Number Of Neutrons Research Articles

A study on light charged particle accompanied ternary fission of 253Cf

We investigated 253Cf ternary fission followed by a light-charged particle (LCP) accompanied ternary fission. The many LCPs, include 4He, 6Li, 9Be 10B, 12C, 14N, 16O, 19F 20Ne, 23Na 24Mg, 26Al, 28Si, 30P 32S, 35Cl, 40Ar, 39K and 40Ca. Using Coulomb potential and proximity potential, the overall potential has been investigated. In estimating potential, deformations and angle of orientation were taken into account. Using cold valley plots, the driving potential at its lowest level is determined. Using WKB integral, the penetration probability is evaluated. When the fission fragment combinations include equal or close to the magic number of protons or neutrons, the minimal driving potential, maximum penetration probability, and maximum logT1/2 are observed. Therefore, 138Ba+4He+111Ru are the most likely fission fragment combination when 253Cf undergoes LCP followed ternary fission. Therefore, 4He particle-emission coupled with two likely fission fragments are the most likely fission fragments if the nuclei 253Cf undergo LCP-accompanied ternary fission. The significance of this finding may thus be seen in the ternary fission half-lives.

Novel features of nuclear spectra of light mass Os isotopes

The (N=88-108) light mass Os isotopes exhibit level spectra different from the heavier (N > 108) isotopes. The spectral pattern, for ground, β- and γ- bands is illustrated empirically, and analyzed in terms of the collective rotation vibration model and the algebraic sd Interacting Boson Model IBM-1. The variation of the spectral features with neutron number N has been linked to the odd-A neighbors and to the occupation of the underlying Nilsson orbits. The quadrupole β vibration produces the axially symmetric shape of light mass Os isotopes, in contrast to the main role of the asymmetry parameter γ in the heavier Os isotopes. The energy level spectra, and the inter band B(E2) ratios in IBM-1 reproduce the shape variation from spherical to the X(5) symmetry status, and to the prolate deformed rotor, as in experiment. This reveals the interesting physics of the rotation vibration model by high lighting the special features of the light mass 164−184Os isotopes. The detailed band structure and their variation with neutron number N of the Os isotopes is presented empirically and in IBM-1.

Photo-neutron production of medical linear accelerator Elekta, precise model: A study with the Geant4 MC toolkit

We use Geant4 Monte Carlo (MC) toolkit to simulate a Precise Series Elekta linear accelerator. The simulation is validated for 6 and 15 MV X-rays with measured dose taken along the central axis of the radiation and off axis. The measurements are used in a clinical system, The neutrons generated from a (X, n) reaction when the 15 MV X-ray beam is on, are unwated byproducts that add up to the patient’s dose. Through the MC simulation we quantify the neutron dose contribution per delivered x-ray dose. Neutron fluence, in the units of neutron/cm2, contamination of the beam’s central axis was found to be proportionally dependent on the size of radiation field and decreases with the field size. This indicated that the number of neutrons produced in the head is constant, and when the field size opened wider, the neutrons distributed to a larger area, hence the fluence decreases. On the other hand, the neutron contamination outside the boundaries of the beam did not depend on its size and was found to be constant. This is intuitive, as those are the neutrons leaking from the head of the linac laterally, and as such are independent of the radiation beam size. Moreover, the maximum dose, dmax, for 15 MV x-rays from neutrons was found to be at a voxel 2 at the central axis at a depth of 2.5 cm inside the water phantom and it contributes an amount of 0.0003% to total dose.

Density-dependent relativistic mean field approach and its application to single-Λ hypernuclei in oxygen hyperisotopes* *Supported by the Fundamental Research Funds for the Central Universities, Lanzhou University (lzujbky-2022-sp02, lzujbky-2023-stlt01), the National Natural Science Foundation of China (11875152, 12275111), and the Strategic Priority Research Program of Chinese Academy of Sciences (XDB34000000)

The in-medium feature of nuclear force, which includes both nucleon-nucleon () and hyperon-nucleon () interactions, impacts the description of single-Λ hypernuclei. With the alternated mass number or isospin of hypernuclei, such effects may be unveiled by analyzing the systematic evolution of the bulk and single-particle properties. From a density-dependent meson-nucleon/hyperon coupling perspective, a new effective interaction in the covariant density functional (CDF) theory, namely, DD-LZ1-, is obtained by fitting the experimental data of Λ separation energies for several single-Λ hypernuclei. It is then used to study the structure and transition properties of single-Λ hypernuclei in oxygen hyperisotopes, in comparison with those determined using several selected CDF Lagrangians. A discrepancy is explicitly observed in the isospin evolution of spin-orbit splitting with various effective interactions, which is attributed to the divergence of the meson-hyperon coupling strengths with increasing density. In particular, the density-dependent CDFs introduce an extra contribution to reduce the value but enhance the isospin dependence of the splitting, which originates from the rearrangement terms of Λ self-energies. In addition, the characteristics of hypernuclear radii are studied along the isotopic chain. Owing to the impurity effect of the Λ hyperon, a size shrinkage is observed in the matter radii of hypernuclei compared with the cores of normal nuclei, and its magnitude is further elucidated to correlate with the incompressibility of nuclear matter. Moreover, there is a sizable model-dependent trend in which the Λ hyperon radii evolve with neutron number, which is decided partly by the in-medium interactions and core polarization effects.

Decay Characteristics of Neutron Excess Chlorine Nuclei

In neutron star mergers, neutron excess nuclei and the r-process are important factors governing the production of heavier nuclear systems. A single-particle model evaluation of chlorine nuclei suggests that the heaviest Z = 17 nucleus will have mass 62 with filling of the 1g9/2 neutron shell. A = 48 – 62 chlorine isotopes have limited experimental half-life data, but the model predicts beta decay half-lives in the range of 0.535 – 51.9 ms. Based on previous calculations for Z = 9 - 16, 20, 26, and 30 systems and comparisons to the 48Cl - 53Cl, and 55Cl calculations, summarized in the Japanese Nuclear Data Compilation, the single-particle model results likely overestimate the half-lives of A = 48 – 62 neutron excess chlorine nuclei.

α decay half-lives of nuclei W, Re, Os, Ir and Pt in the range 157≤A≤193 using the modified generalised liquid drop model (MGLDM)

The α-decay half-lives for the isotopes of nuclei W, Re, Os, Ir and Pt in the range have been studied by using the Modified Generalised Liquid Drop Model (MGLDM). The half-lives predicted for some even–even nuclei by using the deformed Two Potential Approach (TPA) [Comm. Theo. Phys. 74, 055301 (2022)] are considered and included for the comparison. Additionally, we have analysed the α-decay half-lives using eight ℓ-dependent empirical formulae, and compared the results with the experimental data. The standard deviation and the average deviation for by using MGLDM is obtained as 0.6025 and 0.5403, respectively. Also, the results of MGLDM match well with predictions of TPA, with standard deviation of 0.47 and 0.44 respectively. A dip in the half-life curve or a peak in the decay energy curve at 82, a magic neutron number of the daughter nuclei of increases the viability of the calculations. Also, the linear nature of Geiger-Nuttall law, Universal law, the relation connecting and and the New Geiger-Nuttall law helps to calculate the half-lives of newly synthesized and unknown isotopes, making MGLDM more reliable.

Inference and visualization of nuclear magnetic moment studies with neuro-fuzzy systems

This study aims to predict the magnetic moments of nuclei with odd-A numbers in a certain region of which the magnetic moment has not yet been calculated, using the Adaptive Neuro-Fuzzy Inference System (Anfis) method. In our Anfis model the proton number (Z), neutron number (N), and spin value (I) are used as inputs for nuclei with 1 ≤ Z ≤ 88. With 652 nuclei in the dataset, consisting of the provided input data, 528 odd-A nuclei were used for training, and 124 odd-A nuclei were used for testing. The fact that the Anfis model was closer to the experimental data in the training and testing processes than the theoretical methods encouraged us to make inferences about the nuclei of which experimental nuclear magnetic moment is unknown. Motivated by the presence of odd-A nuclei exhibiting I π = 1/2±, 3/2±, and 5/2± ground-state configurations near the doubly closed-shell, within the 1 ≤ Z ≤ 28 regions, along with the limited knowledge of nuclear properties in this range. This study has conducted magnetic moment inferences for 165 nuclei lacking experimental data. Specifically, Na, F, and P isotopes have been chosen as Magnetic moment value inferences made for these isotopes using Anfis have also been compared with the theoretical results of the Quasiparticle-Phonon Nuclear Method (QPNM) and with the Shell Model calculations. There is a satisfactory agreement between our predictions and the results of these two theories. Furthermore, it is noteworthy that within the same isotope series, nuclei with identical ground-state configurations consistently yield compatible results, irrespective of the availability of experimental magnetic moments. In addition, the fact that the values obtained from test and train operations remain within acceptable error limits, with a range of approximately 0.03%–0.04%, reveals the reliability of our system. Since the Neuro-Fuzzy system will be a first in the field of nuclear technologies, we believe that the outputs of our study will be a good reference for future studies.

Alpha clustering in nuclear astrophysics and topology

When we think of clustering in nuclear physics, the astrophysical importance within light nuclei and structural manifestations with classical analogs immediately come to mind. 4He, also known as the alpha particle, is the most abundant nucleus in the Universe, being quite tightly bound for its mass, with a first excited state of over 20 MeV. The nature of the alpha particle places it in a unique position within nuclear astrophysics and structure (including geometry). The plurality of energy release from stellar hydrogen fusion—whether quiescent or explosive—comes from the conversion of hydrogen to helium. Within more complex nuclei, the alpha particles are continuously arranged, leading to fascinating phenomena such as excited rotational bands, Borromean ring ground states, and linear structures. Nuclei with an equal and even number of protons and neutrons are colloquially referred to as “alpha conjugate nuclei,” where such special properties are the most pronounced and easiest to spot. However, when a single nucleon or a pair of nucleons is added to the system, alpha clustering not only remains evident but it may also be enhanced. Excited states with large alpha partial widths are a signature of clustering behavior, and these states can have a profound effect on the reaction rates in astrophysical systems when the excitation energy aligns with the so-called Gamow energy—the preferential thermal energy to statistically overcome the Coulomb barrier. In this article, we will consider in detail the specific ramifications of alpha clustering in selected scenarios for both nuclear astrophysics and topology. In particular, we discussed the astrophysical reactions of 7Li (α, γ), 7Be+α, 11C (α, p), and 30S (α, p), where α-clusters may increase the reaction rates from 10% to an order of magnitude; large α resonances make the astrophysical rate of 18F (p, α) quite uncertain. We also focused on the α rotational bands of both positive and negative parities of 11B and 11C, and finally on the strongest evidence for the linear-chain cluster state observed in 14C.

Shell evolution and emerging paradigm changes

The shell structure conceived by Mayer and Jensen in 1949 has been shown to be quite appropriate for stable and near-stable nuclei, but substantial deviations from it have also been observed more recently for exotic nuclei with notable neutron excess. Such changes of the basic picture of the nuclear shell structure, called the shell evolution, seem to be the subject studied most extensively and most elaborately by RI beam experiments worldwide. An overview of the shell evolution is presented in this talk, from both theoretical and experimental perspectives. The shell structure is shown to be varied, for instance, from the one presented by Mayer and Jensen, by particular types of the monopole components of the effective nucleon-nucleon interaction in nuclei. Among various contributions, the importance of the tensor force is illuminated here, with an outstanding example: the emergence of new neutron magic number 34 in neutron-rich Ca isotopes. The mechanism of the shell evolution produces significant impacts also on the nuclear shapes. Type II shell evolution shifts the excitation energies of intruder deformed bands, for instance, in some Ni isotopes. In other more general cases, the monopole interaction is shown to produce unexpected crucial effects on the patters of rotational bands of heavy deformed nuclei. In fact, the shape of the ellipsoidal deformation is investigated by large-scale shell model calculations, which is nothing but the Monte Carlo Shell Model. The unique role of the monopole component of the tensor force is clarified: the interplay between this monopole interaction and the quadrupole interaction provides us with various patterns of triaxial shapes for many nuclei, such as 166Er, one of the traditional prolate deformed heavy nuclei. Thus, the prolate preponderance hypothesis by Aage Bohr is investigated for its microscopic validity. Some of the nuclear paradigms are changing now in this way, due to emerging aspects of nuclear-force effects.

A systematic study of α-decay half-lives for Ac, Th, Pa, U and Np isotopes with A = 205–245 using the modified generalized liquid drop model

The Modified Generalized Liquid Drop Model (MGLDM) has been used for calculating the ground-to-ground states of [Formula: see text]-decay half-lives for various Ac, Th, Pa, U and Np isotopes in the mass number range of [Formula: see text]. To account for the nuclear proximity energy, the potential of Blocki et al. 74 [J. Blocki, J. Randrup, W. J. Swiatecki and C. F. Tsang, Ann. Phys. NY 105 (1977) 427] is used. The experimental [Formula: see text] values are used to evaluate the [Formula: see text]-decay half-lives. It can be observed that the logarithm of [Formula: see text]-decay half-life increases with increasing neutron number ([Formula: see text]), with evident minimum at the magic number 126, where the neutron shell is closed. The calculated results are compared with available experimental data and with the predictions of different empirical formulae such as, ARF, MARF, Royer, AKRE, Akrawy, NRB, VS, MVS, YQZR and MYQZR. It is found that the MGLDM is able to predict the experimental half-lives with a standard deviation of 0.6892 (the lowest one among all the other applied empirical formulae), and is therefore suitable for predicting the [Formula: see text]-decay half-lives for unknown and new heavy nuclei.

Symmetry Energy in the Inner Crust Region of Neutron Stars: A Study Around the Neutron Drip Density Point using the Compressed Liquid Drop Model

The properties of neutron star’s inner crust have been investigated using the Compressible Liquid Drop Model, particularly around the neutron drip density region, which is the boundary between the outer and inner crust. Symmetry energy in the equations of state SLy4 and BSk3 was calculated to determine the density data between the outer and inner crusts. The properties of the inner crust can be understood through parameters such as the change in the number of nucleons in the atomic nucleus, the asymmetry parameter in surface energy, and volume energy. It was shown that the choice of the symmetry energy expansion coefficient (L) of order-1 results in a distinct energy range of 9-11 MeV within the neutron drip region. This contrasts significantly with the energy symmetry observed around saturation density, which reaches (30 ± 4) MeV in the reference models used. Furthermore, it was found that symmetry energy affects the neutron composition in the inner crust. As the density increases, neutron numbers rise, while proton counts exhibit relative stability within the range of 40 to 50 for each atomic nucleus. Importantly, we observe a marked decrease in proton fraction at the onset of the neutron drip region, where ???? ≅10 MeV, suggesting electron capture processes transforming protons into neutrons. This phenomenon contributes to the presence of neutron and free neutron gas layers within the inner crust.

Deformation studies on thorium isotopes

The study of the deformation on thorium nuclei are important in nuclear physics due to its fissile nature. Thermally fissile isotopes have importance in energy production. The quadrupole and hexadecapole deformation parameters are important as they provide information on nuclear shape, size and moments of nuclei. The shape degree of freedom plays an important role in determining the fission barrier. In the present study, the quadrupole and hexadecapole deformation parameters of thorium nuclei were estimated by using the relativistic mean-field theory, with density dependent meson exchange interaction DD-ME2 and the density dependent point-coupling interaction DD-PC1. The estimated results of quadrupole deformation parameter are comparable with the available data and the minima point towards the neutron numbers N=126 and 184. The hexadecapole deformation parameter of thorium nuclei are positive along the stability line, negative towards the drip lines and zero at neutron number N=126 and 184.

Present and future constraints on flavor-dependent long-range interactions of high-energy astrophysical neutrinos

The discovery of new, flavor-dependent neutrino interactions would provide compelling evidence of physics beyond the Standard Model. We focus on interactions generated by the anomaly-free, gauged, abelian lepton-number symmetries, specifically Le – Lμ, Le – Lτ , and Lμ – Lτ , that introduce a new matter potential sourced by electrons and neutrons, potentially impacting neutrino flavor oscillations. We revisit, revamp, and improve the constraints on these interactions that can be placed via the flavor composition of the diffuse flux of high-energy astrophysical neutrinos, with TeV–PeV energies, i.e., the proportion of νe, νμ, and ντ in the flux. Because we consider mediators of these new interactions to be ultra-light, lighter than 10−10 eV, the interaction range is ultra-long, from km to Gpc, allowing vast numbers of electrons and neutrons in celestial bodies and the cosmological matter distribution to contribute to this new potential. We leverage the present-day and future sensitivity of high-energy neutrino telescopes and of oscillation experiments to estimate the constraints that could be placed on the coupling strength of these interactions. We find that, already today, the IceCube neutrino telescope demonstrates potential to constrain flavor-dependent long-range interactions significantly better than existing constraints, motivating further analysis. We also estimate the improvement in the sensitivity due to the next-generation neutrino telescopes such as IceCube-Gen2, Baikal-GVD, KM3NeT, P-ONE, and TAMBO.

Lead perovskites as CEνNS detectors

Introduction: The recent discovery of coherent elastic neutrino-nucleus scattering (CEvNS) has created new opportunities to detect and study neutrinos. The interaction cross section in CEvNS scales quadratically with the number of neutrons, making heavy-nuclei targets such as active lead-based detectors ideal. Lead perovskites have emerged in the last decade as revolutionary materials for radiation detection due to their heavy and flexible element composition and their unique optoelectronic properties that result in an excellent energy resolution at an economic cost.Methodology: In this study, we discuss, for the first time, the physics potential and feasibility of building neutrino detectors using semiconductor lead perovskite crystals as a target.Results and Discussion: We indicate that existing data with x-rays suggest the suitability of existing lead perovskite sensors to study CEvNS using neutrinos from π decay at rest (π- DAR) sources. Although dedicated research and development will be necessary, we have found significant benefits and no inherent obstacles for the development of lead perovskites as CEvNS detectors.

Post-Neutron Mass Yield Distribution in the Epi-Cadmium Neutron–Induced Fission of 238Pu

The cumulative and independent yields of various fission products within the mass range of 78 to 157 have been measured in the epi-cadmium neutron–induced fission of 238Pu by using an off-line γ-ray spectrometric technique. The lower yield of 136I than the usual trend indicates the formation of delayed neutron emitter 137I. From the cumulative yields, post-neutron mass chain yields were obtained by using the charge distribution correction. From the mass yield data, the peak-to-valley (P/V) ratio, the full-width at tenth-maximum of light and heavy mass wings, the average light mass <AL> and heavy mass <AH> as well as the average number of neutrons <ν> emitted were obtained. The mass chain yield data in the 238Pu(n,f) reaction were compared with similar data of the 238Pu(nth,f) reaction to examine the role of excitation energy on the nuclear structure effect and P/V ratio.

Estimation of radiative capture 13B(n, γ 0+1)14B reaction rate in the modified potential cluster model* *Supported by the Ministry of Science and Higher Education of the Republic of Kazakhstan (AP09259174)

We discuss current attempts to employ the modified potential cluster model to describe the available experimental data on the 13B(n, γ 0+1)14B total cross-sections. The estimated results of the M1 and E1 transitions from the n 13B scattering states to the ground and first excited states of 14B are presented. The 1st resonance at E x = 1. 275 MeV (1+) is revealed in both the cross-section and reaction rate. Within the variation in the asymptotic constant, a thermal cross-section interval of 5.1 – 8.9 mb is proposed. Based on the theoretical total cross-sections at energies of 0.01 eV to 5 MeV, we calculate the reaction rate in the temperature range of 0.01 to 10T 9. The ignition T 9 values of the 13B(n, γ 0+1)14B reaction depending on a neutron number density of ~ 1022 cm−3 are determined. The radiative neutron capture reaction rates on the boron 10-13B and carbon 12-14С isotopes are compared.

Decay probability of oxygen and flourine clusters from 290−320122, 292−332124 and 298−326126 even-even isotopes

Emission probability of 17−23O and 19−25F isotopes from 290−320122, 292−332124 and 298−326126 eve-even parents were studied by calculating the barrier penetrability, decay constant and decay half-lives using the Coulomb and Proximity potential Model (CPPM). The Q-values are estimated using the WS4 mass model. Clusters like 18,20O, 23,25F show the emission probability from the selected parents with a decay half-life less than the experimental upper limit of 1030 seconds. Neutron shell closure at N = 176 and 184 is identified from the plot of log10⁡T1/2 versus the neutron number of parent nuclei.

The neutron number probability distribution in coupled lumped assemblies

The validity of the gamma distribution in describing the neutron number probability distribution function for both isolated and coupled multiplying assemblies when constrained to reproduce the true mean and variance is investigated in lumped geometry by numerical comparison with kinetic Monte Carlo simulations. The mean and variance are obtained from numerical solution of moment equations constructed from the relevant forward Master equation with assembly coupling coefficients obtained from a view factor method. Numerical results for a two-group, two coupled assemblies model, with static and dynamic reactivity insertion, show that except for subcritical assemblies, the gamma distribution well-approximates the number distribution. Differences in the fast and thermal neutron population shapes are explained in terms of effective source strengths due to downscatter and coupling.

Shape evolution of nuclei in the region of (A≈30) using covariant density functional theory

Shape evolution of even–even isotopes of Ne, Mg, Si, S, Ar and Ca in the vicinity of [Formula: see text] mass region of the nuclear chart is studied using covariant density functional theory. It will be studied based on finite range NN-interaction force represented by NL3∗ and DD-ME2 and zero finite range NN-interaction force represented by DD-PC1. Both [Formula: see text]Mg and [Formula: see text]Si exhibit shape coexistence and the ground state shape which is found to be both oblate and prolate. The spherical shape is obtained for the Ca isotopes, and for nuclei that have magic neutron numbers [Formula: see text] and 20. The rest of the isotopic chain has only one minimum and alternates between prolate and oblate shapes. Physical properties are calculated at the location of ground state deformation with neutron number ([Formula: see text]) and proton number ([Formula: see text]), such as the binding energy, two-neutron separation energies, proton, neutron and charge radii. In general, a smooth change in these properties is found, except near [Formula: see text] and 20 one can see a sharp change, which reflects the sudden change in the ground state deformation in the neighboring nuclei. A very good agreement is found with the available experimental data, HF and FRDM models

A study on nuclear binding energy and beta decay energy using deep neural networks

The Artificial Neural Network (ANN) is one of the innovative methods for predicting the structural and dynamic properties of atomic nuclei. In this work, we employed machine learning based on the Deep Neural Network (DNN) technique to find the ground state binding energy and beta decay energy of various nuclei. 3560 experimental nuclear data sets have been used for training and validating the DNN model. Neutron number (N), proton number (Z), the pairing term (δ), a magic number greater than or equal to N and Z, asymmetry factor (a) and promiscuity factor (P) are used as input parameters. The Rectified Linear Unit (ReLU) function and Mean Absolute Error (MAE) are used as activation and Loss functions for the training process. We perform the predictions of ground state binding energy per nucleon and beta decay energies in Zinc and Promethium isotopes using the DNN model, which is in good agreement with experimental results.