[mctavjb9]

Sorry to be a buzzkill, but the LHC beam circulates in an extremely high vacuum. There's no way a hand could even get in the beam without breaking the vacuum, thereby causing the accelerator to shut down automatically. Also, it's cryogenically cooled. Radiation dose aside, the hand would freeze and probably fall off.

http://www.lhc-closer.es/php/index.php?i=1&s=4&p=15&...

Incidentally, when I was working at CERN in the mid 1990's, the Large Electron-Positron Collider (the predecessor to the LHC) was shut down by an act of sabotage involving 2 Heineken bottles placed in the beam pipe. The electrons and positrons (and many physicists) were not happy bunnies. http://blogs.nature.com/news/thegreatbeyond/Beer%20bottles.p...

Update: Now I see that the vacuum point has already been made. There are no heavy ions in the LHC main collider, they're produced by bashing protons into a target in one of the secondary beamlines. Also, antimatter is frequently the byproduct of extremely high center of mass proton-proton collisions.