Re:Radiation - Seems to be a recurring problem. (Score 1)

I'm afraid nothing that currently exists can shield gammas and at the same time let RF out. Microwaves are relatively long wavelengths (compared to light), so screens can be made to let visible light through but block the microwaves. For gamma radiation (much, much shorter wavelengths than microwaves), the only shield is thick pieces of "high-Z" material such as lead or steel. Cobalt-60 has fairly high evergy gammas (~1 "MeV" in energy), so you'd need a good-sized plate of Pb to block it (e.g. see http://www.utoronto.ca/safety/RadTraining/Module7. htm; in it they show that a 1.1cm thick lead sheet will reduce the gamma intensity from a Co60 source by 50%). Steel is worse...I *think* you'd be looking at ~ 1" thick for 50% reduction. As the reduction is exponetial with thickness, you'd need many times this quoted thickness to drop the intensity to e.g. 1% (1/2 * 1/2*1/2*.....).