I am doing an essay about particle physics and I need some help.
I am comparing the results in a Wilsonchamber with and without a radioactive material present. I were able to see a lot of traces from alpha particles, but without the radioactive material there were no traces at all. I've tried to improve my chamber by making it more airtight but could still not see any spontanious particle decay. I am using a plastic chamber that is about 0,5cm thick and for the bottom a sheet metal plate.
I know I am not giving you all information there is about the chamber but what reasons could there be for not seeing spontanious decay while the decay with a radioactive material is so obvious.