Precision measurement of neutron spin asymmetry An1 at large xBj using CEBAF at 5.7 GeV

Nucleon spin structure has remained one of the key issues of hadronic physics since the 1980's. Among the unsolved questions, the neutron spin structure in the valence quark region (the large Bjorken variable XBj region) is of particular interest. The few data that existed in the large XBj region are very imprecise. Also, theoretical predictions based on Quantum Chromo-Dynamics (QCD) are difficult to carry out accurately in this non-perturbative region and having good experimental data is very important to test the models. Taking advantage of the polarized continuous-wave (CW) electron beam at Jefferson Laboratory (JLAB) and a high-density polarized 3He target in Hall A, we have measured the neutron spin asymmetry An1 and spin structure function gn1 to a good precision at three kinematics x = 0.33, 0.47 and 0.60, with Q2 = 2.7, 3.6 and 4.9 (GeV/c)2, respectively. The data at the two higher XBj points have improved the statistical accuracy of the world data by one order of magnitude. They show a zero crossing point around XBj = 0.47 and the datum at XBj = 0.60 is significantly positive. To determine An and g, cross sections and asymmetries of inclusive 3He(e,e') scattering have been measured in the deep-inelastic region. The transverse spin asymmetry An and structure function g were also extracted from data, though with less statistical precision. The asymmetries of pion photoproduction A[pi]⁻ were obtained as a byproduct.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Zheng, Xiaochao, 1977-

Advisor dc:contributor.advisor

• William Bertozzi.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29310

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29310