Measurement of the proton $$A_1$$ and $$A_2$$ spin asymmetries. Probing Color Forces
The Spin Asymmetries of the Nucleon Experiment (SANE) measured the proton spin structure function $$g_2$$ in a range of Bjorken x, 0.3 < x < 0.8, where extraction of the twist-3 matrix element $$d_2^p$$ (an integral of $$g_2$$ weighted by $x^2$) is most sensitive. The data was taken from $Q^2$ equal to 2.5 $GeV^2$ up to 6.5 $GeV^2$. In this polarized electron scattering off a polarized hydrogen target experiment, two double spin asymmetries, A∥ and A⊥ were measured using the BETA (Big Electron Telescope Array) Detector. BETA consisted of a scintillator hodoscope, gas Cerenkov counter, lucite hodoscope and a large lead glass electromagnetic calorimeter. With a unique open geometry, a threshold gas Cerenkov detector allowed BETA to cleanly identify electrons for this inclusive experiment. A measurement of $$d_2^p$$ is compared to lattice QCD calculations.
- Publication Date:
- OSTI Identifier:
- Report Number(s):
- JLAB-PHY-15-2094; DOE/OR/23177-3454
- DOE Contract Number:
- Resource Type:
- Research Org:
- Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
- Sponsoring Org:
- USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
- Country of Publication:
- United States
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
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