Just right, Beth. Build a big enough one and you wouldn't need fireworks. I am not sure that would be safer, though.
Long ago I worked on spark and wire chambers. I even helped with a needle chamber. In those cases we wanted to see the track of any charged particle, so we had a chamber of a noble gas. This ionized and the spark followed the ionized trail. This simple detector is a great little project. Now all we need is a cirsuit to count the particles. Next project?
A counter circuit would be very easy to implement. A Geiger counter works in an identical way, except that there is some gas inside a Geiger tube. There is both analog and digital means to do the job. Of course, without a known standard, you couldn't calibrate it. Although this is a cool gadget to play around with and for educational purposes, does it have any practical use? I understand that skin, and even paper stops alpha particles. That's why an alpha source (Americium, I think) is used in smoke detectors.
Ouch Sparky! Well if you must have a visual show I suggest abandoning the dangerous HV and going for a Cloud Chamber. They are easy to build and the thickness of the vapor trail makes it easy to distinguish between alpha, beta or gamma (cosmic) radiation. As a child I saw my first cloud chamber at a Russian technology exhibit at the New York Coliseum back in the late 1950's. Both the Soviet Union and that NY exhibition hall are long gone.
Why publish something so useless? Your alpha source would need to be actually sitting on the metal plate to show activity. Alpha particles, even high energy particles, are stopped by our surface layer of dead skin. If you've ever used a cloud chamber you would know that alpha particles are stopped by a few inches (the size of the project) of air.
"Useless" is a relative word and is very inappropriate for this forum. Establishing the uselessness of a demonstration, experiment or idea is impossible - if the demonstration inspires just one person to build off of it somehow, it is not useless.
In a related story, apparently some in Pakistan don't think finding the "God particle" is all that amazing or important. It is a very useless endeavor in their minds. Heck,some members of our own Congress think that scientific data is useless and that science has no role in public policy.
So bravo to John Iovine for taking the time to investigate and build a device that addressed his curiosity.
Dead on that the term "useless" is inappropriate in this forum. While watching the video I was thinking about the possibility of adding a light sensor and micro to act as an event recorder. I have piles of what others would consider useless devices, but I learned from each project. In my life TV and sports watching are useless, but I would not wish to stop anyone from doing so. I too want to thank John for taking the time for his contribution in both hardware and the video production.
You do not need a light sensor to electronically detect the sparks. Do what they do in a Geiger counter. Connect a capacitor from the ballast resistor (the metal plate in this case) to a small one-transistor amplifier. Each spark would would produce a pulse from the transistor that could be counted by a microcontroller or other counter circuit. There would not be two sparks simultaneously. Once a spark starts, the voltage is too low for another to begin. If two particles hit at EXACTLY the same time, the one with the most energy would prevail IMO. It should therefore, be an accurate count of the number of sparks.
I would move the ballast resistor and the capacitor to the grounded side of the HV power supply, however. Less stress on the coupling capacitor and the connected transistor.
Al;ha detection useless? Unless you consider Ernest Rutherford's historical Experimenmt that led to our modern nuclear atomic theory. This was based on the production and detection of alpha particles. Alpha detection through ionization and sparks has been insespensible throughout the development of modern atomic and particle physics. Please. Mr shjacks, do your homework before picking up your pen.
They love sparks and noise and yes a little danger. This project is a great way to introduce the alpha partical. Inserting paper between the alpha source and the detector would be a good demonstration of the size of the alpha.
While a cloud chamber is certainly a good demonstration tool, its use is more difficult because dry ice is required. In addition, cloud chamber has a limited field of view and difficult to see at a distance. Using the "spark detector", in a darkened room, the entire class could see the effect.
Good thinking, MrBill. All of these Gadget Freak submissions are good teaching tools. Many of them are even submitted by students. We've had a bunch submitted by college-level engineering student teams. Recently we had a submission by a 15 year old.
Great project by John who is masterful in High Voltage Electronics. Gadget Freak projects are excellent teaching materials for all levels of science and engineering classes and student. Keep up the great work Design News staff.
You know someone has re-spun the classic cloud chamber to use Peltier coolers instead of dry ice: http://www.nothinglabs.com/cloudchamber/
This spark detector design is different from the Willis design, particularly in the size of the ballast resistor (500 ohms vs "several megohms"); and explanations for the changes?
Hi. This was great. Very Nostalgic for me. I haven't seen a spark chamber at work since the 1960s worlds fair in Seattle.
Of value? Well, that depends on whether or not you do particle physics. I can see I will have to build one to impress my 4 year old grand daughter. Just have to figure out the safety protocols for little fingers and 8KV, eh.
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