(A New Proposal to Jeerson Lab PAC-30) Measurement of Neutron Spin Asymmetry An1 in the Valence Quark Region Using an 11 GeV Beam and a Polarized 3He Target in Hall C

We propose here precision measurements of the neutron spin asymmetry An1 in the deep inelastic scattering region 0:3 < x < 0:77 and 3 < Q2 < 10 (GeV/c)2. We plan to use a polarized 3He target in Hall C, together with the high momentum spectrometer (HMS) and the planned Super HMS (SHMS). The wide Q2 span of this measurement will explore possible Q2-dependence of An1. The proposed measurement will provide the rst precision data in the valence quark region above x = 0:6 and therefore test various predictions including those from the relativistic constituent quark model and perturbative QCD. In addition to installing the polarized 3He target in Hall C, the collaboration is committed to make signicant labor contribution to Hall C beamline commission-ing at the 12 GeV Upgrade, including the Compton and the Moller polarimeters, the ARC energy measurement and the fast raster system. In this document, we rst review physics motivation of the An1 measurement. We then present the experimental setup, including the polarized 3He target w