RE: Alpha contamination survey meters

["Wes Van Pelt" <vanpeltw@idt.net>]

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

-----Original Message-----
From: radsafe@romulus.ehs.uiuc.edu
[mailto:radsafe@romulus.ehs.uiuc.edu]On Behalf Of Rodney Bauman
Sent: Thursday, March 09, 2000 2:19 PM
To: Multiple recipients of list
Subject: Re:Alpha contamination survey meters


Many vendors supply such instruments - Eberline, Ludlum, and Bicron-NE, just
to
name a few.  I would recommend using alpha scintillation probes (e.g.,
Zinc-Sulfide).  They provide a sufficient detection efficiency and exhibit
no
beta/gamma interference.

In order to detect 10 - 20 dpm, a static count time of many seconds to a few
minutes will be required, depending mainly upon background count time,
instrument efficiency and probe size (for direct measurements corrected to
100
cm2).  One cannot frisk/scan with a portable alpha probe and obtain a 10 -
20
dpm decision level.  Static counts are required.  Do you need to detect 10 -
20
dpm total activity?  I can see the need for detecting such levels on a
smear,
but that sounds low for a total measurement.

Rodney Bauman, CHP, RRPT
rodney_bauman@wssrap-host.wssrap.com


____________________Reply Separator____________________
Subject:    Alpha contamination survey meters
Author: <radsafe@romulus.ehs.uiuc.edu>
Date:       03/09/2000 12:56 PM

I am interested in recommendations for a portable alpha contamination survey
instrument and probe capable of accurately detecting 10 - 20 DPM on a smear
or a
direct frisk. The instrument must not have a response to beta or gamma
radiations. The instrument will be used for unconditional release of
equipment
and personnel, so the response time needs to be tolerable for
personnel frisking. If anyone has a positive experience with an instrument
matching these characteristics I would appreciate your feedback.


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