RealClearScience - What Would Happen if You Stuck Your Head in the Large Hadron Collider's Particle Beam?: "But let's say, completely hypothetically, that all of CERN's stringent safety mechanisms failed (which is highly unlikely to the point of impossibility), and someone managed to climb inside the LHC as it was turned on, and was subsequently struck by the particle beam? What would happen?
"I certainly wouldn't advise doing that," CERN scientist David Barney told the University of Nottingham's Sixty Symbols. "The beam itself is focused down very tightly to less than a millimeter across, extremely intense. The actual energy carried by the beam is like an aircraft carrier in motion."
Another scientist at CERN, Steven Goldfarb, was more blunt and to the point. "It would burn right through you."
Barney explained that a much wider halo of radioactive subatomic particles, mostly electrons and muons, accompanies the "extremely" intense proton beam.
"Your whole body would be irradiated. You'd die pretty quickly.""
'via Blog this'