Don't Cross the LHC Stream! (Maybe)
jamie points out this piece from always-entertaining Bad Astronomer Phil Plait, who asks this week the simple question "What happens if you put your hand in the beam of the Large Hadron Collider?" The thrill of discovery to me doesn't sound worth the worst-case scenario.
An artist makes unusual "sculptures" by putting acrylic blocks into the beam path of a relatively small electron accelerator:
http://www.dailymail.co.uk/sciencetech/article-1232908/Captured-lightning-The-artist-traps-fossilised-bolts-electricity-inside-acrylic-blocks.html
Fermilab had a beam loss event in 2003 (beam came into contact with part of the ring). The beam drilled a 2.8 mm hole through a 5mm tungsten support. It also etched a groove 25 cm long and 1.5 mm deep into a stainless steel collimator (after passing through the tungsten). Apparently this took about 8.3 ms (over several turns of the beam) before the beam dissipated.
I'm guessing if you could insert your hand fast enough (not possible, even if there wasn't a vacuum tube) you would end up with a nice small hole drilled through your hand.
This is the report from the Fermi incident:
http://beamdocs.fnal.gov/DocDB/0011/001185/001/FN-751.pdf