photomultiplier

photomultiplier

(foh-toh-mul -tă-plÿ-er) (photomultiplier tube; phototube) An electronic device used to convert a low-intensity light signal into an electrical signal and to amplify this signal very considerably. It contains a photocathode from which electrons are liberated by the incident light photons. The electrons are accelerated down an evacuated tube by a series of positively charged electrodes to which an increasingly high potential is applied. At each electrode a number of additional electrons are released by each impacting electron (by secondary emission). The electrons are all collected at the final electrode in the chain, which is held at a very high potential, and a large current pulse is produced.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

photomultiplier

[¦fōd·ō′məl·tə‚plī·ər]

(electronics)

multiplier phototube

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.