Re: GM response to neutrons?

[John Andrews <andrewsjp@chartertn.net>]

You can get some sensitivity to neutrons from GM tubes by wraping them 

with Indium foil.  This will become radioactive from thermal neutrons 

and decay fairly quickly.  The response will therefore be smoothed out 

and it will not be prompt as with a GM in a gamma or beta field.  We put 

indium foil around the GM detectors in chirpers used in our accelerator 

facility in the mid 60's.  They worked.



John Andrews

Knoxville, Tennessee





Phil Hypes wrote:



> Based on the times I've played around with GM counters and neutron 

> sources, I'd guess you were responding to the Am gammas.  Of course, 

> there are AmBe sources that are shielded to prevent gamma exposure, so 

> if that was the case you were either detecting higher energy gammas 

> from the Am, or you were in fact detecting neutrons.  My guess would 

> be gammas.  You really need H3 tubes to get any kind of decent neutron 

> response in gas filled detectors.

>

> Phil Hypes

> Los Alamos Radiation Consultants

> laradcon@hotmail.com

> 505.920.9712

>

>

>

>

>

>> From: Kai Kaletsch <eic@shaw.ca>

>> Reply-To: Kai Kaletsch <eic@shaw.ca>

>> To: RadSafe <radsafe@list.vanderbilt.edu>

>> Subject: GM response to neutrons?

>> Date: Wed, 29 Jan 2003 13:39:09 -0600

>>

>> Friends,

>>

>> could someone educate me about the response of GM tube based 

>> instruments to neutrons?

>>

>> I remember playing with Am/Be neutron generators and using a GM based 

>> meter to confirm that the source actually got back in the holder. 

>> (And the regulators where OK with us only having GM based detectors 

>> on hand to locate a possibly lost source. [They did want the 

>> operators to be badged with neutron dosimeters.])

>>

>> So, the question is: Was the detector seeing some interaction of the 

>> neutrons, or was it only seeing Am gamma?

>>

>> Thanks in advance,

>> Kai

>> http://www.eic.nu

>> http://www.gammawatch.com/

>

>

>

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