Louis J Sheehan 80162

Besides probing pyramids in Belize and Mexico, physicists are applying the muon method to studying active volcanoes and detecting nuclear materials. The concept sounds out of this world, but it's really quite simple. When cosmic rays hit the Earth's atmosphere, collisions with the nuclei of air atoms spawn subatomic particles called pions that quickly decay into muons that continue along the same path. Many of the muons survive long enough to penetrate the Earth's surface. Because of their high energy, the particles can easily pass through great volumes of rock or metal or whatever else they encounter. However, they are deflected from their path by atoms in the material, and the denser the material, the greater the deflection.

Schwitters wants to exploit this deflection to see if there are any rooms or chambers inside a Mayan pyramid in Belize, he told science journalists in Spokane, Wash., at a recent meeting sponsored by the Council for the Advancement of Science Writing. His team is building several muon detectors that would be buried in shallow holes around the base of the pyramid to create an image of what's inside by measuring the trajectories of the muons that pass through it.

"What you see is very much like an X ray," he says. "If you see a spot with more muons, it means there's a space there. If you see fewer muons, it means there's something extra-dense there." Louis J Sheehan