A Measurement of the Neutron Electric Form Factor in D (e, Eń)p Quasi-elastic Scattering at Q2
Author : Hongguo Zhu
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Page : 574 pages
File Size : 32,10 MB
Release : 2000
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Author : Hongguo Zhu
Publisher :
Page : 574 pages
File Size : 32,10 MB
Release : 2000
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Page : 6 pages
File Size : 12,45 MB
Release : 2003
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We have measured the electric form factor of the neutron, GEn, at two momentum transfers (Q2= 0.5 and Q2= 1.0 GeV/c2) through quasielastic scattering in Jefferson Lab's Hall C. Longitudinally polarized electrons scattered from polarized deuterated ammonia and GEn was extracted from the beam-target asymmetry AVed which, in quasielastic kinematics, is particularly sensitive to GEn and insensitive to MEC and FSI.
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Page : pages
File Size : 26,46 MB
Release : 2004
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The nucleon elastic electromagnetic form factors are fundamental quantities needed for an understanding of nucleon and nuclear electromagnetic structure. The evolution of the Sachs electric and magnetic form factors with Q2, the square of the four-momentum transfer, is related to the distribution of charge and magnetization within the nucleon. High precision measurements of the nucleon form factors are essential for stringent tests of our current theoretical understanding of confinement within the nucleon. Measurements of the neutron form factors, in particular, those of the neutron electric form factor, have been notoriously difficult due to the lack of a free neutron target and the vanishing integral charge of the neutron. Indeed, a precise measurement of the neutron electric form factor has eluded experimentalists for decades; however, with the advent of high duty-factor polarized electron beam facilities, experiments employing polarization degrees of freedom have finally yielded the first precise measurements of this fundamental quantity. Following a general overview of the experimental and theoretical status of the nucleon form factors, a detailed description of an experiment designed to extract the neutron electric form factor from measurements of the neutron's recoil polarization in quasielastic 2H(e, e')1H scattering is presented. The experiment described here employed the Thomas Jefferson National Accelerator Facility's longitudinally polarized electron beam, a magnetic spectrometer for detection of the scattered electron, and a neutron polarimeter designed specifically for this experiment. Measurements were conducted at three Q2 values of 0.45, 1.13, and 1.45 (GeV/c)2, and the final results extracted from an analysis of the data acquired in this experiment are reported and compared with recent theoretical predictions for the nucleon form factors.
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Page : pages
File Size : 50,30 MB
Release : 2000
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The form factors of the neutron give information on fundamental properties of the nucleons and provide a critical testing ground for models based on QCD. In late 1998, Jefferson Lab (JLAB) experiment E93-026 measured the spin-dependent part of the exclusive (e, e'n) scattering cross section from a polarized deuterated ammonia (15ND3) target at a four momentum transfer squared of Q2 = 0.5 (GeV/c)2. A longitudinally polarized electron beam was scattered from the polarized target and the quasi-elastically scattered electron was detected in coincidence with the knocked-out neutron. The data have been analyzed in terms of the spin-correlation parameter, or the electron-deuteron vector asymmetry (A{sub ed}{sup V}), of (e, e'n) to determine the neutron electric form factor G{sub E}(superscript n). The result is consistent with data from existing experiments and shows a good agreement with the Galster parameterization of G{sub E}(superscript n) within experimental uncertainty.
Author : Bradley Robert Plaster
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Page : 541 pages
File Size : 30,80 MB
Release : 2004
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(Cont.) Following a general overview of the experimental and theoretical status of the nucleon form factors, a detailed description of an experiment designed to extract the neutron electric form factor from measurements of the neutron's recoil polarization in quasielastic 2H(e, e')1H scattering is presented. The experiment described here employed the Thomas Jefferson National Accelerator Facility's longitudinally polarized electron beam, a magnetic spectrometer for detection of the scattered electron, and a neutron polarimeter designed specifically for this experiment. Measurements were conducted at three Q2 values of 0.45, 1.13, and 1.45 (GeV/c)2, and the final results extracted from an analysis of the data acquired in this experiment are reported and compared with recent theoretical predictions for the nucleon form factors.
Author : Frank Wesselmann
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Page : pages
File Size : 28,57 MB
Release : 2004
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We determined the electric form factor of the neutron GEn via the reaction d(e, e?n)p using a longitudinally polarized electron beam and a frozen, polarized 15ND3 target at Jefferson Lab. The knocked out neutrons were detected in a segmented plastic scintillator in coincidence with the quasi-elastically scattered electrons which were tracked in Hall C's High Momentum Spectrometer. To extract GEn, we compared the experimental beam-target asymmetry with theoretical calculations based on different GEn models. We report the results of the fall 2001 run at Q2=0.5 and 1.0 (GeV/c)2.
Author : Shigeyuki Tajima
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Page : 538 pages
File Size : 32,59 MB
Release : 2003
Category : Neutrons
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Page : pages
File Size : 47,43 MB
Release : 2007
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Nucleon form factors allow a sensitive test for models of the nucleon. Recent experiments utilising polarisation observables have resulted, for the first time, in a model-independent determination of the neutron electric form factor GnE. This method employed an 80% longitudinally polarised, high intensity (10 uA) electon beam (883 MeV) that was quasi-elastically scattered off a liquid deuterium target in the reaction D (e, en)p. A neutron polarimeter was designed and installed to measure the ratio of transverse-to-longitudinal polarisation using neutron scattering asymmetries. This ratio allowed a determination of the neutron elastic form factor, GnE, free of the previous large systematic uncertainties associated with the deuterium wave function. The experiment took place in the A1 experimental hall at MAMI taking advantage of a high resolution magnetic spectrometer. A detailed investigation was carried out into the performance of the neutron polarimeter.
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Page : pages
File Size : 47,74 MB
Release : 2010
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The electric form factor of the neutron was determined from studies of the reaction \rea{} in quasi-elastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the $Q^2$-range over which it is known, we find \GEn{}$ = 0.0225 \pm 0.0017 (stat) \pm 0.0024 (syst)$, $0.0200 \pm 0.0023 \pm 0.0018$, and $0.0142 \pm 0.0019 \pm 0.0013$ for $Q^2$ = 1.72, 2.48, and 3.41~\gevsq, respectively.
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Page : pages
File Size : 31,87 MB
Release : 2004
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The electric form factor of the neutron was determined from measurements of the d ((almost equal to)e, e n) p reaction for quasielastic kinematics. Polarized electrons were scattered o a polarized deuterated ammonia (15ND3) target in which the deuteron polarization was perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle detector. We find Gn E = 0.0526 ± 0.0033(stat) ± 0.0026(sys) and 0.0454 ± 0.0054 ± 0.0037 at Q2 = 0.5 and 1.0 (GeV/c)2, respectively.