Wood ash radioactivity? Chernobyl fallout detected by Astro Cam?

[vlaiv]

Hm, it's a funny story

Just yesterday (or the day before, can't remember) I was reading about calibration if astro images. I was doing a research if it is feasible to do sigma clip on darks. Main suspect for pixel removal in my mind at the time were transient hot pixels. But I stumbled across this discussion about cosmic rays (and other rays in general - of earthly origin - i.e. radiation). Before having a read on that subject I thought that cosmic rays happen very seldom and that particles to some extent behave like regular photons - meaning they bounce of mirrors, whatever - so I thought cosmic ray impacts happen only during imaging - when sensor is exposed to sky.

Discussion also pointed out that not all cameras are equally susceptible to phenomenon, namely ASI1600 that I also use, has seen very few of these by respective owners. That was also my experience, I remember maybe seeing once or twice something that I would call cosmic ray impact.

Totally unrelated to that, I left yesterday evening and tonight, camera on my balcony (I usually do this in basement, but for some reason I decided to do it on balcony as it is closer to my work/study space and temperature is lower outside so it does not put that much strain on cooling), and since I updated the drivers and fiddled with some settings, decided to shoot another batch of darks - I'm finally expecting some imaging time next week, so it's good to be prepared

When I examined darks that I took, I was surprised to find couple of "cosmic ray" strikes in 1 minute subs, and a bit more in 4 minute subs. Interesting fact is that many of those are in fact streaks (10-15 pixels long and 1px wide) rather than few grouped pixels.

So I thought to myself - there must be some wild solar weather outside for this much cosmic rays to hit sensor as ASI1600 is not that sensitive to it. But then it struck me - if strikes are streaks rather than points, could this mean that particle was traveling at a shallow angle to sensor surface? Camera was placed on a desk, covered with cap, "face" (or better said sensor) down. If particles were traveling at shallow angle - that would mean source is somewhere near? Do I have something radioactive on my balcony?

Then I remembered something about wood ash from fireplace containing a bit of radioactivity, just a bit more than environment flux. I was shooting my darks at a desk where I used to put away tools I used to clean my fireplace, and next to desk was a cardboard box where I used to put bags of ash before disposing of them. Since we haven't done "proper spring cleaning" - whole place must be contaminated with ash particles. It still did not sound like plausible explanation - given that ash is not that much above environment. So I googled how much radioactivity there can be in ash, and found an article where this guy in Stats found very increased level of radioactivity in his wood ash (100 times above environment) - which he explained as being deposited from nuclear tests in '50s and '60s and absorbed by wood. Article was dated 1991. So it takes about 30-40 years for radioactivity to get to firewood ready for burning (assuming age of trees at which they cut it for firewood, and what ever is involved)? Guess what happened 32 years ago? Yes Chernobyl !!!

Could it be that this much "cosmic ray" hits is indeed due to Chernobyl fallout absorbed by trees, cut down for firewood and then ended up as ash particles on my balcony desk?

[Thalestris24]

Hiya

Could well be connected to Chernobyl fallout! It reached Glasgow too  

 

I think most cosmic rays don't penetrate to ground level but do give rise to muons which can then be used for tomography ( had a lecture on it last year). I don't know whether camera sensors are sensitive to muons? In any case there's always plenty of background radiation around. Maybe get a Geiger counter to compare?

Louise

[Thalestris24]

ps Fukushima has added a bit too - we're all doomed!

 

[DaveS]

Wood ash will be slightly radioactive from the potassium-40. We use a specific quantity of KCl to calibrate the beta sensitivity of our school's GM tube.

[robin_astro]

Cosmic Rays in this context is a "catch all" phrase for artifacts caused by various sources of radiation. (From showers of Muons produced in the upper atmosphere by cosmic rays, Compton scattering from background Gamma radiation and even beta radiation from the glass used in lenses, cover glasses etc.  I believe this latter source caused big problems in the early days of CCD as some high dispersion glasses are very radioactive !

High energy photons (X rays, gamma rays) are not reflected off conventional mirrors, you need special "mirrors" with very shallow angle reflections to focus these

Robin

[vlaiv]

11 hours ago, Thalestris24 said:

Hiya

Could well be connected to Chernobyl fallout! It reached Glasgow too  

 

I think most cosmic rays don't penetrate to ground level but do give rise to muons which can then be used for tomography ( had a lecture on it last year). I don't know whether camera sensors are sensitive to muons? In any case there's always plenty of background radiation around. Maybe get a Geiger counter to compare?

Louise

By the looks of it, we received a splash of red stuff at some point

I've been looking into getting a Geiger counter, but they seem quite expensive to buy one just to verify. I'll ask around if I can find someone to borrow from.

In the mean time I figured out a way to test "Ash hypothesis" - I might do a few darks next to fireplace, if there is a contamination, that is the place where it will be most visible.

On a separate note, interestingly, just few days ago:

http://powerlinks.news/article/6a73f1/accident-reported-in-romania-nuclear-power-plant?fieldname=industryids&t=Nuclear&query&fieldvalue=68

They say that there were no leak of any sorts, and everything is safe, but it is exactly 400ml away

2 hours ago, DaveS said:

Wood ash will be slightly radioactive from the potassium-40. We use a specific quantity of KCl to calibrate the beta sensitivity of our school's GM tube.

Yes, that was what I thought, it is just a bit above environment. Do you have any idea of ratio between "normal wood ash" and environment?

My guess is that this source was at least 50 times stronger than environment. This is just based on number of recorded "hits". I can't remember exactly but I would say under normal conditions, I would get on average 1-2 per 20h of imaging. This was just 3h of darks and it recorded at least 10 times more than that.

 

[Thalestris24]

Hi Again

I've always wanted a Geiger counter too but, as you say Vlaiv, good ones are quite expensive. I'm not sure why they are so expensive, I guess because of quantities made? Your post inspired me to do a little experiment last night. I used a mono gpcam without a window to look at the Americium 241 from an old smoke detector. It's a strong alpha particle emitter and weak gamma emitter. It's difficult to pick up the alpha particles because they are so easily stopped. I was getting a random flash about once every two or three seconds, occasionally several flashes at once. I would have thought that if the camera was picking up alpha particles then there would be very many flashes at a high rate, so I presume I was just picking up the gamma photons but I'm not certain. I have some lo-salt in the kitchen so I'll see if I can pick up the potassium-40 therein . I was thinking that anything which penetrates a telescope must be quite high energy. I think you need a scintillator + photomultiplier to detect muons.

Louise

[vlaiv]

46 minutes ago, Thalestris24 said:

Hi Again

I've always wanted a Geiger counter too but, as you say Vlaiv, good ones are quite expensive. I'm not sure why they are so expensive, I guess because of quantities made? Your post inspired me to do a little experiment last night. I used a mono gpcam without a window to look at the Americium 241 from an old smoke detector. It's a strong alpha particle emitter and weak gamma emitter. It's difficult to pick up the alpha particles because they are so easily stopped. I was getting a random flash about once every two or three seconds, occasionally several flashes at once. I would have thought that if the camera was picking up alpha particles then there would be very many flashes at a high rate, so I presume I was just picking up the gamma photons but I'm not certain. I have some lo-salt in the kitchen so I'll see if I can pick up the potassium-40 therein . I was thinking that anything which penetrates a telescope must be quite high energy. I think you need a scintillator + photomultiplier to detect muons.

Louise

Great little experiment!

From what I understand gamma rays are quite difficult to pick up on a sensor (I might be wrong at that, I don't really know much on that topic). It has something to do with cross section and the fact that gammas penetrate deep ... I wonder if we would be able to calibrate sensor to figure out rate of emission of gammas.

[Thalestris24]

41 minutes ago, vlaiv said:

Great little experiment!

From what I understand gamma rays are quite difficult to pick up on a sensor (I might be wrong at that, I don't really know much on that topic). It has something to do with cross section and the fact that gammas penetrate deep ... I wonder if we would be able to calibrate sensor to figure out rate of emission of gammas.

I was just guessing they might be gammas - I've no real way of testing for sure. The gamma emitted by Americium are low energy - only 59.5 keV so are on a par with low energy x-rays and probably don't penetrate very far or through any objects in the way. I didn't seem to pick up anything with some thin plastic put between the sensor and the source. I might do some more experiments tonight - a bit hard to do in the day.

Louise

 

[George 47]

Guys, I am afraid the answer to your question is no you will not be detecting the deposition from Chernobyl or Fukushima. But as you seem to be enjoying and learning from this carry-on. Alpha particles can be stopped by a sheet of paper so you can rule that out. Any incineration process will 'concentrate' any radioactivity present as the volume of the wood material is reduced and any activity per unit mass increases.  Remember your ASI1600 will have a piece of glass protecting the chip so any radiation has to get through that. 

[Thalestris24]

Oh well, the Americium was the only thing I could detect any radiation from and maybe only 8-10 pixels lit up with 15s exposures. Nothing from the lo-salt, nothing from my vintage Takumar or any other potential radiation sources. I've seen YouTube vids of the alpha particles from a smoke detector source - like an on-screen blizzard! But you have to remove the sensor glass and the radiation does appear to damage pixels.

Louise

[Stub Mandrel]

Try a banana

http://mentalfloss.com/article/63768/7-most-radioactive-items-your-home

[DaveS]

We tried to get a beta reading from a banana but it was inconclusive. Perhaps our GM tube wasn't sensitive enough.

[Oddsocks]

11 hours ago, Thalestris24 said:

I've always wanted a Geiger counter too

Louise, this bought back some memories of me a teenager, rummaging through the military surplus and electronics stores in Londons Tottenham Court Road after school in the 1970's for a photomultiplier tube to complete an electronics magazine project "Build your own Geiger counter", can't recall which magazine though. It worked too, and despite being bitten by the PM tube's HT a couple of time during the build it provided endless hours of fun, particularly for family, neighbours and friends who thought my brother and I were quite mad testing everything we could find for radioactivity.

The luminous paint on the face of old Timex clocks from Glasgow? seemed particularly active and my father had some masonry drill bits (cobalt?) that gave quite a high reading too.

William.

[Thalestris24]

21 minutes ago, Oddsocks said:

Louise, this bought back some memories of me a teenager, rummaging through the military surplus and electronics stores in Londons Tottenham Court Road after school in the 1970's for a photomultiplier tube to complete an electronics magazine project "Build your own Geiger counter", can't recall which magazine though. It worked too, and despite being bitten by the PM tube's HT a couple of time during the build it provided endless hours of fun, particularly for family, neighbours and friends who thought my brother and I were quite mad testing everything we could find for radioactivity.

The luminous paint on the face of old Timex clocks from Glasgow? seemed particularly active and my father had some masonry drill bits (cobalt?) that gave quite a high reading too.

William.

Haha

I remember Tottenham Court Rd too! And Edgeware rd, and Exchange and Mart. Also, 'Hobbies' Magazines back in the '60s, lol.

Happy Days!

Louise

 

[saac]

There is a device (CCD) called the Timepix, I believe a commercial spin off from CERN and primarily developed commercially for medical imaging use. A number of the devices have also been made available to schools together with access to data from a number of the devices flown on the ISS when Tim Peak was there. It is basically a mini particle detector aimed at schools to allow a more meaningful investigation of radiation than say conventional cloud chambers. I attended a presentation on it two years ago I think now and I remember being impressed where by downloading data from the ISS overflights a class would be able to investigate the nature of the mid Atlantic anomaly. Any school teachers out there who would like to know more and possibly register to get involved here's the link:

Timepix in education

 

Jim 

 

[George 47]

20 hours ago, Thalestris24 said:

Oh well, the Americium was the only thing I could detect any radiation from and maybe only 8-10 pixels lit up with 15s exposures. Nothing from the lo-salt, nothing from my vintage Takumar or any other potential radiation sources. I've seen YouTube vids of the alpha particles from a smoke detector source - like an on-screen blizzard! But you have to remove the sensor glass and the radiation does appear to damage pixels.

Louise

 

Wow, there are some fruit-cakes around. Taking the Am 241 source out of a smoke detector is not a great thing to do.

If you want an alpha source try a granitic rock from Cornwall or Scotland. If you want to get paranoid then Brazil nuts and coffee have higher than average levels of alpha in them and guess what, they still taste nice and do no harm although the chocolate Brazil nuts are ideal.

[George 47]

16 hours ago, Oddsocks said:

The luminous paint on the face of old Timex clocks from Glasgow? seemed particularly active and my father had some masonry drill bits (cobalt?) that gave quite a high reading too.

Old watches had radium 226 in them which was luminous due to the radioactivity interacting with a luminising agent (ZnS).  New watches use tritium or Pm147 where the beta radiation can't penetrate the glass of the watch.  Cobalt exists in nature as a stable isotope. Co 60 is radioactive but I would doubt it is in drill bits unless a Co60 source had been inadvertently melted.

[Stub Mandrel]

7 minutes ago, George 47 said:

Wow, there are some fruit-cakes around. Taking the Am 241 source out of a smoke detector is not a great thing to do.

Google 'the radioactive boy scout'

[George 47]

10 minutes ago, Stub Mandrel said:

Google 'the radioactive boy scout'

Fairytales and fables.....breeder reactor....really.....He disassembled some fire detectors plus some low-level radioactive materials. Next, it will be red mercury....

[Stub Mandrel]

59 minutes ago, George 47 said:

Fairytales and fables.....breeder reactor....really.....He disassembled some fire detectors plus some low-level radioactive materials. Next, it will be red mercury....

I think the Wikipedia article is very balanced and unsensational.

"His homemade reactor never came anywhere near reaching critical mass—but it ended up emitting dangerous levels of radiation, likely well over 1,000 times normal background radiation."

[Thalestris24]

2 hours ago, George 47 said:

Wow, there are some fruit-cakes around. Taking the Am 241 source out of a smoke detector is not a great thing to do.

If you want an alpha source try a granitic rock from Cornwall or Scotland. If you want to get paranoid then Brazil nuts and coffee have higher than average levels of alpha in them and guess what, they still taste nice and do no harm although the chocolate Brazil nuts are ideal.

I'm sure it's fine. I've kept the part with Americium in it wrapped in foil in a safe place. The old detector has been lying around in my flat for years - since before I moved in in 2011. There must be loads of these detectors simply discarded in the environment and they remain cheap to buy.

Louise

[CraigT82]

4 hours ago, George 47 said:

Wow, there are some fruit-cakes around. Taking the Am 241 source out of a smoke detector is not a great thing to do.

Referring to a fellow member as 'fruit-cake' in the way you have done here is quite frankly offensive and there is no need for it. 

[saac]

So long as you have taken sensible precautions which I know Louise would have there is absolutely nothing wrong with this. Short of removing the material itself from its enclosure.  What is dangerous is people being overly cautious because they are ill informed. Like Lousie said, many of these detectors have been incorrectly discarded by many folk over the years, I hate to think how many simply ended up in land fill. 

Jim 

[SilverAstro]

The Americium in a smoke detector poses no significant risk,
there is no significant risk even if someone breaks the encapsulation*.
It would not be in a consumer/houshold product if it had not been through a rigorous certification/regulation process.

If someone were to find a method to 'scrape it off' the electrodes and eat it (or snort it !) then there would be a long term risk,
The Radon that people breath daily is a much greater risk.

There is no above background risk in disposing of them in the trash either.

* and the woowoo 'scary' encapsulation is only round the reference electrodes, not round the 'open to the smoke' electrodes.

In short Louise @Thalestris24 has nothing to be worried about, which she already knew.