Choosing BG soil

[brehwens]

Hi guys

As some of you might know, I am interested in doing absolute activity measurements of soil samples, looking for Cs-137.

I have a few samples here at home, some of which are measured by a reference lab. Still, I have not really chosen what will be my reference soil sample for background. To only have the room background as background is probably not a good idea, but what soil sample to use? So I was looking at two old soil samples which I had not measured previously, and here are the results:

Delsbo soil comparison.png (77.97 KiB) Viewed 4549 times

I wasn't really expecting and Cs-137, but it was interesting to note that one of the samples probably has a small Cs-137 activity, as a 662 keV "peak" and also the 32 keV X-ray is visible.
That means, both samples are useful: One as a good soil "blank" and the other as a very low activity Cs-137 sample.

I think I will ship these two samples plus a high activity sample off for analysis by a certified lab. I should then be able to calibrate the activity of Cs-137 in BeqMoni even better!

[cicastol]

Great Spectrum Karl,
i can't get BeqMoni work very well with my setup, plus the program crash very frequently :-( .

[Sesselmann]

Karl,

Nice spectrum, can you tell us how and where you collected these samples, what preparation you did and what the volume of the sample is?

I assume the blue line is one soil sample and the red area the comparison, is that right?

Steven