Gamma Spectrometry Forum

I am looking for help and explanation! During some measurements of the spectrum of uranium glass, uranium compounds and the soil sample from Gottow, I made an observation that I couldn't explain. The line at 63.3 keV for Th234 varies greatly. Both in the soil sample and in a uranium glass from Schott (old colored glass GG17) the ratio to 92.4 keV Th234 is about 1: 1.15, whereas in the other samples of UO2 and uranyl nitrate (Merck) the ratio is 1: 1 , 96 is. What is the explanation for this? Peter

https://www.osti.gov/servlets/purl/1525592
This is my go to for uranium spectroscopy, as it has some very nice tipps and tricks.
Have you considered self shielding of your sample? you can see that the lower lines < 50 keV are even more affected.

There is a characteristic of differential self-shielding one sees when superimposing spectrums that I call the "ramp effect" . If you equalize counts on a particular energy, the source with more self-shielding will have larger peaks above the equalized peak. The source with less self-shielding will have larger peaks below the equalized peak. The attached spectrum is an example. The blue and brown lines are from two different brands of thoriated lantern mantles. The green line is a Monazite mineral sample. The mantles have little self-shielding, the Thorium rock has much more.

At higher energies, self-shielding has less effect, and at lower energies it has more. Quantitative conclusions about such ratios is tricky with different sample compounds or geometries.

Peter-1
I think a sample of Gottow Uranium is a very interesting World War 2 historical artifact. Better than Trinitite or even a piece of graphite from CP-1. The only thing better would be finding one of Heisenberg's lost cubes. Did you post more about this soil sample earlier? What was the subject line? Thanks.

Mike L.

https://www.npr.org/2019/08/31/75547886 ... nt-to-know

hello Mike,

my first spectra of soil samples were in Sept. 25, 2019. The title: soil sample

Peter