Simple expansion cloud chamber
Yeah, atom physics find one's way into LMR. Here is my simple expansion cloud chamber. An expansion cloud chamber works by saturating the air in a chamber with water or isopropyl alcohol vapour. Dropping the pressure in the chamber suddenly, causes super-saturation. Cloud will form wherever electric charges are. Unwanted charges in the chamber are eliminated by an electrostatic clearing field. Alcohol droplets then forms on the tracks of charge recently left by ionizing alpha particles. An advantage of the expansion cloud chamber is, that you don't need try ice like for a diffusion cloud chamber.
The photographs below show typical alpha particle tracks. The tracks are displaced from the original paths by the air flow during expansion. The tracks only last for a fraction of a second, so I converted the recorded video into individual frames.
Things I have learned:
- Water, methyl alcohol, ethyl alcohol work also but isopropyl alcohol is best
- The syringe for expansion should be as big as possible (100 ml glass syringe)
- I got the best results in compressing the air in the chamber first by the syringe, putting the squeezed rubber hose from the syringe and open then the hose suddenly to release the overpressure
- The felt I used on the metal platform is not really felt. It is a piece of cloth from an old laptop bag. It sop up the isopropyl alcohol very well, but it has a kind of structure which produces unintended light reflections. Fine black felt would be better
- The required voltage for the electrostatic clearing field is not problematic, works in a wide range
This guy here also built an expansion cloud chamber as well as other amazing stuff.
I'll try to upload a video within today or tomorrow.