Simple Question about Intesifierscreens

R. John Lye rjl6n at
Fri Aug 29 10:20:53 EST 1997

Mathias Drexler wrote:
> I am wondering, why intensifier-screens are working better at -80°C.

Its not that intensifier screen work better at -80 (as far
as i know).  It is that film gets more sensitive to weak
signals at low temperatures.  It takes two photons to activate
the silver grains in film, and the second photon must arrive
before the excited state induced by the first photon decays away.
The low temperature porlongs the lifetime of that excited state,
and therefore makes it more likely that a second photon can
arrive to do its work.
John Lye

e-mail to: rjl6n at Virginia.EDU

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