Thanks Trevor,
That is an unusual site - I hadn't seen it before!
Believe it or not, I used to work with gamma rays (very powerful, and very damaging radiation)... The source was a radioactive isotope. I did it as part of a field of physics called
Mossbauer Spectroscopy, where we'd measure the shifts in the energy levels of atomic nuclei. However, I got out of that field because I didn't like the idea of being exposed to radiation all the time! (Even with the "lead apron" we'd wear to protect ourselves!)
Best wishes,
Dien