Spin structure measurements from E143 at SLAC

Measurements were made of the proton and deuteron spin structure functions g{sub 1}{sup p} and g{sub 1}{sup d} at beam energies of 29.1, 16.2, and 9.7 GeV, and g{sub 2}{sup p} and g{sub 2}{sup d} at a beam energy of 29.1 GeV. The integrals {Lambda}{sub p} = {integral}{sub 0}{sup 1} g{sub 1}{sup p} (x, Q{sup 2})dx and {Lambda}{sub d} = {integral}{sub 0}{sup 1} g{sub 1}{sup d}(x, Q{sup 2})dx were evaluated at fixed Q{sup 2} = 3 (GeV/c){sup 2} using the 29.1 GeV data to yield {Lambda}{sub p} = 0.127 {+-} 0.004(stat.) {+-} 0.010(syst.) and {Lambda}{sub d} = 0.041 {+-} 0.003 {+-} 0.004. The Q{sup 2} dependence of the ratio g{sub 1}/F{sub 1} was studied and found to be small for Q{sup 2} > 1 (GeV/c){sup 2}. Within experimental precision the g{sub 2} data are well-described by the twist-2 contribution, g{sub 2}{sup WW}. Twist-3 matrix elements were extracted and compared to theoretical predictions. The asymmetry A{sub 2} was measured and found to be significantly smaller than the positivity limit {radical}R for both proton and deuteron targets. A{sub 2}{sup p} is found to be positive and inconsistent with zero