Re: GM response to neutrons?

[Doug Aitken <daitken@sugar-land.oilfield.slb.com>]

At 01:39 PM 1/29/2003 -0600, Kai

wrote:

> 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?


Kai:

The AmBe source emits not only the 60keV gamma from the americium, but

also 4.4MeV gamma from the C13 -> C12 transformation (responsible for

the neutron yield of the source).

These are the source of the GM response, which responds to alpha (which

are present in the source, but contained by its encapsulation), beta and

gamma.


In well logging operations with AmBe sources, we are required (by US

Regs) only to carry Gamma ray meters to the wellsite, for the specific

purpose you mention. We are required to have Neutron meters

"available" to our facilities.


Regards

Doug




Doug

Aitken

     

        

Schlumberger

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