Cross Section Research Articles

Radiation and scattering by a multilayer uniaxial bianisotropic circular cylindrical scatterer

The eigenfunction solution of electromagnetic radiation and scattering from a multilayer uniaxial bianisotropic circular cylindrical scatterer is presented. The expressions for the electric and magnetic field equations are decomposed into transverse and longitudinal components. The boundary conditions are enforced by matching the transverse and axially directed fields at the interfaces between regions with different constitutive parameters. Matrices are constructed from the linear algebraic equations to solve the unknown series coefficients. On the one hand, numerical results are presented for the near zone fields and radar cross section in the two dimensional case. On the other hand, numerical solutions are presented for the radiation pattern when a dipole is present in the vicinity of the cylindrical scatterer in the three dimensional case. Results obtained using the eigenfunction series for the multilayer uniaxial bianisotropic circular cylindrical scatterer are in excellent agreement with results in existing literature and solutions computed using other formulations.

Cross section and isomeric ratio measurements along with covariance analysis for the (n,2n) reactions on 120,130Te

Cross section and isomeric ratio measurements along with covariance analysis for the (n,2n) reactions on 120,130Te

Neuroprotection of retinal ganglion cells by agonism of the beta but not the alpha oestrogen receptor in the axotomized retina of male and female mice.

To compare the course of retinal ganglion cell (RGC) loss following optic nerve crush (ONC) in male and female mice and to assess the neuroprotective potential of intravitreally administered oestrogen receptor alpha (ERα) or beta (ERβ) agonists. Optic nerve crush was performed on the left optic nerve of male and female C57BL/6 mice. RGC loss was evaluated at 3-21 days post-lesion. ERα and ERβ agonists (PPT and DPN, respectively) were injected either immediately after ONC with retinas analysed at 5 days or immediately post-ONC and again at 9 days, with retinas analysed at 21 days post-lesion. Intact retinas served as controls. The total population of Brn3a+RGCs was quantified in retinal flat mounts. To assess the retinal expression of ERα and ERβ, immunodetection was performed on cross sections, and the percentage of RGCs expressing each receptor was determined in flat mounts. Retinal ganglion cell loss in both sexes followed two distinct linear phases: A rapid phase up to 9 days post-lesion, followed by a slower phase. However, the onset of RGC loss was earlier in males than in females. Both ERα and ERβ were expressed in all retinal layers and by the majority of RGCs. While ERα agonism did not confer RGC protection, ERβ agonism was neuroprotective during the second phase of axotomy-induced RGC loss. Preclinical results may be influenced by pooling data from male and female mice. The neuroprotective effects of ERβ during the second phase of RGC loss, likely linked to neuroinflammation, suggest potential therapeutic applications for chronic conditions such as glaucoma.

Research on soft errors induced by alpha particles and atmospheric neutrons based on 28 nm field programmable gate array

ABSTRACT The susceptibility of 28 nm static random access memory (SRAM)-based field programmable gate arrays (FPGAs) to soft errors was evaluated using alpha particles and atmospheric neutrons at the China Spallation Neutron Source (CSNS). A single event effect (SEE) test system was established to assess the sensitivity of various FPGA modules, including the configuration RAM (CRAM), block RAM (BRAM), configurable logic module (CLM), and arithmetic processing module (APM), utilizing both dynamic and static methods. The SEE error types for different sensitive modules were identified, and the SEE cross sections were calculated. The findings of this study can serve as a useful theoretical foundation for the design of radiation-hardened FPGA to enhance their reliability in radiation-prone environments.

NNLO PDFs driven by top-quark data

We study the impact of state-of-the-art top-quark data collected at the large hadron collider on parton distribution functions (PDFs). Following the ABMP methodology, the fit extracts simultaneously proton PDFs, the strong coupling αs(MZ) and heavy-quark masses at next-to-next-to-leading order (NNLO) accuracy in QCD. It includes recent high-statistics data on absolute total inclusive cross sections for tt¯+X, the sum of (t+X) and (t¯+X) hadroproduction, and normalized inclusive data double-differential in the invariant mass and rapidity of the tt¯ pair at S=13 TeV. The gluon PDF at large x and the top-quark mass value derived from these data are well compatible with the previous ABMP16 results, but with significantly smaller uncertainties, reduced by up to a factor of two. At NNLO in QCD we obtain for the strong coupling the value αs(nf=5)(MZ)=0.1150±0.0009 and for the top-quark mass in the MS¯-scheme mt(mt)=160.6±0.6 GeV, corresponding to mtpole=170.2±0.7 GeV in the on-shell scheme. The new fit, dubbed ABMPtt, is publicly released in grids in LHAPDF format.

Inclusive photoproduction of vector quarkonium in ultra-peripheral collisions at the LHC

We explore the possibility of using ultra-periphe- ral proton-lead collisions at the LHC to study inclusive vector-quarkonium photoproduction, that occurs when a quasi-real photon emitted by a fully stripped lead ion breaks a proton to produce a vector quarkonium. Owing to the extremely large energies of the colliding hadrons circulating in the LHC, the range of accessible photon-nucleon centre-of-mass energies, Wγp, largely exceeds what has been and will be studied at lepton-hadron colliders, HERA and the EIC. We perform a tune to HERA photoproduction data, use this tune to predict the yields of photoproduced J/ψ, and estimate the corresponding transverse-momentum reach at LHC experiments. We also model the hadroproduction background and demonstrate that inclusive photoproduction can be isolated at the LHC from such background by imposing constraints on the hadronic activity in the lead-going direction at mid, forward, or far-forward rapidities depending on the capability of the detector under consideration. We find that the resulting cross sections are large enough to be measured by ALICE, ATLAS, CMS, and LHCb. We estimate the background-to-signal ratio after isolation to be of the order of 0.001 and 0.1 in the low and large transverse-momentum regions, respectively. In addition, we propose and assess the Jacquet–Blondel method to reconstruct the photon-nucleon centre-of-mass energy and the fractional energy of the quarkonium with respect to the photon.

Calculation of the abundance of $$^{187}Re $$–$$^{187}Os $$ nuclear clock nuclides in S-process and sensitivity analysis of Maxwellian-averaged neutron capture cross sections

Calculation of the abundance of $$^{187}Re $$–$$^{187}Os $$ nuclear clock nuclides in S-process and sensitivity analysis of Maxwellian-averaged neutron capture cross sections

Nozzle Geometry Evaluation for Cold Spray Applications by Using 3D-CFD Calculations

Abstract In cold spray applications, optimum process conditions to accelerate particles may vary with different densities of the feedstock. These conditions could depend on the geometry of the spray nozzle, suggesting possible benefits of material-specific nozzle designs. The present study developed a nozzle geometry optimization concept based on three-dimensional computational fluid dynamics (3D-CFD) simulations to provide a specific nozzle design. Applying a design of experiments (DoE) approach, the proposed model seeks an optimal nozzle geometry, using aluminum Al6061 and pure copper with mean particle diameters of 40 µm as examples. Different geometry parameters were varied to reach the highest particle velocities before impact on the substrate, such as the nozzle’s divergent section length, throat cross section, and expansion ratio. The process gas was nitrogen with set stagnation pressure and temperature of 5 MPa and 500 °C, respectively. For high particle impact velocities, the simulation identified the divergent section length as the most influential parameter, followed by the throat cross section. In addition, the results show that the expansion ratio must be carefully tuned to avoid over-expansion of the gas already inside the nozzle, which is detrimental to the particle acceleration.

Pauli form factor contributions to the inelastic proton bremsstrahlung and dark photon production

We study the production of hypothetical vector particles, dark photons γ′, with masses in the range 0.4–1.8 GeV via inelastic proton bremsstrahlung. We further develop the approach of refs. [1, 2–3], where for the first time we considered the contributions to the cross section that are associated with the Pauli form factor in ppγ′ vertex and obtained new splitting functions. We demonstrate numerically the importance of these corrections to full inelastic proton bremsstrahlung cross section and refine the sensitivity of the ongoing and future fixed-target experiments T2K, DUNE and SHiP to the parameters of dark photon model. A dedicated experiment on measurements of the proton electromagnetic form factors in the time-like region below the proton-antiproton threshold, like those suggested in PANDA at FAIR, would help to obtain the robust predictions for the dark photon production by a proton beam at fixed target.

Ultraheavy multiscattering dark matter: DUNE, CYGNUS, other kilotonne detectors, and tidal streams

In direct searches of dark matter, multiscatter signatures are now being sought to probe scattering cross sections that are large enough to make the detector optically thick to incident particles. We provide some significant updates to the multiscatter program. Using considerations of energy deposition, we derive the reaches in cross section and mass of various proposed large-volume detectors: a kilotonne fiducial mass “module of opportunity” at DUNE, a kilotonne xenon detector suggested for neutrinoless double beta decay, the gaseous detector CYGNUS, and the dark matter detectors XLZD and Argo. Where the velocity vector can be reconstructed event-by-event, the Galactic dark matter velocity distribution may be inferred. We exploit this to show that halo substructure such as tidal streams can be picked up if they make up about 10% of the local dark matter density. Published by the American Physical Society 2025

Coulomb corrections for coherent neutrino nucleus scattering

Abstract In this work we consider sub-leading O(Z 2 α 3) corrections to coherent elastic neutrino nucleus scattering (CEvNS). These corrections are not negligible by power counting since nuclei with large coherent cross sections have sizeable nuclear charges e.g. Zα ∼ 0.4. We find that the corrections are much smaller than naive power counting in Zα would suggest and that Coulomb corrections do not substantially alter predictions for CEvNS in the Standard Model. We comment on similarities to older literature on mesonic and muonic atoms.

Dimuon and ditau production in photon-photon collisions at next-to-leading order in QED

Next-to-leading-order (NLO) quantum electrodynamics (QED) corrections to the production of muon and tau pairs in photon-photon collisions, γγ → μ+μ−, τ+τ−, are calculated in the equivalent photon approximation. We mostly consider γγ processes in ultraperipheral collisions of hadrons at the LHC, but the γγ → τ+τ− process in e+e− collisions at LEP is also discussed. The NLO terms are found to modify the total fiducial cross sections by up to 5%, increasing the tails of the dilepton acoplanarity and transverse momentum distributions, and depleting by up to 15% the yields at high masses, with respect to the leading-order predictions including the very small virtuality of the colliding photons. At the LHC, the calculations obtained with the charge form factor for protons and lead ions including the NLO QED corrections improve the data-theory agreement for all measured differential distributions, and prove an indispensable ingredient for the extraction of precision quantities in photon-photon processes, such as the anomalous magnetic moment of the tau lepton.

Prediction of both diffusive and hydraulic conductance in the pore network model extracted from 3D images using deep learning

Abstract Pore network modeling (PNM) with network extracted from 3D images is widely used for studying mass transport in porous media, with its accuracy heavily dependent on the precise determination of hydraulic and diffusive conductance values of local pore pairs. Deep learning (DL) prediction based on true pore geometry offers a promising approach for conductance estimation. However, due to arbitrarily orientation and the lack of explicit inlet and outlet surfaces in 3D extracted pore pair geometries, existing studies [24,25] have relied only on 2D cross section images for hydraulic conductance prediction. A custom finite difference method was recently developed, capable exclusively of estimating diffusion conductance from 3D pore geometry [26]. In this work, a convolutional neural network (CNN) was trained to estimate both diffusive and hydraulic conductance values, with reference ground truth values obtained by applying the Lattice Boltzmann Method (LBM) on 3D pore pair geometries. The predicted pore pair conductance values from the CNN closely matched the LBM results on unseen segmented image data. This study highlights the importance of using the full 3D pore pair geometry for accurate hydraulic conductance evaluation, rather than relying solely on 2D throat cross sections. To evaluate the generality of our method, we calculated the permeability and diffusivity of 3D porous media across a wide range of porosities using PNM with local conductance values predicted by our DL model. Comparisons with results of LBM indicate that while diffusivity was accurately predicted, permeability was underestimated. This underestimation is attributed to the over-segmentation of pore spaces, which resulted in an underestimated flow rate.

Production of J/ψ within the Soft Gluon Resummation Approach and Nonrelativistic QCD

In our study we analyse prompt J/ψ production in proton-proton collisions within the Soft Gluon Resummation approach, collinear parton model and nonrelativistic QCD. We extract a set of long-distance matrix elements for octet color states from experimental data at √s = 200 GeV. We use the InEW scheme for matching cross section and description of J/ψ production in a domain of intermediate transverse momenta. We also provide prediction for J/ψ production using fitted matrix elements at the kinematics of SPD NICA.

Low Energy Electron Induced Dissociation of Acetylacetone.

We report a detailed investigation of the dissociative electron attachment (DEA) to acetylacetone, an important molecule for industrial and atmospheric chemistry. We find that the DEA process leads to several dissociation channels, leading to the formation of and other anions with m/z 39, 41, 43, 57, 83, and 85, with the H- and OH- being the most dominant channels. The absolute cross sections for both of these channels peak around 8.8 and 9 eV with cross-section values of 3.1 × 10-18 and 3.7 × 10-19 cm2, respectively. We also report the DEA dynamics for these channels based on the Velocity Slice Images that were obtained. We also compare the dissociation pattern from DEA with that from photodissociation reported for 248 and 266 nm wavelengths and propose the possibility of the neutral excited state's role as the underlying parent state for the negative ion resonance.

Detection of Electron Temperature Anisotropy by an X-ray Crystal Spectrometer in the Large Helical Device

Abstract We examine Ar XVI spectra measured by an X-ray crystal spectrometer to estimate electron temperature anisotropy in high-temperature electron cyclotron heated plasmas in the Large Helical Device (LHD). We calculate the atomic structure and electron impact excitation cross section between magnetic sublevels of Ar XVI. By assuming a bi-Maxwellian electron distribution function and considering the mount parameters of the X-ray spectrometer in LHD, we model the expected intensity ratio q/r as a function of Te⊥B and Te||B, where ⊥ B and ||B denote perpendicular and parallel components to the magnetic axis of the toroidal plasma, respectively. The calculation results show that the intensity ratio of q and r, which are formed by inner-shell excitation from the ground state of Ar15+, is sensitive to electron temperature anisotropy. We apply the calculation results to the LHD experiments. The ratio of q/r changes with variations in electron density and collision frequency. In the core and low νe region, Te⊥B is predominant, and the electron temperature becomes isotropic above νe > 104 Hz. By combining electron temperature measurements from Thomson scattering and radial profile of Ar15+ ions estimated using the extreme ultraviolet spectrometer, local values of Te⊥B/Te||B are quantitatively estimated using the q/r ratio. The derived Te⊥B/Te||B is compared with collision frequency, radial electric field, and effective helical ripple, and the experimental results are explained qualitatively.

Two-loop master integrals for e+e− → μ+μ− process with account of electron mass

Abstract We calculate a subset of two-loop master integrals relevant for the differential cross section of e + e − → μ + μ − process. We consider only those families for which the account of the electron mass m is necessary. Our results have the form of the Frobenius series in m with coefficients expressed via Goncharov’s polylogarithms.

Particle production by γ−γ interactions in future electron-ion colliders

The particle production in photon-photon (γγ) interactions present in electron-ion collisions is investigated. We present calculations for the total cross sections and event rates related to the production of light mesons [η,η′,f0 and f2], charmonium [ηc and χc], and charmoniumlike [X(3915),X(3940),X(4140), and X(6900)] states, considering the Electron - Ion Collider, Electron - ion collider in China, Large Hadron electron Collider, and Future Circular Collider - electron hadron energies. Our predictions demonstrate that experimental studies of these processes are feasible and useful to constrain the properties of light mesons and quarkonium states and shed some light on the configuration of the considered charmoniumlike states. Published by the American Physical Society 2025

Effect of SiO+ Rotational Excitation on Dynamics of SiO+ + H2 → SiOH+ + H Reaction.

Quasi-classical trajectory calculations and quantitative trajectory classification using DBSCAN and K-NN algorithms have been employed to study the specifics of the significant promotion of the SiO+ + H2 reaction by high rotational excitation of SiO+. There are three different reaction pathways identified. Path-I is a direct reaction process in which the product is formed when H2 collides with the O atom side of SiO+ and the H-H bond breaks. H2 first collides with the Si atom in path-II, then bounces back, and encounters the O atom to complete the reaction. Path-III is characterized by the formation of an HSiOH+ complex, is less affected by rotational excitation, and has the smallest contribution to the entire reaction. At low collision energies, rotational excitation slightly promotes the reaction, possibly due to the coupling of the rotational mode of SiO+ and the reaction coordinate of the submerged saddle point. However, this effect weakens with increasing rotational excitation, leading to a complex change in the total integral cross section. Among them, only path-I shows increased reactivity at high rotational excitation. At high collision energies, the integral cross section of the reaction is less sensitive to the rotational quantum number of the reactant, and only a slight increase is observed at the high rotational excitation of SiO+.

Diagnostics of Spin-Polarized Ions at Storage Rings

Polarized heavy ions in storage rings are seen as a valuable tool for a wide range of research, from the study of spin effects in relativistic atomic collisions to the tests of the Standard Model. For forthcoming experiments, several important challenges need to be addressed to work efficiently with such ions. Apart from the production and preservation of ion polarization in storage rings, its measurement is an extremely important issue. In this contribution, we employ the radiative recombination (RR) of polarized electrons into the ground state of initially hydrogen-like, finally helium-like, ions as a probe process for beam diagnostics. Our theoretical study clearly demonstrates that the RR cross section, integrated over photon emission angles, is highly sensitive to both the degree and the direction of ion polarization. Since the (integrated) cross-section measurements are well established, the proposed method offers promising prospects for ion spin tomography at storage rings.