Cross Sections For Different Channels Research Articles

Rotational energy transfer in the collision of N2O with He atom.

The quantum state-to-state rotationally inelastic quenching of N2O by colliding with a He atom is studied on an abinitio potential energy surface with N2O lying on its vibrational ground state. The cross sections for collision energies from 10-6-100cm-1 and rate constants from 10-5-10K are calculated employing the fully converged quantum close-coupling method for the quenching of the j = 1-6 rotational states of N2O. Numerous van der Waals shapes or Feshbach resonances are observed; the cross sections of different channels are found to follow the Wigner scaling law in the cold threshold regime and may intersect with each other. In order to interpret the mechanism and estimate the cross sections of the rotational energy transfer, we propose a minimal classical model of collision between an asymmetric double-shell ellipsoid and a point particle. The classical model reproduces the quantum scattering results and points out the attractive interactions and the potential asymmetry can affect the collision process. The resulting insights are expected to expand our interpretations of inelastic scattering and energy transfer in molecular collisions.

Triple top quark production in standard model

In this paper, the triple top quark production processes have been investigated and calculated in the scope of the Standard Model. The cross-sections for different channels are provided for the proton–proton collision energies of [Formula: see text] and 100 TeV. The importance of the electroweak contribution has been demonstrated. For the main channels, the interference between the gluon and the weak bosons mediated contributions is negative and significant, therefore the complete set of diagrams has to be taken into account. Estimated total rates are about 1.9 fb for [Formula: see text] TeV and 530 fb for [Formula: see text] TeV. A simple estimation of the uncertainty of the calculated cross-sections gives about 20%. The integrated luminosity of 3 ab[Formula: see text] at HL-LHC allows expecting about 5700 events, giving a chance to detect this rare process.

An Approximation of Cross Sections of Channels of the 9Be(α, n) Reaction on the Basis of the Gamow Interaction Radius

Radiation transport of α-particles requires cross sections of inelastic interaction of α-particles with nuclei. At low energies the inelastic interactions are limited to the 9Be(α, n) reaction, whose channel cross sections are assessed only in the specialized evaluated nuclear data library JENDL/AN-2005. The new TPT (Toolkit for Particle Transport) approximation of the 9Be(α, n) reaction cross sections for different channels takes into account the lowest resonance and, at high energies, relies on the exponential decrease in the S-factor, which is a consequence of the theory of direct nuclear reactions.

Elastic, inelastic, and 1n transfer cross sections for the B10+Sn120 reaction

The $^{10}\mathrm{B}+^{120}\mathrm{Sn}$ reaction has been investigated at ${E}_{\mathrm{Lab}}=37.5$ MeV. The cross sections for different channels, such as the elastic scattering, the excitation of the ${2}^{+}$ and ${3}^{\ensuremath{-}}\phantom{\rule{4pt}{0ex}}^{120}\mathrm{Sn}$ states, the excitation of the ${1}^{+}$ state of $^{10}\mathrm{B}$, and the $1n$ pick-up transfer, have been measured. One-step distorted-wave Born approximation and coupled-reaction-channels calculations have been performed in the context of the double-folding S\~ao Paulo potential. The effect of coupling the inelastic and transfer states on the angular distributions is discussed in the paper. In general, the theoretical calculations within the coupled-reaction-channels formalism yield a satisfactory agreement with the corresponding experimental angular distributions.

Computer Simulation Analysis of Microchannel for a Continuous-Flow PCR Chip

The purpose of this study is to analyze the model of a continuous-flow Polymerase Chain Reaction (PCR) chip with CoventorWare software. It offered the ability of fast heating and cooling rate when the DNA duplication process happened. The main idea was to compare the effects of different cross sections of channel and find out the better one for heat transfer.

Multiple ionization of CO due to electron impact

The absolute cross sections of all the possible dissociation channels following the electron-impact multiple ionization of CO have been measured. The cross sections of the channels corresponding to the production of ion pairs are measured by coincidence techniques. Those of the channels associated with neutral fragments are obtained indirectly. At high excitation energies, the total cross sections of different stages of ionization show an exponential decrease as the ionization stage increases. The cross sections of different channels reveal the internal dissociation dynamics of the dissociation following the multiple ionization of the molecules. The appearance potentials corresponding to different dissociation channels are also measured, which show that the ground states of triply and quadruply ionized CO are nearly Coulomb-like because the Coulomb interactions inside the molecules are stronger.

7Li+12C and 7Li+13C fusion reactions at subbarrier energies

Abstract The 7Li+12C and 7Li+13C reactions have been studied at incident energies below and around the Coulomb barrier, by the measurement of cross sections for the characteristic γ-rays emitted from the residual nuclei. Statistical model calculations of the decay of the compound nucleus have been used to deduce the absolute cross sections for different channels and to obtain the total fusion cross sections. There is no evidence for fusion cross section limitations for these systems at energies near the Coulomb barrier as observed in an earlier experiment.

The role of the Δ (1920) resonance for kaon production in heavy ion collisions

The long mean free path of K + mesons in nuclear matter this particle a suitable messenger for the dynamics of nucleus-nucleus reactions at intermediate energies (100 MeV to 3 GeV per nucleon). A prerequisite for this is the knowledge of the elementary production cross sections πN→∑ K. Here these cross sections are studied for the first time with the explicit inclusion of the relevant baryon resonances up to 2 GeV as intermediate states. The baryon resonances - N(1710)I(J P) = 1 2 ( 1 2 +), N(1720) 1 2 ( 3 2 +) and Δ(1920) 3 2 ( 3 2 +) - are taken into account coherently in the calculations of the πN→∑ K process. Also K ∗(892) 1 2 (1 −) vector meson exchange is included. It is shown that the total cross sections for different channels of the πN→∑ K reactions, i.e. π + p→∑ + K +, π − p→∑ − K +, π + n→∑ 0 K + ( π − p→∑ − K +) and π 0 p→∑ 0 K + differ not only by absolute values but also by their energy dependence. This shape differences are due to the mixture of the isospin I = 3 2 Δ(1920) with isospin I = 1 2 nucleon resonances. However, this I = 3 2 resonance does not give a contribution to the πN → λK reactions. So the shapes of the total cross sections πN → λK for different isospin projections are the same. In spite of this, such cross sections averaged over different isospin projections in the same multiplet are often used for studies of kaon production in heavy ion collisions. Here we give an explicit separate parametrization of the cross sections for each channel πN → ∑ K, which are calculated in this work.

General characteristics of the annihilation reaction p → 2π+2π−(πo) at 3.6 GeV/c

About 43 000 four prong events of antiproton-proton interactions at 3.6 GeV/c have been analysed in order to investigate pion annihilation. The cross sections of different channels are determined. Resonance production (including associated resonances) in 4π and 5π final states is analysed in detail. More than one resonance per event is produced. Associated resonance production is important (25% of the cases). Angular and momentum distributions of single pions and those of resonances are given. The influence of resonance production is analysed. Peripheral character appears in particular in two body (ϱofo, fofo, ϱogo, fogo, ωofo) and three body (ϱ±ϱoπ±) annihilations.

The cross sections for different channels in heavy ion nuclear reactions

Estimates have been made for the critical value lc of the orbital angular momentum above which a complete fusion nucleus cannot be formed. The results have been obtained by measurements of cross sections for noncompound inelastic processes (inelastic scattering, transfer. reactions, α particle emission) when Ag targets were bombarded by 86 MeV 12C ions and by 78 and 113 MeV 14N ions. The average value of lc was found between 38 and 45 ħ. A short discussion is given on the range of angular momenta at which transfer reactions occur. It is shown that quasi elastic single and multi-nucleon transfer reactions are possible only for large values of l called lT. When the bombarding energy is high enough, theses values lT are larger than lc and there is a region of l between l c and lT where a very inelastic mechanism takes place. A model called « fusion prompt scission » process is proposed. It is suggested that a deformed shape for the two fissioning nuclei is temporarly formed and breaks off very shortly after.

Strange particle production in 8 GeV/ c positive pion interactions in hydrogen

Results are presented on strange particle production in 8 GeV/ c π +p interactions with three and four particles in the final state. Total cross sections for different channels and for production of different resonances are estimated. Differential cross sections for quasi two-body reactions are given. Evidence is presented for the production of a (ΛK) enhancement with a mass of 1755 ± 21 MeV and a full width of 220 ± 60 MeV. Branching ratios for rare decay modes of A 1, A 2, f o and f′ into strange particles are given. In the ( K Kπ ) mass distribution possible enhancements are observed at 1490 and 1690 MeV.

Elastic scattering, pion production, and annihilation into pions in antiproton-proton interactions at 5.7 GeV/c

An extensive investigation of antiproton-proton interactions at 5.7 GeV/c without strange-particle production was carried out using a hydrogen bubble chamber. Cross-sections for different channels are given and discussed. The reliability of the analysis was checked using artificially generated events. The cross-sections for elastic scattering, for all processes involving annihilation, and for all other inelastic processes are respectively σel=(16.3±0.6)mb,σannlbil=(22.5±2.0)mb, σinel=(24.8±2.0)mb. TheN*1:38 is present both in the single and multiple pion production channels. For the reactionOpen image in new window a cross-section of (1.05±0.21) mb was obtained. Cross-sections forN*1238 production in other channels are also given. Some indication of the presence ofI=1/2 isobars was found in the nucleon-pion and the nucleon-two-pion systems. The inelastic nonannihilation reactions were found to be strongly peripheral. The one-pion exchange model including either a form factor or corrections for absorption was applied to the reactionOpen image in new window. Neither version of the model could correctly account for all features of the reaction. The average number of pions in the annihilation was found to be 7.3±0.6. The presence of an asymmetry in the angular distribution of the charged pions was confirmed at this energy; it is due mostly to high-energy pions. The production of ρ and ω mesons was observed in various annihilation channels. Rates of up to 80% for ρ production and up to 15% for ω production were obtained by fitting phase-space and Breit-Wigner curves to the effective-mass distributions of different channels.