Measurements of the neutron polarized structure function at SLAC

Detailed measurements of unpolarized or spin-averaged nucleon structure functions over the past two decades have led to detailed knowledge of the nucleon's internal momentum distribution. Polarized nucleon structure function measurements, which probe the nucleon's internal spin distribution, started at SLAC in 1976. E-142 has recently measured the neutron polarized structure function g1n(x) over the range 0.03 ≤ x ≤ 0.6 at an average Q2 of 2 GeV2 and found the integral In = ∫01g1n(x)dx=-0.022±0.011. E-143, which took data recently, has measured g1p and g14. Two more experiments (E-154 and E-155) will extend these measurements to lower x and higher Q2