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photomultiplier

An evacuated electronic tube which converts light into a measurable electric current. Light falling on a photocathode releases electrons, which are accelerated by an electric field and ...

photomultiplier

photomultiplier   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

... An evacuated electronic tube which converts light into a measurable electric current. Light falling on a photocathode releases electrons, which are accelerated by an electric field and attracted to the first dynode (positive electrode), where they liberate more electrons which are attracted to the second dynode, and so on. A common type of photomultiplier in astronomical use has ten dynodes, each at an increasingly positive electric potential. The flow of electrons arriving at the final anode is proportional to the amount of light falling on...

photomultiplier

photomultiplier   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
117 words

...photomultiplier A sensitive type of photoelectric cell in which electrons emitted from a photocathode are accelerated to a second electrode where several electrons are liberated by each original photoelectron, as a result of secondary emission . The whole process is repeated as many times as necessary to produce a useful electric current by secondary emission from the last electrode. A photomultiplier is thus a photocathode with the output amplified by an electron multiplier. The initial photocurrent can be amplified by a factor of 10 8 . Photomultipliers...

photomultiplier

photomultiplier   Reference library

Oxford Dictionary of Biochemistry and Molecular Biology (2 ed.)

Reference type:
Subject Reference
Current Version:
2008
Subject:
Science and technology, Life Sciences
Length:
34 words

... a photocell consisting of a photocathode linked to an electron multiplier . Photons striking the photocathode cause the emission of electrons, which are then amplified by the electron multiplier to give an enhanced...

photomultiplier

photomultiplier   Quick reference

A Dictionary of Electronics and Electrical Engineering (5 ed.)

Reference type:
Subject Reference
Current Version:
2018

... An electron multiplier that contains a photocathode . Primary electrons, emitted from the photocathode as a result of the photoelectric effect , initiate the cascade. A suitable scintillation crystal is often used as the source of illumination for the photocathode in order to provide a sensitive radiation detector or counter . ...

photomultiplier tube

photomultiplier tube   Quick reference

Concise Medical Dictionary (10 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Medicine and health, Clinical Medicine
Length:
44 words

... tube an electronic device that magnifies the light emitted from a scintillator by accelerating electrons in a high-voltage field. The resulting signal can be used to display the scintillations on a TV screen. Such devices are commonly used in gamma cameras...

photomultiplier

photomultiplier noun   Quick reference

New Oxford American Dictionary (3 ed.)

Reference type:
English Dictionary
Current Version:
2015
Subject:
English Dictionaries and Thesauri
Length:
41 words
photomultiplier

photomultiplier noun   Quick reference

Oxford Dictionary of English (3 ed.)

Reference type:
English Dictionary
Current Version:
2015
Subject:
English Dictionaries and Thesauri
Length:
41 words
photomultiplier

photomultiplier noun   Reference library

The Canadian Oxford Dictionary (2 ed.)

Reference type:
English Dictionary
Current Version:
2005
Subject:
English Dictionaries and Thesauri
Length:
26 words
photomultiplier

photomultiplier noun   Reference library

Australian Oxford Dictionary (2 ed.)

Reference type:
English Dictionary
Current Version:
2004
Subject:
English Dictionaries and Thesauri
Length:
25 words
photomultiplier

photomultiplier  

An evacuated electronic tube which converts light into a measurable electric current. Light falling on a photocathode releases electrons, which are accelerated by an electric field and attracted to ...
photomultiplier tube

photomultiplier tube  

Reference type:
Overview Page
An electronic device that magnifies the light emitted from a scintillator by accelerating electrons in a high-voltage field. The resulting signal can be used to display the scintillations on a TV ...
high-speed photometry

high-speed photometry  

A form of photometry in which the photons are counted at short time intervals, generally between 10 ms and 10s, to detect rapid changes in brightness of objects such as pulsars and variable stars. ...
photoelectric photometer

photoelectric photometer  

An instrument for measuring the brightness of a star by means of the electric current produced when its light falls on a light-sensitive surface (the photoelectric effect). The light gathered by a ...
Johnson photometry

Johnson photometry  

Photometry based on the work of the American astronomer Harold Lester Johnson (1921–80). It falls into three natural parts: UBV, RI, and infrared photometry. UBV photometry was based on a ...
NaI detector

NaI detector  

An instrument for detecting high-energy X-rays and gamma rays. Crystalline sodium iodide (NaI) converts an X-ray or gamma-ray photon into a pulse of visible light, the brightness of which is ...
secondary emission

secondary emission  

The emission of electrons from a surface as a result of the impact of other charged particles, especially as a result of bombardment with (primary) electrons. As the number of secondary electrons can ...
scintillometer survey

scintillometer survey  

A geophysical prospecting method using a scintillation detector in which radioactivity causes crystals to emit flashes of light which can be recorded by a photomultiplier tube. It is much more ...
photocathode

photocathode  

The light-sensitive surface of a photomultiplier. It is a coating of a material such as caesium, rubidium, or potassium applied to the inside of a clear window of an evacuated tube.
gamma camera

gamma camera  

Reference type:
Overview Page
A piece of apparatus that detects radioactivity in the form of gamma rays emitted by radioactive isotopes that have been introduced into the body as tracers. It contains an activated sodium iodide ...
Cerenkov counter

Cerenkov counter  

A device for detecting high-energy charged particles via the Cerenkov radiation they generate. This radiation, which appears as a predominantly bluish light, can be detected using photomultiplier ...

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