Precision measurements of the proton and deuteron polarized structure functions.

摘要

Experiment E155 at the Stanford Linear Accelerator Center measured the longitudinal and transverse polarized deep-inelastic scattering asymmetries for the proton and deuteron using longitudinally-polarized electron beams with energies of 48.3 GeV and 38.8 GeV, respectively. The electron beam polarization was measured by Møller polarimetry to be 0.81 ± 0.02. Dynamically-polarized solid 15N₃ and 6Li2H were used as the target materials. The scattered electrons were detected in three independent spectrometers at 2.75°, 5.5°, and 10.5°, covering a kinematic range of 0.014 ≤ x ≤ 0.9 and 1.0(GeV/ c)2 ≤ Q2 ≤ 40(GeV/ c)2. The 10.5° spectrometer was constructed for this experiment. The structure functions $gp1$ and $gd1$ were extracted from the asymmetry data, and, in combination with world data, were fit in next-to-leading order perturbative QCD. The Q 2 dependence of g₁ differed slightly from that of F₁. The g₁ results are consistent with the Bjorken sum rule. The structure functions $gp2$ and $gd2$ were extracted from the asymmetry data, and were used to extract the twist-3 reduced matrix elements $dp2,dd2$, and $dn2$.