So yesterday at work, I had some free time and decided to take our shiny new cloud chamber out for a test drive. At this point, you might be asking: "What's a cloud chamber?" "Wait, why are my thoughts being typed out on this blog post?" "What unholy power is responsible for revealing my innermost deliberations onto this miniscule and insignificant blog?" "Wait, is this just E trying to be witty and whimsical?" "Haha, very funny, now get back to writing your post." "Anymore of these shenanigans and I'll stop reading right here." Good point. Sorry about that.
A cloud chamber is a simple device that has a chamber (about the size of an average piece of Tupperware) that is filled with an alcohol vapor. Simply, the bottom of the chamber is filled with an alcohol (like isopropyl alcohol) and with a little cooling around the chamber provided by cold tap water, the chamber becomes filled with a vapor of these alcohol molecules. And the purpose of all this? This vapor is really good at interacting with high energy particles, like those you'd find from nuclear processes (for those who want to know: alpha particles, beta particles, gamma rays, etc). When a high energy particle flies through this vapor, it can collide with these alcohol molecules and, in the process, ionize them. When an alcohol molecule becomes ionized, the neighboring alcohol molecules become attracted to it and condense onto this "seed" ionized molecule. It's like the same process that makes water vapor in the air condense into a larger cloud (hence: cloud chamber). So this newly formed, larger cloud of alcohol becomes big enough that we can see it. And because it's so much bigger (and heavier) than the vapor of molecules around it, it falls downwards.
So as the high energy particle flies through the alcohol vapor, it leaves a thin alcohol cloud trail behind it, showing us the path that the high energy particle travels along. Cool!
So, we set up the cloud chamber and had everything running. Our high energy source was a piece of radioactive cobalt that emits gamma rays (high energy photons - just like light, but with a lot more energy and WAY outside of the visible spectrum). We placed the cobalt sample near the chamber. As the gamma rays from the cobalt enter the chamber (traveling at the speed of light) they can collide with the molecules in the alcohol vapor. When that happens, the gamma rays can knock electrons off the molecules, sending them shooting across the chamber at high speeds (think of the breaking shot in billiards)! And it's these high speed photoelectrons (the electrons that are knocked off the alcohol molecules by the gamma rays - i.e. photons) that create the cloud trails through the vapor. So, in this chamber, we don't see the path of the high energy gamma rays, we see the path of the photoelectrons that are created when these gamma rays enter the chamber and collide with the alcohol molecules. But still, seeing those cloud trails is evidence of the gamma rays being there. Plus it just looks so cool.
So without further ado, here's a video showing the subatomic fireworks display:
Isn't science cool? It totally it is.
And now back to our regularly scheduled programming.