Calculated Cross Sections Research Articles

Measurement of the production cross section of prompt Ξc0 baryons in p–Pb collisions at sNN=5.02 TeV

The transverse momentum (pT) differential production cross section of the promptly produced charm-strange baryon Ξc0 (and its charge conjugate Ξc0¯) is measured at midrapidity via its hadronic decay into π+Ξ- in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision sNN=5.02 TeV with the ALICE detector at the LHC. The Ξc0 nuclear modification factor (RpPb), calculated from the cross sections in pp and p–Pb collisions, is presented and compared with the RpPb of Λc+ baryons. The ratios between the pT-differential production cross section of Ξc0 baryons and those of D0 mesons and Λc+ baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt Ξc0 baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p–Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model that includes string formation beyond leading-colour approximation or in which hadronisation is implemented via quark coalescence. The pT-integrated cross section of prompt Ξc0-baryon production at midrapidity extrapolated down to pT = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p–Pb collisions at midrapidity.

Fully relativistic distorted-wave method for collision excitation process between electron and atom

The electron-atom (ion) collision excitation process is one of the most common inelastic scattering processes. It is of great significant in the fields of astrophysics and laboratory plasma. The relativistic distorted-wave method is a widely used theoretical tool for studying electron-atom (ion) collisions, with the aim of obtaining scattering parameters, such as impact cross sections and rate coefficients.<br>In recent years, we have developed a set of fully relativistic distorted-wave methods and programs for studying the electron-atom collision excitation processes. This method is based on the multi-configuration Dirac-Hartree-Fock (MCDHF) method, along with the corresponding packages GRASP 92/2K/2018 and RATIP. The present paper introduces the calculations of continuum state wave functions, total and differential cross sections, state multipoles, integral and differential Stokes parameters of the radiation photon following the impact excitation processes of polarized electrons and atoms. The influence of electron correlation effects, Breit interaction, and plasma screening effects on the excitation cross sections is discussed. The present methods and programs offer several advantages:<br>(1) In the calculations of the continuum electron wave functions, the direct and exchange interactions between the bound electron and the continuum electron are included. Then, the anti-symmetrized coupling wave functions, which is composed of the continuum electron and the ion wave functions, are utilized as the wave function of the system. This method has been employed to study the low to high energy electron scattering processes.<br>(2) In this method, the target state wave function is obtained using the MCDHF theory and the corresponding GRASP packages. The MCDHF method has the advantage of being able to consider the electron correlation effects, including valence-valence, core-valence, and core-core correlations, as well as the Breit interaction and quantum electrodynamics (QED) effects effect on the target state wave function. Furthermore, the calculation of the collision excitation matrix elements also incorporates the contribution of the Breit interaction. Consequently, the present method combines the advantages of both the MCDHF method and distorted-wave method, making it suitable for studying the scattering processes of highly charged ions. In addition, it facilitates the study of the influence of higher-order effects on the collision dynamics, thereby enabling the obtaining high-precision theoretical data.<br>(3) The current method and program can also be utilized to study the scattering cross section of electron-atom collision excitation processes, as well as the impact of plasma screening effects on collision excitation. Furthermore, the state multipoles, differential Stokes parameters, integral Stokes parameters and orientation parameters of electron-complex atom collision excitation can be studied in detail using the present method and program.

Ab Initio Study of Electron Capture in Collisions of Protons with CO2 Molecules.

Ab initio calculations of cross sections for electron capture by protons in collisions with CO2 are carried out at energies between 100 eV/u and 50 keV/u, employing a semiclassical method within the Franck-Condon framework. The scattering wave function is expanded in a set of ab initio electronic wave functions of the HCO2+ supermolecule. The calculation is performed on several trajectory orientations to obtain orientation-averaged total cross sections. A two-state model with an exponential interaction between the entrance and the lowest charge transfer channel is proposed to describe the main aspects of the charge transfer process and to estimate the precision of the molecular expansion. The symmetry of the HOMO πg of CO2 is relevant to choose the signs of the molecular functions and to set up the orientation average of the cross sections. Very good agreement is found with the experimental charge transfer cross sections.

A comparative study of 14N and 16O projectiles on 148Nd target at low energy through experimental analysis

Abstract One of the standout techniques that is stack foil activation technique has been used to calculate excitation functions of evaporation residues formed in the reaction of 14N projectile with 148Nd target at beam energy ≈ 4 − 7 MeV/nucleon in this research. The analysis of presently calculated cross sections with standard theoretical tool PACE4 shows the population of xn/pxn channels through complete fusion only, while the α-emitting channels were found to populate through incomplete fusion as well as complete fusion. These results suggest the breakup of 14N as α + 10B results in incomplete fusion. A connection tied to the collective impact of total asymmetry and total deformation was examined including the asymmetry and deformation effects of both the projectile and the target. Two separate standard reduction methods have been used to reduce the cross-sections of complete fusion and total fusion for present system 14N + 148Nd and earlier measured system 16O + 148Nd, which reveals that 16O induced reactions have more incomplete fusion probability than that of 14N. A suppression in complete fusion functions has been noted for systems 14N + 148Nd and 16O + 148Nd when compared to universal fusion function. It can be inferred from the varying values of suppression factors of 14N and 16O that the possibility of α-breakup differs for 14N and 16O. Moreover, the total fusion functions for 14N + 148Nd and 16O + 148Nd show strong alignment with the universal fusion function.

Cross-Section Calculations for Electron-Impact Ionization of Pyrimidine Molecule and Its Halogenated Derivatives: 2-Chloropyrimidine, 5-Chloropyrimidine, 2-Bromopyrimidine and 5-Bromopyrimidine.

The total cross-sections for the single electron-impact ionization of pyrimidine (C4H4N2), 2-chloropyrimidine (2-C4H3ClN2), 5-chloropyrimidine (5-C4H3ClN2), 2-bromopyrimidine (2-C4H3BrN2) and 5-bromopyrimidine (5-C4H3BrN2) molecules have been calculated with the binary-encounter-Bethe model from the ionization threshold up to 5 keV. The input data for the BEB calculations concerning electronic structure of the studied targets have been obtained with quantum chemical methods including the Hartree-Fock (H-F) and the outer valence Green function (OVGF) methods. The calculated cross-section for the ionization of the pyrimidine molecules due to electron impact is compared with available experimental and theoretical data. The question of the magnitude the pyrimidine ionization cross-section is also discussed, as is the efficiency of the ionization process of studied halogenated derivatives of pyrimidine.

Laboratory Studies on Absolute n-resolved Charge-exchange Cross Sections and Modeling X-Ray Emissions for Ne8+ Colliding with H2 and He

Charge exchange is a predominant process in inelastic collisions in astronomical plasmas, influencing the charge state balance and leading to X-ray emissions when solar wind ions interact with neutral gas in astrophysical environments. Accurate analysis of these dynamic properties to diagnose the solar wind composition and velocities, as well as the spatial distribution of the heliospheric neutral gas, can be hindered by the limited availability of relevant electron capture studies in the corresponding energy range. The absolute total and n -resolved state-selective cross sections of single electron capture have been measured in the collisional energy range from 2.8 to 40 keV u−1, covering velocities corresponding to fast solar wind and coronal mass ejections. In comparison with existing atomic data, we observe good agreement with other results at overlapping energies. Based on the absolute n -state electron capture cross sections, the absolute cross sections of photon emissions following charge exchange between Ne8+ and H2, as well as He gas, were determined for the potential applications in high-resolution X-ray spectra studies of solar wind charge exchange. This work serves as a benchmark for validating the theoretical calculations of charge exchange cross sections and astronomical plasma models, providing valuable insights into the investigation of soft X-ray emissions in solar wind plasma environments.

CALCULATION OF CROSS SECTIONS FOR RESONANCE NUCLEAR REACTIONS BASED ON AB INITIO COMPUTATIONS OF SPECTRAL CHARACTERISTICS OF LIGHT NUCLEI LEVELS

Based on the ab initio scheme developed by the authors for calculating the asymptotic characteristics of decay channels of nuclear states — the method of orthogonal functions of cluster channels — an approach has been created that makes it possible to directly implement the results of ab initio calculations of Anucleon wave functions, as well as the partial decay widths of resonant states of compound nucleus obtained through their use, into calculations of cross sections for resonance nuclear reactions. Both calculated and reliably measured resonance energies can be employed in these calculations. Using the examples of such a theoretical analysis of the reaction cross sections for 7Li(𝑝, 4He)4He and 7Be(𝑛, 4He)4He, the efficiency of this approach and the wide prospects of its use in nuclear spectroscopy are demonstrated

Supernova electron-neutrino interactions with xenon in the nEXO detector

Electron-neutrino charged-current interactions with xenon nuclei were modeled in the nEXO neutrinoless double-β decay detector (∼5 metric ton, 90% Xe136, 10% Xe134) to evaluate its sensitivity to supernova neutrinos. Predictions for event rates and detectable signatures were modeled using the Model of Argon Reaction Low Energy Yields (MARLEY) event generator. We find good agreement between MARLEY’s predictions and existing theoretical calculations of the inclusive cross sections at supernova neutrino energies. The interactions modeled by MARLEY were simulated within the nEXO simulation framework and were run through an example reconstruction algorithm to determine the detector’s efficiency for reconstructing these events. The simulated data, incorporating the detector response, were used to study the ability of nEXO to reconstruct the incident electron-neutrino spectrum and these results were extended to a larger xenon detector of the same isotope enrichment. We estimate that nEXO will be able to observe electron-neutrino interactions with xenon from supernovae as far as 5–8 kpc from Earth, while the ability to reconstruct incident electron-neutrino spectrum parameters from observed interactions in nEXO is limited to closer supernovae. Published by the American Physical Society 2024

∼2 μm broadband luminescence in Tm3+/Ho3+/Er3+-doped tellurite glass

Improving the broadband luminescent properties in ∼2 μm band has always been a serious challenge. This paper proposed a Tm3+, Ho3+ and Er3+ doped combination in tellurite glass, which was synthesized through melt-quenching and characterized by a series of physical and spectral tests. Firstly, tellurite glass of Tm3+–Ho3+ co-doping produced a ∼2 μm broadband luminescence ranging from 1570 to 2200 nm with FWHM (full width at half maximum) of 379 nm under 808 nm pumping. This broadband luminescence originated from 3F4 to 3H6 level transition of Tm3+ and 5I7 to 5I8 level transition of Ho3+. Furthermore, after adding an appropriate amount of Er3+, the luminescent intensity was improved by 116 %, mainly attributed to the direct or indirect energy transfers from Er3+ to Tm3+ and Ho3+ ions. Calculations of Judd-Ofelt spectroscopic parameters and gain cross-sections supported the results obtained from Tm3+/Ho3+/Er3+ doped tellurite glass in ∼2 μm band. In addition, DSC (differential scanning calorimetry) curves exhibited excellent thermal stability, XRD (X-ray diffraction) patterns and Raman spectra disclosed the non-crystalline and network structural units of the synthesized tellurite glasses. The findings in this work demonstrate that tellurite glass with Tm3+, Ho3+ and Er3+ combination is an efficient strategy which can be applied in ∼2 μm band ultra-short pulse lasers and broadband amplifiers.

Theoretical investigation of iodine plasma through detailed electron impact excitation cross-section calculations and collisional-radiative model analysis

Abstract In the present study, we consider the electron impact excitation of neutral iodine and its application in developing a collisional-radiative model for plasma diagnostics of iodine plasma. Electron impact excitation cross- sections are calculated using fully relativistic distorted wave theory. The required atomic structure calculations for iodine are carried out using the relativistic multi-configuration Dirac-Fock method. The excitation energies obtained are reported and compared with values from the NIST database. The electron impact excitation cross-sections are calculated from the ground (5p5 2P3/2) and first- excited state (5p5 2P1/2) to the several upper fine structure levels. Our cross- section results align well with previous studies, reported by Ambalampitiya et al. [Atoms, 9, 103, 2021] using the Breit-Pauli B-spline R-matrix method. Further calculated cross-section results are incorporated into the collisional-radiative model. Our model also includes electron impact ionization, de-excitation, three- body recombination, and radiative decay. We validate our model using emission spectra from inductively coupled iodine plasma. For this purpose, we used the recorded intensities for the emission lines, 486.23 nm, 511.92 nm, 523.45 nm, 589.40 nm, and 608.24 nm are compared with those obtained from our model to calculate electron temperature and electron density of the iodine plasma.

Study of gluon GPDs in exclusive J/ψ production in electron-proton scattering

Exclusive photoproduction of heavy J/ψ meson is performed within the handbag factorization method. The general parton distributions (GPDs) for gluons, which are an essential ingredient here, are constructed using double distribution (DD) representation. The calculated cross section for few sets of gluon GPDs Hg describe fine J/ψ production experimental data from HERA to LHC energies. Based on this approach we estimate J/ψ spin asymmetries determined by Eg and H˜g. The GPDs factorization approach can be employed to analyze heavy vector meson production in electron-proton scattering. Investigations of this reactions at future electron-ion colliders in USA and China can give essential information on gluon GPDs. Published by the American Physical Society 2024

17O Destruction Rate in Stars

In recent years, several laboratory studies of CNO cycle-related nuclear reactions have been carried out. Nevertheless, extant models of stellar nucleosynthesis still adopt CNO reaction rates reported in old compilations, such as NACRE or CF88. In order to update these rates, we performed new calculations based on a Monte Carlo R-Matrix analysis. In more detail, a method was developed that is based on the collection of all the available data, including recent low-energy measurements obtained by the LUNA collaboration in the reduced background environment of the INFN-LNGS underground laboratory, on R-Matrix cross-section calculations with the AZURE2 code and on uncertainty evaluations with a Monte Carlo analysis. As a first scientific benchmark case, the reactions 17O(p,γ)18F and 17O(p,α)14N were investigated. Among the different stellar scenarios they can influence, the 16O/17O abundance ratio in RGB and AGB stars is the one that can be directly confirmed from spectroscopic measurements. The aim is to reduce the nuclear physics uncertainties, thus providing a useful tool to constrain deep mixing processes eventually taking place in these stars. In this work, we present the procedure we followed to calculate the 17O(p,γ)18F and the 17O(p,α)14N reaction stellar rates and preliminary comparisons with similar rates reported in widely used nuclear physics libraries are discussed.

Relativistic calculations of photoionization cross-section of Mg-like Ca IX

Relativistic calculations of photoionization cross-section of Mg-like Ca IX

Atomic and electronic structures of the [formula omitted]-FeSi2/Si(001) interface

The atomistic interface structure between β-FeSi2 and Si substrate was investigated by cross-sectional scanning transmission electron microscopy and density functional theory calculations (DFT). A high quality single crystalline β-FeSi2 film was epitaxially grown on Si(001) substrate. We demonstrate that the β-FeSi2(100) plane is bonded to the Si(001) plane with two Si dimers per unit cell. With such interface structure, DFT band calculations reveal that metallic electronic states are localized at the interface. This finding implies the presence of two dimensional electronic states at the interface of β-FeSi2/Si(001), which may have potential applications in silicon-based electronic devices.

Search for the Exclusive W Boson Hadronic Decays W^{±}→π^{±}γ, W^{±}→K^{±}γ and W^{±}→ρ^{±}γ with the ATLAS Detector.

A search for the exclusive hadronic decays W^{±}→π^{±}γ, W^{±}→K^{±}γ, and W^{±}→ρ^{±}γ is performed using up to 140 fb^{-1} of proton-proton collisions recorded with the ATLAS detector at a center-of-mass energy of sqrt[s]=13 TeV. If observed, these rare processes would provide a unique test bench for the quantum chromodynamics factorization formalism used to calculate cross sections at colliders. Additionally, at future colliders, these decays could offer a new way to measure the W boson mass through fully reconstructed decay products. The search results in the most stringent upper limits to date on the branching fractions B(W^{±}→π^{±}γ)<1.9×10^{-6}, B(W^{±}→K^{±}γ)<1.7×10^{-6}, B(W^{±}→ρ^{±}γ)<5.2×10^{-6} at 95% confidence level.

Cross-Sections of Neutral-Current Neutrino Scattering on 94,96Mo Isotopes

In our recent publications, we presented neutral-current ν–nucleus cross-sections for the coherent and incoherent channels for some stable Mo isotopes, assuming a Mo detector medium, within the context of the deformed shell model. In these predictions, however, we have not included the contributions in the cross-sections stemming from the stable 94,96Mo isotopes (abundance of 94Mo 9.12% and of 96Mo 16.50%). The purpose of the present work is to perform detailed calculations of ν–94,96Mo scattering cross-sections, for a given energy Eν of the incoming neutrino, for coherent and incoherent processes. In many situations, the Eν values range from 15 to 30 MeV, and in the present work, we used Eν = 15 MeV. Mo as a detector material has been employed by the MOON neutrino and double-beta decay experiments and also from the NEMO neutrinoless double-beta decay experiment. For our cross-section calculations, we utilize the Donnelly–Walecka multipole decomposition method in which the ν–nucleus cross-sections are given as a function of the excitation energy of the target nucleus. Because only the coherent cross-section is measured by current experiments, it is worth estimating what portion of the total cross-section represents the measured coherent rate. This requires the knowledge of the incoherent cross-section, which is also calculated in the present work.

Cross sections for electron scattering from atomic gallium

Abstract The relativistic convergent close-coupling method was applied to calculate cross sections for electron scattering on atomic gallium. The integrated and momentum-transfer cross sections for elastic scattering are presented from the 4 s 2 4 p 4P 1 / 2 , 3 / 2 electronic states for incident energies between 0.03 eV and 1000 eV. Integrated excitation cross sections are also presented from these initial states to the 4 s 2 4 [ d , f ] , 4 s 2 5 [ s , p , d ] , 4 s 2 6 [ s , p ] and 4 s 2 7 s manifolds, as well as cross sections for excitation of the 4 s 2 4 p 2P 1 / 2 state to the 4 s 2 4 p 2P 3 / 2 state. Estimates were presented for the total single ionisation cross section and total cross section for scattering on gallium in the 4 s 2 4 p 2P 1 / 2 , 3 / 2 states, including direct ionisation from the 4p, 4s and 3d electrons, and excitation-autoionisation contributions from the 4s and 3d electrons. The estimated total single ionisation cross section was found to agree well with existing experimental data.

Activation cross-sections of proton-induced nuclear reactions on natural zinc in the energy range of 4–30 MeV

In the present work, the excitation functions for the proton-induced nuclear reactions on natural zinc were measured in the energy range of 4–30 MeV using the well-established stacked-foil activation procedure. The activation products were measured based on their characteristic gamma lines using HPGe γ-ray spectrometry. The radioactivities determined were used for the calculation of cross-sections of the radionuclides of interest, i.e., 61Cu, 62,65,69mZn, 57Co and 66,67,68Ga. The cross-sections have also been compared with the available literature data and the theoretical prediction of the TALYS code via its latest TENDL-2023 library as well as the prediction of EMPIRE-3.2.2 model code. The results show a reasonable agreement when compared with the available literature data. This work, however, shows that the theoretical data extracted from the TENDL-2023 library and EMPIRE-3.2.2 default calculation significantly underestimate the experimental cross-sections of 57Co nuclide while they overestimate those of 69mZn. The present result has potential applications to improve the predicting capability of the model codes as well as to serve as additional data for the nuclear reaction cross-section database.

Cross-Section Calculation and Comparative Assessment of Al and Zr as Cladding for NIRR-1

Cross-Section Calculation and Comparative Assessment of Al and Zr as Cladding for NIRR-1

Calculations of positron scattering from F, F2, HF, and various fluorocarbons

Abstract Single center convergent close-coupling (CCC) calculations have been completed for positron scattering from atomic fluorine. Total, electron-loss, positronium-formation, direct ionization, momentum transfer, elastic, bound-state excitation, and stopping power cross sections have been determined for energies between threshold and 5000 eV. Past calculations for this scattering system exist only for elastic and momentum-transfer cross sections. For high energies, good agreement is found between current and past results. At low energies, however, large differences are found between the current calculations and previous results. The atomic fluorine results are then used in a modified independent atom approach to calculate cross sections for positron scattering on F2, HF, CF4, C2F6, C3F6, C3F8, and C6F6. The current molecular results are typically higher than previous positron experiments across the calculated energy range, however, these experiments were not corrected for the forward angle scattering effect and likely underestimate the true result. Good agreement is found between the current positron results and previous electron experiments and calculations at high energies.