Pretty cool. I will try to build one myself. I wonder if a high voltage and a smaller chamber may work ? Well just like a Geiger Tube, except you build one as a ion chamber, higher voltage ( 50 – 300 ) and small ( medicine bottle with alumunium as cathode ) I really like these homemade projects. I call them “McGiver” projects. I just read Electronics Now – January 1994, an article about build a radon dectector. It use a pop can as a chamber , high voltage and a JFET to receive the signal. Intersting.
Where can I buy 1/4 mil aluminized mylar for the window?
I bought a roll from e-bay. The seller was selling it for basement type grow rooms, but it is aluminized Mylar that is extremely thin.