Search results for "ELASTIC SCATTERING"
showing 10 items of 735 documents
K− over K+ multiplicity ratio for kaons produced in DIS with a large fraction of the virtual-photon energy
2018
The K$^{-}$ over K$^{+}$ multiplicity ratio is measured in deep-inelastic scattering, for the first time for kaons carrying a large fraction $z$ of the virtual-photon energy. The data were obtained by the COMPASS collaboration using a 160 GeV muon beam and an isoscalar $^6$LiD target. The regime of deep-inelastic scattering is ensured by requiring $Q^2>1$ (GeV/$c)^2$ for the photon virtuality and $W>5$ GeV/$c^2$ for the invariant mass of the produced hadronic system. Kaons are identified in the momentum range from 12 GeV/$c$ to 40 GeV/$c$, thereby restricting the range in Bjorken-$x$ to $0.010.75$. For very large values of $z$, $i.e.$ $z>0.8$, we observe the kaon multiplicity ratio to fall …
Inclusive pion-nucleus double charge exchange.
1989
Inclusive double charge exchange reaction is studied by using a model which combines a microscopic many-body calculation of reaction probabilities with a Monte Carlo simulation procedure. Comparison with present experimental results requires that the (\ensuremath{\pi},2\ensuremath{\pi}) reaction be included and a proper evaluation of this latter reaction is also done. The combined results compare favorably with experiment, giving extra support to this model of the pion-nucleus interaction which was previously shown to provide a good description of all other inclusive reactions and elastic scattering.
QCD resummation effects in forward J/ψ and very backward jet inclusive production at the LHC
2017
´ We propose and study the inclusive production of a forward J/ψ and a very backward jet at the LHC as an observable to reveal high-energy resummation effects à la BFKL. Our different predictions are based on the various existing mechanisms to describe the production of the J/ψ, namely, NRQCD singlet and octet contributions, and the color evaporation model. © 2017 Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Peer reviewed
4He+Ni elastic scattering near the Coulomb barrier and optical model parameters
2002
Cross sections for the elastic scattering system of 4He+Ni have been investigated. Natural nickel was bombarded by 4He ions in the laboratory energy range of 3.0–14.3 MeV and the intensity of helium backscattering through laboratory angles of 96°, 117°, and 137° was observed. From measured yield data, the cross sections were extracted for the direct Ni(4He,4He)Ni scattering process as well as for the inverse recoil scattering process 4He(58Ni,4He)58Ni by calculating the kinematical reversal of the reaction. The experimental helium scattering angles convert to helium recoil angles of 20°, 30°, and 40°, and the incident helium ion energies to 43.5–207 MeV for incident 58Ni ions in the reverse…
Comparing proton momentum distributions in A = 2 and 3 nuclei via 2H 3H and 3He (e,e′p) measurements
2019
We report the first measurement of the $(e,e'p)$ reaction cross-section ratios for Helium-3 ($^3$He), Tritium ($^3$H), and Deuterium ($d$). The measurement covered a missing momentum range of $40 \le p_{miss} \le 550$ MeV$/c$, at large momentum transfer ($\langle Q^2 \rangle \approx 1.9$ (GeV$/c$)$^2$) and $x_B>1$, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with plane-wave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for $^3$He$/d$ and $^3$H$/d$ extend to just above the typical nucleon Fermi-momentum ($k_F \approx 250$ …
Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector
2019
This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √sNN=5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb−1, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy EγT>3 GeV and pseudorapidity |ηγ|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events…
Search for Effects Beyond the Born Approximation in Polarization Transfer Observables ine→pElastic Scattering
2011
Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $$G_{E}/G_{M}$$, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange (TPEX) contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic $$H(\vec{e},e'\vec{p})$$ reaction for three different beam energies at a fixed squared momentum transfer $Q^2 = 2.5$ GeV$^2$, spanning a wide range of the virtual photon p…
Study of internal structures of 9,10Be and 10B in scattering of 4He from 9Be
2013
A study of inelastic scattering and single-particle transfer reactions was performed by an alpha beam at 63 MeV on a 9$Be target. Angular distributions of the differential cross sections for the 9Be(4He,4He')9Be*, 9Be(4He,3He)10Be and 9Be(4He,t)10B reactions were measured. Experimental angular distributions of the differential cross sections for the ground state and a few low-lying states were analyzed in the framework of the optical model, coupled channels and distorted-wave Born approximation. An analysis of the obtained spectroscopic factors was performed.
Inelastic Neutron Scattering Experiments on Van der Waals Glasses - A Test of Recent Microscopic Theories of the Glass Transition
1989
Etude realisee sur un verre d'o-terphenyle afin de montrer l'existence d'une relaxation secondaire presentant des caracteristiques inhabituelles et le comportement Kohbrausch de la fonction de correlation de densite decrivant la relaxation structurale
Resonant formation of pionic atoms with neutron collisions
1992
We study the {ital n}+{ital A}{r arrow}({ital A}{prime}{pi}{sub {ital b}}{sup {minus}}){r arrow}{ital n}+{ital A} reaction, or resonant formation of pionic atoms, with neutron scattering. We evaluate the contribution of the interference of this reaction channel in {sup 40}Ca and {sup 208}Pb to the elastic scattering amplitude at backward angles. The ratio of signal to the background at 80{degree} is about 10{sup {minus}3}, and we estimate that the ratio does not improve at higher angles, hence making this reaction impractical. Our findings have repercussions on a similar reaction now running at the Indiana University Cyclotron Facility.