the function of -70 for X-ray film

[bart janssen]

In article <1995Nov1.145830 at molbiol.ox.ac.uk>, rpgrant at molbiol.ox.ac.uk
(Mad Dan Eccles) wrote:

> In article <199510281917.OAA13346 at visar.wustl.edu>, nikolaic at VISAR.WUSTL.EDU (Nikolai Chitaev) writes:
> >> 
> >> I have a question to ask.   What is the real function of exposure
> >> the p32 X-ray film in -70 c?
> >> 
> >> lili
> > 
> > I guess that at -70oC your ENHANCEMENT SCREENs will reflect emmited 
> > b-particles toward the film, so providing more energy otherwise being 
> 
> No.  The screen actually phosphoresces (or fluoresces); the b-particle hits 
> the screen, a photon(s) of light then comes back and darkens the film.

I always thought that the advantage of -70 C was simply that at colder
temperatures nuclei and beta particles have less energy and hence are more
likely to interact with the film and/or the intensifier screen.  While this
energy decrease will not affect the original particle it will certainly
affect the energy level of secondary beta particles, photons, and
brehmstrahlung radiation all of which contribute to the final image on the
film.

Of course I could be completely wrong :).

cheers
Bart