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oai:www.ideals.illinois.edu:2142/21511 2023-07-10 col_2142_5131 col_2142_8859 com_2142_5130 com_2142_8858 com_2142_234

1993 Cardman, Lawrence S. Dunham, Bruce Matthew 2011-05-07T13:10:44Z 2011-05-07T13:10:44Z 10000-01-01 This experiment measured the polarization and quantum efficiency as a function of wavelength for the chalcopyrite semiconductor Zn(Ge$\rm\sb{0.7}Si\sb{0.3})As\sb2.$ Also, the onset of space charge growth of a 100 keV electron beam passing through the Illinois/CEBAF polarized electron injection system was studied by measuring the beam emittance as a function of current. Finally, the thermal properties of GaAs were investigated by measuring the beam emittance as functions of the excitation laser wavelength and the laser spot size. The experiments were performed at the University of Illinois Nuclear Physics Laboratory using a 100 keV photoemission polarized electron gun, a electron spin manipulation system of a novel design, a Mott polarimeter, and an emittance measuring system. The design and performance of the entire system is described. The maximum polarization of Zn(Ge$\rm \sb{0.7}Si\sb{0.3})As\sb2$ was measured to be $\sim$19%, much lower than the expected 100%. Also, the expected transition of the polarization through zero was not observed. The beam emittance as a function of current was measured and the onset of space charge effects was found to be $\sim$0.5 mA, much lower than predicted by the electron gun design program scEGUN. Finally, the effective transverse thermal energy of the electrons emitted from GaAs at 100 keV as a function of excitation wavelength was measured by a new method for low beam currents. The electron thermal energy for wavelengths between 840 and 633 nm was found to be $\sim$33 meV, a factor of 3 lower than for a thermionic electron gun. It was also found to increase sharply for photon wavelengths less than 633 nm. Made available in DSpace on 2011-05-07T13:10:44Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9329021.pdf: 6185337 bytes, checksum: 672eda44fe0e96373550fe8c8d0edbdf (MD5) Previous issue date: 1993 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:51:17Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:23:31-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9329021 (UMI)AAI9329021 http://hdl.handle.net/2142/21511 eng Copyright 1993 Dunham, Bruce Matthew Physics, Elementary Particles and High Energy Investigations of the physical properties of photoemission polarized electron sources for accelerator applications text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.