron-rich nuclei has been determined through ([Formula: see text], [Formula: see text]) reaction in the projectile energy range from 3 to 26[Formula: see text]MeV. The theoretical angular differential cross-sections of ([Formula: see text], [Formula: see text] reactions in scattering center-of-mass angles from [Formula: see text] to [Formula: see text] have been calculated using FRESCO and NRV-DWUCK5 codes. By comparing the theoretical angular differential cross-sections with available experimental angular differential cross-sections, the values of SF have been determined. The exponential increase of SF as a function of neutron separation energy normalized by spin of the recoil nuclei has been shown for the first time for doubly-magic nuclei. The similar type of trend has also been observed for neutron-rich as well as neutron shell closed nuclei as a function of neutron separation energy normalized by asymmetric factor of recoil nucleus. More experimental data are required to verify the trend predicted by this investigation.

Structural properties and decay modes of Z = 122, 120 and 118 superheavy nuclei

Structural properties and the decay modes of the superheavy elements [Formula: see text] and 118 are studied in a microscopic framework. We evaluate the binding energy, one- and two- proton and neutron separation energy, shell correction and density profile of even and odd isotopes of [Formula: see text] [Formula: see text] which show a reasonable match with FRDM results and the available experimental data. Equilibrium shape and deformation of the superheavy region are predicted. We investigate the possible decay modes of this region specifically [Formula: see text]-decay, spontaneous fission (SF) and the [Formula: see text]-decay and evaluate the probable [Formula: see text]-decay chains. The phenomena of bubble like structure in the charge density is predicted in [Formula: see text], [Formula: see text] and [Formula: see text] with significant depletion fraction around 20–24% which increases with increasing Coulomb energy and diminishes with increasing isospin ([Formula: see text]) values exhibiting the fact that the coulomb forces are the main driving force in the central depletion in superheavy systems.

A study of shell structure in normal to exotic nuclides within relativistic Hartree–Bogoliubov approximation

The purpose of this work is to study theoretically the shell structure of even–even isotopes in Si, S, Ar and Ca and isotones at neutron number N = 0, 28, 50 and 82. We employed Covariant Relativistic self-consistent mean field models analogous to Kohn–Sham density functional theory to construct the Nuclear Density Functionals from Lagrangian densities based on meson exchange and point coupling models. The pairing correlations of nucleons are considered by the relativistic Hartree–Bogoliubov functional based on quasi-particle operators of Bogoliubov transformations. The theoretical calculations of shell closure parameter [Formula: see text](N) and the differential variation of the two-neutron separation energy [Formula: see text](Z, N) provide recognizable signature of shell closure at N = 14 and 20 in case of Si, N = 14, 20 and 28 in S, Ar and Ca isotopes and are consistent with recent experimental investigations of new sub-shell gaps.

Distinct ground state features and the decay chains of Z = 121 superheavy nuclei

A fully systematic study of even and odd isotopes [Formula: see text] of [Formula: see text] superheavy nuclei is presented in theoretical frameworks of Relativistic mean-field plus state dependent BCS approach and macroscopic–microscopic approach with triaxially deformed Nilsson-Strutinsky prescription. The ground state properties namely shell correction, binding energy, two- and one-proton and neutron separation energy, shape, deformation, density profile and the radius are estimated that show strong evidences for magicity in [Formula: see text], 228. Central depletion in the charge density due to large repulsive Coulomb field indicating bubble like structure is reported. A comprehensive analysis for the possible decay modes specifically [Formula: see text]-decay and spontaneous fission (SF) is presented and the probable [Formula: see text]-decay chains are evaluated. Results are compared with Finite Range Droplet Model (FRDM) calculations and the available experimental data which show excellent agreement.

The role of the elemental nature of A = 3 nuclei in neutron-rich nuclei

The idea of treating the trinucleon systems as elementary entities in the elementary particle model (EPM) as an Effective Field Theory has been a success in explaining the weak charge-changing processes in nuclei. The EPM results are found to be as good as those obtained from nuclear microscopic models using two-and three-body forces. We extend this concept to investigate the validity of the elemental nature of [Formula: see text] nuclei through studies of nuclear structure of neutron-rich nuclei. By treating neutron-rich nuclei as primarily made up of tritons as its building blocks, we extract one- and two-triton separation energies of these nuclei. Calculations have been performed here within relativistic mean field (RMF) models with latest interactions. Clear evidence arises of a new shell structure with well-defined predictions of new magic nuclei. These unique predictions have been consolidated by standard one- and two-neutron separation energy calculations. The binding energy per nucleon plots of these nuclei also confirm these predictions. We make unambiguous prediction of six magic nuclei: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text].