Double Differential Cross Sections Research Articles

Theoretical Calculations and Evaluations of Neutron-Induced Reactions on 121Sb, 123Sb, and Natural Sb

An optical model potential for neutron-antimony isotopes collision systems is obtained at the incident energies up to 200 MeV. Cross sections, angular distributions, energy spectra and double differential cross sections for neutron-induced reactions on 121Sb, 123Sb and natural Sb are consistently calculated and analyzed at incident energies below 20 MeV by using theoretical nuclear models for nuclear energy applications. The calculated results are compared with experimental data and the evaluated data from CENDL-3 and JENDL-4.

Electron-loss-to-continuum cusp in collisions of U89+ with N2 and Xe

We study the electron-loss-to-continuum (ELC) cusp experimentally and theoretically by comparing the ionization of U$^{89+}$ projectiles in collisions with N$_2$ and Xe targets, at a beam energy of 75.91 MeV/u. The coincidence measurement between the singly ionized projectile and the energy of the emitted electron is used to compare the shape of the ELC cusp at weak and strong perturbations. A significant energy shift for the centroid of the electron cusp is observed for the heavy target of Xe as compared to the light target of N$_2$. Our results provide a stringent test for fully relativistic calculations of double-differential cross sections performed in the first-order approximation and in the continuum-distorted-wave approach.

Electron emission from fluorene (C13H10) upon 3.5 MeV/u Si8+ ion impact: double differential distributions

We have studied the electron emission from one of the polycyclic aromatic hydrocarbon (PAH) molecules namely, fluorene (C13H10), upon 3.5 MeV/u Si8+ ion impact. The experimentally measured absolute double differential cross sections (DDCS) are compared with the continuum distorted wave-eikonal initial state (CDW-EIS) model and the first Born approximation including correct boundary conditions (CB1). The measurements are carried out in the ejected e−-energy range of 1 eV–400 eV and in the angular range of 20°–160°. We have obtained the single differential and the total cross sections (TCSs) of e−-emission as well. The CB1 calculation largely underestimates the data. The CDW-EIS model, which is applied for the PAH molecule for the first time, provides an overall better agreement with the double differential, single differential and TCS data. The DDCS data for fluorene has also been compared with that for CH4 molecule, at a few angles. The forward–backward angular asymmetry shows a relatively flatter distribution compared to the theoretical predictions. The contribution due to the giant plasmon resonance could not be clearly observed except a mild indication in the asymmetry parameter. The angular distribution of the carbon KLL Auger electron cross section shows certain variations. The study of the KLL hyper-satellite component indicates the double K-ionization cross section is about 8.6% of the single K-ionization one.

Double differential cross section for the single ionization of methane molecule by swift proton projectile

In the present work, single ionization of the methane molecule is studied. The double differential cross section for the ejected electron is considered. The target is ionized by the effect of perturbation created by proton impact with high incident velocity. In our theoretical formalism, the one Coulomb wave model is employed in the framework of the first Born approximation, which means that the final state is considered as a product of a plane wave function for the scattered heavy particle and a Coulomb wave function for the ejected electron. The initial state is a product of a plane wave function for the fast incident charge and wave functions centered over the heavy nuclei to describe the active electron. In our formalism, the one Coulomb wave model is corrected by Salin factor to take into account the effect of the electron transfer to the continuum. The obtained results are compared to the available experimental data.

Investigation of the isoscalar response ofMg24toLi6scattering

Background: Mg 24 is a strongly deformed nucleus in the ground state. Deformation effects can be observed in the structure of the isoscalar giant monopole and quadrupole resonances. Mg 24 is also a nucleus that is well known to present different types of cluster-oscillation modes. Both giant resonances and cluster states are strongly populated by isoscalar transitions. Purpose: To extract the E 0 , E 1 , and E 2 transition strengths via Li 6 scattering. The Li 6 probe is a powerful tool for investigating the isoscalar nuclear response with a very favorable ratio of resonance-to-continuum background. Method: Double-differential cross sections of Li 6 inelastic scattering, at the beam energy of 100 MeV/u, were measured in the excitation-energy range 10 – 40 MeV and scattering angles 0 − 3 ∘ . A multipole-decomposition analysis was performed for extracting the isoscalar E 0 , E 1 , and E 2 strength distributions. Results: The extracted multipole strengths were compared with predictions from consistent quasiparticle random phase approximation calculations. The theoretical predictions are in fair agreement with the experimental data. The E 0 strength was also compared with results from antisymmetrized molecular dynamics calculations found in the literature. A few peaks in the experimental data might be associated with clustering in Mg 24 . Conclusions: Ground-state deformation effects were observed in the isoscalar giant monopole resonance (ISGMR) and isoscalar giant quadrupole resonance (ISGQR) distributions. The ISGMR strength is split in two peaks around 19 and 28 MeV. The ISGQR exhibits a pronounced peak at 20 MeV with a broadening at the low-energy region, similar to predictions from microscopic calculations. Signatures of excitation of cluster states were observed in the E 0 response. Further studies including particle-decay measurements will be required to confirm the nature of the observed peaks.

Cross Sections for Neutron-Production from 6- and 10-MeV Neutrons Incident on 10B and 11B

Using time-of-flight techniques, we have measured neutron emission spectra from 6- and 10-MeV incident neutron energies on 10B and 11B for laboratory angles between 20 and 145 deg using the unique neutron source reaction 1H(t,n). Double-differential cross sections and their integrated values have been extracted for elastic and inelastic processes, and their integrated values are summarized. In cases where discrete scattering peaks could be analyzed, differential cross-section angular distributions have been extracted and are compared to other results and to evaluated nuclear data.

Which nuclear data can be validated with LLNL pulsed-sphere experiments?

It is shown here that 14-MeV D+T LLNL pulsed-sphere experiments bring complementary information into the process of validating nuclear data compared to experiments that are traditionally used for this purpose—such as critical assemblies. To be more specific, the 14-MeV D+T LLNL pulsed-sphere neutron-leakage spectra enable to validate scattering and fission nuclear data up to 15 MeV (compared to approximately up to 5 MeV when using criticality experiments) and employ to this end simple compound targets containing only few isotopes. Sensitivity profiles of the spectra to nuclear data are calculated in order to understand in detail which isotopes, observables, and energy ranges of nuclear data contribute significantly to their simulation. These profiles are presented for a few selected spheres containing 16O, 12C, 56Fe, and 239Pu. It is shown that the neutron-leakage spectra of spheres containing light elements are mostly sensitive to elastic- and inelastic-scattering cross sections on discrete levels and corresponding angular distributions. Spheres of structural materials are sensitive to elastic- and inelastic-scattering cross sections, including scattering on discrete levels and the continuum, and double-differential cross sections. Actinide spheres are also strongly sensitive to the fission observables, in particular to the total-fission neutron spectrum. Thin spheres (in which neutrons experience on average less than one scatter) are mostly sensitive to data near the elastic peak, in the energy range from 12–15 MeV, while thicker ones can be sensitive to data at lower incident-neutron energies due to multiple-scattering effects. This information is brought together with simulations of 71 pulsed-sphere neutron-leakage spectra using the ENDF/B-VII.1 and ENDF/B-VIII.0 nuclear-data libraries. This analysis highlights ENDF/B-VIII.0 data that could be further investigated for potential shortcomings (6Li, 12C, 16O, 24-26Mg, 27Al, 48Ti, 56Fe, and 208Pb) or are likely reliable (1,2H, 7Li, 9Be, 14N, 235,238U, and 239Pu) as indicated by validating with LLNL pulsed-sphere experiments.

Production of high-energy neutrons by interaction of a deuteron beam with matter

Experimental double differential cross section data for neutrons in the high-energy region are still scarce because of the difficulty of producing high-energy neutrons. The present work studies the possibility of producing high-energy neutrons by interaction of a deuteron beam with matter. The Geant4 toolkit is used to simulate the interaction between a deuteron beam and matter. An analytical method is also developed to calculate the neutron yields produced in the interaction of the deuteron beam with matter. The input cross section data are not only taken from the TEDNL-2017 library but are also calculated by the isospin-dependent quantum molecular dynamics model. It is shown that it is possible to produce high-energy neutrons by interaction of a deuteron beam with matter. If one wishes to produce high-energy neutrons, a low-Z target and a small emission angle may be considered. A thin target is a good choice if one wishes to produce neutrons with a smaller energy peak width.

Double and Triple Differential Cross Sections for Single Ionization of Benzene by Electron Impact.

Experimental results for the electron impact ionization of benzene, providing double (DDCS) and triple differential cross sections (TDCS) at the incident energy of 90 eV, measured with a multi-particle momentum spectrometer, are reported in this paper. The most intense ionization channel is assigned to the parent ion (C6H6+) formation. The DDCS values are presented for three different transferred energies, namely 30, 40 and 50 eV. The present TDCS are given for two fixed values of the ejected electron energy (E2), at 5 and 10 eV, and an electron scattering angle (θ1) of 10°. Different features related to the molecular orbitals of benzene from where the electron is extracted are observed. In addition, a semi-empirical formula to be used as the inelastic angular distribution function in electron transport simulations has been derived from the present DDCS result and compared with other expressions available in the literature.

P−p(p¯) cross section of isolated single photon production in the kt factorization and different angular ordering unintegrated parton distributions frameworks

In the present work, it is intended to calculate and study the single and double differential cross-sections of the prompt single-photon production as a function of produced single-photon transverse momentum and rapidity, in the high-energy P-P(\={P}) colliders, such as LHC and TEVATRON. The differential cross-sections of prompt single-photon production are calculated in the $k_t$-factorization frameworks using various angular ordering unintegrated parton distribution functions (UPDF), namely the Kimber et al. and Martin et al. procedures. These scheme-dependent UPDF are generated in the leading and next-to-leading order levels to predict and analyze the different partonic contributions to the above cross-sections. The above two procedures utilize the phenomenological parton distribution functions (PDF) libraries of Martin et al., i.e., MMHT2014. It is shown that the calculated prompt single-photon production differential cross-sections in the above frameworks are relatively successful in generating satisfactory results compared to the experimental data of different collaborations, i.e., CDF (2017), ATLAS (2017), CMS (2011) and D0 (2006), as well as the other theoretical predictions such as collinear factorization Monte Carlo calculations (the JETPHOX, SHERPA, PYTHIA, and MCFM methods). Also, for a closer precision, the differential cross-section for the NLO gluon-gluon , quark-gluon and quark-(anti)quark processes are calculated. An extensive discussion and comparison are made regarding (i) the behavior of the contributing partonic sub-processes, (ii) the possible double-counting between the $2\to 2$ and $2\to 3$ sub-processes, i.e., gluons-fusion, in our calculated prompt single-photon production differential cross-sections and (iii) the sensibility check of our results to the different angular ordering constraints.

Model calculation of the differential cross sections and angle-integrated cross sections of the emitted triton for neutron-induced Li6 reactions at low incident energies

Regarded as important for applications and theoretical studies, the differential cross sections of the emitted triton for the neutron-induced $^{6}\mathrm{Li}$ reaction at low incident energies were calculated, based on the zero-range distorted-wave Born approximation theory with the assumption of $^{6}\mathrm{Li}$ nucleus consisting of $t{+}^{3}\mathrm{He}$ or $d+\ensuremath{\alpha}$. As a function of widths and excited energies of the discrete energy levels, an effective excited energy formula was proposed to describe their partial contributions. In addition, the optical model potential parameters, which had been successfully used to reproduce the double-differential cross sections of the emitted neutrons in our previous works in incident energy range from 5.0 to 20.0 MeV were extended in a low-energy range from 1.0 eV to 3.0 MeV in this paper. The calculated results agreed well with the measured differential cross sections recently published in 2020 and were further consistent with the measured angle-integrated cross sections. This indicates that the knock-out process and heavy-particle knockout process were dominant in an energy range from 1.0 eV to 3.0 MeV, whereas the shapes of the measured angular distributions in incident energy range from 0.1 to 1.0 MeV could be successfully explained by the Hauser-Feshbach model.

Theoretical calculation of n+235U reaction

The design of Generation-IV nuclear reactors and the studies of advanced fuel cycles require high-precision nuclear data in the fast neutron energy region, one of the most important of which is n+235U reaction data. The cross sections, angular distributions, energy spectra and double differential cross sections of neutron, proton, deuteron, triton, 3He and α particle emissions and the γ production cross section and spectrum from n+235U reaction are analyzed by using theoretical nuclear models in the energy range of En⩽150 MeV. The calculated results are compared with recent experimental data and the evaluated data from ENDF/B-VIII.0 and JENDL-4.0.

EFT for soft drop double differential cross section

We develop a factorization framework to compute the double differential cross section in soft drop groomed jet mass and groomed jet radius. We describe the effective theories in the large, intermediate, and small groomed jet radius regions defined by the interplay of the jet mass and the groomed jet radius measurement. As an application we present the NLL′ results for the perturbative moments that are related to the coefficients C1 and C2 that specify the leading hadronization corrections up to three universal parameters. We compare our results with Monte Carlo simulations and a calculation using the coherent branching method.

Exact Theory of Nonrelativistic Quadrupole Bremsstrahlung

Abstract The quantum mechanical treatment of quadrupole radiation due to bremsstrahlung exact to all orders in the Coulomb interaction of two nonrelativistically colliding charged spin-0 and unpolarized spin-1/2 particles is presented. We calculate the elements of the quadrupole tensor, and present analytical solutions for the double-differential photon emission cross section of identical and nonidentical particles. Contact is made to Born-level and quasi-classical results in the respective kinematic limits and effective energy loss rates are obtained. A generally valid formula for soft-photon emission is established and an approximate formula across the entire kinematic regime is constructed. The results apply to bremsstrahlung emission in the scattering of pairs of electrons and are hence relevant in the study of astrophysical phenomena. A definition of a Gaunt factor is proposed which should facilitate broad applicability of the results.

A new approach to computing the incoherent neutron scattering function

A new method for calculating the incoherent neutron scattering function for solids is introduced, based on the traditional phonon expansion, where the terms are calculated using the saddle point approximation for each term. The method is simple enough to be used in calculation systems of practical application. It provides very accurate results even for the tails of the scattering function, and is superior to the Gaussian approximation to the phonon terms. Numerical and experimental comparisons are presented in different types of magnitudes derived from the double differential cross section, using vanadium as a test case.

Measurements of top-quark pair single- and double-differential cross-sections in the all-hadronic channel in pp collisions at sqrt{mathrm{s}} = 13 TeV using the ATLAS detector

Differential cross-sections are measured for top-quark pair production in the all-hadronic decay mode, using proton-proton collision events collected by the ATLAS experiment in which all six decay jets are separately resolved. Absolute and normalised single- and double-differential cross-sections are measured at particle and parton level as a function of various kinematic variables. Emphasis is placed on well-measured observables in fully reconstructed final states, as well as on the study of correlations between the top-quark pair system and additional jet radiation identified in the event. The study is performed using data from proton-proton collisions at sqrt{s} = 13 TeV collected by the ATLAS detector at CERN’s Large Hadron Collider in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb−1. The rapidities of the individual top quarks and of the top-quark pair are well modelled by several independent event generators. Significant mismodelling is observed in the transverse momenta of the leading three jet emissions, while the leading top-quark transverse momentum and top-quark pair transverse momentum are both found to be incompatible with several theoretical predictions.

Cross section of neutrons from the H2(n,2n) reaction at En=15 MeV

The double-differential cross section of the deuteron breakup reaction $^{2}\mathrm{H}(n,2n$) has been studied experimentally with a neutron beam energy of 15 MeV. Special attention has been devoted to estimation of background condition and multiple scattering effect in the scattering sample. Experimental data have been compared with models based on phase-space approximation used in the ENDF/B-VIII.0 data library and in the MCNP neutron transport code, as well as with rigorous model based on Faddeev equations used for cross section evaluations in JENDL data library. It was found that experimental data are better reproduced by Faddeev model, however, the model overestimates data in the low-energy region of the neutron spectrum ($<4$ MeV).

Energy and angular distribution of photo-neutrons for 16.6 MeV polarized photon on medium–heavy targets

The energy spectra as well as the angular distribution of photo-neutrons, called the double differential cross sections (DDXs) of the (γ, xn) reaction were measured for 16.6 MeV linearly polarized photons on Pb, Au, Sn, Cu, Fe, and Ti targets. Polarized photons were prepared using the laser Compton scattering technique at BL01, NewSUBARU, Hyogo, Japan. The photo-neutrons were measured using liquid organic scintillators, placed at six different angles. The time-of-flight technique was used to determine the neutron energy. The low energy and high energy components on the DDXs were identified for all the targets. Flat angular dependence was observed for the low energy component; however, a cos(2Θ) distribution was observed for the high energy component, where Θ is the angle between the photon polarization direction and neutron emission. The angular dependences were parameterized by fitting the experimental data. The obtained parameters were compared with those from previous studies conducted decades ago.

Radiobiological effectiveness of iodouracil and the influence of atomic giant resonance

Hadron therapy combined with nanotechnology has been proposed as an elegant alternative for cancer treatment. Internal amplification of electron emission causing radiobiological effectiveness in nanoinserted biomolecules is of prime importance and has been measured here for the iodouracil molecule. Our experiment involves the measurement of angle and energy resolved double differential cross section (DDCS) of electron emission from iodouraciil and uracil (and also water) in collisions with fast ${\mathrm{C}}^{6+}$ ions. The electron emission from iodouracil is substantially enhanced over that from uracil or water. The enhancement is much larger than the state-of-the-art model for Coulomb ionization based on the continuum distorted wave-eikonal initial state (CDW-EIS) approximation. The electron sensitizing factor ($\ensuremath{\approx}2.4$) is in excellent agreement with the strand-breaking sensitizing factor ($\ensuremath{\approx}2.0$) for metal nanoparticle embedded in a DNA. The enhancement is explained in terms of collective excitation of strongly correlated 4d electrons, known as atomic giant dipole resonance (GDR) in I atoms. The GDR contribution to the enhancement is derived, which is in excellent agreement with recent theoretical prediction, thereby providing conclusive experimental evidence of the crucial role of collective excitation in radio sensitization.

Impact of LHCb 13 TeV W and Z pseudo-data on the parton distribution functions * *Supported by the National Natural Science Foundation of China (11875142, 11965020) and the U.S. National Science Foundation (PHY-2013791. C.-P)

We study the potential of the LHCb 13 TeV single W ± and Z boson pseudo-data for constraining the parton distribution functions (PDFs) of the proton. As an example, we demonstrate the sensitivity of the LHCb 13 TeV data, collected with integrated luminosities of 5 and 300 , to reducing the PDF uncertainty bands of the CT14HERA2 PDFs, using the error PDF updating package EPUMP. The sensitivities of various experimental observables are compared. Generally, sizable reductions in PDF uncertainties can be observed in the 300 data sample, particularly in the small-x region. The double-differential cross section measurement of Z boson p T and rapidity can greatly reduce the uncertainty bands of u and d quarks in almost the whole x range, as compared to various single observable measurements.