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Download or read book Experimental Study of the Spin Structure of the Neutron (3He) at Low Q2 written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
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ISBN 13 :
Total Pages : 216 pages
Book Rating : 4.:/5 (16 download)
Download or read book The Spin Structure of 3He and the Neutron at Low Q2 written by and published by . This book was released on 2007 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the 1980's, the study of nucleon (proton or neutron) spin structure has been an active field both experimentally and theoretically. One of the primary goals of this work is to test our understanding of Quantum Chromodynamics (QCD), the fundamental theory of the strong interaction. In the high energy region of asymptotically free quarks, QCD has been verified. However, verifiable predictions in the low energy region are harder to obtain due to the complex interactions between the nucleon's constituents: quarks and gluons. In the non-pertubative regime, low-energy effective field theories such as chiral perturbation theory provide predictions for the spin structure functions in the form of sum rules. Spin-dependent sum rules such as the Gerasimov-Drell-Hearn (GDH) sum rule are important tools available to study nucleon spin structure. Originally derived for real photon absorption, the Gerasimov-Drell-Hearn (GDH) sum rule was first extended for virtual photon absorption in 1989. The extension of the sum rule provides a unique relation, valid at any momentum transfer ($Q{̂2}$), that can be used to study the nucleon spin structure and make comparisons between theoretical predictions and experimental data. Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) to examine the spin structure of the neutron and ${̂3}$He. The Jefferson Lab longitudinally-polarized electron beam with incident energies between 1.1 and 4.4 GeV was scattered from a longitudinally or transversely polarized ${̂3}$He gas target in the Hall A end station. Asymmetries and polarized cross-section differences were measured in the quasielastic and resonance regions to extract the spin structure functions $g_{1}(x,Q{̂2})$ and $g_{2}(x,Q{̂2})$ at low momentum transfers (0.02 $
Download or read book Measurement of the Neutron (3He) Spin Structure at Low Q2 and the Extended Gerasimov-Drell-Hearn Sum Rule written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the results of E-94010, an experiment at Thomas Jefferson National Accelerator Facility (TJNAF) designed to study the spin structure of the neutron at low momentum transfer, and to test the "extended" Gerasimov-Drell-Hearn (GDH) sum rule. The first experiment of its kind, it was performed in experimental Hall-A of TJNAF using a new polarized 3He facility. It has recently been shown that the GDH sum rule and the Bjorken sum rule are both special examples of a more general sum rule that applies to polarized electron scattering off nucleons. This generalized sum rule, due to Ji and Osborne, reduces to the GDH sum rule at Q2 = 0 and to the Bjorken sum rule at Q2” 1 GeV2. By studying the Q2 evolution of the extended GDH sum, one learns about the transition from quark-like behavior to hadronic-like behavior. We measured inclusive polarized cross sections by scattering high energy polarized electrons off the new TJNAF polarized 3He target with both longitudinal and transverse target orientations. The high density 3He target, based on optical pumping and spin exchange, was used as an effective neutron target. The target maintained a polarization of about 35% at beam currents as high as 151tA. We describe the precision 3He polarimetry leading to a systematic uncertainty of the target polarization of 4% (relative). A strained GaAs photocathode was utilized in the polarized electron gun, which provided an electron beam with a polarization of about 70%, known to 3% (relative). By using six different beam energies (between 0.86 and 5.06 GeV) and a fixed scattering angle of 15.5°, a wide kinematic coverage was achieved, with 0.02 GeV2
Download or read book Precision Measurements of the Neutron Spin Structure at Jefferson Lab Hall A. written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present here recent progress on the experimental study of the neutron spin structure at Jefferson Lab Hall A. They focus on two precision experiments. The physics motivation and the experimental setup will be described first. Then they present results for the neutron spin asymmetry A1(superscript n) and results for spin-flavor decomposition of the nucleon spin in the valence quark region, and preliminary results for the neutron spin structure function g2(superscript n) at low Q2.
Download or read book Neutron (3He) Spin Structure Functions at Low Q^2 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility to provide a precise measurement of the $^{3}$He spin structure functions at low $Q^{2}$ from 0.02 to 0.3~[GeV$/c$]$^{2}$. A longitudinally-polarized electron beam was scattered from a longitudinally or transversely polarized $^{3}$He target. From these data, we have extracted moments of the neutron and $^{3}$He spin structure functions at very low momentum transfers. These data allow us to make a benchmark check of Chiral Perturbation Theory calculations in a region where they are expected to be valid. In these proceedings, the experimental details are discussed and preliminary results on the first moments of the $g_1\left(x, Q^{2}\right)$ and $g_2\left(x, Q^{2}\right)$ structure functions are presented.
Author :
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ISBN 13 :
Total Pages : 216 pages
Book Rating : 4.:/5 (953 download)
Download or read book Measurement of the Neutron (3He) Spin Structure Functions at Low Q2 written by and published by . This book was released on 2002 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents results of experiment E94-010 performed at Jefferson Laboratory (simply known as JLab) in Hall A. The experiment aimed to measure the low Q2 evolution of the Gerasimov-Drell-Hearn (GDH) integral from Q2 = 0.1 to 0.9 GeV2. The GDH sum rule at the real photon point provides an important test of Quantum Chromodynamics (QCD). The low Q2 evolution of the GDH integral contests various resonance models, Chiral Perturbation Theory ([chi] PT) and lattice QCD calculations, but more importantly, it helps us understand the transition between partonic and hadronic degrees of freedom. At high Q2, beyond 1 GeV2, the difference of the GDH integrals for the proton and the neutron is related to the Bjorken sum rule, another fundamental test of QCD. In addition, results of the measurements for the spin structure functions g1 and g2, cross sections, and asymmetries are presented. E94-010 was the first experiment of its kind at JLab. It used a high-pressure, polarized 3He target with a gas pressure of 10 atm and average target polarization of 35%. For the first time, the polarized electron source delivered an average beam polarization of 70% with a beam current of 15 micro A. The limit on the beam current was only imposed by the target. The experiment required six different beam energies from 0.86 to 5.1 GeV. This was the first time the accelerator ever reached 5.1 GeV. Both High-Resolution Spectrometers of Hall A, used in singles mode, were positioned at 15.5 ° each.
Download or read book Neutron Spin Structure Study at Jefferson Lab Hall A. written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: With a high-intensity highly-polarized 6 GeV electron beam, and a high-density polarized 3He target, we have carried out a number of experiments to study the neutron spin structure at Hall A in Jefferson Lab. Taking advantage of the high luminosity of Jefferson Lab, we completed two inclusive deep-inelastic-scattering experiments this summer. In the first, precision measurements were made of the spin asymmetry A(superscript n)1 in the valence quark (high Bjorken x) region; and in the second, higher-twist effects were studied via precision measurements of g(superscript n)2. Physics motivation and preliminary results from the first experiment will be presented and discussed. I will also present nearly final results from an earlier experiment, which measured the generalized GDH sum for the neutron in the Q2 range of 0.1 to 1 GeV2. Planned near-term experiments will be briefly discussed.
Author : Vincent Sulkosky
Publisher :
ISBN 13 :
Total Pages : 12039 pages
Book Rating : 4.:/5 (316 download)
Download or read book Low Q^2 Measurements of the Neutron and 3He Spin Structure written by Vincent Sulkosky and published by . This book was released on 2006 with total page 12039 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thomas Jefferson National Accelerator Facility experiment E97-110 was performed to provide a precise measurement of the extended Gerasimov-Drell-Hearn integral and of moments of the neutron and of the {sup 3}He spin structure functions. The momentum transfer range 0.02
Author :
Publisher :
ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (946 download)
Download or read book Q2 Evolution of the Neutron Spin Structure Moments Using a 3He Target written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the spin structure functions g1 and g2 of 3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.07 GeV off a polarized 3He target at a 15.5{sup o} scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q2 evolution of [Gamma]1(Q2)=/int01 g1(x, Q2) dx, [Gamma]2(Q2)=/int01 g2(x, Q2) dx and d2 (Q2) = /int01 x 2[2g1(x, Q2) + 3g2(x, Q2)] dx for the neutron in the range 0.1 GeV2 /leq Q2 /leq 0.9 GeV2 with good precision. [Gamma]1(Q2) displays a smooth variation from high to low Q2. The Burkhardt-Cottingham sum rule holds within uncertainties and d2 is non-zero over the measured range.
Download or read book The Spin Structure of 3He and the Neutron at Low Q^2 written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the 1980's, the study of nucleon (proton or neutron) spin structure has been an active field both experimentally and theoretically. One of the primary goals of this work is to test our understanding of Quantum Chromodynamics (QCD), the fundamental theory of the strong interaction. In the high energy region of asymptotically free quarks, QCD has been verified. However, verifiable predictions in the low energy region are harder to obtain due to the complex interactions between the nucleon's constituents: quarks and gluons. In the non-pertubative regime, low-energy effective field theories such as chiral perturbation theory provide predictions for the spin structure functions in the form of sum rules. Spin-dependent sum rules such as the Gerasimov-Drell-Hearn (GDH) sum rule are important tools available to study nucleon spin structure. Originally derived for real photon absorption, the Gerasimov-Drell-Hearn (GDH) sum rule was first extended for virtual photon absorption in 1989. The extension of the sum rule provides a unique relation, valid at any momentum transfer ($Q^{2}$), that can be used to study the nucleon spin structure and make comparisons between theoretical predictions and experimental data. Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) to examine the spin structure of the neutron and $^{3}$He. The Jefferson Lab longitudinally-polarized electron beam with incident energies between 1.1 and 4.4 GeV was scattered from a longitudinally or transversely polarized $^{3}$He gas target in the Hall A end station. Asymmetries and polarized cross-section differences were measured in the quasielastic and resonance regions to extract the spin structure functions $g_{1}(x, Q^{2})$ and $g_{2}(x, Q^{2})$ at low momentum transfers (0.02 $
Download or read book The Neutron and 3He Spin Structure Functions at Low Q^2 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility in Hall A to provide a precise measurement of the moments of the neutron and $^{3}$He spin structure functions. A longitudinally-polarized electron beam was scattered from a longitudinally or transversely polarized $^{3}$He target. The extended Gerasimov-Drell-Hearn integral and other moments of the neutron and $^{3}$He spin structure functions were extracted at very low momentum transfers (0.02 $
Author : Vincent Anthony Sulkosky
Publisher :
ISBN 13 :
Total Pages : 396 pages
Book Rating : 4.:/5 (213 download)
Download or read book The Spin Structure of 3He and the Neutron at Low Q2 written by Vincent Anthony Sulkosky and published by . This book was released on 2007 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Zein-Eddine Meziani
Publisher :
ISBN 13 :
Total Pages : 5 pages
Book Rating : 4.:/5 (316 download)
Download or read book Neutron Spin Structure Results from JLab Hall A. written by Zein-Eddine Meziani and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: My presentation will focus on some of the latest results of the neutron spin physics program at Jefferson Laboratory in Hall A using a polarized 3He target. This program includes several completed experiments in which the spin structure functions of 3He were measured. The covered kinematic regions were these measurements were performed include the low Q2 resonance and inelastic regions and the high Q2 deep inelastic region. These experiments offer a ground for testing our understanding of the strong regime of quantum chromodynamics (QCD) through the determination of the neutron spin-dependent structure functions and their moments.
Author : Aron M Bernstein
Publisher : World Scientific
ISBN 13 : 9814490326
Total Pages : 495 pages
Book Rating : 4.8/5 (144 download)
Download or read book Chiral Dynamics: Theory And Experiment Iii written by Aron M Bernstein and published by World Scientific. This book was released on 2001-12-04 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an authoritative, up to date, overview of the field of chiral dynamics, and also provides an excellent introduction to the field. The workshop is known for the interplay of theory and experiment and as a meeting place for most of the leading researchers in the field.
Author : Ioannis Kominis
Publisher :
ISBN 13 :
Total Pages : 238 pages
Book Rating : 4.:/5 (493 download)
Download or read book Measurement of the Neutron (3He) Spin Structure at Low Q2 and the Extended Gerasimov-Drell-Hearn Sum Rule written by Ioannis Kominis and published by . This book was released on 2001 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 214 pages
Book Rating : 4.:/5 (16 download)
Download or read book Measurement of the 3He Spin Structure Functions in the Resonance Region written by and published by . This book was released on 2006 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the biggest challenges in the study of the nucleon structure is the understanding of the transition from partonic degrees of freedom to hadronic degrees of freedom. In 1970, Bloom and Gilman noticed that structure function data taken at SLAC in the resonance region average to the scaling curve of deep inelastic scattering (DIS). Early theoretical interpretations suggested that these two very different regimes can be linked under the condition that the quark-gluon and quark-quark interactions are suppressed. Substantial efforts are ongoing to investigate this phenomenon both experimentally and theoretically. Quark-hadron duality has been confirmed for the unpolarized structure function F2 of the proton and the deuteron using data from the experimental Hall C at Jefferson Lab (JLab). Indications of duality have been seen for the proton polarized structure function g1 and the virtual photon asymmetry A1 at JLab Hall B and HERMES. Because of the different resonance behavior, it is expected that the onset of duality for the neutron will happen at lower momentum transfer than for the proton. Now that precise spin structure data in the DIS region are available at large x, data in the resonance region are greatly needed in order to test duality in spin-dependent structure functions. The goal of experiment E01-012 was to provide such data on the neutron (3He) in the moderate momentum transfer (Q2) region, 1.0 Qsup2/sup 4.0 (GeV/csup2/sup), where duality is expected to hold. The experiment ran successfully in early 2003 at Jefferson Lab in Hall B. It was an inclusive measurement of longitudinally polarized electrons scattering from a longitudinally or transversely polarized sup3/supHe target. Asymmetries and cross section differences were measured in order to extract the sup3/supHe spin structure function gsub1/sub and virtual photon asymmetry Asub1/sub in the resonance region. A test of quark-hadron duality has then been performed for the sup3/supHe and neutron structure functions. The study of spin duality for the neutron will provide a better understanding of the mechanism of the strong interaction. Moreover, if duality is well understood, our resonance data will bring information on the high x region where theoretical predictions for A
Download or read book Measurement of the Neutron Spin Structure Function at Low 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 spin dependent cross sections,?{sup T}12 and?{sup T}32, and asymmetries, A{sub {parallel}} and A{sub {perp}}, for 3He have been measured at the Jefferson Lab's Hall A facility. The inclusive scattering process 3{vec He}({vec e}, e)X was performed for initial beam energies ranging from 0.86 to 5.1 GeV, at a scattering angle of 15.5°. Data includes measurements from the quasielastic peak, resonance region, and the deep inelastic regime. An approximation for the extended Gcrasimov-Drell-Hcarn integral is presented at a 4-momentum transfer Q2 of 0.2-1.0 GeV2 . Also presented are results on the performance of the polarized 3He target. Polarization of 3He vvas achieved by the process of spin-exchange collisions with optically pumped rubidium vapor. The 3He polarization was monitored using the NMR technique of adiabatic fast passage (AFP). The average target polarization was approximately 35% and was determined to have a systematic uncertainty of roughly ±4% relative.
