Here's the story of one guy who's head was in the path of a proton particle beam: http://boingboing.net/2011/02/22/what-happens-when-yo-6.html http://boingboin

Here's the story of one guy who's head was in the path of a proton particle beam: http://boingboing.net/2011/02/22/what-happens-when-yo-6.html http://boingboing.net/2011/02/22/what-happens-when-yo-6.html "The radiation absorbed by his head was in the region of 1000 gray. 5 gray worth of X-rays is generally considered fatal, but Bugorski survived and went on to complete his PhD (a proton beam moving near the speed of light has different characteristics from an X-ray!). The side of his face that was burned by the beam's exit has not visibly aged in the years since the accident. " Note that such a beam contains millions (or a few orders of magnitude more?) of protons. I can't say whether millions of protons with a millionth of the energy as this particle do more or less damage.