Surprisingly (at least to me), you may not die. I recently ran across an article about Anatoli Bugorski's firsthand experience with a proton beam, written up in Wired
several years ago. This year's startup of CERN's Large Hadron Collider
(LHC) prompted questions about what would happen if you stuck your hand in particle beam (or your face). Anatoli put his head in the path of a particle beam coming from an accelerator that he believed was shut down. He supposedly saw a blindingly bright flash, yet felt no pain. The left side of his face swelled up. He was taken to a hospital so that researchers could care for him and also record the manner of his death... except he didn't die. His skin peeled away and tissue irradiated by the beam died. Though the left side of his face was paralyzed and he suffered permanent neurological damage, Anatoli retained most normal human functioning. He suffered seizures, but he was able to maintain a career in science. Obviously getting nuked by a particle acclerator is a bad plan (and wouldn't happen at the LHC because I believe the beam is in a vacuum). Were you amazed such an encounter might be survivable?