Download or read book Study of Neutron Spin Structure Functions at Low Q 2 with Polarized He 3 written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of the Polarized Structure Functions of the Neutron at Low Q 2 Using Polarized He 3 written by S. H. Choi and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the electron-He-3 longitudinal and transverse spin dependent inclusive cross sections {pol}He-3({pol}e, e-prime), mostly in the resonance region (up to W ~ 2.5 GeV), over a wide range of four-momentum transfer (Q**2 = 0.03 - 1GeV**2). The longitudinally polarized electron beam of energy ranging from 0.86 to 5.1 GeV of the Jefferson Lab was scattered at a fixed angle of 15.5 degrees, on a high pressure polarized He-3 target in Hall A. The spin dependent structure functions g_1(x), g_2(x) have been extracted and their moments were evaluated. The GDH integral shows dramatic transition from large Q**2 domain to low Q**2 domain in the Burkhardt-Cottingham sum rule for g_2 seems to hold within experimental errors. d_2 is quite large and positive consistent with the SLAC data but at odds with lattice QCD calculation.
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.
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 $
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.
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 A Study of the Spin Structure on the Neutron in Deep Inelastic Scattering of Polarized Electrons on Polarized Neutrons written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The internal spin structure of the neutron, was studied in deep inelastic scattering of longitudinally polarized electrons from a polarized [sup 3]He target in the End Station A of the Stanford Linear Accelerator Center (SLAC). The spin asymmetry of the neutron was measured at energies between 19 and 26 GeV in the range 0.03 [le] x [le] 0.06 at an average Q[sup 2] of 2 (GeV/c)[sup 2]. The results are in agreement with a new measurement of the asymmetry by SMC within their six times larger uncertainties. The spin dependent structure function g[sub 1](x) for the neutron was determined from the asymmetry measurement and, its integral over x is found to be [integral]g[sub 1][sup n](x)dx = -0.038 [+-] 0.009. This result is 2.7 standard deviations from the Ellis-Jaffe Sum Rule and combined with the EMC results from the proton in very good agreement with the Bjorken Sum Rule. In the Quark Parton Model (QPM), in conjunction with the weak coupling constants F and D, from baryon decay, the result implies that the quarks contribute approximately 32% of the nucleon helicity. Finally, different ways of evolving the data, based on various theoretical models, is attempted and future aspects for spin physics, with emphasis at spin physics at SLAC, are discussed.
Download or read book The Spin Structure Of The Nucleon written by Bernard Frois and published by World Scientific. This book was released on 1998-02-24 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: From its early beginnings at SLAC in the 1970's, the study of nucleon spin structure using polarized lepton beams and polarized nucleon targets has become increasingly important in nuclear and particle physics, with current experiments at several of the world's high energy and nuclear physics laboratories (CERN, DESY, SLAC and Jefferson Lab) and with enormous related theoretical studies. The understanding of the fascinating but complicated problem of nucleon spin structure has progressed substantially, but fundamental questions remain and it can be confidently predicted that future activity will be high.The Erice Course on The Spin Structure of the Nucleon covered both the experimental and theoretical aspects of the subject, and this volume includes the lectures given at the School. In many cases the lecture material has been extended and updated by the authors. In addition, several recent publications on experimental work have been added in an appendix.
Download or read book A Determination of the Neutron Spin Structure Function written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors report the results of the experiment E142 which measured the spin dependent structure function of the neutron, g[sub 1][sup n](x, Q[sup 2]). The experiment was carried out at the Stanford Linear Accelerator Center by measuring an asymmetry in the deep inelastic scattering of polarized electrons from a polarized[sup 3]He target, at electron energies from 19 to 26 GeV. The structure function was determined over the kinematic range 0.03
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 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 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
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.
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:
Download or read book Gdh 2000 The Gerasimov drell hearn Sum Rule The Nucleon Spin Structure In The Resonance Region written by Dieter Drechsel and published by World Scientific. This book was released on 2001-02-05 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: The history of spin in general, and of the nucleon spin structure in particular, has been full of surprises. For the past 25 years deep inelastic lepton scattering has been studied to determine the carriers of the nucleon spin. However, it was realized only recently that a full understanding of the nucleon spin will also require detailed information on the helicity structure in the resonance region, i.e. in the realm of nonperturbative QCD.This volume gives a status report on the spin structure in the nucleon resonance region, focusing on: new experimental results from SLAC and HERMES; a first glance at the JLab experiments to map out the spin structure functions at low and intermediate four-momentum transfers; the pioneering experiment at MAMI (Mainz) to determine the Gerasimov-Drell-Hearn sum rule for real photons; and recent theoretical concepts and investigations to describe the spin structure in the frameworks of higher twist expansion, phenomenological models and chiral perturbation theory.
Download or read book The Search for Higher Twist Effects in the Spin structure Functions of the Neutron written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Jefferson Lab experiment E97-103 measured the spin structure function gn2 from a Q^2 of 0.58 to 1.36 with a nearly constant x of 0.2. Combining this data with a fit to the world gn1 data, the size of higher twist contributions to gn2 can be extracted using the Wandzura-Wilczek relation. These higher twist contributions result from quark-gluon correlations and are expected to be larger as Q^2 decreases. This experiment was performed in Hall A with a longitudinally polarized electron beam and a high density polarized He-3 target. The physics motivation and an overview of the experiment will be presented.
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 in the Resonance Region and Quark Hadron Duality written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Quark-Hadron duality has been experimentally demonstrated for the spin independent structure function F2. Duality is observed when, at the same value of scaling variable x{sub bj}, the smooth scaling curve at high momentum transfer becomes an average over the resonances at lower momentum transfer. Jefferson Lab experiment 01-012 used the polarized 3He target in Hall A for an extraction of the neutron spin structure function g1(superscript n) and the virtual photon asymmetry A1(superscript n) in the resonance region over a Q2 range from 1.0 to 4.0 (GeV/c)2. Data from E01-012 combined with Deep Inelastic Scattering data will provide a test of quark-hadron duality predictions for g1(superscript n) and A1(superscript n). This will be one of the first tests of the spin and flavor dependence of quark-hadron duality. The demonstration of duality for spin structure functions will enable us to use the resonance data to study the nucleon spin structure in the large x{sub bj} region.
