Jefferson Lab IR demo FEL photocathode quantum efficiency scanner
- Resource Type
- Authors
- Robin J. Evans; T. Siggins; A. Grippo; Joseph Gubeli; Michelle D. Shinn; Kevin Jordan
- Source
- Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 475:554-558
- Subject
- Physics
Nuclear and High Energy Physics
Scanner
business.industry
Free-electron laser
Particle accelerator
Laser
Photocathode
law.invention
Gallium arsenide
chemistry.chemical_compound
Optics
chemistry
law
Quantum efficiency
Wafer
business
Instrumentation
- Language
- ISSN
- 0168-9002
Jefferson Laboratory's Free Electron Laser (FEL) incorporates a cesiated gallium arsenide (GaAs) DC photocathode gun as its electron source. By using a set of scanning mirrors, the surface of the GaAs wafer is illuminated with a 543.5nm helium–neon laser. Measuring the current flow across the biased photocathode generates a quantum efficiency (QE) map of the 1-in. diameter wafer surface. The resulting QE map provides a very detailed picture of the efficiency of the wafer surface. By generating a QE map in a matter of minutes, the photocathode scanner has proven to be an exceptional tool in quickly determining sensitivity and availability of the photocathode for operation.