Monazite Sand from India

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Go-Figure
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Monazite Sand from India

Post by Go-Figure » 26 Aug 2019, 02:42

Hello there.
I’ve been wanting to test Monazite sand for some time now, but it’s not so easy to find. By the way, in case anyone knows where to get some please let me know.
As you probably know Monazite sand contains Thorium 232 and it’s the thing making places like Guarapari in Brazil, Yangjiang in China and Kerala in India the most notable examples of nigh natural background radiation.
Anyway, I eventually found a very small sample, just a few grams in a tiny little plastic box.
Well, still better than nothing. This sample comes from India.
DSC06745-Cut.jpg
With the little box’s plastic cover removed the Geiger gave a respectable 2600 CPM read. Which halved once the cover was back in place.
DSC06762R.jpg
Luckly, even those few grams are enough to give a good spectrum.
In order to maximise exposure on the detector I should have position it vertically with the crystal pointing upwards so I could place the little box on top of it with the sand on the close side of it, I would have certainly got some more counts, but unfortunately I couldn’t do that. I had to be off the whole day - in Rome, recording spectra in San Peter’s Square (a renowned high background spot) incidentally – so I couldn’t risk leaving the detector alone in an unstable position.
Here you see the setup for the experiment.
DSC06734R.jpg
In that position the sample gave me 63 CPS, so I recorded a 24 hours spectrum and the result is below. It’s not bad I would say, with a couple of peaks which I didn’t identified in my previous Th232 spectra, Bismuth 212 at 39.86 keV and Actinium 228 at 129.06 keV.
Monazite Sand - ID - 24 Hours - BG Subtraction - Counts x Bin - No Shield - 0.060 Clean - 24_25-08-19.png
Monazite Sand - ID - 24 Hours - BG Subtraction - Energy x Bin - No Shield - 0.060 Clean - 24_25-08-19.png
Quantitatively the exposure was a little less than 40% of that from the background.
Spectrum Analysis   - 24 Hours.jpg
Anyway, I took another spectrum with the Mirion PDS 100G (15000 seconds) and this time I could place the sample in the closest possible position to the crystal and the equivalent dose measured by the detector was three times as much (background 0.10 µSv/h, background + sample 0.23 µSv/h).
Keep in mind the background is not removed here.
DSC06792R.jpg
DSC06790R.jpg
Monazite Sand - 15000 scecs - 250819 - LIN.png
Monazite Sand - 15000 scecs - 250819 - LIN.png (81.6 KiB) Viewed 126 times
Monazite Sand - 15000 scecs - 250819 - LOG.png
That's it for the Monazite sand, at least until I find another sample.
You know there's a St.Peter's Square thread coming, but it's going to take a little time.

Massimo
Last edited by Go-Figure on 28 Aug 2019, 08:19, edited 3 times in total.

cicastol
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Re: Monazite Sand from India

Post by cicastol » 26 Aug 2019, 04:35

Nice work Massimo!
Ciro

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Go-Figure
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Re: Monazite Sand from India

Post by Go-Figure » 26 Aug 2019, 20:35

cicastol wrote:
26 Aug 2019, 04:35
Nice work Massimo!
Thank you Ciro!
I'd like to test a sample from Guarapari but it's not easy to find.
Hope I don't have to go all the way to Brazil to get it! :)

Massimo

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