Proposal to Measure DeltaSigma(gamma,N)(k) and the High
Energy Contribution to the Gerasimov-Drell-Hearn Sum Rule
Experiment E159 (approved 9 November 2000 by the SLAC
EPAC) is a measurement of the spin-dependent total cross section
for circularly polarized photons absorbed on longitudinally polarized
protons and neutrons in the photon energy range 5 to 40 GeV.
This will be the first measurement of the difference between left- and
right-handed polarized photoproduction above the resonance region.
These data will be used to
learn about the high energy convergence of the fundamental
Gerasimov-Drell-Hearn sum rule for the proton and neutron.
baseline for understanding of soft Regge physics, essential
to the interpretation of data taken with virtual photons.