Digital Camera Radiation Dosimeter

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landrew
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Digital Camera Radiation Dosimeter

Post by landrew »

I created this for the people of Japan. Please help get this video into Japan.
http://www.youtube.com/watch?v=G6Q7VfWdgEg

Thanks for your help,
Landrew
Jerry Biehler
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Re: Digital Camera Radiation Dosimeter

Post by Jerry Biehler »

A banana baseline... Oh boy.

Pretty soon we will be measuring radiation in uBs/hr (microbananas per hour)
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Chris Bradley
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Re: Digital Camera Radiation Dosimeter

Post by Chris Bradley »

The "BED" is already an 'established' measurement!:

http://en.wikipedia.org/wiki/Banana_equivalent_dose
landrew
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Re: Digital Camera Radiation Dosimeter

Post by landrew »

Hi,

No kidding, this is a inexpensive dosimetry technique that can be built and detect gamma emitters within minutes. The idea was using a known source for calibration the 40% potassium in the salt substitute has roughly .oo1% potassium 40 the decay gives you beta minus 89% of the time and electron 11% which emit the gamma 1.46 mev. In order for people to know their detector is working you DO HAVE TO HAVE A KNOWN SOURCE! The salt substitute is better than trying to keep bananas around (one bunch was eaten during this test).
The challenge I think for some people will be making sure their detector does NOT have a light leak. I have been on some of the largest scintillation detector experiments in the world, that wasn't the challenge. The challenge was to try something inexpensive, so far I can build these for sale to schools for under 40$, I have given some to friends that teach physics at the high school level already. If you will notice I include the wiki definition in the video comments back the day I posted it.
landrew
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Re: Digital Camera Radiation Dosimeter

Post by landrew »

So tell me, you think that video is about bananas? That video is about using plastic scintillator and a cheap digital camera to measure a very small amount of radiation!
People of Japan might like to use a inexpensive dosimeter about right NOW! Don't you think wise guy? Yes, the banana equivalent was used back in the fifties. I work with science grade ccds in a dark energy experiment and wasn't even sure I could see a few gammas from household beta/gamma emitters! I guess this forum isn't that interested in helping people. I will withdraw and stick with my high energy friends.
Chris Trent
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Re: Digital Camera Radiation Dosimeter

Post by Chris Trent »

It is a fascinating technique, no doubt invaluable knowledge to anyone who might be in a radiation zone.

For my part I don't know of anyone in Japan, but may pass it on to a few freinds who might find it interesting.


This does have some immediate applications here though. One of the questions that has been bandied about is whether the neutrons produced by a Fusor are in fact isotropic. Nearly all measurements here have been predicated on that assumption, and would be invalid if this was not the case. The conundrum has been how to test for it in such a dynamic system. Fusors are too finicky to simply test at a series of locations in sequence, and few of us could afford the sensor arrays that the professionals use. However, since you have demonstrated that a digital camera can successfully image scintillations in plastic scintillation material, and from what I see can do it with a degree of spatial accuracy, we may now have a way to test conclusively.

You have my thanks, and best of luck getting the word out.
Richard Hester
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Re: Digital Camera Radiation Dosimeter

Post by Richard Hester »

Don't take a little levity amiss - it was an interesting experiment. I'd try it if I had a digicam that would do time exposures like that. I have a can of stump remover that might do as well as the salt substitute. The only problem is figuring out some way of calibrating the response. I'll bet that response might be different camera to camera.
Jerry Biehler
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Re: Digital Camera Radiation Dosimeter

Post by Jerry Biehler »

But the output means nothing. It can detect the presence of some sort of radiation, but thats it. There is no way to quantify the result.

And this kind of information to an uniformed public is not always a good thing. The public has no idea how to interpret the results. This can lead to panic where there need be none.

There are already crowd sourced maps working that show rad levels all over japan, like this one:

http://www.rdtn.org/
richnormand
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Re: Digital Camera Radiation Dosimeter

Post by richnormand »

Interesting experiment landrew.

I watched the video and perhaps I missed a few things. Four questions if you dont mind:

What is the type ( Saint-Gobain or Bicron number for example) of scintillator used here? Looks blue even in the video. Did you have fluorescent lights giving off UV while doing it? The ones I have do not seem as efficient. They show a bit of blue but need a UV source to stand out.

Camera type and the equivalent ISO or ASA setting? It's CCD looks pretty sensitive and low noise for room-temperature readout.

Considering you have the scintillator blocks butted against the lens, are you in macro mode? The before/after shots with the potasium iodide salt substitute bottle shape looks as an outline and the pixels hits look well resolved (as they should be) but the outline looks sharper than I would expect if you were not in focus on an object. Also, the gamma hits in the plastic would create photons in the blue range and undergo internal multiple reflections. I would expect to see an outline of the surfaces and sctratches.

Do you have longer exposures to see what is the ultimate SNR (is the signal growing faster than the noise) Also your pix seem to be in black and white. I also note that the two pix do seem to have an identical pattern of aprox 10 bright dead pixels (bright dots in the same locations between the two pictures), On my camera the noise does show up in random color and random positions pixels at low intensities?

Cheers.
John Futter
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Re: Digital Camera Radiation Dosimeter

Post by John Futter »

Landrew
I do not think that this is going to help the Japanese except to engender more hysteria.
From the number of CCD cameras I have destroyed from radiation damage that have not have had a significant dose for a radiation worker, and these without a scintillator in front.

A better response would be to check the damaged pixels off a camera exposed.
You do not have to have the camera powered-- just expose it to a high enough radiation flux then count the multicoloured pixels under dark conditions with the camera powered.

Ps your scintillator is too thin to react to the most damaging radiation --ie not enough stopping power

I do not think that the Japanese government is hiding anything from the local population --they --we all know the situation is not fantastic --the fear is at the moment the Cs 137 with the 30 year half life -- any amateur or professional would have done the camera calibration with a Cs 137 check source not K /or bananas. Most universities will have at least one or more of these sources in their physics departments.

PS, PS you pop up here with this, without introducing yourself which is against forum rules, and no real name

Move along
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Carl Willis
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Re: Digital Camera Radiation Dosimeter (THREAD CLOSED)

Post by Carl Willis »

This is a cute homebrew project of the type that would be appropriate in our radiation detection forum, even though I'm skeptical of its serious applicability to the situation in Japan.

However, Mr. Andrew Latham, the poster, decided to throw a temper tantrum last week when routinely asked to comply with our registration requirements. He also made clear his narrow interest in self-promotion. So unfortunately he can't be joining us for further discussion. I think it's best just to close the thread about this individual's YouTube link, and if anyone else wants to discuss scintillation detectors or camera adaptations thereof, we'll just start new threads in the radiation detection forum as appropriate.

Thanks for your understanding.
Carl
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