Hey Grandpa, I think you're going to need more than aluminum foil. Cosmic radiation is blocked only by lead, so here's what you could do: Go out to the garage and melt down all of your downrigger weights. Pour the liquid into a large iron kettle. Now insert your head. When the molten lead cools you should be sufficiently protected. :p j/k

p.s. You may have to shave the moustache first to insure a good tight seal.