Skyrme–Hartree–Fock–Bogoliubov Calculations of Even and Odd Neutron-Rich Mg Isotopes

Using the Skyrme functional with SIII, SKM*, SLy4, and UNE0 sets of parameters and the Hartree–Fock–Bogoliubov mean-field method; the ground-state properties of even-even and even-odd neutron-rich Mg isotopes have been investigated. The results of calculations of the binding energy per nucleon (B/A), the one- and two-neutron separation energies (Sn and S2n), proton and neutron rms radii, neutron pairing gap, and quadrupole deformation parameter (B2) have been compared with the available experimental data, the results of Hartree–Fock–Bogoliubov calculations based on the D1S Gogny force, and predictions of some nuclear models such as the Finite Range Droplet Model (FRDM) and Relativistic Mean-Field (RMF) model. Our results show good agreements in comparison with the experimental data and the results of the mentioned models.

A Neutron Star Is Born

A neutron star was first detected as a pulsar in 1967. It is one of the most mysterious compact objects in the universe, with a radius of the order of 10 km and masses that can reach two solar masses. In fact, neutron stars are star remnants, a kind of stellar zombie (they die, but do not disappear). In the last decades, astronomical observations yielded various contraints for neutron star masses, and finally, in 2017, a gravitational wave was detected (GW170817). Its source was identified as the merger of two neutron stars coming from NGC 4993, a galaxy 140 million light years away from us. The very same event was detected in γ-ray, x-ray, UV, IR, radio frequency and even in the optical region of the electromagnetic spectrum, starting the new era of multi-messenger astronomy. To understand and describe neutron stars, an appropriate equation of state that satisfies bulk nuclear matter properties is necessary. GW170817 detection contributed with extra constraints to determine it. On the other hand, magnetars are the same sort of compact object, but bearing much stronger magnetic fields that can reach up to 1015 G on the surface as compared with the usual 1012 G present in ordinary pulsars. While the description of ordinary pulsars is not completely established, describing magnetars poses extra challenges. In this paper, I give an overview on the history of neutron stars and on the development of nuclear models and show how the description of the tiny world of the nuclear physics can help the understanding of the cosmos, especially of the neutron stars.

Production cross-section calculations of 111In via proton and alpha-induced nuclear reactions

[Formula: see text], a known gamma emitter, is used for many medical purposes such as imaging of myocardial metastases. It can be produced by using different nuclear reactions. In this study, the reactions of [Formula: see text]Ag([Formula: see text]2n)[Formula: see text], [Formula: see text](p,[Formula: see text]n)[Formula: see text], [Formula: see text](p,[Formula: see text]2n)[Formula: see text], [Formula: see text](p,[Formula: see text]3n)[Formula: see text] and [Formula: see text](p,[Formula: see text]4n)[Formula: see text], which are the production routes of [Formula: see text], were investigated. Production cross-section calculations were performed by using equilibrium and pre-equilibrium models of TALYS 1.95 and EMPIRE 3.2 nuclear reaction codes. Hauser–Feshbach Model was appointed in both codes for calculations of equilibrium approximations. Exciton and Hybrid Monte Carlo Simulation (HMS) models were used in the EMPIRE 3.2, whereas Two-Component Exciton and Geometry Dependent Hybrid Model, which is implemented to TALYS code, has been used in the TALYS 1.95 for pre-equilibrium reactions. Also, a weighting matrix of the nuclear models was obtained by using statistical variance analysis. The optimum beam energy to obtain [Formula: see text] has been determined by using the results obtained from this weighting matrix.

Highest weight irreducible representations favored by nuclear forces within SU(3)-symmetric fermionic systems

The consequences of the attractive, short-range nucleon-nucleon (NN) interaction on the wave functions of nuclear models bearing the SU(3) symmetry are reviewed. The NN interaction favors the most symmetric spatial SU(3) irreducible representation (irrep), which corresponds to the maximal spatial overlap among the fermions. The consideration of the highest weight (hw) irreps in nuclei and in alkali metal clusters, leads to the prediction of a prolate to oblate shape transition beyond the mid–shell region. Subsequently, the consequences of the use of the hw irreps on the binding energies and two-neutron separation energies in the rare earth region are discussed within the proxy-SU(3) scheme, by considering a very simple Hamiltonian, containing only thethree dimensional (3D) isotropic harmonic oscillator (HO) term and the quadrupole-quadrupole interaction. This Hamiltonian conserves the SU(3) symmetry and treats the nucleus as a rigid rotator.

Inner crust of a neutron star at the point of crystallization in a multicomponent approach

Context. The possible presence of amorphous and heterogeneous phases in the inner crust of a neutron star is expected to reduce the electrical conductivity of the crust, potentially with significant consequences on the magneto-thermal evolution of the star. In cooling simulations, the disorder is quantified by an impurity parameter, which is often taken as a free parameter. Aims. We aim to give a quantitative prediction of the impurity parameter as a function of the density in the crust, performing microscopic calculations including up-to-date microphysics of the crust. Methods. A multicomponent approach was developed at a finite temperature using a compressible liquid-drop description of the ions with an improved energy functional based on recent microscopic nuclear models and optimized on extended Thomas-Fermi calculations. Thermodynamic consistency was ensured by adding a rearrangement term, and deviations from the linear mixing rule were included in the liquid phase. Results. The impurity parameter is consistently calculated at the crystallization temperature as determined in the one-component plasma approximation for the different functionals. Our calculations show that at the crystallization temperature, the composition of the inner crust is dominated by nuclei with charge number around Z ≈ 40, while the range of the Z distribution varies from about 20 near the neutron drip to about 40 closer to the crust-core transition. This reflects on the behavior of the impurity parameter that monotonically increases with density reaching up to around 40 in the deeper regions of the inner crust. Conclusions. Our study shows that the contribution of impurities is non-negligible, thus potentially having an impact on the transport properties in the neutron-star crust. The obtained values of the impurity parameter represent a lower limit; larger values are expected in the presence of nonspherical geometries and/or fast cooling dynamics.

An Alternating Quark Sequence Subnucleonic Structure of Stable Light Nuclei H-1 Through C-13

The proposed structures of stable nuclei of H-1 through C-13 incorporate an alternating up and down quark sequence (AQS) of equally spaced quarks around regular geometries. AQS nuclear models represent quark positions in the same way molecular ball and stick models represent the relative positions of atoms. In AQS, the ball identifies the center of quark mass and the stick length is constant and equal to the most recent radius of the proton (0.8414 fm). AQS radius predictions use current quark masses, and predictions for H-1 to C-13 demonstrate 99.3% average agreement (SD 4%) and statistical correlation of ρ = 0.96, p<0.001, with accepted RMS charge radii. These results compare favorably to a close-packed nucleons model and a spherical nucleus model. A set of AQS parameters is included. Light nuclei tend to form ring structures corresponding to regular polyhedra, the smallest of which is the dodecagon structure of helium-4. Opposite quarks link nucleons to maintain a continuous sequence of alternating equally spaced quarks. Quark sequences may overlap so that protons overlap with neutrons. The more regular polyhedron structures of light nuclei yield better AQS radius predictions, whereas larger nuclei tend to be less regular and are thus less predictable (with the exception of the double overlapping octadecagon structure for the 36 quarks of C-12). The relative certainty in the accepted radius of helium-4, and its geometric relationship to the proton radius, allow a geometric solution to the “proton puzzle” yielding an AQS prediction for the proton radius of 0.8673±0.0014 fm.

An Alternating Quark Sequence Subnucleonic Structure of Stable Light Nuclei H-1 Through Li-7

The proposed structures of stable nuclei of H-1 through Li-7 incorporate an alternating up and down quark sequence (AQS) of equally spaced quarks around regular geometries. AQS nuclear models represent quark positions in the same way molecular ball and stick models represent the relative positions of atoms. In AQS, the ball identifies the center of quark mass and the stick length is constant and equal to the most recent radius of the proton (0.8414 fm). AQS radius predictions use accepted quark masses where necessary, and predictions demonstrate 99.3% average agreement (SD 4%) and statistical correlation of ρ = 0.96, p<0.001, with accepted RMS charge radii. These results compare favorably to a close-packed nucleons model and a spherical nucleus model. A set of AQS parameters is included. Light nuclei tend to form ring structures corresponding to regular polyhedra, the smallest of which is the dodecagon structure of helium-4. Opposite quarks link nucleons to maintain a continuous sequence of alternating equally spaced quarks. Quark sequences may overlap so that protons overlap with neutrons. The more regular polyhedron structures of light nuclei yield better AQS radius predictions, whereas larger nuclei tend to be less regular and are thus less predictable (with the exception of the double overlapping octadecagon structure for the 36 quarks of C-12). The relative certainty in the accepted radius of helium-4, and its geometric relationship to the proton radius, allow a geometric solution to the “proton puzzle” yielding an AQS prediction for the proton radius of 0.8673±0.0014 fm.

Toward Classical Models of Nucleons and Nuclei

Nuclear models can be complicated and far from first principles. Inspired by Mills' Grand Unified Theory of Classical Physics, we will present a model of the interior of nucleons that predicts their masses well considering its simplicity. Then we will apply Mills' nucleon model to the problem of computing nuclear binding energies. Because the theory is constrained to agree with classical physics including Maxwell's Equations and Newton's Laws, for instance lacking special forces that only operate in the nucleus, the possible compatible nuclear theories are strictly limited which should make finding them easier.