Radiation shielded camera, 10000rem/sec 1-4MeV x-rays

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Andrew Seltzman
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Radiation shielded camera, 10000rem/sec 1-4MeV x-rays

Post by Andrew Seltzman » Tue Nov 25, 2014 7:55 am

I recently built a radiation shielded gopro camera for observing the inside of an industrial electron beam irradiator (up to 5MeV, 20mA beam) during a lichtenberg figure production run. The camera was shielded with 1/4" lead with a 1" thick 50% lead glass window and an additional 1/4" thick lead top shield to prevent direct electron beam contact with the camera box. Radiation exposure was measured with a 10Sv(1000rem) dosimeter sticker. Even inside the box the camera was exposed to 2000rem-4000rem during 15 passes through the irradiator. While external radiation was in the ~10krem/sec due to x-rays alone, even more including the electron beam. The camera survived with no apparent damage.

Lead box for camera shielding
SAM_3655a.jpg
Camera on irradiator cart
SAM_3683a.jpg
Calcite being irradiated
calcite55.jpg
External dosimeter after 1 pass(x-ray exposure only, under top beam shield)
SAM_3649a.jpg
Video of an acrylic sample and dosimeter
https://www.youtube.com/watch?v=7H9SA8XCHug

Video of a calcite sample
https://www.youtube.com/watch?v=P35G6oI6x-8

Pictures and videos posted at:
http://www.rtftechnologies.org/physics/radcam2.htm
http://www.rtftechnologies.org/physics/ ... 1y2014.htm
Andrew Seltzman
www.rtftechnologies.org

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Richard Hull
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Re: Radiation shielded camera, 10000rem/sec 1-4MeV x-rays

Post by Richard Hull » Tue Nov 25, 2014 7:18 pm

Cool stuff! I have a friend, Kim Goins, of some 20+ years who sort of started the modern re-surgence of Lichtenberg figure making. Kim is a research physicist with NRL, (Naval Research lab), in DC. She and a friend rented beam time on a linear electron accelerator perhaps15 years ago and had a lot of plastic cut up and took it to be irradiated and create the figures in plastic. Later they shared beam time and expenses with another friend of mine, Bert Hickman. Bert now goes regularly to create hundreds of figures and has a small eneterprise built around their manufacture. I see Bert about once each year at the N.Y. Teslathon and he always has a lot of the figures for show-and-tell as well as to sell. Bert also brings a lot of videos using a camera on the cart to show each year as well, coupled with the odd tales of his results.

After going through about two such efforts, Kim quickly lost all interest, but she paved the way for many other amateur efforts that continue to this day in much the same way that Tom Ligon innoculated me on the fusor back in 1996. Like Kim and the Lichtenberg figures, Tom is now totally out of the fusor effort having left the EMC squared, Bussard effort in the early 2000's. Tom never even really messaged much on Songs or Fusor.net. Of course, many who have come here are now long gone. A significant fraction of the actual Fusioneers are also gone. I guess nothing lasts forever.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Andrew Seltzman
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Re: Radiation shielded camera, 10000rem/sec 1-4MeV x-rays

Post by Andrew Seltzman » Tue Nov 25, 2014 7:24 pm

Yes, this was one on Bert's lichtenberg production runs.
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Richard Hull
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Re: Radiation shielded camera, 10000rem/sec 1-4MeV x-rays

Post by Richard Hull » Tue Nov 25, 2014 7:35 pm

You just can't shield against X-rays at that energy! However it appears that your shilding did save the camera. After 10 years of neutron bombardment I have about 10 pixels in my sony single board camera that are blown.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Andrew Seltzman
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Re: Radiation shielded camera, 10000rem/sec 1-4MeV x-rays

Post by Andrew Seltzman » Tue Nov 25, 2014 9:43 pm

Interestingly enough, even an unshielded camera will survive, but it will pick up MUCH more noise from x-rays. As a test I sent through an older smartphone under the top lead shield(no electron beam bombardment) but otherwise unshielded. The smartphone recorded video throughout the run and was undamaged but you can see a significant increase in noise. The lead box may not be able to shield out the higher energy x-rays, but does provide a significant amount of shielding in received dose, particularly for the lower energy x-rays.

Unshielded cellphone camera under top lead shield
lg-optimus-xray.jpg
lg-optimus-xray.jpg (45.76 KiB) Viewed 2781 times
GoPro in 1/4" lead box under top lead shield
calcite55a.jpg
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John Taylor
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Re: Radiation shielded camera, 10000rem/sec 1-4MeV x-rays

Post by John Taylor » Wed Nov 26, 2014 5:49 pm

That's a really cool post! In the fission business, we often run an underwater camera in the vicinity of irradiated fuel assemblies and they always have a few pixels become unresponsive and you can always see flashes of light when in a radiation field of any strength. An interesting thing that I found out is that the damage to a CCD camera is cumulative. A larger field for a short time can cause the same damage as a longer time in a smaller field. Of course, we try to keep our cameras in fields that are many orders of magnitude smaller than your example!

I really like the calcite glowing so intensely. Something a human would not be able to experience in person for more than a few milliseconds!

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