How to fake a particle reactor WITHOUT Dynamic Paint

Hey! I´ve just finished a video tutorial about how to fake a particle reactor system in Blender without dynamic paint.
Because i wanted to test my greenscreen i made this tutorial a little bit more entertaining :D.
What do you think?

Thanks a lot. Very resourceful, and a heck of a lot faster than the pain-in-the-butt Dynamic Paint method!

Nice solution. I wonder what else you can do with this Boolean analysis?