large diffusion cloud chamber with radon gas double-decaying!
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers and askers link it as a clear visual example of a cloud chamber showing radioactive decay and particle tracks in real time.
Recommended by 1 people across 1 different months, 2013 to 2014.
What it is
A short 2010 demonstration of a large diffusion cloud chamber at a museum, shown with normal background radiation, an americium-241 source, and radon-220 gas. The presenter, from the bionerd23 channel, narrates as particle tracks and decay events become visible.
What people said
Recommends DavePhD · 2014-05 · Physics Stack Exchange · on “Can nuclear transmutation be observed in real time?”
Certainly with a cloud chamber you can. Here is a nice video of using one: [this video] There are many instructions on the internet for making your own cloud chamber and observing decay of radioactive americium-241 from an ionizing smoke detector for example.
Cites Geoffrey · 2013-12 · Physics Stack Exchange · on “Charge to mass ratio inversely proportional to curved path radius?”
Well, the particles won't always follow circular paths (for instance, the particles in this [this video] video). But, if you apply a constant magnetic field across the chamber, charged particles moving in the field will be deflected according to the Lorentz Force Law [LINK] . The centripetal acceleration for a particle moving in a circle is $a=\frac{v^2}{r}$, where $v$ is the particles tangential velocity and $r$ is the radius of the circle. Plugging this into Newton's Second Law [LINK] we get $$ m\frac{v^2}{r}=qvB $$ Rearranging: $$ \Big(\frac{q}{m}\Big)\Big(\frac{B}{v}\Big)=\frac{1}{r} $$ Or, in other words, the charge-to-mass ratio is inversely proportional to radius of the particles circular
Cites user63528 · 2014-11 · Physics Stack Exchange · on “Sensitivity of Cloud Chamber”
I have been watching some videos on cloud chambers: [this video] and they are quite amazing. What I can't figure out, is why aren't these chambers over loaded with tracks when a radioactive source is placed near it? Clearly, they are sensitive enough to pick up all ionization events of a single particle's trajectory. For example, in the above video, the person places Radon-220 in the chamber. By conservative estimates, there should be ~billions of alpha particles emitted. If that is the case, you would never expect an entire particle track to be visible. Either they would be overloaded with condensation, or (if the was a very low probability of condensation) you would see tiny dots all over the p