Uranium Glass - Natural or Depleted Uranium?

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Go-Figure
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Uranium Glass - Natural or Depleted Uranium?

Post by Go-Figure » 07 Jun 2020, 22:24

Hello there,
Today’s sample is a Uranium Glass ashtray.
Uranium has been used as a colorant for a long time, with glass in particular this use goes back to the 19th century. That gave the glass a yellow, yellow-green appearance.
Uranium glass is a general term which refers to several different types of such glassware named as Vaseline glass or Depression glass, they all have Uranium in common.
I have several Uranium Glass samples, this is the hottest one and for a good reason, it’s pretty heavy, almost 1 Kg according to my weight scale.
01 - DSC05186R.jpg
I ran into this particular piece at a permanent flea market, I was there with my Geiger counter looking for something like that and when I read 1800 CPM I knew I had found a good one. I told the market owner what was “special” about that piece of glass and she was pretty surprised when she heard the Geiger clicking. I made clear that the object posed no particular risk probably too soon, otherwise I would have maybe got some discount to get it out of there! 😊

Just like any other Uranium glassware this one gloves in the dark under UV light. Fluorescence has nothing to do with radioactivity, UV light excites the electrons above the ground state and they give off photons as the they transition back to the ground state.
02 - DSC05192R.jpg
As said above the Geiger counter reads 1700-1800 CPM at close contact, nothing particularly impressive but above the average of other Uranium glassware I own.
03 - DSC08020R.jpg
First I run a 3.5 hours test with the PDS. My typical background in that room measured with that particular device is in the region of 50 CPS and 0.900-0.100 μSv/h. The test (without background subtraction) gave me roughly 85 CPS and 0.119 μSv/h, so, as expected nothing too hot, but it was an indication that I was going to have enough counts from the sample to be able to run the test with the 2’’x2’’ subtracting the background without needing a lead shield.
04 - DSC08024R.jpg
The spectrum from the PDS, since the background is not subtracted, is not particularly clear, albeit you can identify the Th234 peaks at 63 and 92 keV and the U235 peak at 186 keV. The other U235 peak at 143 keV is buried somewhere in the background slope and it’s not visible being too weak. Here is the spectrum in linear and logarithmic view.
05 - Uranium Glass Ashtray - LIN - 210 Minutes - 06-06-20.png
06 - Uranium Glass Ashtray - LOG - 210 Minutes - 06-06-20.png
And then I started the serious test. Accumulation time for the background was 16 hours which, with no shielding, was enough to give me almost 15 million counts (259 CPS). And here’s my unshielded background, always good to see it, it doesn't happen often these days.
07 - Background - Stanza Fondo - 16 Hours - 0.035 Gauss - No Shield - 02-06-20.png
07 - Background - Stanza Fondo - 16 Hours - 0.035 Gauss - No Shield - 02-06-20.png (45.52 KiB) Viewed 383 times
The geometry of the ashtray fits pretty well with the probe which can go right into it. In the end an accumulation time of 8 hours was good enough, the sample gave me nearly 100 CPS distributed among pretty few peaks, so the picture got clear pretty early.
08 - DSC08011R.jpg
And here we are with the result. As with the Fiestaware the Uranium used for this kind of object is chemically purified first, so you won’t find the typical Uranium progeny in it, only the early daughters, Th234 and a hint of Pa234m. Then there’s of course some primordial U235 with its typical two peaks at 144 and 186 keV.
09 - Uranium Glass Ashtray - ID - NU - 8 Hours - BG Subtraction - Counts x Bin - No Shield - 0.035 Clean - 02-06-20.png
10 - Uranium Glass Ashtray - ID - NU - 8 Hours - BG Subtraction - Energy x Bin - No Shield - 0.035 Clean - 02-06-20.png
The strength of U235’s peaks is what tells whether you are dealing with Natural or Depleted Uranium.
Before WW2 natural Uranium was used, then there’s been a hiatus during the Manhattan project where all Uranium in the USA was under government’s control and when production resumed in the 50s they used depleted uranium (byproduct of Uranium enrichment process).
Unlike with the Fiestaware I posted about back in January (viewtopic.php?f=5&t=747&sid=eafec20cb19 ... 4e059664db) this time the result was no so clear-cut, U235 peaks are stronger than what you’d expect from a depleted Uranium sample, but not as strong as I’ve got from other natural Uranium ones.
In the end it looked more natural than depleted Uranium to me so I labelled it that way, but I am not 100% sure I must say.

As with other purified Uranium samples spectra there are things I still need to figure out, like the small bump around 240 keV (the sample is not old enough to have a visible Pb214 peak yet I think) and more importantly a 32-34 keV peak which is there every single time and for which I don’t have a good candidate yet. People tend not to care too much about it in several spectra I saw, they simple put a "X-Rays" label on it, I don’t think that’s good enough, but I still don’t know where it comes from.

Last, as usual, the quantitative analysis which confirms the early indications I’ve got from the PDS, a decent amounts of counts, but almost all of them coming from pretty low energy peaks, so the exposure at contact is pretty low as well.
11 - Spectrum Analysis-001.jpg
I have more Uranium glassare samples so…you’ll hear about them in due course. Let’s see if I can find some of them with depleted Uranium in it.

Until next time.

Massimo

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Peter-1
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Re: Uranium Glass - Natural or Depleted Uranium?

Post by Peter-1 » 08 Jun 2020, 02:45

hello Massimo,
a good job and a good result. You have to look for a new uranium glass. I bought a small cube and saw that the peak at U235 is then much smaller than that of old objects.
Peter

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Go-Figure
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Re: Uranium Glass - Natural or Depleted Uranium?

Post by Go-Figure » 08 Jun 2020, 02:50

Peter-1 wrote:
08 Jun 2020, 02:45
hello Massimo,
a good job and a good result. You have to look for a new uranium glass. I bought a small cube and saw that the peak at U235 is then much smaller than that of old objects.
Peter
Hi Peter,
Yeah, I need post WW2 pieces, but maybe I already have some among my samples, I just have to test them one by one and find out :)

Anyway, that's not for now, I just started a very long measurement.

Massimo

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Re: Uranium Glass - Natural or Depleted Uranium?

Post by Sparky » 10 Jun 2020, 03:26

Massimo,

You've inspired me to check the one piece of Uranium Glass I own. It looks a lot like DU Fiestaware, except without the lead florescence. I was surprised it was DU, I thought it was older than that. In the USA, a lot of cheap colored glassware, including U-glass, was made in the 1930's and is called "Depression Glass" by collectors. I thought it was from that period. I think my piece is a Votive Candle Holder. About 2000 cpm with a pancake GM probe.

I think yours is natural Uranium. Basically, IMHO, if you have a well defined U235 peak at 144 keV it is almost certain to be NU. I think your specimen is a great relic, what could represent the 20th century better than a radioactive ashtray?
Attachments
Bauer and U glass 06082020.png
Candle Holder and UV.jpg
Candle Holder2.jpg
Michael Loughlin

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Go-Figure
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Re: Uranium Glass - Natural or Depleted Uranium?

Post by Go-Figure » 15 Jun 2020, 00:40

Sparky wrote:
10 Jun 2020, 03:26
Massimo,

You've inspired me to check the one piece of Uranium Glass I own.
Always good to inspire somebody!
I agree it's NU, I put it in the spectrum description as well, albeit I confess I had a few minutes of doubt. Yours is definitely DU.
You know, I think I am probably the worst anti smoke person you can find, back in my childhood I forced both my parents to quit smoking. Back then it wasn't just being concerned for health implications, it's just that my body doesn't tolerate that, I slow down my breathing to an almost apnea-like state. So I really couldn't believe I was buying an ashtray....only for science :)

Massimo

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Re: Uranium Glass - Natural or Depleted Uranium?

Post by Sparky » 17 Jun 2020, 12:58

I posted my spectrum on the GS iogroup and someone replied with this interesting link demonstrating how to make U-glass. I was surprised at how little U is required. I think my candleholder is similar in size and activity to the piece created here.

https://www.youtube.com/watch?v=RGw6fXp ... e=youtu.be
Michael Loughlin

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