How often do positrons appear in a typical Wilson cloud chamber? I would like to know a rough estimate of how often positrons appear per meter cubed per second in a typical Wilson cloud chamber based off of your experience. I'm interested in the same quantity for the other typically observed particles as well. Also on a more theoretical note if you know of reasons behind there proportions that would be cool too. But in general I'm just wondering how often positrons end up running into you body while you're walking around on earth.
 A: A Wilson chamber is an interesting way of seeing the cosmic rays which continually bombard the earth, as well as any radioactive material placed close to it, but it is not good in getting data in an organized method so that  one can answer your question:

But in general I'm just wondering how often positrons end up running into you body while you're walking around on earth

There is a large amount of data on cosmic rays, positrons come from secondary interaction of these high energy particles, either from galactic or intergalactic origin, or by scatterings in the atmosphere, and even from scatterings in the Wilson chamber. The are a secondary component and important only for studying the origin of cosmic rays, example,  they contribute very little to the flux.
In the particle data group one finds the cosmic ray fluxes, a secondary part of which will be any positrons that have been generated from the primary (fig 29.2).
If you are worried about radiation due to positrons, it will be a very small component in the general radiation, discussed here ,
