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Title: Nucleon spin structure at Jefferson Lab

Abstract

In the past decade an extensive experimental program to measure the spin structure of the nucleon has been carried out in the three halls at Jefferson Lab. Using a longitudinally polarized beam scattering off longitudinally or transversely polarized 3He, NH3 and ND3 targets, the double spin asymmetries A|| and A[perpendicular] were measured, providing data of impressively high precision that gives a better understanding of the structure of the nucleon in the deep inelastic scattering and the valence quarks regions. The virtual photon asymmetries A1,2 and polarized structure functions g1,2 were also extracted for the proton, neutron and deuteron over large kinematic ranges, allowing the extraction of first moments and the testing of sum rules and duality.

Authors:
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1028827
Report Number(s):
JLAB-PHY-11-1445; DOE/OR/23177-1890
TRN: US1105515
DOE Contract Number:
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Conference: MENU 2010, 31 May - 4 Jun 2010, Williamsburg, Virginia.
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; DEEP INELASTIC SCATTERING; DEUTERONS; DUALITY; NEUTRONS; NUCLEONS; PHOTONS; POLARIZED BEAMS; QUARKS; SCATTERING; SPIN; STRUCTURE FUNCTIONS; SUM RULES; TARGETS; TESTING; VALENCE

Citation Formats

Angela Biselli. Nucleon spin structure at Jefferson Lab. United States: N. p., 2011. Web. doi:10.1063/1.3647131.
Angela Biselli. Nucleon spin structure at Jefferson Lab. United States. doi:10.1063/1.3647131.
Angela Biselli. 2011. "Nucleon spin structure at Jefferson Lab". United States. doi:10.1063/1.3647131.
@article{osti_1028827,
title = {Nucleon spin structure at Jefferson Lab},
author = {Angela Biselli},
abstractNote = {In the past decade an extensive experimental program to measure the spin structure of the nucleon has been carried out in the three halls at Jefferson Lab. Using a longitudinally polarized beam scattering off longitudinally or transversely polarized 3He, NH3 and ND3 targets, the double spin asymmetries A|| and A[perpendicular] were measured, providing data of impressively high precision that gives a better understanding of the structure of the nucleon in the deep inelastic scattering and the valence quarks regions. The virtual photon asymmetries A1,2 and polarized structure functions g1,2 were also extracted for the proton, neutron and deuteron over large kinematic ranges, allowing the extraction of first moments and the testing of sum rules and duality.},
doi = {10.1063/1.3647131},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2011,
month =
}

Conference:
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  • I will first review the latest development in the nucleon spin structure study with lepton- nucleon deep inelastic scattering (DIS) from high energy laboratories. I will then concentrate on the progress and plan of study of the nucleon spin structure in the low energy region. With the newly built high luminosity 6 GeV electron beam accelerator and the progress in the highly polarized electron source and highly polarized targets, new experiments are being carried out at Jefferson Lab (CEBAF) to study the nucleon spin structure in the resonance region at low Q{sup 2}, with focus on the generalized GDH summore » rule. Some preliminary results are presented. A generalized GDH sum rule study could provide a first comparison of experimental data with calculations from a fundamental theory over the entire Q{sup 2} regime. Taking advantage of the high luminosity of Jefferson Lab, selected spin structure experiments in the DIS region are also planned, concentrating in the valence quark region and the stud y of the quark-gluon correlations through higher twist effects. The parton-hadron duality provides the link between the DIS and the resonance region. Experimental study of duality in spin structure is planned. Outlook of spin structure study with a future 12 GeV energy upgraded Jefferson Lab is discussed.« less
  • We propose to measure the semi-inclusive double-spin asymmetries in deep-inelastic (,eh)X and (,eh)X reactions (h = +, -, K+ and K-) on longitudinally polarized NH3 and LiD targets. The high statistic data will allow a leading order five-flavor decomposition (Delta u, Delta d, Delta u, Delta d, Delta s ) of the nucleon spin structure in the region of x = 0.12 {approx} 0.43 at a Q2 of 1.21 {approx} 3.22 GeV2. The combined spin dependent pi+ + pi- yield ratios will be measured, since the acceptance and the hadron efficiencies of the detectors can be accurately determined. Independent ofmore » fragmentation functions and parton distributions, the z-dependence (z = 0.38 {approx} 0.71) of the combined ratios provides a build-in test of factorization at the moderate Q2. We estimate statistical uncertainties associated with such measurements.« less
  • From inclusive to semi-inclusive and exclusive (polarized) deep inelastic scattering, the quark structure of the nucleon is being studied with increasingly precise experiments at Jefferson Lab. We will review here the ongoing programs to determine polarized parton distributions--helicity and transversity--as well as generalized parton distributions, addressing the question of intrinsic spin and orbital angular momentum of quarks in the nucleon.
  • The JLab 12 GeV upgrade with a proposed solenoid detector and the CLAS12 detector can provide the granularity and three-dimensional kinematic coverage in longitudinal and transverse momentum,more » $$0.1\le x \le 0.5$$, $$0.3 \le z \le 0.7$$ with $$P_T \le 1.5 {\rm GeV}$$ to precisely measure the leading twist chiral-odd and $T$-odd quark distribution and fragmentation functions in SIDIS. The large $x$ experimental reach of these detectors with a 12 GeV CEBAF at JLab makes it {\em ideal} to obtain precise data on the {\em valence-dominated} transversity distribution function and to access the tensor charge.« less
  • We have measured the spin structure of the nucleon in the region of the resonances (final state mass W <~ 2 GeV) at intermediate four-momentum transfer Q^2 ~ 1.3 (GeV/c)^2. Double-spin inclusive asymmetries for longitudinally polarized 5.75 GeV electrons incident on longitudinal and transverse solid polarized targets were measured in Jefferson Lab's Hall C. Frozen ammonia and deuterated ammonia were used as the polarized materials. The neutron spin structure is extracted from the proton and deuteron asymmetries. We present new results for the proton measured asymmetries A|| and A[perpendicular] and spin structure functions g_1 and g_2, and preliminary results formore » the deuteron asymmetries. These are the first measurements of the transverse proton and deuteron spin structure in the resonances. We also report on our measurement of the ratio of the proton electromagnetic form factors with our polarized target.« less