Ratio Of Cross Sections Research Articles

Stress distribution in multilayer structural element subjected to skew bending

Results of researches on strength and stiffness of diagonally bending sandwich girders having geometric and/or stiffness asymmetry have been given. A mathematical module for calculation of normal strain (strength) and stiffness on bending at any cross-section point of sandwich girder has been proposed. The kinetics of stiffness on bending and strength variation dependences when geometric parameters of a cross-section and tension modulus ratios of girder layers are changing have been examined. It has been established that the strength of a diagonally bending sandwich girder on the whole depends on the position of the centre of stiffness and the position of the neutral plane.

Measurement of Ξc+ production in pPb collisions at sNN=8.16 TeV at LHCb

A study of prompt Ξc+ production in proton-lead collisions is performed with the LHCb experiment at a center-of-mass energy per nucleon pair of 8.16 TeV in 2016 in pPb and Pbp collisions with an estimated integrated luminosity of approximately 12.5 and 17.4 nb−1, respectively. The Ξc+ production cross section, as well as the Ξc+ to Λc+ production cross-section ratio, are measured as a function of the transverse momentum and rapidity and compared to the latest theory predictions. The forward-backward asymmetry is also measured as a function of the Ξc+ transverse momentum. The results provide strong constraints on theoretical calculation and are a unique input for hadronization studies in different collision systems. ©2024 CERN, for the LHCb Collaboration 2024 CERN

Improving energy absorption and failure characteristic of additively manufactured lattice structures using hollow and curving techniques

Strut-based lattice structures of various types exhibited a common critical issue, namely, high tensile stress concentration occurred at node-to-strut sites, which often led to lowered energy absorbability as compared to triply periodic minimal surfaces structures. Therefore, this work aimed for improving the Octet-truss structure by a combined technique using hollow core and varying cross-section ratio. Firstly, test specimens were fabricated using a stereo-lithography based additive manufacturing of photopolymer hard resin. Elastic-plastic properties and damage criterion of the used polymer were experimentally determined and applied for finite element models. Validation by compressive tests of lattice samples showed deviations of stress–strain responses less than 12%, in which local deformation and subsequent damages were fairly predicted. Afterwards, finite element simulations of designed lattice structures subjected to compressive, combined shear, shear and tensile loads were performed and obtained stress–strain characteristics including total absorbed energies and deformation behaviors were studied. Under uniaxial compression and combined shear loads, modified Octet-truss structures exhibited considerable increases of energy absorptions up to 173% and 116%, respectively, and stress–strain responses were more stable. On the other hand, by tension mode peak stresses and elongations could be enhanced about 41% and 11%, accordingly. The improved performances of proposed strut-based structures were comparable to those of triply periodic minimal surfaces diamond structure. This was due to that local stress distributions in the structure became more uniform and previously dominated tensile stresses were switched to compressive stresses. Therefore, occurrences of shear bands and plastic hinges could be effectively inhibited.

Research on the Impact of a Fluid Field on an Acoustic Field in Herschel–Quincke Tube

A study concerning the influence of flow on the Herschel–Quincke duct is presented here, which includes the numerical model, the acoustic source and the absorption condition called the Perfectly Matched Layer. For the excitation of a sound field, a normal mode wave is placed at the inlet of the tube. The function of PML is to simulate the infinite tube and avoid the reflection of acoustic wave. To investigate the influence of flow field on sound field, a coupled calculation method combining the finite element method and computational fluid dynamics is used to solve the linearized Euler equation, named the Galbrun equation. Firstly, the influence of the cross-section of the tube on the acoustic field is considered. Secondly, the effects of flow on the acoustic field is also investigated. Lastly, a comparative analysis of the simulation results reveals the influence of flow and other parameters of the tube on sound propagation. Both the Mach number and the cross-section ratio have an influence on the acoustic resonance, and the resonance frequency decreases with the increase in the cross-section ratio.

Characterization of 235U, 238U and 239Pu fission ionization chamber foils by [formula omitted] and [formula omitted]-ray spectrometry

The masses of thin, electroplated deposits of 235U, 238U and 239Pu on titanium backings have been determined to better than 1.3% precision by employing three complementary measurement techniques: α spectrometry, 2π gas counting, and γ-ray spectrometry. A dedicated α spectrometer was designed and calibrated to allow for repeatable, high-precision measurements of the absolute α activity of a sample. The isotopic composition of the sample was determined by fitting the peaks in the α spectrum, a technique which was demonstrated to be generally consistent with mass spectrometry. Independently, the total activity of the deposits were measured in a 2π gas flow proportional counter. A detailed study of the effects of α particle straggling in the actinide deposit and α particle recoil off the sample backing material was performed. The masses of these actinide deposits were also measured via γ-ray spectrometry. We found that all three systematically independent techniques produced consistent results, and could be combined into a weighted average with further reduced uncertainty. The mass ratios of these actinide deposits were determined to better than 1% precision via α spectrometry, enabling high-precision fission cross section ratio measurements.

Predissociation dynamics of D2 revealed by variation in fragment anisotropy parameters along the Fano profile.

We conducted a study on the variations of the fragment anisotropy parameters (β) along the Fano profiles for the predissociation of the D2molecule. These variations, known as β profiles, were measured for the D(2l) fragments from the predissociation of the 4pπD'Πu1υ'=1 and 4pσB″Σu+1υ'=2 states. The measured β profiles show significant asymmetry and broader linewidths compared to the corresponding Fano profiles. By fitting the β profiles, we were able to determine the fragment anisotropy parameters associated with the resonance state, continuum state, and the interference effect between them. Additionally, we determined the ratios of the absorption cross sections between the unperturbed and perturbed continuum states interacting with the resonance states although these ratios were found to be very small. Furthermore, we derived approximate formulas to calculate the parameters characterizing the β profile. Despite the linewidths of the four Fano profiles being narrower than our instrumental resolution, we were still able to determine the product of the linewidth with the Fano q parameters. These findings demonstrate the utility of the β profile as an effective tool for studying the predissociation dynamics in diatomic molecules.

A Study of the Performance of Short-Column Aggregate Concrete in Rectangular Stainless Steel Pipes under Axial Compression

In this study, 18 short-column lightweight ceramsite concrete samples were prepared in rectangular stainless steel pipes, which were used for axial pressure performance tests that took the cross-sectional length–width ratio of the rectangular stainless steel pipe (1.0, 1.5 and 2.0), the wall thickness of the steel pipe (3 mm, 4 mm and 5 mm), and the strength grade of the filled concrete (C20 and C30) as the main parameters. Then, the failure patterns, axial load–displacement curve, axial load–strain curve, ultimate bearing capacity and the interaction between the steel pipe and concrete in the specimens were measured. The test results revealed that the short-column concrete specimens in the steel pipes exhibited typical shear failure and “waist-bulging” failure under axial compressive loads. In the elastic stage, the bearing capacity of the specimens was able to reach 65–85% of the ultimate bearing capacity, with the residual bearing capacity essentially reaching 70% of the ultimate bearing capacity. Furthermore, the ultimate bearing capacity of the specimens demonstrated an increase with the rise in the strength grade of the filled concrete, with the thickness of the stainless steel pipe and with the decrease in the length–width ratio of the steel pipe cross-section. The specimens exhibited a distinct hoop effect. As the length–width ratio decreased and the hoop coefficient increased, the ductility coefficient and the strength enhancement coefficient basically displayed an increasing tendency, while the concrete contribution ratio exhibited a decreasing trend.

Triple charmonium production in pQCD

We study the role of 1→2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1\\rightarrow 2$$\\end{document} and 1→3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1\\rightarrow 3$$\\end{document} processes in triple charmonium production in the leading logarithmic approximation (LLA). We see that the ratio of effective cross sections of TPS and DPS only moderately depends on charmonium transverse momenta, but the total DPS and TPS cross sections each separately may have rather strong dependence on charmonia transverse momenta in the central kinematics region that can be studied experimentally.

Evaluation of 180mTa formation cross-sections in photoneutron reactions

Determining the relative production cross-sections of the short-lived (ground) and long- lived (metastable) states of 180Ta is integral in nuclear physics research. However, direct measurement of these cross-sections is challenging. In this study, we proposed a method for estimating the total flux-weighted average formation cross-section of 180m+gTa based on GEANT4 modeling to evaluate the short-lived (ground) and long-lived (metastable) states of 180Ta. A Ta target was irradiated by a bremsstrahlung photon beam (maximum electron energy: 20 MeV) obtained from the linear electron accelerator LUE-75 at the A.I. Alikhanyan National Science Laboratory (AANL), Armenia. The experiment was performed using the activation technique, and the proposed GEANT4 simulation-based method was employed to evaluate the flux-weighted average formation cross-section of 180mTa. In addition, the isomeric cross-section ratio for the 180m,gTa isomeric pair was calculated. The theoretical results obtained using the TALYS 1.96 and EMPIRE 3.2 codes were consistent with the experimental ones. To the best of the authors’ knowledge, this paper reports the estimated flux-weighted average formation cross-section of 180mTa and isomer ratio for the 180m,gTa isomeric pair, induced by the irradiation of a bremsstrahlung beam with an end-point energy of 20 MeV, for the first time. This study opens new avenues for determining the relative production cross-sections of the ground and metastable states of 180Ta, which is widely studied as a natural isomeric target in various fields, including nuclear transformation reactions, fission dynamics, etc.

A comprehensive assessment and comparison of the impacts of storage parameters on solute transport in streams using a novel framework

Researchers must determine the storage parameter values to understand the storage processes and compare them across streams. These parameters are highly variable in time and space, making them challenging to measure. Individual studies of a single stream cannot characterize the interrelations among the processes involved in solute transport, hydraulic variables, and physical stream characteristics. Despite decades of research, a comprehensive framework is lacking. This study uses a simple and effective Monte Carlo approach to propose a general framework within which most solute transport models can undergo sensitivity analysis. This framework provides a comprehensive depiction of model performance under various scenarios, such as flow properties, stream geomorphology, and solute status. The relative and absolute sensitivities of three solute transport models, namely, the modified advection–dispersion equation (MADE), transient storage model (TSM), and variable residence time (VART), were evaluated and compared within the proposed framework. The main findings can be summarized as follows. In most conditions, storage models are more sensitive to the ratio of the storage zone cross-section to the stream cross-section than other parameters. Increasing the exchange rate between the stream and storage zones reduces the sensitivity to its indicative parameter and, consequently, its impact on the concentration time series. MADE's capability to identify modification parameters is higher for streams where dispersion dominates over advection, and their estimates have lower uncertainty. On the other hand, as advection becomes more dominant over dispersion in TSM and VART, estimated storage parameters have lower uncertainty.“

Numerical study of effective parameters on true triaxial test results in rigid type apparatus

Operational parameters in true triaxial loading devices (TTA), such as the loading rod dimensions, friction between the loading platens and sample faces, loading gap, and one-side loading may affect the test results. Knowledge of the effect of each parameter is very important to correctly interpret rock behavior and to optimize these devices. Employing the Flac3D finite difference software, a rigid type true triaxial systemdesigned and builtat Amirkabir University of Iran (AUT-TTA) was simulated andinvestigated in this study. The results indicate that increasing the ratio of the rod cross-section to the loading platen area leads to an increase in the sample confinement, so, more uniform stress distribution occurs in the rock sample. The loading gap reduces strength of the rock specimen and leads to concentration of tensile stresses at the sample edges. The end effect leads to an increase in the stress level and a pseudo-hardening behavior in the samples. Also, the end effect is intensified under one-side loading condition compared to two-side loading. Comparison between results of AUT-TTA numerical simulation and analytical analysis (ideal conditions without considering operational parameters) indicates that the slope of the stress–strain diagram has low sensitivity to operational parameters. The most important operational factor affecting the stress level and dilatation stress is the end effect and other operational parameters have little effect. All parameters lead to an increase in the dilation strain. The clear edge and one-sided loading under low intermediate principal stresses and the end effect under high intermediate principal stresses have the greatest effect on the dilation strain.

Production of η and η′ mesons in pp and pPb collisions

The production of η and η′ mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of 5.02 and 13TeV and proton-lead collisions are studied at a center-of-mass energy per nucleon of 8.16TeV. The studies are performed in center-of-mass (c.m.) rapidity regions 2.5<yc.m.<3.5 (forward rapidity) and −4.0<yc.m.<−3.0 (backward rapidity) defined relative to the proton beam direction. The η and η′ production cross sections are measured differentially as a function of transverse momentum for 1.5<pT<10GeV and 3<pT<10GeV, respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for η and η′ mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of η mesons are also used to calculate η/π0 cross-section ratios, which show evidence of a deviation from the world average. These studies offer new constraints on mass-dependent nuclear effects in heavy-ion collisions, as well as η and η′ meson fragmentation. ©2024 CERN, for the LHCb Collaboration 2024 CERN

Absolute calibration of the ratio of Xe/O two-photon absorption cross-sections for O-TALIF applications

The paper presents a calibration of the ratio of two-photon absorption cross-sections, σXe(2)/σO(2) , necessary for the absolute O-atom density measurements by two-photon absorption laser-induced fluorescence (TALIF) technique. To calibrate the ratio of the cross-sections, a special discharge with 100% dissociation of molecular oxygen, and so with a known ‘reference’ density of O-atom [O] ref=2⋅ [O2] was suggested. This is a nanosecond capillary discharge in N2:O2 mixtures with a few percent of oxygen at a reduced electric field of a few hundred of Townsend and specific deposited energy of about 1 eV mol−1. Voltage at the electrodes, electrical current in the plasma, longitudinal electric field and energy delivered to the gas were measured with 0.2 ns synchronisation. Additionally, radial distribution of emission of excited nitrogen molecules and gas temperature in the discharge and afterglow were obtained experimentally. Detailed 1D kinetic modeling was suggested to confirm complete O2 dissociation and to analyse the main reactions. By comparing the data measured by TALIF technique with the ‘reference’ density of oxygen atoms [O] ref , the ratio of the two-photon absorption cross-sections σXe(2)/σO(2) was determined.

ψ(2S) Suppression in Pb-Pb Collisions at the LHC

The production of the ψ(2S) charmonium state was measured with ALICE in Pb-Pb collisions at sNN=5.02 TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity (2.5<y<4). The measurement of the ratio of the inclusive production cross sections of the ψ(2S) and J/ψ resonances is reported as a function of the centrality of the collisions and of transverse momentum, in the region pT<12 GeV/c. The results are compared with the corresponding measurements in pp collisions, by forming the double ratio [σψ(2S)/σJ/ψ]Pb−Pb/[σψ(2S)/σJ/ψ]pp. It is found that in Pb-Pb collisions the ψ(2S) is suppressed by a factor of ∼2 with respect to the J/ψ. The ψ(2S) nuclear modification factor RAA was also obtained as a function of both centrality and pT. The results show that the ψ(2S) resonance yield is strongly suppressed in Pb-Pb collisions, by a factor of up to ∼3 with respect to pp. Comparisons of cross section ratios with previous Super Proton Synchrotron findings by the NA50 experiment and of RAA with higher-pT results at LHC energy are also reported. These results and the corresponding comparisons with calculations of transport and statistical models address questions on the presence and properties of charmonium states in the quark-gluon plasma formed in nuclear collisions at the LHC. © 2024 CERN, for the ALICE Collaboration 2024 CERN

Measurement of prompt D+ and Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {D}_s^{+} $$\\end{document} production in pPb collisions at sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s_{NN}} $$\\end{document} = 5.02 TeV

The production of prompt D+ and Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {D}_s^{+} $$\\end{document} mesons is studied in proton-lead collisions at a centre-of-mass energy of sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s_{NN}} $$\\end{document} = 5.02 TeV. The data sample corresponding to an integrated luminosity of (1.58 ± 0.02)nb−1 is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using D+ and Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {D}_s^{+} $$\\end{document} candidates with transverse momentum in the range of 0 < pT< 14 GeV/c and rapidities in the ranges of 1.5 < y∗< 4.0 and –5.0 < y∗< –2.5 in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between D+, Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {D}_s^{+} $$\\end{document} and D0 mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies.

Fission cross-section measurements for the 238U(n,f)97m+gNb, 238U(n,f)133gTe and 238U(n,f)130gSb reactions induced by D-T neutrons

In this study, we conducted measurements of the independent fission cross-sections of 238U(n, f)97m+gNb, 238U(n, f)133gTe reactions and the cumulative cross section of 238U(n, f)130gSb reactions induced by neutron at energies around 14 MeV, i.e., 14.1 ± 0.3, 14.5 ± 0.3 and 14.7 ± 0.3 MeV. The measurement results were obtained by the neutron activation method in combination with off-line γ-ray spectrometry techniques. The neutron flux was monitored on line by the accompanying α-particle from T(d, n)4He reaction, and the neutron energies were determined by the cross-section ratio of 90Zr(n, 2n)8+gZr to 93Nb(n, 2n)92mNb reactions. The independent fission cross-sections of the fission reactions were obtained by subtracting the influence of precursor nuclei or excited states. The obtained results are as follows: for 238U(n, f)97m+gNb, the independent cross sections are 1.0 ± 0.89, 0.98 ± 0.85 and 0.78 ± 0.70 mb at the specified neutron energy points. For 238U(n, f)133gTe, the independent fission cross-sections are 26.8 ± 2.8, 27.7 ± 2.9 and 20.5 ± 2.3 mb, respectively, at the same neutron energy points. As for 238U(n, f)130gSb, the obtained cumulative fission cross-sections are 5.35 ± 0.58, 5.05 ± 0.53 and 4.03 ± 0.44 mb, respectively, at the specified neutron energy points.

Numerical simulation of convective heat transfer behavior of nanofluids in elliptical microchannels

This study employs a numerical simulation approach to investigate the heat transfer performance of elliptical microchannel heat sinks (MCHS) with varying aspect ratios (AR) of the elliptical cross-section. The convective heat transfer behavior of water and water-based nanofluids containing CuO nanoparticles at different volume fractions within the MCHSs is examined. The research results indicate that at Re = 600, as the AR of the elliptical cross-section increases from 1:1 to 1.75:1, the thermal performance of the MCHS improves by 5.33%. Furthermore, with an increase in the volume fraction of nanofluid from 0 to 0.75%, the convective heat transfer coefficient of the nanofluid increases by 11.87%. Compared to the circle MCHS using water as the coolant, the MCHS with an elliptical cross-section with an AR of 1.75:1 and a nanofluid volume fraction of 0.75% can reduce the maximum temperature of the chip by 9.78%.

Studies of the relative suppression of excited quarkonium states with CMS

One of the findings of the LHC heavy ion program is the observation of stronger suppression of the excited quarkonium states compared to the ground states in lead-lead (PbPb) and proton-lead (pPb) collisions. Such differences among the states may imply dissociation effects occurring at late stages, after the evolution of heavy quark pairs into well-defined physical states. The variety of binding energies within the quarkonia families offers an experimental tool to characterize the phenomena at play. Measuring the excited states is crucial as they represent significant feed-down contributions to the production of the ground states and must be accounted for in the interpretation of the data. We present studies of the relative suppression of quarkonia in pPb and PbPb collisions performed by CMS. For the first time, the nuclear modification factor has been extended to the strongly suppressed Υ(3S) state. Moreover, nuclear modification factors as well as excited-to-ground state cross section ratios are measured as a function of particle transverse momentum and rapidity, and event activity. The results are compared with several model calculations incorporating initial- and final-state effects.

Breakup of 8B+natZr at the sub-barrier energy of 26.5 MeV

In our systematic research on reactions with weakly bound nuclei at suband nearbarrier energies, we have studied the system 8B+natZr at the sub-barrier energy of 26.5 MeV. Our measurements, performed at the TriSol radioactive beam facility of the University of Notre Dame, include angular distributions of both elastic scattering and breakup, for the determination of the total reaction and breakup cross sections as well as the direct-to-total reaction cross section ratio. Preliminary results of the breakup analysis will be presented, supported by Continuum Discretized Coupling Channel calculations.

Measurement of charged and full jet production and nuclear modification factor in pp and p–Pb collisions with ALICE

The study of jet production in small collision systems is essential for testing our understanding of perturbative and non perturbative QCD and cold nuclear matter (CNM) effects. In addition, studies at high multiplicity in small collision systems exhibit signatures of collectivity, which is still not fully understood within a unified picture across system size. Jet quenching in small systems is not observed within current measurement precision, calling for more precise jet measurements. Results of charged particle and fully reconstructed jet production in pp and p-Pb collisions are presented at √SNN = 5.02 and 8 TeV, along with the corresponding nuclear modification factor RpPb at √SNN = 5.02 TeV. These results are the most precise measurements of the RpPb by ALICE to date. To investigate whether jet energy is redistributed in CNM, the crosssection ratios for different jet resolution parameters (R) are compared between pp and p–Pb collisions, as well as within each collision system. Finally, comparisons between data and model predictions are discussed. This result extends previous LHC measurements to lower jet transverse momentum, constraining hard parton production and fragmentation mechanisms applied in model calculations, and the impact of the nuclear-modified parton distribution function on jet production. This measurement also provides new constraints on jet quenching in small collision systems.