Nuclear Physics A最新文献

In a rapidly changing shape phase region, the presence of shape coexistence and its possible impact on the decay modes and half-lives, has been explored in astrophysically interesting Mo and Ru isotopes, in an extensive study within the microscopic theoretical framework using Nilsson Strutinsky Method and Relativistic Mean Field Model. The isotopic chains of Mo and Ru exhibit rapid shape phase transitions, triaxial γ softness, shape instability along with many coexisting states mostly with oblate and triaxial shapes. Proton and neutron separation energies have been calculated and compared with the available data. Results obtained from both the formalisms are in good agreement with each other as well as the available experimental data. Our computed β-decay half-lives and separation energy for nuclei exhibiting shape coexistence were examined for the decay mode from second minima state of the parent nuclei to the ground or excited state of the daughter nuclei. The second minima state of the coexisting shapes in Mo and Ru isotopes, were seen to impact the structural properties, β-decay half-lives, separation energy and hence the stability of the nuclei.

Different processes have been yet studied in the noncommutative standard model (NCSM) and various limits on the scale of noncommutative parameter have been determined. In the present work we, for the first time, investigate the production process of heavy hadrons through pair annihilation in the NCSM using Seiberg-Witten maps to the second-order of noncommutative parameter ${\Theta }^{\mu \nu }$. Having experimental data from Belle and OPAL Collaborations for inclusive production of B-mesons we will determine a low limit for the noncommutative scale ${\Lambda }_{NC}$. The effects of noncommutativity will be imposed both on the differential cross section at the parton level ($e^{+}{e}^{-}\to q\overline{q}$) and the fragmentation function of $q/\overline{q}\to B$ so that the limit ${\Lambda }_{NC}>1.10$ TeV is determined. Using analytical result for the pair annihilation cross section we will also predict the production rate of $B_c$ mesons in future electron-positron international linear collider (ILC).

We report systematic large-scale shell-model calculation for Po isotopes with A= 200 to 210. We have performed calculations using KHH7B interaction in the model space Z = 58-114 and N = 100-164 around doubly-magic ²⁰⁸Pb. We allow valence neutrons to occupy in the $1f_{5/2}$, $2p_{3/2}$, $2p_{1/2}$, and $0i_{13/2}$ orbitals, while two valence protons beyond $Z=82$ are occupied in $0h_{9/2}$, $1f_{7/2}$ and $0i_{13/2}$ orbitals. The calculated energies and electromagnetic properties are compared with the available experimental data and predicted where experimental data are not available. We have also reported shell-model results for different isomeric states of these nuclei.

We investigate 15 different Skyrme-interaction parametrizations and apply them to the chains of Te, Xe, Ba, Ce, Nd, Sm, Gd, Dy, Er, and Yb isotopes beyond N = 78 to calculate theoretical binding energies within the mean-field approach based on density functional theory. Results of calculations are compared with available experimental data on binding energies and quadrupole deformation with the aim to find out which interaction is the most convenient for shape and structure studies of these isotopic chains.

The accurate monitors of the electron beams and γ-ray fluxes are very important for laser-driven photonuclear studies. The flux-weighted average cross sections and average cross sections per equivalent quantum of ²⁷Al($\gamma ,x;x=2pn,pd,{}^{3}He$)²⁴Na reactions were measured above the giant dipole resonance region through activation methods. Laser-driven ultra-intense bremsstrahlung γ-rays, generated by laser wakefield accelerated quasi-monoenergetic electrons, were used in the experiment at the 200 TW laser facility of the Compact Laser Plasma Accelerator Laboratory, Peking University. The results demonstrated good agreement with previous works and were compared with theoretical values given by TALYS 1.9 calculations. The experimental cross sections were confirmed to be 2.4 times higher than TALYS 1.9 with default options. This work proved the feasibility of using the ²⁷Al($\gamma ,x$)²⁴Na reactions as monitors for laser wakefield accelerated electrons and their bremsstrahlung γ-ray fluxes.

Cross-sections for the production of ^{181,182m,g,183,184g,186g}Re radioisotopes from proton bombardment of natural tungsten have been measured using the stacked foil activation technique for proton energies up to 14.7 MeV. The results were analyzed and compared with the reported experimental data, and the theoretical excitation functions as calculated by the EMPIRE 3.2.3 and TALYS 1.9 codes. Several attempts have been made to reproduce the experimental excitation functions by different EMPIRE input parameters, and a reasonable agreement was attained. While measuring the activity of radionuclide ¹⁸¹Re, the intensity of the emitted 360-keV γ-photon was estimated at around 10 %, about half of the value reported in various databases. The integral yield of the investigated radioisotopes has been calculated, and a particular interest in the ^186gRe therapeutic radionuclide was discussed.

Charge radii of mirror nuclei are calculated by implementing pairing effects with the Hartree-Fock Bogoliubov approximation. Correlations between the difference of charge radii ($\Delta R_{ch}$) and slope of nuclear symmetry energy (L) are examined for different mirror nuclei pairs of varying masses using 40 different Skyrme energy density functionals. $\Delta R_{ch}-L$ correlations are found to be robust for the binding constraints imposed on density functionals. We observe that $\Delta R_{ch}$ and L show relatively better correlations in relatively heavier pairs than those obtained in the lighter pairs. Our calculations impose a constraint on the slope of nuclear symmetry energy as -20 MeV ≤L≤ 55 MeV with 68% confidence band using available measurements on charge radii. This is a moderately soft symmetry energy, in contrast to stiff and soft symmetry energy indicated by PREX-II and CREX measurements of neutron skin thickness in ${}^{208}Pb$ and ${}^{48}Ca$, respectively. Our result is also in agreement with celestial constraints obtained from observational data for neutron stars.

This article delves into the application of Dimer images in addressing two-body problems within lattice quantum chromodynamics (LQCD), providing the finite volume energy spectrum of deuterons in the context of ${}^{3}S_1$-${}^{3}D_1$ coupled-channels. The author commences by introducing the Dimer-particle method and formulating the Lagrangian for the scattering of two fermions. Additionally, the author defines the relativistic high partial zeta-function in a moving reference system and outlines a method for its rapid convergence calculation. The article further scrutinizes zeta-function representations across various momentum shells and discusses issues related to symmetry breakdown in specific momentum configurations. In sum, this work presents innovative methods for incorporating spin and isospin indices into dimer models, thereby establishing closer relevance to LQCD and deuteron studies.

The phenomena of shape evolution and shape coexistence within the Molybdenum isotopic chain are investigated using the covariant density functional theory with the parameterizations DD-ME2 and DD-PC1. Furthermore, various ground state properties of this chain are investigated, including binding energy, two-neutron separation energy, charge radii, and two-neutron shell gap. A robust agreement is observed when comparing with the available experimental data. The ground state deformation of Mo isotopes evolves smoothly and correlates with the continuous and gradual changes observed in the physical properties. A noticeable phenomenon of shape coexistence can be observed in certain isotopes, marked by the simultaneous existence of both a triaxial and an oblate axial minimum. A pronounced and well-defined shell closure is prominently evident at the neutron magic number $N=82$.

sPHENIX is a next-generation detector experiment at the Relativistic Heavy Ion Collider, designed for a broad set of jet and heavy-flavor probes of the Quark-Gluon Plasma created in heavy ion collisions. In anticipation of the commissioning and first data-taking of the detector in 2023, a RIKEN-BNL Research Center (RBRC) workshop was organized to collect theoretical input and identify compelling aspects of the physics program. This paper compiles theoretical predictions from the workshop participants for jet quenching, heavy flavor and quarkonia, cold QCD, and bulk physics measurements at sPHENIX.