Elastic Scattering Cross Sections Research Articles

Cored dark matter halos in the cosmic neutrino background

We study the impact of the interaction between DM and the cosmic neutrino background on the evolution of galactic dark matter halos. The energy transfer from the cosmic background neutrinos to galactic dark matter can heat the center of the galaxy and make it cored. The core formation is efficient for the small galaxies such as the satellite galaxies of the Milky Way and we can put a conservative constraint on the non-relativistic elastic scattering cross section as σχν ≲ 10-31 cm2 for 0.1 keV dark matter.

а- бөлшектердің 9Be ядросымен соқтығысу кезіндегі серпімді шашырауының жаһандық заңдылықтары

The article investigates the characteristics of the experimental data of the elastic scattering cross section in the low-energy range of the a+9Be nuclear system. General regularities depending on the change in the energy of accelerated ions of the parameters of the obtained cross sections are established. Based on the analysis in the framework of the optical model (OM), energy-dependent optical interaction potentials in a wide range of energies were found.The energy regularity of potentials, revealed as a result of systematic analysis, makes it possible to predict with sufficient accuracy the cross-section of processes at energies at which experimental measurements were not carried out.The potential, which is a complex function of the interaction between nuclei, is an empirical measurement that describes the interaction in the scattering process.Studies of the dependence of the potential on external factors should be carried out individually for each nuclear system. Such analyses carried out in order to improve the accuracy of phenomenological theories should be based on a large array of experimental data. To clarify the truthfulness of the results of phenomenological approaches, it would be theoretically more correct to determine the global patterns of potentials and energy dependences of the full reaction cross-section.The article defines the energy dependence of the potentials and the total cross-section of the reaction based on a systematic analysis of the experimental data set in the energy range of laboratory Elab=30 - 60 MeV for the α+9Be process.Optimal values of the cross-section parameters satisfying global laws depending on the energy of the accelerating beam are found.

An extensive theoretical quantification of secondary electron emission from silicon

Though intensive experimental studies have been carried out on electron emission properties in past decades, the reliable data from accurate experimental measurements for clean and smooth surfaces are still quite limited. In this work, we have performed a comprehensive Monte Carlo simulation of electron emission yields, the secondary electron yield (SEY, δ), backscattered electron coefficient (BSC, η) and total electron yield (TEY, σ=δ+η), from silicon and the uncertainty quantification of the theoretical calculation results for the first time. The simulations were made on total 17280 scattering models. The considered uncertainty factors in the physical modelling that can influence the calculated yields include work function data, optical energy loss function data, dielectric function models for electron inelastic scattering and the scattering potentials for electron elastic scattering. The calculation results show that δ is significantly influenced by the work function while the dielectric function model has a slight effect. Elastic scattering potential (or elastic scattering cross section) and energy loss function affects to a certain extent both δ and η. Our simulated η data agree with most of the experimental measurements while the simulated mean δ data are well below most of the experimental data. At a 75% level of confidence, the experimental σ data measured by Goto et al. lie within the uncertainty range of our simulation results. This work has provided sufficient ground for the necessity of building a theoretical database of electron emission yield considering the fact that most of the previous experimental data are not reliable due to the presence of surface contamination during the measurements.

On particle scattering in Gross-Pitaevskii theory and implications for dark matter halos

Bose-Einstein-condensed dark matter (BEC-DM), also called scalar field dark matter (SFDM), has become a popular alternative to the standard, collisionless cold dark matter (CDM) model, due to its long-held potential to resolve the small-scale crisis of CDM. Halos made of BEC-DM have been modelled using the Gross-Pitaevskii (GP) equation coupled to the Poisson equation; the so-called GPP equations of motion. These equations are based on fundamental microphysical conditions that need to be fulfilled in order for the equations to be valid in the first place, related to the diluteness of the DM gas and the nature of the particle scattering model. We use these conditions in order to derive the implications for the BEC-DM parameters, the 2-particle self-interaction coupling strength g and the particle mass m. We compare the derived bounds with the constraint that results from the assumption of virial equilibrium of the central cores of halos, deriving a relationship that connects g and m. We find that the GPP conditions are greatly fulfilled, for BEC-DM particle masses of interest, if such models also obey the virial condition that turns out to be the strongest constraint. We also derive the implications for the elastic scattering cross section (per particle mass) in BEC-DM halos, based on the scattering model of GPP, and find a huge range of possible values, depending on the self-interaction regime. We put our results into context to recent literature which predicts sub-kpc core size in BEC-DM halos.

Theoretical Study on 10C Elastic Scattering Cross Sections Using Different Cluster Density Distributions and Different Potentials

Elastic scattering cross sections are a fundamental aspect of nuclear physics research, and studying the cross sections of various nuclei can provide important insights into the behavior of nuclei. In this study, the elastic scattering cross sections of 10C projectile by 27Al, 58Ni, and 208Pb target nuclei are analyzed. The aim of this study is to investigate the cluster structure of 10C and the sensitivity of the elastic scattering cross sections to different potentials. To achieve this objective, the double folding optical model and a simple cluster approach are used to analyze the cross sections. The real part of the optical potential is obtained by folding two different effective interactions, Michigan-3-Yukawa (M3Y) and JeukenneLejeune-Mahaux (JLM), with four different cluster density distributions of the 10C nucleus: 6Be + \alpha, 9B + p, 8Be + p + p, and \alpha + \alpha + p + p. The imaginary part is taken to be a Woods-Saxon phenomenological form. The sensitivity of the elastic scattering cross sections to different potentials is assessed by comparing the results obtained using different potentials. The cluster structure of 10C is validated by comparing the theoretical results with experimental data. The results show that the cross sections are sensitive to the choice of potential used and that the cluster structure of 10C is validated. The theoretical results show reasonable agreement with the experimental data.

Cross Sections for Coherent Elastic and Inelastic Neutrino-Nucleus Scattering

The prospects of extracting new physics signals in coherent elastic neutrino–nucleus scattering (CEνNS) processes are limited by the precision with which the underlying nuclear structure physics, embedded in the weak nuclear form factor, is known. We present calculations of charge and weak nuclear form factors and CEνNS cross sections on 12C, 16O, 40Ar, 56Fe and 208Pb nuclei. We obtain the proton and neutron densities, and charge and weak form factors by solving Hartree–Fock (HF) equations with a Skyrme (SkE2) nuclear potential. We validate our approach by comparing 208Pb and 40Ar charge form factor predictions with available elastic electron scattering data. Since CEνNS experiments at stopped-pion sources are also well suited to measure inelastic charged–current and neutral–current neutrino–nucleus cross sections, we also present calculations for these processes, incorporating a continuum Random Phase Approximation (CRPA) description on top of the HF–SkE2 picture of the nucleus. Providing both coherent as well as inelastic cross sections in a consistent framework, we aim at obtaining a reliable and detailed comparison of the strength of these processes in the energy region below 100 MeV. Furthermore, we attempt to gauge the level of theoretical uncertainty pertaining to the description of the 40Ar form factor and CEνNS cross sections by comparing relative differences between recent microscopic nuclear theory and widely-used phenomenological form factor predictions. Future precision measurements of CEνNS will potentially help in constraining these nuclear structure details that will in turn improve prospects of extracting new physics.

Flux-integrated semiexclusive cross sections for charged-current quasielastic and neutral-current elastic neutrino scattering off Ar40 and a sterile neutrino oscillation study

Flux-integrated semiexclusive differential cross sections for charged-current quasielastic and neutral-current elastic neutrino scattering on argon are analyzed. The cross sections are calculated using the relativistic distorted-wave impulse approximation with values of the nucleon axial mass ${M}_{A}=1\text{ }\text{ }\mathrm{GeV}$ and 1.2 GeV. The elastic scattering cross sections are also computed for different strange quark contributions to the neutral-current axial form factor. The flux-integrated differential cross sections as functions of reconstructed neutrino energy are evaluated for the far detector of the SBN experiment. The effects of the short baseline neutrino oscillations are taken into account in a $3+1$ framework. We found that cross sections depend on oscillation parameters and the ratio of the measured and predicted cross sections can be used in a sterile neutrino oscillation study.

Elastic scattering of electrons by water: An ab initio study

In this work we devise a theoretical and computational method to compute the elastic scattering of electrons from a non-spherical potential, such as in the case of molecules and molecular aggregates. Its main feature is represented by the ability of calculating accurate wave functions for continuum states of polycentric systems via the solution of the Lippmann-Schwinger equation, including both the correlation effects and multi-scattering interference terms, typically neglected in widely used approaches, such as the Mott theory. Within this framework, we calculate the purely elastic scattering matrix elements. As a test case, we apply our scheme to the modelling of electron-water elastic scattering. The Dirac-Hartree-Fock self-consistent field method is used to determine the non-spherical molecular potential projected on a functional space spanned by Gaussian basis set. By adding a number of multi-centric radially-arranged s-type Gaussian functions, whose exponents are system-dependent and optimized to reproduce the properties of the continuum electron wave function in different energy regions, we are able to achieve unprecedented access to the description of the low energy range of the spectrum (0.001 < E < 10 eV) up to keV, finding a good agreement with experimental data and previous theoretical results. To show the potential of our approach, we also compute the total elastic scattering cross section of electrons impinging on clusters of water molecules and zundel cation. Our method can be extended to deal with inelastic scattering events and heavy-charged particles.

Imprints of α clustering in the density profiles of C12 and O16

The $^{4}$He nucleus is a well bound and highly correlated four-nucleon system that is also found in form of $\alpha$-clusters as substructure in nuclear many-body systems. The standard single-particle shell model cannot represent these four-body correlations. It is highly desirable to find a simple way to identify and distinguish these fundamental structures without large-scale computations. In this paper, we investigate with intrinsic Slater determinants as trial states in how far these two competing pictures prevail in the ground states of $^{12}$C and $^{16}$O. The trial states can describe both the $j$-$j$ coupling shell-model and $\alpha$-cluster configurations in a unified way. One-body density distributions of the trial states are calculated and compared to elastic scattering cross section data. The parameters of the trial state are chosen to reproduce the experimental charge radii. A well developed cluster structure is characterized by an enhancement of the differential elastic scattering cross sections, as well as the elastic charge form factors around the first peak positions. The density profiles of the internal regions can also be probed at higher momentum transfer regions beyond the second minimum. With these trial states one can visualize the competition between cluster and shell structure in an intuitive and simple way.

Low-energy positronium scattering from O2

The total cross section of positronium (Ps) scattering from molecular oxygen has been measured in the velocity range 0.27--1.50 a.u. (energy range 2--61 eV) and has been found to be close to the corresponding equivelocity electron cross section above 0.87 a.u. $(20\phantom{\rule{0.16em}{0ex}}\mathrm{eV})$, as previously found by Brawley et al., [Science 330, 789 (2010)]. However, below this value the cross section for positronium is observed to exceed that for electrons by up to a factor of 4 at the lowest energy. Measurements are compared to the predictions of low-energy resonant peaks in the elastic-scattering cross section calculated within a free-electron-gas model refined by applying corrections to the correlation energy for the interaction between Ps and the electron gas. Additionally, cross sections for ${\mathrm{O}}_{2}^{\ensuremath{-}}$ formation and positronium breakup have been calculated using a classical-trajectory Monte Carlo approach. Comparisons are made with earlier calculations and discussed in terms of both experimental and theoretical uncertainties.

Gamma-ray flux limits from brown dwarfs: Implications for dark matter annihilating into long-lived mediators

Brown dwarfs (BDs) are celestial objects representing the link between the least massive main-sequence stars and giant gas planets. In the first part of this article, we perform a model-independent search of a gamma-ray signal from the direction of nine nearby BDs in 13 years of \Fermi-LAT data. We find no significant excess of gamma rays, and we, therefore, set 95\% confidence level upper limits on the gamma-ray flux with a binned-likelihood approach. In the second part of the paper, we interpret these bounds within an exotic mechanism proposed for gamma-ray production in BDs: If the dark matter (DM) of the universe is constituted of particles with non-negligible couplings to the standard model, BDs may efficiently accumulate them through scatterings. DM particles eventually thermalize, and can annihilate into light, long-lived, mediators which later decay into photons outside the BD. Within this framework, we set a stacked upper limit on the DM-nucleon elastic scattering cross section at the level $\sim 10^{-38}$ cm$^{2}$ for DM masses below 10 GeV. Our limits are comparable to similar bounds from the capture of DM particles in celestial objects, but have the advantage of covering a larger portion of the parameter space in mediator decay length and DM mass. They also depend only on the local DM abundance, as opposed to the inner Galaxy profile, and are thus more robust.

Influence of Quantum Oscillations in the Thermal Scattering Law of Zirconium Carbide on Neutron Thermalization and Criticality

Zirconium carbide (ZrC) is a candidate material for advanced high temperature reactors, including space nuclear thermal propulsion applications. Thermal scattering laws (TSLs) are generated in the incoherent approximation for carbon bound in ZrC [C(ZrC)] and zirconium bound in ZrC [Zr(ZrC)], using ab initio lattice dynamics methods. Disordered alloy theory is introduced to improve treatment of isotopic composition within the elastic scattering cross section. Localized higher-energy vibrational modes and the presence of a phonon band gap in C(ZrC) cause quantized oscillation in the TSL atypical of nonhydrogenous solids. These oscillations yield a significant likelihood of large energy downscattering and upscattering interactions such that the quanta of energy transfer affecting neutron thermalization is substantially greater than classically expected. MC21 critical mass calculations of ZrC mixtures with high-enriched uranium demonstrate an impact of TSLs when compared to a free-gas treatment for thermal neutron–driven 235U loadings. The critical mass of homogenous mixed moderator systems of ZrC and reactor-grade graphite are also sensitive to the ZrC TSL. Moreover, the effect of quantized energy exchange on the neutron spectra is found to influence the temperature feedback coefficient.

Search for Cosmic-Ray Boosted Sub-GeV Dark Matter Using Recoil Protons at Super-Kamiokande.

We report a search for cosmic-ray boosted dark matter with protons using the 0.37 megaton×years data collected at Super-Kamiokande experiment during the 1996-2018period (SKI-IV phase). We searched for an excess of proton recoils above the atmospheric neutrino background from the vicinity of the Galactic Center. No such excess is observed, and limits are calculated for two reference models of dark matter with either a constant interaction cross section or through a scalar mediator. This is the first experimental search for boosted dark matter with hadrons using directional information. The results present the most stringent limits on cosmic-ray boosted dark matter and exclude the dark matter-nucleon elastic scattering cross section between 10^{-33}cm^{2} and 10^{-27}cm^{2} for dark matter mass from 1 MeV/c^{2} to 300 MeV/c^{2}.

Systematic study of global optical model potentials in (d, p) transfer reactions* *Supported by the National Natural Science Foundation of China (12035011, 11975167, 11535004, 11947211, 11905103, 11761161001, 11375086, 11565010, 11881240623, 11961141003), the National Key R&D Program of China (2018YFA0404403, 2016YFE0129300), the Science and Technology Development Fund of Macau (008/2017/AFJ) and the Fundamental Research Funds for the Central Universities (22120200101)

In the T-matrix form of the transfer reaction, the optical model potentials (OMPs) are used to compute the scattering wave function and transition operator. For most cases, the elastic scattering cross sections, normally used to generate the OMPs, are not directly given in the same experiment. Then, the global OMPs, which fit the experimental data over a broad mass and energy range, are widely used in the theoretical calculations. Different sets of global OMPs with different parameter sets can reproduce the scattering cross section equally well within the uncertainty. Here, we apply different global OMPs to calculate the (differential) cross sections of transfer reactions on the target nuclei , , , and at different energies. The results demonstrate that the effects of deuteron and nucleon global OMPs on transfer (differential) cross sections vary with energy and target mass. Furthermore, the influences of the spin-orbit coupling term of deuteron and nucleon global OMPs on the transfer cross sections are not negligible.

Inelastic Channel Traces in Elastic Scattering Cross Sections in the \(d + {^{13}}\)C Reaction at 14.5 MeV

Inelastic Channel Traces in Elastic Scattering Cross Sections in the \(d + {^{13}}\)C Reaction at 14.5 MeV

Упругое рассеяние атома рутения на атомах Si и O в диапазоне относительных кинетических энергий 2-200 eV

Interconnector technologies of a new generation involve use of ruthenium. The high cost of experimental study of sputtering and etching of trenches in Ru leads to the need to optimize it by modeling, requiring knowledge of the cross sections of elementary processes of interaction of plasma particles with Ru. In this work, the binary interatomic potentials of Ru-Ru and Ru-Si pairs, tested by molecular dynamics method, and the Ru-O one calculated using the multi reference configurational interaction MRCI/AV5Z were used to calculate the elastic scattering cross sections of the atomic pairs in the energy range typical for plasma etching chambers.

Elastic scattering of ruthenium atoms from Si and O atoms in the range of relative kinetic energies of 2-200 eV

Interconnector technologies of a new generation involve the use of ruthenium. The high cost of experimental study of sputtering and etching of trenches in Ru leads to the need to optimize it by modeling that requires knowledge of the cross sections of elementary processes of interaction of plasma particles with Ru. In this work, the binary interatomic potentials of Ru-Ru and Ru-Si pairs tested by the molecular dynamics method, and the Ru-O one calculated by the method of multi-reference configurational interaction MRCI/AV5Z were used to calculate the elastic scattering cross sections of the atomic pairs in the energy range typical of plasma etching chambers. Keywords: ruthenium, elastic scattering, cross sections, sputtering, binary potential.

Annihilation and nuclear elastic scattering of low-energy antiprotons

We perform a fitting procedure to differential elastic scattering cross section data of antiproton at intermediate energy on three different nuclei to evaluate parameters of a six-parameters Woods-Saxon optical potential. Then, with these values, we calculate the reaction cross sections at different momenta and evaluate the differential elastic cross sections for low-momenta antiproton ([Formula: see text]). We find that our analysis underestimates the reaction cross sections for data over the momentum-range 50 MeV/c to 1000 MeV/c. We predict measurable effect for antiprotons with momentum above 50 MeV/c at large angles ([Formula: see text]), in agreement with other recent results. Finally, we consider possible improvements to the model and the analysis.

Systematic investigation of channel-coupling effects on elastic, inelastic, and neutron-transfer channels in Li6+Tb159

Elastic scattering angular distribution for weakly bound nucleus $^{6}$Li on the deformed rare earth $^{159}$Tb target nucleus has been measured at energies around the Coulomb barrier. The elastic scattering cross sections for this reaction consist of inelastic contributions from low lying excited states of $^{159}$Tb. The pure elastic cross-sections have been extracted from the admixture of elastic and inelastic data. The optical model potential parameters for the system have been obtained from the extracted pure elastic scattering cross sections. Coupled channel calculations have been performed with this set of potential parameters, to compare the theoretical and experimental inelastic scattering cross sections. The work has been extended to obtain the spectroscopic factor for $^{158}$Tb+n configuration from the experimental 1n-pickup data.

Precision μ+μ+ and μ+e− elastic scatterings

Abstract The expected measurement precisions of elastic scattering cross sections are estimated for μ+μ+ and μ+e− colliders, which have recently been proposed as future realistic possibilities (μTRISTAN). Compared with contributions from possible new physics represented by higher-dimensional operators, we find that the measurements at a TeV energy μ+μ+ collider can probe the scale of new physics up to O(100) TeV. A μ+e− collider for the Higgs boson factory can also improve the electroweak precision test. For those studies, we assume the expected integrated luminosity at μTRISTAN, Lint = 120 fb−1 (μ+μ+) and 1 ab−1 (μ+e−).