Alpha Radiation Visualizer
I started this project with more of an idea of creating a system that would visualize Cherenkov radiation via webcam utilizing a Gamma radiation source and heavy water in some heavy lead shielding to produce the tell tale bursts of blue light. Perhaps hook it up to the LCD window kit system we did and display it on the windowed screen. When I decided to ramp up the project and also was experimenting with other types and sources of radiation for the project I stumbled across a myriad of new ideas for possible systems with some far reaching and profound results. While this write-up is just discussing in detail the implementation of this apparatus for ones personal amusement via screensaver, there are other far reaching possibilities for this system I will discuss later in the article.
“The most absurd and reckless aspirations have sometimes led to extraordinary success.”
–marquis de vauvenargues
As stated in the introduction, this project was an accident. I did not intend to go down the path on which I eventually arrived. But ultimately it’s something I feel much better about publishing on the site as it’s a far safer project. While I am not playing with huge amounts of Gamma radiation in this project, it was the recklessness of that idea that led to this success.
The basic idea behind this project is using the built in CCD in a USB web camera as a medium for alpha radiation to interact with. The result is a visual presentation of pops and streaks of light as the partials interact with individual pixels of the CCD. While this has a very nice effect and makes for a fantastic “screen saver”, there are more practical and important possibilities with this project.
One of the applications I have envisioned for this project is a cheap and easy genuine random number generator. True random numbers in computing are nearly impossible, and successful solutions are very expensive systems based on radioactive decay or atmospheric measurements, for example. Using a small / relatively safe radioactive source and a high res CCD or CMOS sensor and assigning a value to each pixel and perhaps mixing in an algorithm or two with an inexpensive practical PCI card that is capable of generating genuine random numbers. Applications that could greatly benefit from this would be encryption, security applications, Computer AI and the Gambling establishment to name a few.
Check out http://www.vanheusden.com/ved/ for something you can apply now!
The Web Cam:
The heart of this system uses a Logitech quickcam 5000 for the interception of the alpha particles and the display of the results. The quality of this camera I have to point out is very high. The 1.3 megapixel image quality almost made me regret tearing it apart. But then I saw the lady there on the box cover smiling at me just egging me on (I wish she would stop. The project is complete). I would wager that Logitech never expected their camera to be used like this!
Total cost via NewEgg: $60.00
The Project Box:
This project box is a little large I admit. But for 3.00 at Radio Shack I couldn’t pass it up. The project box in this application doesn’t have to be a mid sized mysterious black box; you could actually fit everything back into the original web cam housing with great ease. But having a “mysterious black box” hooked up to your computer has a certain aesthetically pleasing air to it after all.
I know. I know. your first reaction to seeing that I am using copper as shielding is not a good one. You’re thinking “What a dumb ass, you should use lead, not copper!” well your right. and wrong. Alpha particles actually are stopped in their tracks by a mere sheet of paper. So why the shielding at all then? We’re actually shielding the camera from external electrical noise and not necessarily keeping the radiation in. By using copper shielding and connecting it to our common ground on the webcam itself, we are able to reduce the amount of external EMI and have a cleaner overall result. Cost for the shielding: $11.00, and there’s lots left over for other projects.
The Radiation Source:
So where does your somewhat normal run of the mill geek go to pick up there normal every day alpha radiation source? Well The Home Depot, of course! Smoke detectors for some time have had a radioactive source in them. Traditionally they use about 0.2 milligrams of Americium 241. Americium 241 is a synthetic element, and a strong alpha radiation source. Perfect for our application at hand as it is “relatively” safe to handle by a novice. But as it is a radioactive source, and does emit a small amount of gamma radiation it should be handled with care and only by someone educated in handling such materials. Smoke detector: $14.00
The Operation Begins…
This is the core of the system and therefore the first part of the system we get to take apart. The Logitech webcam is one of the best there is on the market, with a flexible shapeable stand that we will have to use in an upcoming project. One word for the wise with this project is to be vary careful with dissecting electronics. Do not disassemble this project with it plugged into your USB ports on your computer. Additionally, all circuit boards contain lead and other potentially dangerous chemicals. Do not eat or handle food while or after handling lead based circuit boards until you have washed your hands.
So here is the webcam disassembled. Removing outer casing, as well as unplugging the mic and photo button on top, you should have as bare bones of a camera as possible for this project. If you are planning on reinstalling the completed project into the camera body I recommend keeping track of all the parts and screws.
Here is a close-up of the camera board and lens. The lenses is basically a plastic housing screwed onto the board. The CCD the camera uses is actually surface mounted on the board and the plastic housing helps to protect it from dust and other contaminants. The lens is a variable focus lens and can be turned left and right to adjust focus (done at the factory).