A few weeks ago, we had a discussion about using strontium-90 for illumination by Cerenkov radiation in a swimming pool (the concept has since been expanded to ponds and water features). I've blogged about it too.

The real show stopper to the operation was the emission of 2 MeV gamma photons from yttrium-90, the decay product of strontium-90. I'm talking with a friend now about it and we started thinking about more innovative solution to gamma ray shielding.

We have a single wavelength of gamma to worry about, 5.7e-13m. What is the possibility of blocking this by making use of destructive interference?