If you are a certain age, there were certain science toys you either had, or more likely wanted. A chemistry set, a microscope, a transparent human body, and (one of several nuclear toys) a cloud chamber. Technically, a Wilson cloud chamber (named after inventor Charles Wilson) isn’t a toy. For decades it was a serious scientific tool responsible for the discovery of the positron and the muon.
The principle is simple. You fill a sealed chamber with a supersaturated water or alcohol vapor. Ionizing radiation will cause trails in the vapor. With a magnetic field, the trails will curve depending on their charge.
If you didn’t have a cloud chamber, you can build your own thanks to the open source plans from [M. Bindhammer]. The chamber uses alcohol, a high voltage supply, and a line laser. It isn’t quite the dry ice chamber you might have seen in the Sears Christmas catalog. A petri dish provides a clear observation port.
We’ve covered cloud chamber builds before, ranging from the simple to ones that use thermoelectric coolers.
Nice project!
“A chemistry set, a microscope, a transparent human body, and (one of several nuclear toys) a cloud chamber.”
I had all of those except the human body before I was 15. The cloud chamber was built from the one in the Scientific American book of projects. That book is the only thing I have left from my childhood, and the family all know they damn well better keep their hands off of it!
I’m going to build this one, maybe as soon as the HackaDay prize is over and I get some more time. :)
That was a fabulous book, I still have my copy.
I believe there was a DVD recently made with a full set of every Scientific American project ever featured for those who want more than just the book.
Pdf warning:
http://www.sciencemadness.org/library/books/projects_for_the_amateur_scientist.pdf
What an interesting TOC, thanks for the link!
“I had all of those except the human body before I was 15.” Ah, were you just a brain in a jar, that’s sad, glad you got a body.
Lol. Yeah, I should have left the word ‘transparent’ in there. Should have known better…. :P
I’ve heard that Wilson cloud chambers are finicky and hard to get working.
Kudos if he can make a system that’s reliable and easy to reproduce. HAD should post an update article when he has a “results” video.
A prototype I built in 2010:
https://www.youtube.com/watch?v=RooYG0bLx7s
Why all this complexity? I recently made a Wilson chamber with nothing more exotic than a beaker and a piece of plexiglas. The beaker with a piece of black cardboard on the bottom was placed on dry ice and closed with a piece of clear plastic with some isopropanol-soaked napkins attached along the rim of the glass. The chamber operated continuously for about ten or twenty minutes, at which point I decided to call it a night. It visualised tracks of a few alpha-particles, a few dozen photoelectrons and a lot of something that looked like muons (thin straight long tracks).
No dry oce and wants it to work longer than twenty minutes, possibly.
The design with dry ice works for as long as you have liquid alcohol at the top of the chamber and dry ice (or anything similarly cold) to cool the bottom. I stopped at 20 minutes because the goal was to test whether this thing worked; it’s not like I was going to discover another elementary particle by staring at it for another six hours. As for dry ice, it should be readily available; just ask at the nearest ice cream cart=)
On the plus side, it can operate continuously and has no moving parts.
A Wilson cloud chamber does not use dry ice.
The *original* Wilson chamber does not use dry ice. Mine did, and it was still a Wilson chamber, with supersaturated alcohol vapour and all that. It’s a pretty common design, actually; I learned it from a colleague who found out about it at a workshop for physics teachers at CERN.
Disagree. What you are referring to is called diffusion cloud chamber. This kind of chamber differs from the expansion cloud chamber (Wilson cloud chamber) in that it is more or less continuously sensitized to radiation.The bottom of the chamber must be cooled by dry ice or Peltier elements instead of adiabatic expansion.