microchannel plate detector

microchannel plate detector

(mÿ -kroh-chan-ĕl) (MCP) A high-resolution (15–25 μm pixel) imaging device for recording X-ray, ultraviolet, or electron images. The incident photon (or electron) strikes the front surface of a thin glass plate consisting of a very large number of fine-bore tubes (usually aligned perpendicular to the plate surfaces). Secondary electrons are produced and are accelerated down the tubes by an applied voltage, striking the walls and creating further electrons. Charge multiplication factors of about 10³ (or 10⁶ in a ‘cascaded pair’ of MCPs) yield a signal that is easily read on a collector at the rear of the plate(s). Proximity focusing ensures retention of the initial photon (or electron) image and resolutions of 20–50 μm have been achieved. MCP detectors have been used successfully in a number of X-ray astronomy satellites, including the Einstein Observatory, EXOSAT, and ROSAT. MCPs are also the basis of the highest resolution X-ray camera in AXAF–I.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006