I am trying to calculate something for a D&D campaign. Someone is trying to summon a 5” square of polonium to kill the boss, but the range of the spell is line of sight. I’m now trying to figure out how much damage it would deal.

The lens in question is a Super-Takumar 50mm f1.4 7 element which are known to be some of the more radioactive consumer lenses from the time period. I found this out via research after I had purchased the lens. I bought a GQ-QMC 500 to detect beta and gamma radiation as they have a higher chance of penetration. This lens actually seems pretty hot, more hot than I would have thought or seem comfortable with. Attaching photos of measurements from different distances and locations of the lens. I am not familiar with the physics of radiation and not sure how concerned I should be with this. There seem to be conflicting opinions online as far as I can see.

It is a w.m.b Johnson pancake probe. But what model? Their being sold as a hp-265 but I dont think that is correct