| The Spin Asymmetries of the Nucleon Experiment (SANE) measured the proton spin structure function g2 in a range of Bjorken x, 0.3 < x < 0.8, where extraction of the twist-3 matrix element d2 p (an integral of g2 weighted by x2) is most sensitive. The data was taken from Q2 equal to 2.5 GeV 2 up to 6.5 GeV2. 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 d2 p is compared to lattice QCD calculations. |
