Calculation Of Total Cross Sections Research Articles

Xenon photonuclear cross sections for the production of 123I radionuclide

A simple reliable theoretical model for the calculation of total photo-absorption cross sections by atomic nuclei has been presented and applied it to get the relevant data needed for the evaluation of the production rate of 123I radionuclide isotope. Since experimental measurements are not available, the model calculation represents the only source of information. The present results, based on an accurate model of nuclear structure, are in very good agreement with the observed photoabsorption cross sections of Te isotopes, which provide reliable cross sections for the neighboring Xe nuclei, where the usual simple estimates are clearly discordant.

Dynamic effective charge in the continuum of the CDW-EIS model for ionization in ion–atom collisions: angular and energy dependence

In this work, a dynamic charge is employed in the continuum distorted wave–eikonal initial state theoretical model to describe the non-Coulomb potential of the residual target for single ionization in bare ion–multielectron atom collisions. A comparison between the well-known Belkić prescription and the effective charge depending on emission angle and energy in the final residual-target continuum state is shown. The obtained results show that this effective charge improves the description of double-differential cross sections for backward emission angles over the whole emission energy range allowing the calculation of simple differential and total cross sections.

Deterministic sampling approach for the propagation of uncertainties in nuclear reaction models

Uncertainty propagation of model parameters through nuclear reaction models is critical for nuclear data evaluation and other applications. Nuclear reaction models generally contain nonlinear functions of the model parameters, making the process of uncertainty propagation difficult. Usually stochastic approaches like the Monte Carlo method are employed to propagate the uncertainties through nuclear reaction models. The Monte Carlo method does provide proper results, but it takes a lot of computational power and time, which makes the process of uncertainty propagation difficult. Deterministic sampling approaches may provide results with accuracy using less computational time making the process of uncertainty propagation fast. In this study we have explored the use of a deterministic sampling approach called the unscented transform method for the uncertainty propagation in the nuclear reaction models. As a test case we have propagated the uncertainties of correlated optical model parameters through the optical model calculations for total and reaction cross sections of the $n+^{56}\mathrm{Fe}$ reaction. The results obtained using the unscented transform method are then compared with the results of the Monte Carlo method. It has been observed that the unscented transform method provides results practically similar to the Monte Carlo method in less computational time. It is concluded in this study that the unscented transform method can propagate uncertainties effectively through optical model calculations and there should be further investigation of the use of this method for other nuclear reaction models.

Neutrino-induced single pion production and the reanalyzed bubble chamber data

In this work we report the calculation of the charged current total and differential cross sections for weak pion production with neutrinos and antineutrinos, with the final pion-nucleon pair invariant mass ${W}_{\ensuremath{\pi}N}\ensuremath{\lesssim}2\text{ }\text{ }\mathrm{GeV}$. Our results are compared with the recent reanalyzed data from the old bubble chamber experiments, that solved the discrepancy between the Argonne National Laboratory and Brookhaven National Laboratory data. We implement a model previously tested for the cuts ${W}_{\ensuremath{\pi}N}<1.4$, 1.6 GeV, which explicitly includes resonances in the first and second resonance regions within different approaches for the resonances self-energy and $\frac{3}{2}$ vertexes and propagators, a fact not usually analyzed. Our model leans on consistently effective Lagrangians that generate resonant amplitudes together with nonresonant and resonant backgrounds. Effects of hadrons' finite extension and more energetic resonances correspond to the emitted pion-nucleon invariant mass in the $1.6<{W}_{\ensuremath{\pi}N}<2\text{ }\text{ }\mathrm{GeV}$ region are taking into account using appropriate form factors in consistency with previous results on neutral current pion production calculations. Our results reproduce well the reanalyzed data without cuts and are compared with other models.

Calculated electron impact ionisation fragmentation patterns

There are many measurements and calculations of total electron impact ionisation cross sections. However, many applications, particularly in plasma physics, also require fragmentation patterns. Approximate methods of deducing partial cross sections are tested based on the use of total cross section computed within the well-used binary encounter Bethe approximation. Partial ionisation cross sections for three series of molecules including CH4, CF4 and CCl4; SiH4 and SiCl4; NH3 and PH3, were estimated using two methods. Method one is semi-empirical and uses mass spectroscopy data to fix the partial cross sections at a single electron energy. The second is a fully computational method proposed by Huber et al (2019 J. Chem. Phys. 150 024306). Comparisons with experimental results suggest that the mass spectroscopy method is more accurate. However, as Huber’s method requires no experimental input, this method could be used as a first approximation when no experimental data is available. As mass spectroscopy sometimes provides incomplete datasets, a hybrid method based on the use of both methods is also explored.

Electron scattering from molecules relevant to Titan's atmosphere

Present article reports calculation of elastic, momentum transfer, ionization, and total cross sections for electron scattering from C2N2, C4N2, C6N2, and HC5N molecules, relevant to Titan's atmosphere. The cross sections are predicted using spherical complex optical potential and complex potential ionization contribution method in the energy range from ionization threshold of the molecules to 5 keV. The cross section data reported here consider geometrical screening correction to avoid overestimation of cross section due to the overlap of charge density. A strong correlation is observed between Qionmax and (α/I)12 for C2N2, C4N2, and C6N2 molecular systems, which confirms the consistency of predicted ionization data. The cross sections reported here are important for mass spectrometry, especially in modelling Titan's atmosphere due the presence of these molecules along with abundant electrons in its environment. Most of the data are reported for the first time.

Study of total, absorption, and 3He and 3H production cross sections in 4He-proton collisions

Light ion breakup cross sections are important for studies of cosmic ray interactions in the inter-stellar medium or radiation protection considerations of energy deposition in shielding and tissues. Abrasion cross sections for heavy ion reactions have been modeled using the Glauber model in the large mass limit or Eikonal form of the optical potential model. Here we formulate an abrasion model for 4He fragmentation on protons using the Glauber model avoiding the large mass limit and include a model for final state interactions. Calculations of energy dependent total, absorption, elastic and breakup cross sections for 4He into 3He or 3H with proton targets are shown to be in good agreement with experiments for energies from 100 to 100,000 MeV/u. The Glauber model for light nuclei with and without a large mass limit approximation is shown to be in fair agreement above 300 MeV/u, however important differences occur at lower energies.

Theoretical investigations of e ± –CO scattering

The differential, integrated elastic, total, momentum transfer, viscosity cross sections and spin-polarization for electron and positron elastic scattering from carbon monoxide (CO) molecule are calculated for the energy range of 1 eV–10 keV. The work also includes the calculations of inelastic and total ionization cross sections for the same scattering system. Calculations of the above scattering observables for CO over such a wide range of energy are reported for the first time. Single scattering independent atom model (IAM) and the screening correction within the same framework, are used for the present analysis. Dirac partial wave analysis is used to calculate the phase-shifts required for the generation of the scattering observables, using a complex optical model potential. Comparison of our calculated results with the available experimental observations and other theoretical calculations is presented. The screening corrected independent atom model is found to provide better description of the results than the IAM.

Top pair production at ultra-high energies

The top quark, the heaviest quark and, indeed, the heaviest elementary particle known today, constitutes a novel probe of the long-lived medium in quark-gluon phase which, as expected, can be produced even in light nuclei collisions at ultra-high energies. Some distinctive features are considered for particle production in the top sector in ultra-high energy domain. The antitop-top pair production is studied within the quantum chromodynamics and effective field theory approach used for calculations of total partonic cross sections. Predictions for all observables are computed at NNLO in quantum chromodynamics and at LO in effective field theory. These quantitative results can be important for both the future collider experiments at center-of-mass energy frontier and the improvement of the phenomenological models for development of the cosmic ray cascades in ultra-high energy domain. Thus the study allows the better understanding of heavy particle production and emphasizes the exciting interrelation between the high-energy physics on accelerators and ultra-high energy cosmic ray measurements.

Calculations of total electron impact ionization cross sections for fluoroketone and fluoronitrile

Potential substitutes for SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> such as fluoroketone (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O) and fluoronitrile (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> N and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> N) gases have been widely studied. The electron impact ionization cross section (Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> ) is the key parameter in the simulation of gas discharges. Moreover, the Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> can be used in the preliminary screening of large scale alternatives of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> . In this paper, the Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O, C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O, C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> N and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> N are calculated via the BEB method. The orbital parameters are obtained by Moller-Plesset perturbation function with second order approximation (MP2), which is validated by comparing the theoretical and experimental Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> for CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> CN, CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> CN, C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> O, C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> O and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> O. The linear relationship between the maximum Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> and polarisability supports the validity of the BEB method with MP2 function, which suggests that the results of the calculated maximum Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> for C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> O and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> N are reasonable by BEB method. Lastly, the correlation between the maximum Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> and E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> is discussed. The analysis shows that there is a correlation between the maximum Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> and E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> , and the correlation coefficient reaches 0.598. It is thought that Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub> can be as a new predictor to estimate the dielectric strengths for SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> replacements.

Charged-current neutrino-nucleus scattering off Xe isotopes

Xenon detectors are used in the search for dark matter and neutrinoless double-beta decay ($0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta})$. As the next-generation detectors reach masses in the ton scale, neutrinos from astrophysical sources are soon predicted to become background in such detectors. Theoretical predictions of neutrino scattering cross sections and information of nuclear structure effects therein are crucial in accounting for the background. We perform calculations for differential and total cross sections of charged-current neutrino scattering off the most abundant xenon isotopes. The nuclear-structure calculations are made in the proton-neutron quasiparticle random-phase approximation and the microscopic quasiparticle phonon model for even-mass and odd-mass nuclei, respectively. We compute total cross sections as a function of the neutrino energy, and also give estimates of total averaged cross sections for $^{8}\mathrm{B}$ solar neutrinos and supernova neutrinos using realistic energy distributions.

Total and partial electron impact ionization cross sections of fusion-relevant diatomic molecules.

We report calculations of total (and absolute) electron-impact ionization cross sections (EICSs) for the fusion-relevant diatomic molecular species BeH, BeN, BeO, WH, WBe, WN, WO, O2, and N2 by means of the Deutsch-Märk and the binary-encounter-Bethe methods in the energy range from threshold to 10 keV. In addition, we discuss an empirical scheme to estimate partial cross sections from the total ones based on reaction energetics and empirical threshold laws and explore its accuracy by assessing available experimental data on total and partial EICSs. Finally, we also report parameters obtained by fitting the calculated cross sections to an expression commonly used in fusion edge plasma modeling.

Structure of forward pp and pp¯ elastic amplitudes at low energies

Exact analytical forms of solutions for Dispersion Relations for Amplitudes and Dispersion Relations for Slopes are applied in the analysis of pp and $\rm {p \bar p}$ scattering data in the forward range at energies below $\sqrt(s)\approx 30 \GeV$. As inputs for the energy dependence of the imaginary part, use is made of analytic form for the total cross sections and for parameters of the $t$ dependence of the imaginary parts, with exponential and linear factors. A structure for the $t$ dependence of the real amplitude is written, with slopes $B_R$ and a linear factor $\rho-\mu_R t$ that allows compatibility of the data with the predictions from dispersion relations for the derivatives of the real amplitude at the origin. A very precise description is made of all $d\sigma/dt$ data, with regular energy dependence of all quantities. It is shown that a revision of previous calculations of total cross sections, slopes and $\rho$ parameters in the literatures is necessary, and stressed that only determinations based on $d\sigma/dt$ data covering sufficient $t$ range using appropriate forms of amplitudes can be considered as valid.

Neutral-Current Neutrino-Nucleus Scattering off Xe Isotopes

Large liquid xenon detectors aiming for dark matter direct detection will soon become viable tools also for investigating neutrino physics. Information on the effects of nuclear structure in neutrino-nucleus scattering can be important in distinguishing neutrino backgrounds in such detectors. We perform calculations for differential and total cross sections of neutral-current neutrino scattering off the most abundant xenon isotopes. The nuclear-structure calculations are made in the nuclear shell model for elastic scattering and also in the quasiparticle random-phase approximation (QRPA) and microscopic quasiparticle-phonon model (MQPM) for both elastic and inelastic scattering. Using suitable neutrino energy distributions, we compute estimates of total averaged cross sections for ​8B solar neutrinos and supernova neutrinos.

Effect of resonance states of the weakly bound 6Li on total fusion in reactions with targets 28Si, 96Zr and 209Bi

Continuum Discretized Coupled-Channel calculations of total fusion cross sections for reactions induced by the weakly bound nucleus 6Li with targets 28Si, 96Zr and 209Bi at energies around the Coulomb barrier are presented. In the cluster structure frame of 6Li → α+d, short-range absorption potentials are considered for the interactions between the α- and d-fragments with the targets. In the model, the effect of resonance (l = 2, Jπ = 3+, 2+, 1+) and non-resonance breakup states of 6Li on fusion is studied by using two approaches: (1) by omitting the resonance states from the full discretized CDCC breakup space and 2) by considering only the resonance discretized sub-space. Among other things, it is found that resonance breakup states produce strong repulsive polarization potentials that lead to fusion suppression. The particular effect on fusion of a single resonance is calculated. It is found that resonances 2+ and 1+ have a more significant role on incomplete fusion, while the 3+ on complete fusion.

Systematic continuum-discretized coupled-channels calculations of total fusion for Li6 with targets Si28, Co59, Zr96, Pt198 , and Bi209 : Effect of resonance states

Continuum discretized coupled-channel (CDCC) calculations of total fusion cross sections for reactions induced by the weakly bound nucleus $^{6}\mathrm{Li}$ with targets $^{28}\mathrm{Si}, ^{59}\mathrm{Co}, ^{96}\mathrm{Zr}, ^{198}\mathrm{Pt}$, and $^{209}\mathrm{Bi}$ at energies around the Coulomb barrier are presented. In the cluster structure frame of $^{6}\mathrm{Li}\ensuremath{\rightarrow}\ensuremath{\alpha}+d$, short-range absorption potentials are considered for the interactions between the $\ensuremath{\alpha}$ and $d$ fragments with the targets. The effect of resonance ($l=2, {J}^{\ensuremath{\pi}}={3}^{+},{2}^{+},{1}^{+}$) and nonresonance states of $^{6}\mathrm{Li}$ on fusion is studied by using two approaches: (1) by omitting the resonance states from the full discretized CDCC breakup space and (2) by considering only the resonance subspace. A systematic analysis of the effect on fusion from resonance breakup couplings is carried out from light to heavy mass targets. Among other things, it is found that resonance breakup states produce strong repulsive polarization potentials that lead to fusion suppression. Couplings from nonresonance states give place to weak repulsive potentials at high energies; however, these become attractive for the heavier targets at low energies.

Calculations of Total Classical Cross Sections for a Central Field

In order to find the total collision cross-section a direct method of the effective potential (EPM) in the framework of classical mechanics was proposed. EPM allows to over come both the direct scattering problem (calculation of the total collision cross-section) and the inverse scattering problem (reconstruction of the scattering potential) quickly and effectively. A general analytical expression was proposed for the generalized Lennard-Jones potentials: (6–3), (9–3), (12–3), (6–4), (8–4), (12–4), (8–6), (12–6), (18–6). The values for the scattering potential of the total cross section for pairs such as electron–N $$_{2}$$ , N–N, and O–O $$_{2}$$ were obtained in a good approximation.

Calculation of total reaction cross sections of 6He, 8,9Li on nuclei within the microscopic optical potential model

Experimental data on total reaction cross sections of exotic nuclei 6He, 8,9Li interaction with the 181Ta, 59Co, 28Si and 9Be targets in a wide energy range are analyzed in the framework of a hybrid model of microscopic optical potential (OP). The real part of OP is obtained on the basis of the double folding model, while the imaginary part of OP is calculated within the high energy approximation. This theoretical approach demonstrates the fairly well agreement with experimental data at the wide energy regions.

Study of elastic and inelastic cross sections by positron impact on inert gases

In this article, a modified computational method recently introduced is used for the calculation of total, positronium (Ps) formation and ionization cross sections including direct and total ionization cross sections for positron scattering from noble gases. The incident positron is assumed to have energies over a wide range from ~5 eV to 5 keV. The positron–atom interaction potential is developed under an optical potential framework and the computations of cross sections for each process are performed by introducing appropriate absorption thresholds. The calculated results obtained by employing this modified approach are found to be in reasonably good agreement with most of the existing data.

Single crystal to polycrystal neutron transmission simulation.

A collection of routines for calculation of the total cross section that determines the attenuation of neutrons by crystalline solids is presented. The total cross section is calculated semi-empirically as a function of crystal structure, neutron energy, temperature, and crystal orientation. The semi-empirical formula includes the contribution of parasitic Bragg scattering to the total cross section using both the crystal's mosaic spread value and its orientation with respect to the neutron beam direction as parameters. These routines allow users to enter a distribution of crystal orientations for calculation of total cross sections of user defined powder or pseudo powder distributions, which enables simulation of non-uniformities such as texture and strain. The spectra for neutron transmission simulations in the neutron thermal energy range (2 meV-100 meV) are presented for single crystal and polycrystal samples and compared to measurements.