On 21 Apr 2005 15:22:24 GMT, Dave Hinz wrote:

On Thu, 21 Apr 2005 00:04:24 -0500, Tim Williams wrote:
"Dave Hinz" wrote in message
...
I'll also note that granite is radioactive yet we build buildings
with it without concern.

It's detectable, but that doesn't mean that it's a problem.

Actually, it is! As I recall, removed granite waste is a low-level
radiation "hazard".

Well...somewhere, in some secure storage facility, are dozens or hundreds
of white "bunny suits", gloves, masks, hats, and assorted clothing worn
by me, while working in the "hot lab". I was packaging _very_ low level
solid sources into test fixtures (for tuning medical nuclear imaging
scanners). Even the packing materials are in some "low level nuclear
waste" facility, even though the bags couldn't leave our hot lab if there
was _any_ detectable radiation level.

Banannas will also kick off geiger counters, I guess they are too commonly
used by the public to be classed though.

I have to try that tonight. The potassium, I suppose?

Dave "What, doesn't _everyone_ have a Geiger counter at home?" Hinz

I have 4 . And various dosimeters. All work just hunkey dory.
I hope they never get used.

Gunner

Rule #35
"That which does not kill you,
has made a huge tactical error"

So where does one buy a geiger counter, if one were so inclined?

- -
Rex Burkheimer

Gunner wrote:
Dave "What, doesn't _everyone_ have a Geiger counter at home?" Hinz


I have 4 . And various dosimeters. All work just hunkey dory.
I hope they never get used.

Gunner

On Thu, 21 Apr 2005 12:38:04 -0500, Rex B wrote:
So where does one buy a geiger counter, if one were so inclined?

First thought is "American Science and Surplus" in Milwaukee and Chicago.
They do mail order. Mine came from a former employer - we moved a factory
from England to the US, and the test equipment came along. The type of
geiger counter they sent wasn't certified by the NRC, so it couldn't be used
for production (or at all) here, so I was told to make sure it went away
and never came back.

On Thu, 21 Apr 2005 12:38:04 -0500, Rex B wrote:

So where does one buy a geiger counter, if one were so inclined?

You start out by thinking what on earth you want it for. Then you buy
the right sort. You also need to read up on radiation, its monitoring,
its hazards and its devices. This is _not_ a simple subject (although
reading military training pamphlets is often a good simple start - the
relevant FM is probably on-line)

If you buy a mil-surplus G-M then you have three problems; it's
insensitive, because it was designed for measuring fairly high rates.
Secondly it's _really_ insensitive, because it's 30 years old and the
tube has gone soft - GM tubes age badly, especially those sensitive to
beta. Thirdly it's likely to run on valves and require some weird 90V
battery that's no longer available.

So if you want to play science, buy a brand new (or still-boxed surplus)
tube and build yourself a transistor power supply and counter circuit
for it.

Here in the UK, the military didn't use that many G-M devices. The
standard battlefield meter was an ionisation chamber device, because
this is more appropriate for military levels. For training there was a
very similar meter, except it was a different case colour (black and
silver). This did use a G-M tube and was sensitive enough to sniff out
small training sources, pinned to a squaddie's battledress.

For civil defence use, the standard device was a G-M tube mounted above
one of the ROC's bunkers.
http://www.scottishroc.org.uk/theroc/monitoring.html
There were also hand-held variants (cream metal cases)

In later years these were all replaced by variants of the ubiquitous
Plessey PDRM82
http://www.users.globalnet.co.uk/~mccamley/pdrm82a.htm
http://www.users.globalnet.co.uk/~mccamley/pdrm82.htm
These are still around on eBay ($50 street price) and the surplus market
(Bull electrical) as good NOS. They're robust, they use common
batteries, they;re just the ticket for environmental monitoring and best
of all they're PDRM82's. It's a problem with low-level env radiation
monitoring that calibration is a Black art and the only way to get
decent results is for everyone to be using the same meter.

http://hps.org/publicinformation/ate/q4099.html


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