Search results for "Electron Scattering"
showing 10 items of 105 documents
Determination of the neutron electric form factor from the reaction 3 He(e,e'n) at medium momentum transfer
1999
The electric form factor of the neutron GEn has been determined in double polarized exclusive 3He(e,e'n) scattering in quasi–elastic kinematics by measuring asymmetries A⊥, A∥ of the cross section with respect to helicity reversal of the electron, with the nuclear spin being oriented perpendicular to the momentum transfer q in case of A⊥ and parallel in case of A∥. The experiment was performed at the 855 MeV c. w. microtron MAMI at Mainz. The degree of polarization of the electron beam and of the gaseous 3He target were each about 50%. Scattered electrons and neutrons were detected in coincidence by detector arrays covering large solid angles. Quasi–elastic scattering events were reconstruc…
The three-spectrometer setup for (e,e'x) coincidence experiments at the Mainz microtron MAMI
1995
A setup of three high-resolution magnetic spectrometers has been built up as the central facility for the precise determination of electron scattering cross sections in coincidence with hadrons. The operational experiencies with two of the spectrometers, A and B, demonstrate that both spectrometers exceed the specifications. With A and B, a series of ( e, e′x ) coincidence experiments were successfully performed. The third spectrometer, C, will be ready for operation in late autumn 1994.
Virtual Compton Scattering at MAMI γ*p→ γ1p1
1999
The virtual Compton scattering (VCS) is the electron scattering on a proton which radiates a real photon before being detected. The new observables, called Generalized Polarizabilities (GP), extracted from this VCS at threshold can be understood as the deformation of the charge and current distributions of the proton [1]. These GP are functions of the mass of the virtual photon Q2. In real Compton scattering (Q2 = 0), some polarizabilities of the nucleon are already measured [2]. With the VCS, we will generalize these observables by measuring them at different values of Q2.
Nuclear charge distribution and rms radius ofC12from absolute elastic electron scattering measurements
1982
Elastic electron scattering cross sections for the nucleus $^{12}\mathrm{C}$ have been measured in a momentum transfer range from 0.25 to 2.75 ${\mathrm{fm}}^{\ensuremath{-}1}$. The data were analyzed in a model independent way with a Fourier-Bessel parametrization of the charge distribution. For the rms radius, the value ${〈{r}^{2}〉}^{\frac{1}{2}}=(2.464\ifmmode\pm\else\textpm\fi{}0.012)$ fm (no dispersion corrections applied) has been obtained, and agrees with those of other electron scattering experiments and with muonic atom experiments, but disagrees with data obtained from measurements of muonic x-ray transitions with a crystal spectrometer which show a larger rms radius. The extracte…
Inclusive quasielastic charged-current neutrino-nucleus reactions
2004
The Quasi-Elastic (QE) contribution of the nuclear inclusive electron scattering model developed in Nucl. Phys. A627 (1997) 543 is extended to the study of electroweak Charged Current (CC) induced nuclear reactions, at intermediate energies of interest for future neutrino oscillation experiments. The model accounts for, among other nuclear effects, long range nuclear (RPA) correlations, Final State Interaction (FSI) and Coulomb corrections. Predictions for the inclusive muon capture in $^{12}$C and the reaction $^{12}$C $(\nu_\mu,\mu^-)X$ near threshold are also given. RPA correlations are shown to play a crucial role and their inclusion leads to one of the best existing simultaneous descri…
Search for Light Gauge Bosons of the Dark Sector at the Mainz Microtron
2011
A new exclusion limit for the electromagnetic production of a light U(1) gauge boson {\gamma}' decaying to e^+e^- was determined by the A1 Collaboration at the Mainz Microtron. Such light gauge bosons appear in several extensions of the standard model and are also discussed as candidates for the interaction of dark matter with standard model matter. In electron scattering from a heavy nucleus, the existing limits for a narrow state coupling to e^+e^- were reduced by nearly an order of magnitude in the range of the lepton pair mass of 210 MeV/c^2 < m_e^+e^- < 300 MeV/c^2. This experiment demonstrates the potential of high current and high resolution fixed target experiments for the search fo…
Measurement of the Inclusive Electron Neutrino Charged Current Cross Section on Carbon with the T2K Near Detector
2014
The T2K off-axis near detector, ND280, is used to make the first differential cross-section measurements of electron neutrino charged current interactions at energies ~1 GeV as a function of electron momentum, electron scattering angle and four-momentum transfer of the interaction. The total flux-averaged $\nu_e$ charged current cross-section on carbon is measured to be $1.11\pm0.09~(stat)\pm0.18~(syst)\times10^{-38} cm^2/nucleon$. The differential and total cross-section measurements agree with the predictions of two leading neutrino interaction generators, NEUT and GENIE. The NEUT prediction is $1.23\times10^{-38} cm^2/nucleon$ and the GENIE prediction is $1.08\times10^{-38} cm^2/nucleon$…
High-Precision Determination of the Electric and Magnetic Form Factors of the Proton
2010
New precise results of a measurement of the elastic electron-proton scattering cross section performed at the Mainz Microtron MAMI are presented. About 1400 cross sections were measured with negative four-momentum transfers squared up to Q^2=1 (GeV/c)^2 with statistical errors below 0.2%. The electric and magnetic form factors of the proton were extracted by fits of a large variety of form factor models directly to the cross sections. The form factors show some features at the scale of the pion cloud. The charge and magnetic radii are determined to be r_E=0.879(5)(stat.)(4)(syst.)(2)(model)(4)(group) fm and r_M=0.777(13)(stat.)(9)(syst.)(5)(model)(2)(group) fm.
Zerstörungsfreie Phasenanalyse dünner Oberflächenschichten mittels Konversionselektronen
1987
By use of an appropriate gamma radiation, conversion electrons may be produced by Mossbauer effect also in a depth below the sample surface deeper than the free path for inelastic electron scattering. Because the Mossbauer spectrum of the conversion electrons reflects the local phase composition, the recording of all electrons escaping from the surface allows an integral phase analysis of a layer of some 10–100 nm thickness. If only electrons within a narrow range of energy are recorded, a depth selective phase analysis is possible. The applicability of these two techniques of conversion electron spectroscopy is demonstrated by a few examples concerning oxidation and passivation of steel. C…
Spectroscopy of the neutron-rich hypernucleusHeΛ7from electron scattering
2016
The missing mass spectroscopy of the HeΛ7 hypernucleus was performed using the Li7(e, e ′K+)HeΛ7 reaction at the Thomas Jefferson National Accelerator Facility Hall C. The Λ- binding energy of the ground-state (1/2+) was determined with a smaller error than that of the previous measurement, being BΛ=5.55±0.10stat.±0.11sys.MeV. The experiment also provided new insight into charge symmetry breaking in p-shell hypernuclear systems. Finally, a peak at BΛ=3.65±0.20stat. ±0.11sys.MeV was observed and assigned as a mixture of 3/2+ and 5/2+ states, confirming the "gluelike" behavior of Λ, which makes an unstable state in He6 stable against neutron emission.