Don't be a hero in a particle accelerator by stepping in front of someone to block them from the ray
You'll do more harm than good, because your body will deflect the radiation as it passes through you, so instead of having a small highly concentrated ray passing through the victims body, the ray passes through you and covers the victim in wash of still pretty dangerous pions or whatever they are called.
The actual mass of the atoms won't hurt you at all though, so that's good.
