title: Performance of Au transmission photocathode on a microchannel plate detector.
abstract: 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 A thick) on a MCP and are evaluating it using a 1.5 keV Al K alpha 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.
authors.affiliation: University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Lowenstern
authors.forename: E C
authors.initials: EC
authors.lastname: Harding
authors.forename: C M
authors.initials: CM
authors.lastname: Huntington
authors.forename: A J
authors.initials: AJ
authors.lastname: Visco
authors.forename: G
authors.initials: G
authors.lastname: Rathore
authors.forename: R P
authors.initials: RP
authors.lastname: Drake