Gamma Spectrometry Forum

Hello everybody,

I don't know if this makes sense at all, but maybe you experienced folks may know:

I have here several historic Uranium glasses and some modern ones (made recently). Thing is that all spectra from historic glasses look rather similar and also the newer ones I have look similar among each other. The difference between "historic/new" seems to be the x-ray signal at 32keV. In modern glasses it is much more present, in historic ones it is much weaker, sometimes even missing.

So this could be the K-alpha line from Barium, maybe? Baryte and Bariumoxide have been used more often in the 20th century on, as an excipient, at first for special glass (lenses, optical purposes), later also for broader applications. Maybe that's the explanation: modern glasses have more Barium inside, used as an excipient?

Do you see that signal in your glasses?

What I did is to place a baryte crystal on top of uranium glasses and collect the spectra to see if I can spike that Ba-X-ray signal actually (Uranium 60ish keV could actually trigger K-alpha on Barium).

Unfortunately I can't increase that signal that way. Maybe a tiny increase with Baryte, with both, historic and modern glasses. But I guess the experiment setup is false and it could be that Baryte just absorbs the radiation without emitting x-ray fluorescence that much OR the X-rays are emitted at an angle, so measuring all in one line makes no sense...also my equipment is much less sophisticated to do such experiments

And I see Bariumsulfate is a contrast agent in medicine, so quite likely it does hardly emitt anything, rather absorbing radiation.

Any thoughts?

In a post that I made under Detectors regarding use of a SrI(Eu) detector are some uranium spectra. I have one of uranium ore and two of "processed" uranium. The processing to produce Uranium metal and Uranium oxide would likely have removed most of the built-up daughters from the decay of uranium. The processed metal and oxide samples came from United Nuclear; I understand that sometimes the uranium might be slightly depleted in the U-235 isotope. The enrichment of naturally occurring uranium throughout most of the world is about 0.72 wt percent U-235. The amount of U-235 in depleted uranium can vary.

The SrI(Eu) spectra of uranium begin on page 3 on my computer. The link to this thread follows -
viewtopic.php?f=14&t=885&start=20

The build-up of daughter products from radioactive decay of U-235 and U-238 can be calculated using the Bateman equation. The equation can be implemented in a spreadsheet or computer program.

More info can be found in the links below -
https://en.wikipedia.org/wiki/Radioactive_decay
https://en.wikipedia.org/wiki/Bateman_equation
https://en.wikipedia.org/wiki/Uranium-235
https://en.wikipedia.org/wiki/Uranium-238

Following are links to a python program for radioactive decay calculations. I have not used this program. My older programs are in fortran.

https://radioactivedecay.github.io/overview.html
https://github.com/radioactivedecay/radioactivedecay
https://pypi.org/project/radioactivedecay/
https://arxiv.org/pdf/2203.09761

Thank you Rob! .....okay, my fault (me beginner).

Now I get it, thank you, it seems like the U235 content differs from older to newer glasses. The X-Ray at 19-20keV just becomes so big with larger U235 content that you hardly can see sometimes that small peak at 32keV. So that one actually stays the same, it's just the U235 content which is the difference. I am new to InterSpec, now I figured it out to shift the spectra directly over each other (Scaling slider):

So this is a 10h measurement each, blue is modern glass, green is historic glass and pink is the background. The modern glas has actually much more activity, I had to scale it down, now we see that the U235 Xray and U235 at 186keV are much higher. Rest seems similar.

But still what is at 32keV?

Following is a link to an on-line tool that will allow one to calculate the isotopic activities in the Uranium decay series over a defined time span.
https://www.wise-uranium.org/rccu.html