Thursday, September 23, 2010

Don’t cross the LHC stream

Don't cross the LHC stream
What would happen if you put a hand in LHC beam?
I think most of the question has already been answered. After experiment, LHC beam is dumped into beam dump which is made from graphite. It heats graphite to quite high temperatures, while making some secondary radiation, but it does not stop within first few centimetres of graphite. Your hand is not graphite, but it is close enough. Also, note that while the energy is equivalent to the kinetic energy of the cargo airplane, momentum is fairly small (it does not have a lot of punch).

So what I believe would happen is that it would *burn* a hole through your hand, turning a line into steam, while giving you a fatal dose of all sorts of secondary radiation from collision of protons with atoms in your hand, and sending some hydraulic compression shock wave (from steam expansion) through your body, which may or may not kill you when it reaches vital organs (i would guess it won't be strong enough to kill you, but i dont know if it will rip your hand apart). To summarize, you're gonna die if you stick your hand in LHC beam, i would say probably from radiation poisoning.

edit: correction. The beam energy is 350 megajoules, and the length of beam dump is 700 centimetres. I would say that the beam surely deposits >0.5 megajoule per centimetre at the entry, that is, your hand is going to get >1 megajoule deposited, significant fraction of this as heat. That is >250 grams of TNT . I would guess >1kg of TNT even, as the beam dump is so long as to stop the beam entirely, the beam deposits most of energy near start of dump. So I would guess that resulting explosion would kill you in a quite messy way, but at least it would be a quite quick death.


  1. What if you pee into the lhc stream?
    What if you replace graphite with bubbles with Hydrogen in them?
    What if the graphite was 1 meter instead of 7 meters thick?


    Patiently awaiting some answers here!!!

  2. pee: big mistake. Kaboom, same as hand in the beam basically. Bubbles: hmm mmm will burn the spiral figure into it, and I'd say ignite that thing if its in air.
    Graphite, well, I'd guess most of beam would go through that graphite, the concrete and steel shielding and ground behind beam dump would take some extra beating. Would look pretty. It would be sparking some if its hitting a dielectric (concrete).

    The real question is: can beam deflectors be reprogrammed to draw arbitrary path with the beam? :)