Performance of Au transmission photocathode on a microchannel plate detector

• Published in: Review of scientific instruments 2008-10, Vol.79 (10), p.10E912-10E912-5
• Main Authors: Lowenstern, M. E., Harding, E. C., Huntington, C. M., Visco, A. J., Rathore, G., Drake, R. P.
• Format: Article
• Language: English
• Subjects: CAMERAS; DETECTION; ELECTRIC FIELDS; ELECTRIC POTENTIAL; ELECTRONS; ENERGY DENSITY; GOLD; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; MICROCHANNEL ELECTRON MULTIPLIERS; PHOTOCATHODES; PHOTONS; RADIATION DETECTORS; SIGNALS; TRANSMISSION; X RADIATION; X-RAY SOURCES
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.2971970

X-ray framing cameras, employing microchannel plates (MCPs) for detection and signal amplification, play a key role in research in high-energy-density physics. These instruments convert radiographic x-rays into electrons produced by plasma during such experiments into electrons that are amplified in the channels and then detected by a phosphor material. The separation of detection from signal amplification offers potential improvements in sensitivity and noise properties. We have implemented a suspended Au transmission photocathode ( 160   Å thick) on a MCP and are evaluating it using a 1.5 keV Al K α x-ray source. We find an approximately twofold increase in the ratio of detected events to incident photons when the photocathode-to-MCP voltage difference is sufficiently large. Our calculations indicate that this increase is probably caused by a combination of signal produced by the photocathode and an increase in the efficiency of detection of x-rays that reach the MCP surface through modification of the local electric field.