Fiestaware (Natural Uranium)

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Hi there,
This is the cleanest spectrum of depleted uranium I got so far.
My previous depleted Uranium spectra came from Uranium Glass, this time it's Fiestaware (ceramic dinnerware with uranium oxide in its glaze).
Since the spectrum shows depleted uranium the plate dates between 1959 and 1972.

This is also the first time I detected Protactinium 234m, at first I wasn't sure about it, but since the peaks are right on the money it seemed to me it must be it. They are pretty weak in the counts per bin view, much more visible in the energy per bin view.

When I first received the plate I was surprised to read 31000 CPM on my geiger counter's screen, that was almost 20% higher than the read I got from the Pentax Super-Takumar 50mm back lens (see here viewtopic.php?f=5&t=519), but in terms of gammas this sample was not even close to the Pentax lens, which gave me a level of energy per unit time (at contact) 20 higher than the background, while this one showed an energy per unit time 15% lower than the background (again, at contact).
It was a reminder of how badly a geiger counter can get it wrong, even just comparing samples.

Massimo

Edit 11 July 2020: Differently from what originally stated, this sample contains natural, and not depleted Uranium. For a better comparison between NU and DU see this post viewtopic.php?f=5&t=747

[pilgrim]

This is my spectrum recorded from a little piece of Fiestaware, about 12-14g.

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This is my spectrum recorded from a little piece of Fiestaware, about 12-14g.
Fiestaware 14g, 2q, GS1100-PRO+P14, 930V 19,5h.JPG

Did it give you anything above 600 keV? I wasn't entirely sure putting the Protactinium labels so I'd like to know if you got something there as well.

[pilgrim]

I'm sorry but I din't checked that part of energies, because I didn't know about the Protactinium :-(
I could try again, maybe with the Uranium glass together the piece of Fiestaware, to have greater activity...

[Sparky]

Mossimo,

I made a few Fiestaware spectrums that provide a little more detail on the lower end. The first file has multiple spectrums superimposed for four different pieces of Fiestaware, plus one for a depleted Uranium Check Source (CDV-700). All the spectrums were scaled from the big Th-234 peak at about 92 keV. This peak acts as a proxy for U238 and basically scales the sources for relative activity. The relative strength of the U235 peaks at 144 and 186 keV indicate if the piece contains Natural U or Depleted U in the ceramic glaze. It is easy to see the difference between NU and DU in the superimposed spectrums, and the color code is explained in the notes section.

All of the Fiestaware spectrums show a peak around 77 keV, indicating the x-ray fluorescence of lead. Unlike ore or mineral samples (having all the U238 lower daughters, including various lead isotopes) this xrf is from lead intentionally added to the glaze. This toxic additive was used to provide a glossy appearance. This was common with many antique ceramics.
The lead xrf peak is not found with the DU check source, because it does not contain lead.

The one DU piece of Fiestaware I own is a “Individual Salad bowl” , a pattern introduced after 1959. All of these are of the DU variety.

The second file is of a single spectrum of a fragment of a Bauer saucer. Bauer was a Fiestaware competitor in the 1940’s. I used some modest shielding for this spectrum. It is pretty much the same as the others, except I could identify a lower probability Th-234 photopeak at 112.8 keV.

Mike Loughlin

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Very nice report Michael.
I will have something new on Fiestaware shortly, back in June when I first posted this I had holes in my Fiestaware knowledge. I still have, but they got smaller :)

Massimo