Per the wikipedia article on the guy who got hit:

On 13 July 1978, he was checking a malfunctioning piece of equipment when the safety mechanisms failed. Bugorski was leaning over the equipment when he stuck his head in the path of the 76 GeV proton beam. He reportedly saw a flash “brighter than a thousand suns” but did not feel any pain.[1] The beam passed through the back of his head, the occipital and temporal lobes of his brain, the left middle ear, and out through the left-hand side of his nose. The exposed parts of his head received a local dose of 200,000 to 300,000 roentgens (2,000 to 3,000 Sieverts).