Re: Use of unsealed thorium

[Ccja@aol.com]

Thorium is a rare earth, or close to one, and is used in the manufacture of
glass lens, as a dopant, to achieve certain optical properties, and in the
manufacture of electron tubes, to, I take it, optimize emissive properties.
One can get counts well above background, especially with a scintillometer,
from, e.g., camera lens that are doped with Th. It can also, annoyingly,
cause fogging of the film!