From: Brad Dolan <bdolan@use.usit.net>
Date: Tue, 7 Nov 1995 14:59:04 +0800
To: "Timothy C. May" <tcmay@got.net>
Subject: Re: consumer products that make nice sources
In-Reply-To: <acc00caf110210040ee2@[205.199.118.202]>
Message-ID: <Pine.SOL.3.91.951106233235.10925A-100000@use.usit.net>
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On Fri, 3 Nov 1995, Timothy C. May wrote:


> 
> I'd say they make poor sources. Far too large. A smaller source has better
> access to the detector without adding much to the overall background the
> user is exposed to. (I'm not saying low-level uranium or thorium sources
> are much of a hazard, but the fluence presented at the detector is very low
> for such an extended source.)
> 
> It depends on the detector type (alpha, beta, gamma, neutrino?), but high
> count rates can be obtained in a variety of ways. (Don't get too high a
> count rate, or the dead time characteristics of the pulse-height analyzers
> will introduce spurious correlations that decrease entropy--I mention this
> to show that even radiation detector sources of entropy have non-random
> issues to take into account.)


Gotta watch yourself around the physicist....

Most of the sources I mentioned are fairly anemic, however the Coleman 
lantern mantles are pretty good beta emitters.  I can get count rates 
approaching 1000 cpm on a tired GM tube detector with a beta window of 
unknown thickness.

Brad D.