Download or read book The Q2 Dependence of the Neutron Spin Structure Function G2 20 at Low Q2 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the first measurement of the Q2-dependence of the neutron spin structure function g2??20--?? at five kinematic points covering 0.57 (GeV/c)2 d"Q2 d"1.34 (GeV/c)2 at x H"0.2. Though the naive quark-parton model predicts g2=0, non-zero values for g2 occur in more realistic models of the nucleon which include quark-gluon correlations, finite quark masses or orbital angular momentum. The sensitivity of g2 to physics beyond the simple quark-parton model provides a unique opportunity to examine QCD dynamics in nucleon structure. When scattering occurs from a non-interacting quark, a prediction for g2??20--?? can be calculated using next-to-leading order fits to world data for g1??20--??. Our results show a positive deviation from this prediction indicating that contributions such as quark-gluon interactions may be important. Data were also obtained for g1??20--?? and are consistent with a next-to-leading order fit to world data evolved to our kinematic range.
Download or read book Moments of the Neutron G2 Structure Function at Intermediate Q2 written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present new experimental results of the 3He spin structure function g2 in the resonance region at Q2 values between 1.2 and 3.0 (GeV/c)2. Spin dependent moments of the neutron were then extracted. Our main result, the inelastic contribution to the neutron d2 matrix element, was found to be small (Q2) = 2.4 (GeV/c)2 and in agreement with the Lattice QCD calculation. The Burkhardt-Cottingham sum rule for 3He neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low x unmeasured region.
Download or read book Measurement of the Spin Structure Function G2 x Q2 for the Neutron written by David E. Reyna and published by . This book was released on 1998 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Q sup 2 Dependence of the Neutron Spin Structure Function G sub 2 sup N at Low Q sup 2 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Results on Nucleon Spin Structure written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Spin Structure Function G 2 X Q 2 for the Neutron written by and published by . This book was released on 2003 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: The asymmetry A2(x, Q2) and structure function g2(x, Q2) were measured for the neutron using deep inelastic electron scattering. The measurement was made using the 50 GeV longitudinally polarized electron beam at the Stanford Linear Accelerator Center. The target consisted of gaseous 3He which was polarized through spin exchange with optically pumped rubidium vapor. Data were taken simultaneously with two magnetic spectrometers fixed at 2.75{sup o} and 5.5{sup o} scattering angles, covering a combined kinematic range of 0.014 d"x d"0.7 and 1.0 d"Q2 d"17.0 (GeV/c)2. The A2 data were found to be well bounded by the positivity constraint.
Download or read book Measurements of the Q2 Dependence of the Proton and Neutron SpinStructure Functions G1 sup P and G1 20 written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure functions g1{sup p} and g1??20--?? have been measured over the range 0.014
Download or read book Spin Structure Functions of the Nucleon at Low Q2 And written by and published by . This book was released on 1993 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phenomenological approaches to describe the spin structure functions an spin sum rules for proton and neutrons at low momentum transfer Q2 and energy transfer?, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A1{sup p}, A2{sup p} and N1??20--?? structure functions at CEBAF in a Q2 range from 0.15 to 2.0 GeV2, and a W range from threshold to 2.2 GeV are presented.
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 Measurements of the Q sup 2 Dependence of the Proton and Neutron Spin Structure Functions G sub 1 sup P and G sub 1 sup N written by and published by . This book was released on 2000 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nucleon Spin Structure Functions G1 and G2 from Polarized Inclusive Scattering written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper will present a survey of recent experimental results for the g1 and g2 spin structure functions. Over the past decade, these structure functions (and the virtual photon asymmetries A1 and A2) have been well-measured in the large-Q2 scaling region using inclusive polarized deep-inelastic scattering. New precision results from Jefferson Lab are now becoming available which cover kinematic regions that were previously poorly measured or completely unmeasured. Topics covered will include: recent experiments at Jefferson Lab which have made precise measurements of g1 in the resonance region for both proton and neutron to investigate the Q2 evolution of the GDH sum rule, a new measurement of A1 for the neutron in the large-x region where valence quark dynamics dominate, new precision results for g2 from Jefferson Lab, a review of the g1 results and NLO analyses in the scaling region for the SLAC, HERMES, and SMC data. Finally, a survey of results expected from several new experime.
Download or read book The Generalized GDH Sum Rule and the Spin Structure of the Neutron written by Jin Yuan and published by . This book was released on 2008 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nucleon spin structure has been of great interest since the CERN SMC experiment found that quarks carry only a small fraction of the nucleon spin. Since naively quarks are expected to carry most of the nucleon's spin, this observation became known as spin crisis. The availability of polarized beams and targets since the late 1970's has allowed the measurement of the nucleon spin structure functions, and furthermore checks of Quantum Chromodynamics (QCD), the theory of strong interactions, in its perturbative regime. Sum rules involving the spin structure of the nucleon offer an important opportunity to study QCD. It has recently been shown that the GDH sum rule and 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 applies at all Q2. By studying the Q2 evolution of the extended GDH sum, one learns about the transition from quark-like behavior at high Q2, larger than 1 GeV2, to hadronic-like behavior at low Q2, close to 0. The transition between these two regimes is far from understood; it is a key issue in our understanding of the strong interaction. During mid 2003, we measured inclusive polarized cross sections in the scattering of high energy polarized electrons off the Jefferson Lab Hall A polarized 3He target. A strained GaAs photocathode was utilized in the polarized electron gun to provide an electron beam with a polarization of 70%. The high density polarized 3He target, based on optical pumping of rubidium and spin echange, was used as an effective neutron target. The polarization of the target was maintained at about 40% at beam currents as high as 15 muA. The target polarization was measured by Nuclear Magnetic Resonance methods calibrated using two independent techniques: proton thermal polarization (water calibration) and Electron Paramagnetic Resonance (EPR). The relative uncertainty on the target polarization was better than 4%. The target was operated with both longitudinal and transverse target spin orientations. In Jlab Hall A, in order to reach very low Q2 in experiment E97-110, a new septum magnet was used to make very small scattering angle measurements with the Hall A right spectrometer. The left spectrometer was used without a septum to monitor an unpolarized carbon target, downstream of the polarized 3He target, to check for possible false asymmetries. A wide range of data were measured: beam energies from 1.15 to 4.40 GeV were used at scattering angles of 6 and 9 degrees. The invariant mass W ranged across the resonance region, from inelastic threhold to the beginning of the deep inleastic region (W = 2 GeV). From the measured spin-dependent cross sections we extract the 3He spin structure functions g_{1} and g_{2}. Finally, we determined the extended GDH sum and other quantities for the Q2 range between 0.04 and 0.3 GeV2. The range of data allows extrapolation to the real photon point, studying the convergence of the sum rule, determining the slope of GDH sum rule as Q2 to 0 to check Chiral Perturbation Theory, and overlap with the previous higher Q2 experiment E94-010.
Download or read book 96 QCD and High Energy Hadronic Interactions written by J. Thanh Van Tran and published by Atlantica Séguier Frontières. This book was released on 1996 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Search for Higher Twist Effects in the Neutron Spin Structure Function Gn 2 x Q2 written by Kevin Michael Kramer and published by . This book was released on 2003 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Neutron Spin Structure Function and Its Implications for QCD Sum Rules written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Search for Higher Twist Effects in the Neutron Spin Structure Function Gn2 x Q2 written by and published by . This book was released on 2003 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jefferson Lab experiment E97-103 measured the spin structure function gn2(x, Q2) from a Q2 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 the spin structure functions can be extracted using the Wandzura-Wilczek relation. These higher twist contributions result from quark-gluon correlations and are expected to be larger as Q2 decreases. This experiment was performed in Hall A with a longitudinally polarized electron beam and a high density polarized 3He target. The physics motivation and an overview of the experiment will be presented.
