Measurement of the Spin Asymmetries of the Proton

Conference · Mon Oct 01 00:00:00 EDT 2012

OSTI ID:1993366

Jones, Mark ^[1]

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1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

The Spin Asymmetries of the Nucleon Experiment (SANE) measured the parallel, $$A_\parallel$$, and near-perpendicular, $$A_{80}$$, double spin asymmetries of the proton in inclusive electron scattering. Longitudinally polarized electrons were scattered from an ammonia target which provided polarized protons via dynamic nuclear polarization. The scattered electrons were detected using the Big Electron Telescope Array, BETA, which was centered at 40$$^\circ$$ and covered a large solid angle. BETA consisted of a scintillator hodoscope, gas Cherenkov, lucite hodoscope and a large array of lead glass detectors. The data was taken at the Thomas Jefferson National Accelerator Facility's Hall C at beam energies of $4.7$ and $5.9~GeV$ and covered $2.5~GeV^2 < Q^2 < 6.5~GeV^2$. From the $$A_\parallel$$ and $$A_{80}$$ measurements, the proton's spin asymmetries, $$A_1$$ and $$A_2$$, and the spin structure functions of the proton, $$g_1$$ and $$g_2$$, can be extracted. The measurements are in a range of Bjorken $$x$$, $0.3 < x < 0.8$, where extraction of the twist three matrix element $$d_2^p $$ (an integral of $$g_1$$ and $$g_2$$ weighted by $x^2$) is most sensitive.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1993366
• Report Number(s): JLAB-PHY-12-1712; DOE/OR/23177-6828
• Country of Publication: United States
• Language: English