Spontaneous electron emission from a cold surface

At cryogenic temperature, the dark rate in a photomultiplier is caused by single electrons, emitted spontaneously from the cathode surface. This “cryogenic” dark rate increases with decreasing temperature down to at least 4 K. The average event rate is proportional to the area of the emitting surfac...

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Bibliographic Details
Published in:Europhysics letters 2010-03, Vol.89 (5), p.58001
Main Author: Meyer, H. O
Format: Article
Language:English
Subjects:
79.75.+g
85.60.Ha
Bursts
Cold surfaces
Correlation
Cryogenic temperature
Emittance
Photomultipliers
Power law
Single electrons
Spontaneous
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Summary:At cryogenic temperature, the dark rate in a photomultiplier is caused by single electrons, emitted spontaneously from the cathode surface. This “cryogenic” dark rate increases with decreasing temperature down to at least 4 K. The average event rate is proportional to the area of the emitting surface and insensitive to the electric field at that surface. The electrons are emitted in bursts. The bursts are distributed randomly in time, but the events within a burst are highly correlated. The burst durations are distributed according to a power law. As the temperature decreases, the rate of bursts, as well as the number of events per burst, increase. The observed time distributions are indicative of a trap mechanism. So far, there is no physics explanation of the observed phenomenon.
ISSN:0295-5075
1286-4854
DOI:10.1209/0295-5075/89/58001