Compton Scattering from a High Pressure Polarized He Target at HIγS

M.W. Ahmed, C.W. Arnold, T. Averett, J.P Chen J.R. Calarco, T. Clegg, D. Dutta, H. Gao (Spokesperson), C. Howell, M. Huang,H. Karwowski, G. Laskaris, A. Nathan, X. Qian, H.R. Weller, Y. Wu, Q. Ye, Q.J. Ye, A. Young, W.Z. Zheng Duke University 2 University of North Carolina, Chapel Hill College of William & Mary Thomas Jefferson Lab National Accelerator Facility, Newport News, VA 5 University of New Hamsphire 6 University of Illinois, Urbana-Champaign 7 North Carolina State University, Raleigh Abstract The High Intensity Gamma Source (HIγS) at Duke Free Electron Laboratory opens new window to the study of fundamental quantities related to the structure of the nucleon through polarized Compton scattering from a polarized nuclear target. We propose first measurements of the spindependent asymmetries from elastic Compton scattering of circularly polarized photons on a highpressure polarized 3He gas target. The proposed experiment will be carried out at a photon energy of 120 MeV. The Compton scattered photons will be detected by HIγS NaI Detector Array (HINDA) system. In combination with the forward and backward polarizabilities extracted from existing experiments, the proposed experiment will allow for the first time the extraction of all four neutron spin polarizabilities, and provide crucial tests of predictions based on effective field theories, dispersion theories, and lattice QCD calculations. We request a total beam time of 1260 hours with 100 % efficiency photon beam at a minimum photon flux of 5 × 10 7/sec for a photon energy spread of 3.0%.