Search results for "Elastic"
showing 10 items of 2162 documents
The elastic scattering of 25MeV α-particles and neutron shell effects in the A = 50 TO A = 93 mass region
1982
Abstract Experimental elastic scattering angular distributions of 25 MeV α-particles scattered from 28 nuclei ranging from 50Cr to 93Nb have been measured and then analysed in terms of a regular optical model with standard Woods-Saxon geometries for both the real and imaginary potentials. The experimental distributions are well fitted over the whole angular range from 5° to 175° c.m. by the predictions, provided that a smaller than normal diffuseness is used for the imaginary potentials. The usual families of potentials with volume integrals differing by approximately 100 MeV · fm3 are found. The family with volume integral ranging from 540 to 420 MeV· fm3 over the nuclei studied has been c…
Direct measurement of the radiative tail in electron scattering from atomic nuclei
1985
We have made a direct measurement of the radiative tail of the eleastic peak from several tungsten targets. The measured data have been compared to the results expected for both internal and external bremsstrahlung contributions. Even for targets as thick as 4% of a radiation length of tungsten, agreement between the results of the experiment and the predictions of the theory has been found to be unexpectedly good.
The coherent weak charge of matter
2017
We study the long-range force arising between two aggregates of ordinary matter due to a neutrino-pair exchange, in the limit of zero neutrino mass. Even if matter is neutral of electric charge, it is charged for this weak force. The interaction is described in terms of a coherent charge, which we call the weak flavor charge of aggregated matter. For each one of the interacting aggregates, this charge depends on the neutrino flavor as $Q_W^{\nu_e} = 2Z-N$, $Q_W^{\nu_\mu} = Q_W^{\nu_\tau} = -N$, where $Z$ is the number of protons and $N$ the number of neutrons. $Q_W^{\nu_e}$ depends explicitly on $Z$ because of the charged current contribution to $\nu_e e$ elastic scattering, while the $N$ t…
Two-photon exchange corrections in elastic electron-proton scattering
2015
We apply a subtracted dispersion relation (DR) formalism with the aim to improve predictions for the two-photon exchange (TPE) corrections to elastic electron-proton scattering observables at small momentum transfers. We study the formalism on the elastic TPE contribution in comparison with existing data for unpolarized cross sections. We extend the general formalism of TPE to elastic scattering with massive lepton and perform a numerical estimate of the muon-proton scattering at low momentum transfer in view of the upcoming muon-proton scattering experiment (MUSE). We study the influence of the double-virtual Compton scattering (VVCS) subtraction function on the unpolarized lepton-proton s…
Monte-Carlo calculations of keV electron and positron slowing down in solids
1983
A Monte-Carlo simulation technique based on the screened Rutherford differential cross section for the elastic scattering and Gryzinski's semiempirical expression for the inelastic core and valence electron excitation is used to describe electrons and positrons slowing down in solids. The theoretical results are compared with the experimental backscattering, absorption and transmission results for aluminum, silicon, copper, and gold thin film and semi-infinite targets and good agreement is observed. The simulated stopping profiles are fitted with a simple analytic expression. The profiles are Laplace-transformed to give a useful data base for analyzing phenomena associated with slow positro…
Positrons and Electrons Emitted in Elastic and Dissipative Heavy Ion Collisions
1987
The main research line of the Tori group is the study of the reaction dynamics of dissipative collisions between heavy ions ia positron and electron spectroscopy. The last five years since the Lahnstein-Conference1 are marked for our group by the installation of a new experimental device for detecting positrons and electrons emitted in these collisions, the so-called Tori spectrometer2. The first part of this report is devoted therefore to describe the main characteristics of this apparatus.
ISR Experiment at A1-Collaboration
2019
The discrepancy between the proton charge radius extracted from the muonic hydrogen Lamb shift measurement and the best present value obtained from the elastic scattering experiments, remains unexplained and represents a burning problem of today’s nuclear physics. In a pursuit of reconciling the puzzle an experiment is underway at MAMI, which exploits the radiative tail of the elastic peak to study the properties of electromagnetic processes and to extract the proton charge form factor $ \left( {\mathop G\nolimits_E^p } \right) $ at extremely small Q2. This paper reports on the latest results of the first such measurement performed at the three-spectrometer facility of the A1-Collaboration,…
Measurement of the Transverse Beam Spin Asymmetry in Elastic Electron Proton Scattering and the Inelastic Contribution to the Imaginary Part of the T…
2004
We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A$_\perp$, at two Q$^2$ values of \qsquaredaveragedlow (GeV/c)$^2$ and \qsquaredaveragedhighII (GeV/c)$^2$ and a scattering angle of $30^\circ < ��_e < 40^\circ$. The measured transverse asymmetries are A$_{\perp}$(Q$^2$ = \qsquaredaveragedlow (GeV/c)$^2$) = (\experimentalasymmetry alulowcorr $\pm$ \statisticalerrorlow$_{\rm stat}$ $\pm$ \combinedsyspolerrorlowalucor$_{\rm sys}$) $\times$ 10$^{-6}$ and A$_{\perp}$(Q$^2$ = \qsquaredaveragedhighII (GeV/c)$^2$) = (\experimentalasymme tryaluhighcorr $\pm$ \statisticalerrorhigh$_{\rm stat}$ $\pm$ \combinedsyspolerrorhi…
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…
Comparison of woods-saxon and double-folding potentials forα-particle scattering from54Fe at 24.5 MeV
1988
Inelastic-scattering data are presented forα-particles of 24.5 MeV from54Fe over the range 15° to 175° in the centre-of-mass system. The real part of the optical potential is calculated microscopically using the M3Y effective interaction of Bertschet al. and the DDM3Y density-dependent interaction. Elastic scattering has been analysed by using as real part of the optical potential M3Y, DDM3Y and Woods-Saxon forms (WS), taking in all three cases as imaginary part a WS potential. To fit the data the double-folding potential needs to be normalized by a factor of ⋍1.6 for the M3Y interaction and of ⋍1.13 for the DDM3Y interaction. By the study of the invariant-point ambiguity it has been observ…