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Re: NUMEC Pu-Be sources
At 12:17 PM 02/22/2000 -0600, you wrote:
>If you have access to a good germanium detector, the FRAM program can give
>you plutonium isotopics with the following typical precisions:
>
> 238 1-10%
> 239 0.1-0.5%
> 240 0.5-4%
> 241 0.2-0.8%
> Am241 0.2-10%
>
> Pu 242 is calculated by isotopic correlation because of the lack
> of useful
>gamma rays.
>
>The precisions will vary depending on factors such as count rate/time,
>filtering, and sample characteristics, but with good statistics (sufficient
>counts in the important peaks), the effects should be small. Under the
>best conditions, precisions can approach those possible with destructive
>analysis. The program can also handle spectra from heavily lead shielded
>sources.
>
>If you can get a good Ge spectrum from the source, send it to me and I'll
>analyze it for you. We can adapt the program for just about any energy
>calibration, provided the spectrum shows all the peaks, but our standard
>(for a coax detector) is 8k channels, 0.125 keV/channel. When I'm
>researching with the program, I try to stick close to 10kHz input and 1
>hour counts. Multiple measurements let us get an even better handle on
>precision, of course. I have gotten good results with shorter counts and
>lower input rates as well. I should be able to get some results to you on
>a same-day basis (in minutes if all goes well).
Phil,
Good morning!
I noticed the above response that you provided via RADSAFE, and I thought
I'd ask a related question. Do you have any knowledge regarding a "typical"
gamma spectrum resulting from a PuBe source? I recognize all the factors
that contribute to the spectral shape (e.g. isotopic composition, size,
etc.), but at this point, I'm really interested in an "example" spectra. If
you could point me to any useful references, it would be appreciated.
I've been calculating neutron dose equivalent rates from PuBe (and AmBe,
AmLi, etc.) sources and have now been asked to show what the dose rate
might be from photons. Unfortunately, I haven't been able to track much
down from text books or the literature. Most of what I've seen is related
to neutrons. Again, any information would be greatly appreciated. Thanks!
Regards,
Erik
________________________________________
Erik F. Shores
Los Alamos National Laboratory
ESH-12, Radiological Engineering Team
Mailto:eshores@lanl.gov
505.665.7643 (phone)
505.667.9726 (facsimile)
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