[ RadSafe ] Measuring alphas with GM? Re: Survey MDAs vs. Scan MDAs

[NIXON, Grant]

No joke Emil. Some GM detectors, equipped with a thin mica window, would
be able to measure high-energy alphas. For example, a pancake probe that
is typically used for detecting contamination (e.g., betas from Co-60)
can also detect alphas from uranium.

Grant

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Emil
Sent: Wednesday, May 10, 2006 5:03 PM
To: radsafe at radlab.nl
Cc: Ron Reif
Subject: [ RadSafe ] Measuring alphas with GM? Re: Survey MDAs vs. Scan
MDAs

Ron,

Is it a joke?

Not to offend anybody but I am wondering how do you measure alphas
with GM detector???
The GM window thickness makes it impossible.

Regards,

Emil.


@radlab.nl>
Cc: 'John Andrews' <jandrews at whoi.edu>, 'steven pike'
	<spike at whoi.edu>,	'Mary McGeoghegan' <Dear Radsafe list:

 I'm trying to determine the Minimum Detectable Activity (MDA) for 
gross
alpha measurements using a GM detector coupled to a rate meter.  Some
colleagues have pointed me to NUREG-1757, which I have reviewed.  
NUREG-1757
refers to NUREG-1507, "Minimum Detectable Concentrations with Typical
Radiation Survey Instruments for Various Contaminants and Field 
Conditions",
June 1998.  However, I cannot locate this document on NRC's web site.
Apparently, they do not keep 'older' documents on their web site.  
Does
anyone have the proper MDA equations for evaluating (a priori) the
sensitivity of a rate meter?  It is my understanding that the 
standard MDA
equation for integrated measurements (scaler mode) does not apply to 
rate
meters.  A link to NUREG-1507 would also be appreciated.  

 

Please reply directly to me.  Thank you.

 

 

-----

Ron Reif, P.E.,CHP,CIH

EH&S Manager

Woods Hole Oceanographic Institution

http://ehs.whoi.edu

p:508-289-3788

f:508-457-2015

 



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