[43023] in Cypherpunks
Re: consumer products that make nice sources
daemon@ATHENA.MIT.EDU (Brad Dolan)
Tue Nov 7 00:12:31 1995
Date: Mon, 6 Nov 1995 23:41:48 -0500 (EST)
From: Brad Dolan <bdolan@use.usit.net>
To: "Timothy C. May" <tcmay@got.net>
Cc: cypherpunks@toad.com
In-Reply-To: <acc00caf110210040ee2@[205.199.118.202]>
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.
