Calculation Of Sections Research Articles

Publisher Correction to: Theoretical calculations of the photoionization cross sections for the ground and lowest two excited states of Ni XVIII ion

Publisher Correction to: Theoretical calculations of the photoionization cross sections for the ground and lowest two excited states of Ni XVIII ion

A new route to produce 52gMn with high purity for MultiModal Imaging

The 52gMn radionuclide is suitable for the innovative MultiModal Imaging technique, and in particular for a PET/MRI scan, due to its physical properties. The standard cyclotron-based production of 52gMn relies on the nuclear reaction NatCr(p,x)52gMn, but we have investigated theoretically the possibility of an alternative and competitive route, the reaction NatV(α,x)52gMn, which has not been considered for this purpose so far. By using the nuclear reaction code TALYS, we found some discrepancies between the theoretical calculations of the cross sections and the corresponding experimental data. Therefore we tuned the parameters governing the nuclear level densities in the microscopic models implemented in TALYS, thus improving the agreement with the data. Then, by studying the cross sections for 52gMn and its contaminants, we have identified an optimal energy window for the production of high purity 52gMn, around 40 MeV. We have also calculated the time evolution of the number of nuclei of the different Mn isotopes, for an irradiation in this energy window, finding that this route is expected to lead to a higher yield and Radionuclidic Purity with respect to the standard reaction with NatCr. The study suggests the reaction NatV(α,x)52gMn as a promising alternative route for the production of 52gMn.

Worldline master formulas for the dressed electron propagator. Part 2. On-shell amplitudes

In the first part of this series, we employed the second-order formalism and the “symbol” map to construct a particle path-integral representation of the electron propagator in a background electromagnetic field, suitable for open fermion-line calculations. Its main advantages are the avoidance of long products of Dirac matrices, and its ability to unify whole sets of Feynman diagrams related by permutation of photon legs along the fermion lines. We obtained a Bern-Kosower type master formula for the fermion propagator, dressed with N photons, in terms of the “N-photon kernel,” where this kernel appears also in “subleading” terms involving only N − 1 of the N photons.In this sequel, we focus on the application of the formalism to the calculation of on-shell amplitudes and cross sections. Universal formulas are obtained for the fully polarised matrix elements of the fermion propagator dressed with an arbitrary number of photons, as well as for the corresponding spin-averaged cross sections. A major simplification of the on-shell case is that the subleading terms drop out, but we also pinpoint other, less obvious simplifications.We use integration by parts to achieve manifest transversality of these amplitudes at the integrand level and exploit this property using the spinor helicity technique. We give a simple proof of the vanishing of the matrix element for “all +” photon helicities in the massless case, and find a novel relation between the scalar and spinor spin-averaged cross sections in the massive case. Testing the formalism on the standard linear Compton scattering process, we find that it reproduces the known results with remarkable efficiency. Further applications and generalisations are pointed out.

Antiproton-nuclei cross sections with Woods-Saxon potential at low energies

The present knowledge of the antinucleons elastic scattering and annihilation processes in matter at low energies is limited to a few nuclei data in a small phase-space. Optical potential models are useful tools for modelling nuclear strong interaction of antinucleons with matter providing predictions at very low energies where data are missing. New calculations of elastic and annihilation cross sections for antiproton with nuclei using an optical potential of Woods-Saxon (WS) shape are presented. Preliminary predictions at low energies for carbon and calcium show clearly-measurable nuclear effects for nuclear elastic cross sections at large angles and momenta greater than 50 MeV/c. Some discrepancies in annihilation cross section comparing predictions and data are present using the same fitting parameters.

УСИЛЕНИЕ ОСНОВАНИЙ ФУНДАМЕНТОВ ФИЗИЧЕСКИ УСТАРЕВШИХ ЗДАНИЙ

The problems and prospects of existing methods of strengthening the foundations of physically obsolete buildings are outlined, which is relevant for the preservation of buildings of architectural and historical value, as well as for mass renovation in large cities in cramped conditions with a high density of existing buildings. Method of calculation of hollow rectangular and round sections filled with concrete during bending is considered. In this article the dependence of compacted zone radius on initial characteristic of soil density and diameter of pressed pipe concrete element is analyzed. The conclusion is formed that the method of arrangement of the pipe-concrete horizontal distributor for simultaneous reinforcement of soil of the base and foundations chosen for the study allows to regulate the process of leveling the building settlement as a whole, and is also the most environmentally safe and does not negatively affect the surrounding buildings and structures.

Matching N3LO QCD calculations to parton showers

The search for new interactions and particles in high-energy collider physics relies on precise background predictions. This has led to many advances in combining precise fixed-order cross-section calculations with detailed event generator simulations. In recent years, fixed-order qcd calculations of inclusive cross sections at n3lo precision have emerged, followed by an impressive progress at producing differential results. Once differential results become publicly available, it would be prudent to embed these into event generators to allow the community to leverage these advances. This note offers some concrete thoughts on me+ps matching at third order in qcd. As a method for testing these thoughts, a toy calculation of e+e− → u overline{u} at mathcal{O} ( {alpha}_s^3 ) is constructed, and combined with an event generator through unitary matching. The toy implementation may serve also as blueprint for high-precision qcd predictions at future lepton colliders. As a byproduct of the n3lo matching formula, a new nnlo+ps formula for processes with “additional” jets is obtained.

The interaction of methylene with molecular hydrogen: potential energy surface and inelastic collisions

ABSTRACT The potential energy surface describing the interaction of methylene (CH) in its ground electronic state with molecular hydrogen has been calculated through explicitly correlated coupled cluster theory with inclusion of single, double, and (perturbatively) triple excitations [RCCSD(T)-F12a] and a correlation-consistent aug-cc-pVTZ basis. The calculated points for various geometries of the CH–H complex were fit to a functional form suitable for use in time-independent quantum scattering calculations of cross sections for collision-induced transitions between CH rotational levels. The well depth of the CH–H complex was found to equal 92.1 cm in a planar geometry and intermolecular separation . A representative set of cross sections is presented and compared with cross sections for the corresponding transitions in methylene induced by collisions with helium.

Reactivity Effect Evaluation of Fast Reactor Based on Angular-Dependent Few-Group Cross Sections Generation

Among all the possible occurring reactivity effects of a fast reactor, the situations whereby the control rod was inserted, or the coolant was voided could lead to strong anisotropy of neutron flux distribution, therefore the angular dependence on neutron flux should be considered during the few-group cross-sections generation. Therefore, the purpose of this paper is to compare the influence whether the angular dependence on neutron flux is considered in the calculation of few-group cross sections for the reactivity effect calculation. In the study, the 1-D SN finite difference neutron transport equation solver was implemented in the TULIP of SARAX code system so that the high-order neutron flux could be obtained. Meanwhile, the improved Tone’s method was also applied. The numerical results were obtained based on three experimental FR cores, the JOYO MK-I core, ZPPR-9 core, and ZPPR-10B core. Both control rod worth and sodium void reactivity were calculated and compared with the measurement data. By summarizing and comparing the results of 46 cases, significant differences were found between different consideration of the neutronic analysis. The consideration of angular dependence on neutron flux distribution in the few-group cross-sections generation was beneficial to the neutronic design analysis of FR, especially for the reactivity effect calculation.

Development of technologies for the pour point depressant treatment of an annular near-wall layer of oil pumped through a main pipeline

The technology of depressant utilization, which essentially depends on the method of its addition to oil, has a substantial impact on the efficiency of the main pipeline. Direct injection of a pour point depressant into the reservoir enables to maintain optimal conditions for oil processing, namely, to cool the oil at an optimal rate and, which is especially important, in static conditions. But in this case, significant capital investments will be required for mixing devices, devices for cooling oil, for the construction of additional tanks, etc. The addition of pour point directly into the pipeline (before or after the head pumping and heating stations) cannot provide optimal cooling conditions. This process does not significantly improve the rheological properties of oil as compared to the introduction of a depressant directly into the reservoir. The introduction of a pour point depressant directly into the pipeline will significantly reduce capital costs for processing highly paraffinic oil and the advantages of this method are obvious. The proposed method of depressant utilization will reduce their consumption, and energy consumption for heating oil. This goal is achieved by the fact that the pour point depressant is not added to the entire volume of highly paraffinic oil pumped through the pipeline, but only to the annular near-wall layer of oil in the pipe, thus creating a low-viscosity near-wall layer of the pumped highly paraffinic oil. This paper presents a scheme for the implementation of the proposed method and formulas for thermal calculations of the pipeline sections considering depressant addition to oil.

Three-Dimensional Stopping Sight Distance Calculation Method under High Slope Restraint

Sight distance is an important indicator to ensure the safety of drivers, and is also an indispensable evaluation basis in highway safety engineering. In mountainous highways, high slopes and small radius often lead to poor visibility and traffic accidents. Through the combined calculation of horizontal and vertical sections, this paper comprehensively considers the specific sizes of roadside clearance, high slope, as well as the position and height of the driver’s view point and other factors, and it analyzes the limited visibility of the driver in the process of driving right turn. An effective and simplified calculation method based on design data for three dimensional (3D) stopping sight distance (S.S.D.) in high fill sections is proposed. Finally, the S.S.D. inspection of the actual highway, based on design speed and operating speed, is carried out, and the sight distance of the calculated point is judged by comparing the value with the normal value and the calculation result of the horizontal sightline offset. The results show that the method proposed in this paper is consistent with the sight distance results obtained by the horizontal sightline offset method, which indicates the calculation method is accurate and provides a technical reference for S.S.D. evaluation in highway safety engineering.

Electron Recombination as a Way of Deexciting the 129mSb Isomer

A way of exciting nuclei using reverse conversion is studied. Nuclear excitation occurs due to resonance absorption of the kinetic energy of the recombining electron and its binding energy in the final state. Calculations of triggering cross sections are made using reverse conversion of the energy of ions of isomeric nucleus 129mSb on a bare nucleus and lithium-like ions. Experiments to study this process are performed in the storage rings of the GSI in Darmstadt and the IMP in Lanzhou.

Photoelectron Angular Distributions of Nonresonant Two-Photon Atomic Ionization Near Nonlinear Cooper Minima

Photoelectron angular distributions of the two-photon ionization of neutral atoms are theoretically investigated. Numerical calculations of two-photon ionization cross sections and asymmetry parameters are carried out within the independent-particle approximation and relativistic second-order perturbation theory. The dependence of the asymmetry parameters on the polarization and energy of the incident light as well as on the angular momentum properties of the ionized electron are investigated. While dynamic variations of the angular distributions at photon energies near intermediate level resonances are expected, we demonstrate that equally strong variations occur near the nonlinear Cooper minimum. The described phenomena is demonstrated on the example of two-photon ionization of magnesium atom.

Nuclear physics applied to the production of innovative radiopharmaceuticals

In this work, we review the theory of nuclear reactions induced by charged particles at cyclotrons and we show in a pedagogical way how to perform a reaction yield calculation in a realistic irradiation case. The topic is currently of great interest in the field of radioisotope production for medical applications, in which an international effort is underway to find efficient production routes of novel radiopharmaceuticals that could be used in theranostics or for multimodal imaging: Particular interest is devoted to the reaction channels that allow the production of a given isotope with high yield and high purity. In part I, the nuclear reaction theory is reviewed, with a discussion on the main reaction mechanisms that are important for the calculation of the cross sections: direct reactions, compound nucleus formation and decay and pre-equilibrium emission. The role of modern nuclear reaction codes, such as Talys, for the calculation of nuclear cross sections is also shown with examples. In part II, a tutorial demonstrates how calculate the production yield of the isotope $$^{52g}$$ Mn starting from the Talys cross section for the specific reaction $$^{52}$$ Cr(p,n) $$^{52g}$$ Mn: This is a real and up-to-date research case motivated by the search of a $$\beta ^+$$ emitting radioisotope with paramagnetic properties that could be used for a combined PET–MRI imaging. In the exercise, all the steps to calculate the yield and activities of the reaction are shown in great detail and the result is compared with the reference values. The calculation is performed both in Excel and in Python, and the input files are provided as supplementary material.

DIFFERENTIAL CROSS SECTIONS FOR ELASTIC ELECTRON SCATTERING BY A CALCIUM ATOM AT LOW ENERGY RANGE.

In this study the distorted wave method was applied in calculation of the differential cross sections (DCS) for elastic scattering of electron by a calcium atom at electron impact energies of 10, 15, 20, and 40 eV. At lower incident energies, 10, 15, and 20 eV the present DCS results are not in good agreement with other theoretical and experimental results. However, at 40 eV the present DCS results are in good agreement with other theoretical and experimental results. Key words : Cross-sections, distortion potential, distorted wave, static potential and spherical harmonics. DOI : 10.7176/APTA/83-09 Publication date: September 29 th 2020

Calculation of proton transfer cross sections in the 14N+12C reaction at 116 MeV using the DWBA method

Calculation of proton transfer cross sections in the 14N+12C reaction at 116 MeV using the DWBA method

Calculation of Particle Emissions and Fusion Cross Sections After 8B(t,*), 9B(t,*), and 10B(t,*) Reactions by Monte Carlo Simulations

Boron nuclide and tritium projectile interactions are considerable in terms of nuclear energy systems. This study aims to investigate the realization of the nuclear fusion reactions of the bombardment of boron nuclei with tritium. In addition, the 8B(t,*), 9B(t,*), and 10B(t,*) reactions have focused on the use of the resulting product particles in nuclear technology applications, particularly in nuclear medicine applications, in terms of energy and number. Tritium-induced reactions from boron isotopes (8B, 9B, and 10B) at 50 and 100 MeV were modeled by the GEANT4 and EMPIRE Monte Carlo codes. Gamma, alpha, tritium, deuteron, proton, and neutron emission spectra (GEANT4-10.3) were obtained, and cross sections per energy (EMPIRE-3.2-MALTA) were calculated. Fusion cross sections and 6Li and 7Li production cross sections, which are critical in thermonuclear fusion reactors as basic fusion reactions, are discussed based on the 8B(t,*), 9B(t,*), and 10B(t,*) reactions.

Effects of tunnel-fire on load bearing capacity of tunnel-lining and surrounding rock mass. Part 2 (Sectional Calculation)

Effects of tunnel-fire on load bearing capacity of tunnel-lining and surrounding rock mass. Part 2 (Sectional Calculation)

Coherent and Incoherent Elastic Photoproduction of π0 Meson on Light Nuclei

The paper presents calculations of the cross sections of the elastic photoproduction for π0 meson on 6Li, 7Li and 9Be nuclei in terms of the impulse approximation using the intermediate coupling p-shell model. Measurements are performed in the excitation energy region of Δ(1232)3/2+ resonance. The algorithm of the cross section selection is proposed for γ7Li → π07Li reaction. These calculation results are in good agreement with the experimental data on the elastic photoproduction cross sections for π0 meson on 7Li nucleus obtained by other authors [2].

Inelastic cross sections for pentane isomers by positron impact

ABSTRACTThis work aims at the calculation of various inelastic cross sections for three pentane isomers, namely normal pentane, isopentane and neopentane. The direct ionisation, positronium formation, total ionisation and total inelastic cross section are reported for these targets using modified spherical complex optical potential (mSCOP) and complex scattering potential-ionisation contribution (CSP-ic) method. The cross sections are computed for a wide energy range from their respective thresholds to 5 keV. We have also attempted to probe the isomeric effect in the inelastic scattering of positrons from the pentane isomers. The cross sections for the three isomers were found to overlap for the entire comparative energy range except at the peak region. Hence, in general no appreciable isomeric effect was beheld for the pentane isomers.

Precise calculation of differential cross sections for the Z boson plus jets production in proton-proton collisions at a center-of-mass energy of 13 TeV

The differential cross section predictions for the associated production of a Z boson and jets are presented in proton-proton collisions at a center-of-mass energy of 13 TeV. The differential cross sections are calculated by using a computational framework for the dielectron decay mode of the Z boson. Higher-order differential cross section predictions are obtained in the fiducial phase space and are compared at next-to-leading order (NLO) and next-to-NLO (NNLO) in perturbative quantum chromodynamics (pQCD). The predicted results are reported as functions of the variables including the jet multiplicity, the invariant mass of the Z boson, and transverse momenta of the Z boson and of the decay products. The predicted results are also reported for the angular correlation variables for the final state decay products. The differential results are generally improved in precision upon inclusion of the NNLO corrections. The total cross sections are calculated in the fiducial phase space at different orders in pQCD up to NNLO. The total production rates are predicted more accurately by the NNLO calculation.