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Nuclear Structure Observable with Polarized Target and Polarized Real Photon Beam at MAMI

Fri., Nov. 25, 2016 3:00 p.m. - Fri., Nov. 25, 2016 4:00 p.m.

Location: CL 130

Abstract: The nucleon polarizabilities are fundamental structure observables, like the nucleon mass or charge. While the electric E1 and magnetic βEM1 scalar polarizabilities of the nucleon have been measured, little effort has been made to extract the spin dependent polarizabilities. These nucleon polarizabilities (γE1E1,γM1M1,γM1E2,γE1M2) describe the spin response of a proton to an electric and magnetic dipole and quadrupole interactions. We plan to extract them using polarized photon beam and polarized target at the MAMI tagged photon facility in Mainz, Germany. This requires precise measurement of the double polarization observable ∑2z which is sensitive to these polarizabilities. The ∑2z is measured via a circulary polarized photon beam on a longitudinally polarized butanol target in the resonance region (E = 250 - 310 MeV). Together with constraints from the spin independent polarizabilities E1andβEM1,theforwardspinpolarizability(γ0),andQCDbasedmodels,shouldallowustoextract all four spin polarizabilities independently with small statistical, systematic and model-dependent uncertainities from the experimental data. In this seminar I will present preliminary experimental results for the measurement of ∑2z from 2014/2015 data set at dierent energies and angles.

Speaker: Dilli Paudyal, Ph.D Candidate, Department of Physics, University of Regina