RE: Alpha contamination survey meters

["McDonald, Michael P" <mpmcdon@sandia.gov>]

Wes,

Any chance of condensation developing on or in the detector(s) as the "warm"
instrument was brought out into the cold?  This would most likely shield
alphas from the detector or reduce the quantity of light making it to the PM
tube.?

Mike McDonald
mpmcdon@sandia.gov

-----Original Message-----
From: Wes Van Pelt [mailto:vanpeltw@idt.net]
Sent: March 09, 2000 1:51 PM
To: Multiple recipients of list
Subject: RE: Alpha contamination survey meters


Radsafers,

I have experience using Ludlum alpha probes (ZnS scintillator type) and have
encountered a difficulty. Outdoors in the winter in NJ (35-40F) the Ludlum
alpha probes stopped working.....i.e., went to zero efficiency. I eventually
had three probes in the field and 2 or 3 had this same difficulty. I never
quite figured out what was happening. After being brought indoors, they
worked the next day, but stopped working when taken outdoors for an hour or
so.

Just some real field experience...

Wes

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