Download or read book Measurement of the Neutron s Electric Form Factor G E n Via Doubly Polarized Quasi elastic Scattering at Jefferson Lab written by Frank Wesselmann and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Measurement of the Neutron Electric Form Factor GEn in Quasielastic Scattering written by and published by . This book was released on 2003 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Measurements of the Electric Form Factor of the Neutron Up to Q2 written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book The Electric Form Factor of the Neutron at Q2 written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Jefferson Laboratory E93-038 collaboration measured the ratio of the electric form factor to the magnetic form factor of the neutron, g = Gne/Gnm, via recoil polarimetry from the quasielastic 2H(e, en)1 H reaction at q2 = 0.45, 1.17 and 1.47 (GeV/c)2 in Hall C of the Thomas Jefferson National Accelerator Facility. A polarimeter designed specifically for E93-038 was used to measure the up-down scattering asymmetry from the transverse component of the recoil neutron's polarization vector, and a dipole magnet located in front of the polarimeter was used to precess the polarization vector in the scattering plane through an angle of x. Sequential measurements of the scattering asymmetry with the polarization vector precessed through angles x = 0s and x = ±90s for Q2 = 1.47 (GeV/c)2 were made during January 2001 and through angles x = ±40s for Q2 = 1.17 (GeV/c)2 during April 2001 and will be reported on in this dissertation. This ratio method removes the need to know the analyzing power.
Download or read book Measurements of the Electric Form Factor of the Neutron at JLab Via Recoil Polarimetry in the Reaction written by J. M. Finn and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Preliminary results are reported for measurements of the ratio of the electric form factor to the magnetic form factor of the neutron, GEn/GMn, obtained via recoil polarimetry from the quasielastic 2H(e, e?n) 1H reaction at Q2 values of 0.45, 1.13, and 1.45 (GeV/c)2. The measurements, conducted in Hall C of the Thomas Jefferson National Accelerator Facility, together with other recent polarization measurements, are the result of a decade long effort to establish a firm experimental database for the important, but elusive, electric form factor of the neutron.
Download or read book A Measurement of the Neutron Electric Form Factor in Dvec evec E n p Quasielastic Scattering at Q2 written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Electric Form Factor of the Neutron written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent polarization-based precision measurements of the nucleons' elastic electric form factors have led to surprising results. The measurement of the ratio of the proton's electromagnetic form factors, $\mu_p G_E^p/G_M^p$, was found to drop nearly linearly with $Q^2$ out to at least $5 \mathrm{GeV}^2$, inconsistent with the older Rosenbluth-type experiments. A recent measurement of $G_E^n$, the neutron's electric form-factor saw $G_E^n$ does not fall off as quickly as commonly expected up to $Q^2 \approx 1.5 \mathrm{GeV}^2$. Extending this study, a precision measurement of $G_E^n$ up to $Q^2=3.5 \mathrm{GeV}^2$ was completed in Hall A at Jefferson Lab. The ratio $G_E^n/G_M^n$ was measured through the beam-target asymmetry $A_\perp$ of electrons quasi-elastically scattered off polarized neutrons in the reaction ${}^{3}\overrightarrow{He}(\overrightarrow{e}, e' n)$. The experiment took full advantage of the electron beam, recent target developments, as well as two detectors new to Jefferson Lab. The measurement used the accelerator's 100\% duty-cycle high-polarization (typically 84\%) electron beam and a new, hybrid optically-pumped polarized ${}^{3}\overrightarrow{He}$ target which achieved in-beam polarizations in excess of 50\%. A medium acceptance (80msr) open-geometry magnetic spectrometer (BigBite) detected the scattered electron, while a geometrically matched neutron detector observed the struck neutron. Preliminary results from this measurement will be discussed and compared to modern calculations of $G_E^n$.
Download or read book A Measurement of the Neutron Electric Form Factor at Very Large Momentum Transfer Using Polaried Electrions Scattering from a Polarized Helium 3 Target written by and published by . This book was released on 2010 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Knowledge of the electric and magnetic elastic form factors of the nucleon is essential for an understanding of nucleon structure. Of the form factors, the electric form factor of the neutron has been measured over the smallest range in Q2 and with the lowest precision. Jefferson Lab experiment 02-013 used a novel new polarized 3 He target to nearly double the range of momentum transfer in which the neutron form factor has been studied and to measure it with much higher precision. Polarized electrons were scattered off this target, and both the scattered electron and neutron were detected. Gn E was measured to be 0.0242 ± 0.0020(stat) ± 0.0061(sys) and 0.0247 ± 0.0029(stat) ± 0.0031(sys) at Q2 = 1.7 and 2.5 GeV2 , respectively.
Download or read book The Neutron Electric Form Factor to Q2 written by and published by . This book was released on 2004 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book The Neutron Electric Form Factor to Q2 written by Bradley Robert Plaster and published by . This book was released on 2004 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: (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.
Download or read book Measurement of the Neutron Electric Form Factor at Q2 written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Measurement of the Electric Form Factor of the Neutron at Q2 written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Testing QCD Through Spin Observables in Nuclear Targets written by Don G. Crabb and published by World Scientific. This book was released on 2003 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the invited talks and contributed papers presented at the workshop on ?Testing QCD Through Spin Observables in Nuclear Targets?, held at the University of Virginia in April 2002.The workshop was proposed in the context of the large number of experiments that have used polarized deuterons or polarized 3He to extract information about the spin parameters of the neutron. The motivation for this workshop was to study the effects of the nuclear medium on the spin properties of the bound nucleon and to explore issues in QCD that might be resolved through spin observables in nuclear targets: What is the effect of the nuclear medium on the measured asymmetries? How have the latest results on the spin structure of the nucleon and the nucleon form factors changed our thinking? What advances are anticipated in the development of polarized targets?
Download or read book A Measurement of the Neutron Electric Form Factor in D e E p Quasi elastic Scattering at Q2 written by Hongguo Zhu and published by . This book was released on 2000 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Electric Form Factor of the Neutron at High Momentum Transfer written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The E02-013 collaboration s precision measurement of the electric form factor of the neutron at high momentum took place in Hall A of Jefferson Laboratory [1]. Four kinematic points spread in Q2 from 1.2 to 3.5 (GeV/c)2 reach the region of momentum transfer where there is little ambiguity that the form factors are dominated by the valence quarks. The electric form factor provides important constraints on the generalized parton distributions (GPDs) of the nucleon and therefore to understand the currently unknown quark angular orbital moments. The talk presented newly obtained results for GnE including at Q2 of 2.5 (GeV/c)2. These measurements provide access to twice the range of momentum transfer for complete iso-spin decomposition of the nucleon form factors. The form factors of the u and d quarks were also presented. The measurement used a double polarization asymmetry method [2][3] with He polarized up to 55% (provided by a novel hybrid alkali optical pumping scheme utilizi.
