Neutron Proton Research Articles

Re-examination of the β-decay properties of As isotopes

Abstract The β-decay properties of 67−80As nuclei have been investigated within the framework of the proton–neutron quasi-particle random phase approximation (pn-QRPA) model. The nuclear deformation obtained from the finite range droplet model is used as an input parameter in the pn-QRPA model for the analysis of β-decay properties including Gamow–Teller strength distributions, log ft, β-decay half-lives and stellar β ± decay rates. The predicted log ft values were fairly consistent with the observed data. The computed β-decay half-lives matched the measured values by a factor of 10. The stellar rates were compared with the shell model outcomes. At high densities and temperatures, the β + and electron capture rates had a finite contribution. However, the β − and positron capture rates are only significant at high temperatures and low densities. The pn-QRPA rates outperformed the shell model rates by a factor of 22 or more.

Mixing of isoscalar and isovector characteristics in the low-energy dipole mode

We investigated isospin splitting in low-energy dipole (LED) states of spherical nuclei such as 40Ca, 90Zr, 132Sn, 208Pb, and several N=50 isotones using self-consistent Hartree–Fock plus random phase approximation calculations. Our analysis of isovector dipole (IVD) and isoscalar dipole (ISD) strengths, along with transition densities, reveals a clear energy-dependent relationship between IS and IV modes in 40Ca and 90Zr. For 208Pb and 132Sn, LED states show mixed IS + IV characteristics due to different neutron and proton shell structures. In N=50 isotones, E1 modes exhibit varying IS and IV properties with smooth transitions as neutron excess increases. Our results suggest that compressional ISD strengths could provide valuable insights into the slope parameter of the nuclear equation of state. The observed dependence on nuclear shell structures and neutron–proton correlations highlights the need for precise measurements and further research in nuclear physics.

Electron dynamics in neutron scattering with hydrogen atoms

Gas targets have been used to measure the scattering length in neutron–proton (n–p) scattering experiments. Changes in electron dynamics within the gas target have a negligible effect on the dynamics of nucleons. However, electron dynamics are sensitively related to the specific form of the n–p interaction during the scattering process. We propose a theoretical approach to explore electron dynamics and determine the parameters of the n–p interaction. This approach is based on a three-body scattering process involving a neutron, a proton and an electron. Numerical results indicate significant differences in electron dynamics with varying values of n–p interaction parameters, providing additional information beyond scattering cross-sections to accurately determine these parameters.

Assessing the shielding capability of NiO-infused BPSCCO ceramics against low-energy X-rays

This research examines the improvement of radiation shielding capabilities in Bismuth Strontium Calcium Copper Oxide (BSCCO) superconductors via NiO doping. With the increasing need for advanced shielding materials in high-risk areas, exploring effective and nonhazardous alternatives is becoming increasingly important. The purpose of the study was to investigate the radiation-shielding characteristics of BPSCCO superconducting ceramics and the effects of NiO additives on their shielding properties. Comparisons of linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), as well as fully simulated values for transmission factor (TF), neutron removal cross section (ΣR), electrical conductivity (Ceff), alpha and proton stopping powers, and radiation protection efficiency (RPE) using NIST XCOM, Phy-X, NIST Pstar and NIST Astar for all ceramic samples. The results indicate that optimal NiO doping notably enhances the radiation shielding capabilities of BSCCO ceramics, highlighting their significant potential for use in the medical, aerospace, and nuclear industries. This research provides a fundamental understanding of the potential of doped superconductor ceramics for radiation protection, promoting further research into these materials and the creation of safer, more efficient shielding solutions.

Subshell gaps and onsets of collectivity from proton and neutron pairing gap correlations

Throughout the nuclear chart, particle-hole correlations give rise to giant resonances and, together with the proton–neutron interaction, deformation and rotational bands. In order to shed light on many-body correlations in open-shell nuclei, I explore macroscopic properties that could manifest from the collective behaviour of protons and neutrons. Intuitively, the correlation of proton and neutron Cooper pairs can be inferred from the respective pairing gaps, that can precisely be extracted from the AME 2020 atomic mass evaluation through odd-even atomic mass differences. This work shows that the combination of large and close-lying proton and neutron pairing gaps is sensitive to onsets of collectivity and subshell gaps in superfluid nuclei, away from major shell closures. Trends of reduced transition probabilities or B(E2) values — which describe the collective overlap between the wave functions of initial and final nuclear states — are revealed in overall agreement with data. Specially interesting is the peak of collectivity in the tin isotopes at 110Sn, instead of at midshell, as expected by large-scale shell-model calculations; a situation that has astounded the nuclear physics community for quite some time.

Development of an online neutron beam monitoring system for accelerator-based boron neutron capture therapy in a hospital.

Boron neutron capture therapy (BNCT) is a next-generation radiotherapy, utilizing both an external neutron beam and a -containing pharmaceutical. A compact accelerator for a high intensity neutron source was installed to conduct BNCT in a hospital. The dose administered to a patient was evaluated by measuring the proton beamcurrent. Neutron intensity should be monitored in real-time by measuring the neutrons emitted from the target during BNCT irradiation. This is crucial due to potential neutron target degradation. Online neutron beam monitoring systems are required for reliable measurements of the administered neutron dose. An online neutron beam monitoring system was developed to monitor neutron intensity irradiating on the patient at the National Cancer Center Hospital (NCCH). The neutron detector comprised a back-illuminated thin Si diode of 40- thickness and an ultrathin natural LiF neutron converter of 0.05- thickness. The neutron detector was installed on the neutron target unit, regardless of whether a patient was present, without any additional modifications to the setup. The response functions for high photon dose rates of upto 100 Gy/h were measured. The pulse heights were measured using the neutron beam monitor during BNCT neutron irradiation. Neutron temporal response measured using the online beam monitor was acquired and compared with the proton beam current and the measurements at a patient position. From this measurement at the patient position, the neutron fluence rate irradiating on a patient wasobtained. The neutron events were separated from the photon events. The neutron counting rates increased rapidly with the starting of proton beam irradiation and dropped to zero upon its termination. During intermittent drops and recoveries in the proton beam, the neutron beam monitor for counting rates responded quickly, synchronizing with the beam current. A scatter plot of the neutron counting rate and proton beam current indicated a good linear correlation. A direct relationship between the online neutron beam monitor's neutron counting rates and those of the patient neutron detector showed a good correlation coefficient of 0.84. A ratio of the both neutron counting rates showed a standard deviation of 6%. The correlation coefficient and standard deviation were improved to 0.94 and 1.5%, by re-binning the neutron temporal response with longer acquisition period than 1 s. Using the online neutron beam monitor, the neutron fluence rate was obtained from the direct relationship within 1.5%. Therefore, real-time monitoring of neutron intensity was achieved within the acceptable level as per the International Commission on Radiation Units and Measurementsreport. The online neutron beam monitoring system was developed to monitor the BNCT neutron beam intensity at NCCH. The temporal response of the neutron beam monitor was synchronized with the neutron counting rate at the patient position. Using the online neutron beam monitor, the neutron fluence rate irradiating on the patient can be monitored from the direct relationship. Fluctuation of the neutron beam intensity through BNCT irradiation and the degradation of the lithium target through the lifespan of the neutron target could be monitored using the neutron beammonitor.

Investigation of nuclear structure and [formula omitted]-decay properties of As isotopes

The nuclear ground state properties of 67−80As nuclei have been investigated within the framework of relativistic mean field (RMF) approach. The RMF model with density-dependent (DD-ME2) interaction is utilized for the calculation of potential energy curves and the nuclear ground-state deformation parameters (β2) of selected As isotopes. Later, the β-decay properties of As isotopes were studied using the proton–neutron quasi particle random phase approximation (pn-QRPA) model. These include Gamow Tellar (GT) strength distributions, log ft values, β-decay half-lives, stellar β± decays and stellar electron/positron capture rates. The β2 values computed from RMF model were employed in the pn-QRPA model as an input parameter for the calculations of β-decay properties for 67−80As. The calculated log ft values were in decent agreement with the measured data. The predicted β-decay half-lives matched the experimental values within a factor of 10. The stellar rates were compared with the shell model results. Only at high temperature and density values, the sum of β+ and electron capture rates had a finite contribution. On the other hand, the sum of β− and positron capture rates were sizeable only at low density and high temperature values. For all such cases, the pn-QRPA rates were found to be bigger than the shell model rates up to a factor of 33 or more. The findings reported in the current investigation could prove valuable for simulating the late-stage stellar evolution of massive stars.

Shell-model representations of the microscopic version of the Bohr–Mottelson collective model

The structure of the irreducible collective spaces of the group Sp(12, R), which many-particle nuclear states are classified according to the chain Sp(12, R) ⊃ U(6) ⊃ SO(6) ⊃ SU pn (3) ⨂ SO(2) ⊃ SO(3) of the proton–neutron symplectic model (PNSM), is considered in detail. This chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr–Mottelson collective model. The construction of the relevant shell-model representations of the Sp(12, R) group along this chain is considered for three nuclei with varying collective properties and from different mass regions. It is shown that the SU pn (3) basis states of the Sp(12, R) representations belonging to the SO(6) irreps with seniority υ ≥ υ 0, with υ 0 denoting the maximal seniority SO(6) irrep contained in the Sp(12, R) bandhead, are always Pauli allowed, but organized in a different way into different SO(6) shells. This is in contrast to the case of filling the levels of the standard three-dimensional harmonic oscillator and using the plethysm operation. Although the SU pn (3) multiplets within υ < υ 0 are not all Pauli forbidden, it is safe to discard them. The results obtained in the present work are important for the practical application of the microscopic version of the Bohr–Mottelson collective model.

Low-Energy Theorems for Neutron–Proton Scattering in χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document}EFT Using a Perturbative Power Counting

Low-energy theorems (LETs) for effective-range parameters in nucleon-nucleon scattering encode properties of the long-range part of the nuclear force. We compute LETs for S-wave neutron–proton scattering using chiral effective field theory with a modified version of Weinberg power counting. Corrections to the leading order amplitude are included in distorted-wave perturbation theory and we incorporate contributions up to the third order in the power counting. We find that LETs in the 1S0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^1S_0$$\\end{document} and 3S1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3S_1$$\\end{document} partial waves agree well with empirical effective-range parameters. At the same time, phase shifts up to laboratory scattering energies of about 100 MeV can be reproduced. We show that it is important to consider the pion mass splitting in the one-pion exchange potential in the 1S0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^1S_0$$\\end{document} partial wave while the effect is negligible in the 3S1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3S_1$$\\end{document} partial wave. We conclude that pion exchanges, as treated in this power counting, accurately describe the long-range part of the S-wave nuclear interaction.

Revisiting big bang nucleosynthesis with a new particle species: effect of co-annihilation with nucleons

In big bang nucleosynthesis (BBN), the light matter abundance is dictated by the neutron-to-proton (n/p) ratio which is controlled by the standard weak processes in the early universe. Here, we study the effect of an extra particle species (χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document}) which co-annihilates with neutron (proton), thereby potentially changing the (n/p) ratio in addition to the former processes. We find a novel interplay between the co-annihilation and the weak interaction in deciding the (n/p) ratio and the yield of χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document}. Large co-annihilation strength (GD\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$G_D$$\\end{document}) in comparison to the weak coupling (GF\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$G_F$$\\end{document}), potentially can alter the number of nucleons in the thermal bath modifying the (n/p) ratio from its standard evolution. We find that the standard BBN prediction is restored for GD/GF≲10-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$G_D/G_F \\lesssim 10^{-2}$$\\end{document}, while the mass of χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document} being much smaller than the neutron mass. When the mass of χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document} is comparable to the neutron mass, we can allow large GD/GF(≳102)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$G_D/G_F ~(\\gtrsim 10^2)$$\\end{document} values, as the thermal abundance of χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document} becomes Boltzmann-suppressed. Therefore, the (n/p) ratio is restored to its standard value via dominant weak processes in later epochs. We also discuss the stability of the new particle in an effective theory framework for co-annihilation. Further, the co-annihilation interaction generates elastic scattering of χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document} and nucleons at the next-to-leading order. This provides a way to probe the scenario in direct detection experiments, if χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document} is accidentally stable over cosmological timescale.

Prediction of the 1st excitation energy of odd–odd nuclei with the Bayesian neural network approach

A Bayesian neural network (BNN) is developed to predict the 1st excitation energy of odd–odd nuclei. Aside from the proton number and neutron number, we introduce two empirical physical quantities into the input layer. δ=[−1N+−1Z]/2 is introduced to distinguish even–even, odd–odd and odd-A nuclei; and the so-called Casten factor P≡vpvnvp+vn is introduced to stand for collectivity. The BNN is trained with an experimental dataset of the 1st excitation energy for 434 odd–odd, 649 even–even and 1050 odd-A nuclei. After training, the BNN predicts the 1st excitation energy of odd–odd nuclei with a rms of 0.21 MeV. Examples of Dy, Gd, Eu and Cs isotopes are also shown. The BNN results show moderate predictive ability, in comparison with results from the projected Hartree–Fock method.

Conceptualized Fusion Reactor based on Gas Turbine with High Temperature CO2

Author discovered the mechanism of Cold fusion that covalent bond compression of D-D transition electron to deep orbit which distance is a few femto- meters from the nucleus, which electron density between d-d is so dense that it shields the coulomb repulsive force to cause Fusion, and discovered that nucleus is constituted only by proton and internal electron and neutron is a pair of proton and electron in deep orbit. Dr. Ohmasa claims that his transmutation reactor produce produces precious metal from base metal, which shows experimentally and author discovered that femto-H2 fusion to metal cause transmutation, which proves the existence of femto-H2, and femto-D2 therefore current nucleus model is probed to be incorrect. Dr. Ohmasa also claims that CO2 can be reduced by burning with fossil gas fuel mixed with H2 and O2, and author hypothesized the cause that compression of C-O bond cause fusion between C and O to be P and Si based on the correct nucleus model and based on author’s Cold fusion mechanism of bond compression. Developing this mechanism and hypothesis, I would like to propose the conceptualized fusion reactor based on gas turbine with high temperature CO2. D-D bond can be compressed by high temperature CO2 and by the collision of high-speed blades in gas turbine to cause D+D fusion and C+O fusion, which reduce the CO2 emission. Reactor needs to be cooling to generate power by steam turbine and high- speed blade rotation produce power and causes fusions.

Re-analysis of temperature dependent neutron capture rates and stellar β-decay rates of 95-98Mo

The neutron capture rates and temperature dependent stellar beta decay rates of Mo isotopes are investigated within the framework of the statistical code TALYS v1.96 and the proton neutron quasi particle random phase approximation (pn-QRPA) model. The Maxwellian average cross-section (MACS) and neutron capture rates for the Mo(n,γ) Mo radiative capture process are analyzed within the framework of the statistical code TALYS v1.96 based on the phenomenological nuclear level density model and gamma strength functions. The present model-based computations for the MACS are comparable to the existing measured data. The sensitivity of stellar weak interaction rates to various densities and temperatures is investigated within the framework of the pn-QRPA model. Particular attention is paid to the impact of thermally filled excited states in the decaying nuclei ( Mo) on electron emission and positron capture rates. Furthermore, we compare the neutron capture rates and stellar beta decay rates. It is found that neutron capture rates are higher than stellar beta decay rates at both lower and higher temperatures.

Nuclear structure properties and weak interaction rates of even–even Fe isotopes

Nuclear structure properties and weak interaction rates of neutron-rich even–even iron (Fe) isotopes (A = 50 – 70) are investigated using the Interacting Boson Model-1 (IBM-1) and the proton–neutron Quasiparticle Random Phase Approximation (pn-QRPA) model. The IBM-1 is used for the calculation of energy levels and the B(E2) values of neutron-rich Fe isotopes. Later their geometry was predicted within the potential energy formalism of the IBM-1 model. Weak interaction rates on neutron-rich nuclei are needed for the modeling and simulation of presupernova evolution of massive stars. In the current study, we investigate the possible effect of nuclear deformation on stellar rates of even–even Fe isotopes. The pn-QRPA model is applied to calculate the weak interaction rates of selected Fe isotopes using three different values of deformation parameter. It is noted that, in general, bigger deformation values led to smaller total strength and larger centroid values of the resulting Gamow–Teller distributions. This later translated to smaller computed weak interaction rates. The current finding warrants further investigation before it may be generalized. The reported stellar rates are up to 4 orders of magnitude smaller than previous calculations and may bear astrophysical significance.

Correlation between nutrients, rare earth elements and heavy metals in O. Sativa rice plant organs by instrumentation neutron activation analysis and proton induced x-ray emission techniques

The accumulation of halogens and metals from roots to stems, leaves and grains of Oryza sativa rice plant collected in Northern Senegal (St Louis region) at the same stages of growth but at different salinity soil levels was investigated by measuring their elemental concentration by invasive instrumental techniques of neutron activation analysis and proton induced x-ray emission. The normalized elemental concentration of Na, Cl, K, (Cs, Rb, Sr, Sb, Ba Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Br, Rb, Sb was correlated with one of rare earth elements, La, Ce, Sm, Yb, Nd, Eu, Tb, Tm, and Lu) and the one of the heavy metals Hf, Ta and Th and to assess their subsequent distribution within the Oryza sativa rice plant in a particular salinity environment. The exploration of the experimental data was performed by applying machine learning techniques with Python to find their elemental correlations. This study shows that the accumulation of iron is highly correlated with the amount of rare earth elements and heavy metals investigated. We observe an inverse correlation between Fe and Cl concentrations in the roots and stems of the Oryza sativa rice plant, in which higher levels of Fe in the roots relative to stems correspond to lower levels of Cl. We also remark that there is no accumulation of rare earth elements in the root tissues of the different Oryza sativa rice plants studied. Whereas, in the stem, leaf, and grain organs there is a strong correlation between metal contents and rare earth elements.

Current status and future trends in particle therapy – lessons from an interdisciplinary workshop

PurposeTo provide an introduction to the special issue containing the proceedings of the workshop on cancer therapy using hadrons (proton, carbon ions or boron neutron capture therapy) that was held in Pavia in October 2023 and organized by CNAO and IAEA.MethodsPapers contained in the issue are briefly summarized.ResultsThis issue contains a collection of papers from the workshop that provide a great opportunity to learn about the status and progress of this technology.ConclusionsParticle therapy is exponentially growing worldwide. While several clinical trials are now providing convincing evidence of the effectiveness of the treatment in tumor control and reduced toxicity, the technology remains expensive and the cost effectiveness is still under debate. The IAEA-CNAO workshop provided a clear picture of the state of the art and future prospective of this technology.

Entanglement in Few-Nucleon Scattering Events

We investigate the spin entanglement in few-nucleon scattering processes involving nucleons and deuterons. For this purpose, we consider the entanglement power introduced by Beane et al. We analyze different entanglement entropies as a basis to define the entanglement power of the strong interaction and calculate the corresponding entanglement powers for proton–neutron, neutron–deuteron, proton–deuteron, and deuteron–deuteron scattering. For the latter two processes, we also take into account the modification from the Coulomb interaction. In contrast to proton–neutron scattering, no universal low-energy features are evident in the spin entanglement in neutron–deuteron, proton–deuteron, and deuteron–deuteron scattering.

Isoscaling properties for neutron-rich fragments in highly asymmetric heavy ion collision systems* *Supported by the National Natural Science Foundation of China (12375123, 11975091) and the Program for Innovative Research Team (in Science and Technology) in University of Henan Province (21IRTSTHN011), China

Traditionally, isoscaling has been interpreted and applied within the framework of the grand canonical ensemble, based on the assumption that fragment production occurs following the attainment of a statistical equilibrium state. However, the influence of the symmetry energy can lead to differences in the neutron and density distribution in neutron-rich nuclei. This in turn may impact the isoscaling parameters (usually denoted by α and β). We examine the isoscaling properties for neutron-rich fragments produced in highly asymmetric systems on inverse kinematics, namely Ca and Ni + Be at 140 MeV per nucleon. We evaluate α and β values and sort them as a function of the neutron excess . The significant differences in α extracted from fragments within different ranges of I emphasize the importance of understanding the dependence of isoscaling parameters on fragments generated in various collision regions. Furthermore, the value for a specific fragment in small size and highly isospin asymmetry systems can serve as a probe to detect the variations in neutron density and proton density in different regions of the nucleus and indicate the limitations of theoretical models in investigating these issues.

A study of trends of neutron skin thickness and proton radii of mirror nuclei within the framework of covariant density functional theory

The neutron skin of atomic nuclei impacts the structure of neutron-rich nuclei, but its accurate measurement is quite challenging. We present predictions for neutron skins and proton radii for light to medium mass nuclei by employing Covariant Density Functional Theory (CDFT) based on density-dependent meson-exchange interaction. Using our microscopic predictions, we find a linear correlation between the neutron skin and the isospin asymmetry. The calculations are also extended to find a linear relationship between proton and neutron radii of mirror nuclei. Using the charge symmetry property of nuclear forces, a correlation between the neutron skin of neutron-rich nuclei and difference between the proton radii of the corresponding mirror pair has also been investigated. The inclusion of ISB term is found to affect the mirror difference charge radii of [Formula: see text]Ca-[Formula: see text]Ni mirror pair.

Re-Examination of the Effect of Pairing Gaps on Gamow–Teller Strength Distributions and β-Decay Rates

β-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the β-decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar β-decay rates for 50 top-ranked nuclei possessing astrophysical significance according to a recent survey. The model parameters of the pn-QRPA model affect the predicted results of β-decay. The current study investigates the effect of nucleon–nucleon pairing gaps on charge-changing transitions and the associated β decay rates. Three different values of pairing gaps, namely TF, 3TF, and 5TF, were used in our investigation. It was concluded that both GT strength distributions and half-lives are sensitive to pairing gap values. The 3TF pairing gap scheme, in our chosen nuclear model, resulted in the best prediction with around 80% of the calculated half-lives within a factor 10 of the measured ones. The 3TF pairing scheme also led to the calculation of the biggest β-decay rates in stellar matter.