Hottest Sample so far - Autunite Crystal from China

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Go-Figure
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Hottest Sample so far - Autunite Crystal from China

Post by Go-Figure » 29 Sep 2019, 09:05

Hello there,
I report on a test I did last weekend on an Autunite Crystal from China.
First of all, as an object is a thing of beauty and photos don't do justice to it, particularly the view under UV light.
DSC06928_FC.jpg
DSC06943_FC.jpg
DSC06932R.jpg
This is the hottest sample I tested so far. How about 124K CPM on the geiger counter?
The PDS 100 agreed, 1700 CPS and an average dose over 999 seconds of 5.7 μSv/h.
DSC06950R.jpg
DSC06859R.jpg
Autunite Crystal - 999 Secs - 16092019 - LIN.png
Autunite Crystal - 999 Secs - 16092019 - LIN.png (79.72 KiB) Viewed 1690 times
Autunite Crystal - 999 Secs - 16092019 - LOG.png
Autunite Crystal - 999 Secs - 16092019 - LOG.png (79.21 KiB) Viewed 1690 times
For the measurement with the GS 2''x2'' NaI(Tl) I recorded a 12 hours background spectrum and then subtracted that from the sample results.
Background is the same as for the Trinitite test, the two tests were done the same day (last sunday). A graded shield (lead 1.5 cm equivalent - Copper 1 mm - Plastic 5 mm) was used which reduced counts from the backgroound by about 75% (64 CPS vs 256 CPS), however, as you can see, copper wasn't enough to take care of the x-rays fluorescence from shielding.
DSC06957R.jpg
Background - CPS - 12 Hours - Counts x Bin - Shield V1 - 0.045 Gauss - 21-09-19.png
Background - CPS - 12 Hours - Counts x Bin - Shield V1 - 0.045 Gauss - 21-09-19.png (7.99 KiB) Viewed 1690 times
In the measurement I am doing right now I added an additional 4 mm layer of pewter (thanks for the tip Steven!) and that improved this aspect significantly, more on that in the coming days.
I knew from results from the PDS100 that this sample was going to take my sound card to its limit, therefore I decided to use 50 samples instead of 60 on the PRA software to lower the dead time. I knew this wasn't going to be enough but I didn't want to lose to much quality. Maybe I was too conservative on that.

In the end the 2700 CPS I got were limited by the minimum dead time availabe, while the sampe could have certainly given more.
Anyway, here's the spectrum both in Linear and Logarithmic scale. 3 Hours were more than enough, I recorded nearly 30 million counts.
All classic U238/Ra226 series peaks are there as you can see. The Bi214 peak at 2204.21 keV was there too, but didn't include it for the sake of a better visualisation of the rest.
The fluorescence peak is visible here too, albeit it must be said that a (weaker) 77 keV peak from Pb214 would have been there anyway.
Autunite Crystal - ID - 3 Hours - BG Subtraction - Counts x Bin - Graded Shield V1 - 0.045 Clean - 22-09-19.png
Autunite Crystal - ID - 3 Hours - BG Subtraction - Energy x Bin - Graded Shield V1 - 0.045 Clean - 22-09-19.png
Quantitative analysis is less significant than usual since, as said above, CPS and exposure from the sample were both limited by the minimum dead time available.
Spectrum Analysis @Contact+1 - 3 Hours-001.jpg
As usual, it was a lot of fun.
Massimo
Last edited by Go-Figure on 30 Sep 2019, 23:04, edited 2 times in total.

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pilgrim
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Re: Hottest Sample so far - Autunite Crystal from China

Post by pilgrim » 29 Sep 2019, 18:38

This sample is very beautiful...And quite scary as well!
Excellent report as always!

As soon as I'll be able to finish the copper part of my liner, I'll surely try to buy pewter from the seller Steven suggested.
Daniel, Italy

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Re: Hottest Sample so far - Autunite Crystal from China

Post by gwgw » 29 Sep 2019, 18:50

What's the weight?

I found a guy in OLX that sells a beautiful autunite crystal, 1.4g, he is even located in the city I live in, so overall that would cost just about EUR 20 for the mineral and probably about 2-3 EUR for shipping. He wrote that it gives 3.8 uSv/h at close range and 0.6 uSv/h about 20cm away from the plastic box it's placed in. At the end I got kind of scared and decided not to buy it. Not because of the gamma, it can be easily shielded, but I don't quite like the idea of having that radon source in my room. I did some rough calculations and they scared me a bit :) So I decided to not get it, after all I have two kids and I smoke cigarettes, extra radon is the last thing I want in the room...
Regards,
Milen Rangelov

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pilgrim
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Re: Hottest Sample so far - Autunite Crystal from China

Post by pilgrim » 29 Sep 2019, 20:03

I agree with you Milen, in my opinion is always better not to deal with alpha emitters that can easily crumble.
I have a small sample of Uraninite but it is under a couple of cm epoxy!
Daniel, Italy

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Go-Figure
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Re: Hottest Sample so far - Autunite Crystal from China

Post by Go-Figure » 29 Sep 2019, 23:36

This sample is between 3 and 4 grams.
Of course it must be handled with care. I only took it out of the plastic bag to take pictures and I never touched it without gloves, which is probably an overkill provided that you wash hands right after it but I always do that…and I wash my hands anyway, overkill again.
You can see it’s never even at direct contact with the table where the photos have been taken, it’s on a napkin which is thrown away immediately after the photo have been taken.
You see in the photo under UV light that small pieces crumbled away so yes, you must me careful.

As for the Radon, I deal with Radon in my work, I am a mechanical engineer but I work on buildings a lot, mainly seismic design and energy efficiency, but I occasionally do Radon monitoring as well.

Right now I am monitoring a house with level of Radon around 400 Bq/m3 which we cut in half just by introducing more frequent air change. Radon is often a problem in the underground floor which this house doesn’t have, but it’s still made of tuff (a volcanic rock which here in Italy is also a building material, I tested a sample of it here viewtopic.php?f=5&t=520

I monitor my Radon level, but I never tested what difference the presence of such a sample in a room could make, I imagine that would heavily depend on ventilation. I keep all my samples in a safe in a small building close to my house, taking them out when I want to test them.

Anyway I can tell you this, Radon risk changes a lot depending on being or not being a smoker.

From 13 epidemiological studies the risk of lung cancer due to Radon are:

For a smoker
0.5% for 100 Bq/m3.
0.7% for 400 Bq/m3
0.9% for 800 Bq/m3

For a smoker (one pack per day):
12% for 100 Bq/m3.
16% for 400 Bq/m3
22% for 800 Bq/m3

You can see there’s roughly a factor 25, that’s because smoke and Radon kind of work together and smoke makes life much easier for the Radon to hurt your lungs.
Data come from the BMJ https://www.bmj.com/content/330/7485/223

So I would suggest to quit smoking right away, not just for Radon of course, but being a smoker a given level of Radon can harm you 10-12 times more than a level twice as much could harm a non smoker.
By the way, by smoking you are also exposed to Polonium 210.

My verdict: Quit smoking, get the Autunite crystal and your life will be better on a number of different levels! :)
Sorry for taking the liberty to say that, but I never miss an opportunity to tell people to quit smoking, I made both my parents quit and I wasn’t 12 years old yet, so I can’t help it!

Massimo

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Re: Hottest Sample so far - Autunite Crystal from China

Post by gwgw » 30 Sep 2019, 01:24

Yeah, I know that radon does a lot more damage to smokers. It also does more damage to kids.

Quitting smoking is easier said than done though :) I switched to iqos (smokeless variant still not e-cigarette or vaping stuff) about 1 year ago. Still I don't know if that's better and there is no public study regarding alpha particles in iqos smoke. Besides, I have relatively long-time exposure to "real" cigarette smoke and I am not sure even after completely quitting smoking whether radon risks would be still higher for me. So best of all is, avoid it whatsoever. I ventilate the rooms often.

As for radon in the air...my rough calculations were 1.4 grams of autunite has roughly about 0.7 grams of natural uranium in it. That makes roughly about 17500 Bq. Considering uranium and radon are in secular equilibrium (they aren't of course even after weeks of absent ventilation, but this is a convinient simplification), the radon activity in the air would be also 17500 Bq. Perhaps some of it will remain trapped in the mineral, but still let's assume all of it leaves it. The room is 5x8x2.5m that makes about 100m3. Thus we have 175Bq/m3 of radon activity just from that tiny beautiful 1.4g sample. That's way too much for me. Radon levels are not extremely high here, but they aren't low also (well we have an uranium mine literally in the outskirts of the city, although it's closed, also a granite mountain on the other side). So better be safe than sorry :)
Regards,
Milen Rangelov

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Go-Figure
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Re: Hottest Sample so far - Autunite Crystal from China

Post by Go-Figure » 30 Sep 2019, 02:53

In terms of Radon related increased risk quitting smoke will give you an immediate benefit.
The bigger risk for smokers it's because Radon daughters can enter your body attached to smoke particles, that doesn't depend on past smoke, it happens in "real time".
Other smoke-related risks only decreases overtime and for some of them it can take years, but for Radon it doesn't work like that, it's just that Radon and smoke work sinergically in the very moment you breathe the smoke.
If you calculate the dose from a certain concentration of Radon that's the same whether you are a smoker or not, but there's a factor 25 difference in the actual risk of getting a lung cancer.
So I am not giving up, I have to make you quit! :)

As for the Autunite. Consider that Radon accumulate in rooms with poor or no ventilation and the actual concentration depends on many other factor as well, it can vary a lot during the year, that's why a serious Radon measurement lasts for 12 months.
You can get an idea using an active Radon detector which will give you a relatively significant read after a week, but you still need a year long average to get a reliable picture of the situation. Everyone should be worried about Radon (and few actually are) and I am with you on that, but why don't take a Radon detector? Even an active digital one. So you can monitor the situation, with or without the crystal.
I think I will attemp such a measure myself, I will let you know.

Also consider Radon is a gas, if the crystal is inside a plastic bag with ermetic closure the most of it will stay inside. A gamma ray can go thorugh plastic, but a gas can't. Anyway, I never kept radioactive samples in a living room or a bedroom, regardless of the actual risk I think it's good practice. And when I open a plastic bag with an Uranium ore inside I always make sure not to breathe too close to it in the first few seconds, because Radon could have easily built up in there.
But in the end ventilation is the real key factor, it has a huge impact on the result.

Massimo

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Re: Hottest Sample so far - Autunite Crystal from China

Post by gwgw » 30 Sep 2019, 03:11

Hehe, I know I should quit. I didn't know increased radon risk was due to PM from cigarette smoke attracting radon byproducts though. Thought it's some kind of "synergy" between chemical pollutants from cigarette tar and ionizing radiation from radon.

My wife asked me to get a radon detector a number of times, she graduated medicine and now works in pharmaceutical sector. I didn't get one for some reason (well I decided the bi-214/pb-214 peaks in background would be somewhat indicative, they are not of course). I am getting more and more inclined to order one after all. They aren't cheap though. In fact, we even consulted a company that does radon measurements, but we didn't get that measured, I don't even remember why.

BTW, radon diffuses readily through thin layers of polymers from what I know, not sure if a plastic bag would be enough to contain it. A glass jar well sealed would certainly do the job though.
Regards,
Milen Rangelov

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Go-Figure
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Re: Hottest Sample so far - Autunite Crystal from China

Post by Go-Figure » 30 Sep 2019, 06:37

gwgw wrote:
30 Sep 2019, 03:11
BTW, radon diffuses readily through thin layers of polymers from what I know, not sure if a plastic bag would be enough to contain it. A glass jar well sealed would certainly do the job though.
That's right, actually Radon can penetrate through low density plastic.
Sooner or later I will do the test and see what difference it makes in a medium sized room. I will report on that when I have the data!

Massimo

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Re: Hottest Sample so far - Autunite Crystal from China

Post by gwgw » 30 Sep 2019, 08:44

Well I am kind of radon-phobic, so probably mine is just irrational fear. Still, keeping uranium in the appartment is something I tend to avoid. I keep all of my low-activity samples that give any uranium peaks on the balcony. I don't have that attitude towards thorium though, I keep my calibration material on my desk, inside a metal box, for easy access :) But still the thorium radon byproduct is a different isotope, it has a very short half-life. I guess most of it is already gone before escaping the box. Or at least I hope so :)
Regards,
Milen Rangelov

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