[fezz]

Forgot to mention... in talking with NASA about deploying cameras on the space station, the issue being able to fix pixel death by gamma ray is more relevant. Water is apparently one defense against it but not so practical. How much water would you need?

[TheLoneWolfling]

Water has a halving thickness of ~18cm for gamma rays. So a fair bit.

Unfortunately, most other things are also of the same order of magnitude of ~20g/cm^2 - with gamma rays the single most important thing is just "how much mass is in the way". Which is exactly what you don't want.