Re: Radionuclide ID Help

[Ninni Jacob <njacob@gsosun1.gso.uri.edu>]

On Thu, 18 May 1995, NUCPHARM@aol.com wrote:

> We have recently been asked to identify two samples containing RAM.   One is
> sand and after 15 hours of accumulating a spectrum containing 11 million
> counts(NaI[Tl]) the following major peaks are evident in order of decreasing
> abundance: 250, 366,308,198. Also a watch with luminescent dial (fairly old)
> 14 hours of data acquisition approximately 9 million counts:
> 364,306,198,252,154. I presumed the 364 peaks are from I-131 which is stored
> in an adjacent room but it is not present on the background spectrum.
> 
> nucpharm@aol.com

I have counted a radium dial watch and the peaks one sees are 186keV(from
Ra-226), 295, 352 and 609 keV from radon daughters, (which you would also
see on the background)
In the sand one would expect to see peaks of 295, 352 and 609 because they
are part of the background.
The main difference is that there would be no 186 peak unless Ra-226 was
also present in the sand.

It looks like  the calibration may be off.

Actually, if you look at the data closely, it looks like the energies are
off by about 12kev (the offset is 12keV)  so if you subtract 12Kev from
each ot the energies, it should come out right.

 I hope that helps.