A measurement of the spin-dependent asymmetry in quasielastic scattering of polarized electrons from polarized ^3He

Citation

Jones, Cathleen Elaine (1992) A measurement of the spin-dependent asymmetry in quasielastic scattering of polarized electrons from polarized ^3He. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/4sr4-5y41. https://resolver.caltech.edu/CaltechTHESIS:09232011-084052504

Abstract

The results of a measurement of the spin-dependent asymmetry in inclusive quasielastic scattering of polarized electrons from polarized ^3He are reported. The experiment was run at the MIT-Bates Linear Accelerator Center using a beam of longitudinally polarized electrons at an incident energy of 574 MeV. Scattered electrons were detected independently in two spectrometers, with one measurement sensitive to the spin-dependent transverse quasielastic response function, R_(T'), at Q^2 = 0.20 (GeV/c)^2 and the other sensitive to the spin-dependent interference response function, R(TL'), at Q^2 = 0.16 (GeV/c)^2. The asymmetry in the elastic kinematic region was also measured at a scattering angle of 44°. The target was gaseous ^3He polarized through optical pumping of metastable 2^3S atoms, with the polarization transferred to the ground state atoms through metastability exchange collisions. The target, the first of its kind to be used for an electron scattering experiment, is described in detail.

The analysis of the helicity dependent cross section data and the extraction of the quasielastic asymmetry are discussed. The measured quasielastic asymmetries are compared to theories that model the spin-dependent properties of ^3He as being dominated by the electromagnetic properties of the neutron, and are found to agree with the models. A value of the neutron electric form factor at Q^2 = 0.16 (GeV/c)^2 is extracted from the measured asymmetry sensitive to R_(TL'), demonstrating a new technique for accessing information about the neutron.

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