Studies of the test stand of the polarized electron cathode at the Pohang Accelerator Laboratory
- Title
- Studies of the test stand of the polarized electron cathode at the Pohang Accelerator Laboratory
- Authors
- Park, JH; Park, S; Ko, IS; Cho, MH; Namkung, W; Kim, G; Son, D; 조무현
- Date Issued
- 2004-01
- Publisher
- KOREAN PHYSICAL SOC
- Abstract
- Spin-polarized electrons have been generated from a GaAs crystal whose surface was coated with a NEA (negative electron affinity) layer. The electron polarization was measured using the Mott polarimeter. The work was done utilizing the photocathode test-stand in the Pohang Accelerator Laboratory. That stand was constructed to characterize GaAs photocathodes for use in PES (polarized slectron source) development. The test-stand consists of a GaAs crystal, devices for NEA surface production, an electrostatic bend, and a Mott polarimeter. All components, except the polarimeter are contained in a extremely high vacuum (XHV) chamber that can provide a vacuum better than 5 x 10(-10) Torr. Circularly polarized photons are provided by a multi-color laser with quarter-wavelength plates. In order to have a clean surface on the GaAs crystal, which is essential for successful production of a NEA layer, we have adopted the method of hydrogen glow-discharge cleaning. With careful cathode cleaning and activation (NEA surface production), spin-polarized electrons are routinely generated with a quantum efficiency of 3.01% and a polarization of 30.4%.
- Keywords
- PES (polarized electron source); NEA (negative electron affinity); GaAs photocathode; quantum efficiency; polarization; Mott polarimeter
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/17930
- ISSN
- 0374-4884
- Article Type
- Conference
- Files in This Item:
- There are no files associated with this item.
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