• Question: what would happen if a particle accelerator explodes

    Asked by exit354cup to Edoardo on 13 Jun 2019.
    • Photo: Edoardo Vescovi

      Edoardo Vescovi answered on 13 Jun 2019: last edited 13 Jun 2019 9:36 pm

      It doesn’t blow up. I describe what it is before saying why.

      In short, a particle accelerator is a machine that accelerates particles to high speed. The goal is making them hit each other, produce new particles and measure their properties (mass, electric charge, speed, how fast spinning like a toy top, …) as they fly off from the accelerator. Think of coloured billiard balls hitting head-on, turning into other colours in a split second and bouncing back to you.

      Take LHC for example. It is today’s most famous accelerator in CERN in Switzerland. It is a circular tube with nothing — even air — inside. You see pictures here https://cds.cern.ch/record/1211045. Tiny particles fly in circles at 186 000 miles/second. They’re protons, the same particles that made up atoms in anything around us. I’m no expert in precise numbers, but read that there are 100 billion protons travelling together in one direction, the same number in the opposite, and they collide head-on at some special areas along the ring.

      They cannot possibly cause an explosion, despite number and speed. When they collide, all energy goes into new particles, which fall then on the detectors. If protons go off tangent, the tube stops them, because a nail-sized piece of it contains an extremely huge number of atoms.

      Let’s see what else can fail.
      1) Liquid helium cools the tube down. Pipes break (they did in 2008), release a giant amount of gas and helium doesn’t burn.
      2) A fire breaks out in the electric system. I guess a damaged connection may set wires on fire and release toxic smoke, but no explosion.
      3) An electric black-out shuts the tube down. The worst I can think of is 1) and 2).
      4) It’s true that collisions are energetic, but far more energetic collisions happen in the upper atmosphere when particles from outer space hit air. It has going on for billion years and we’re still alive.
      5) You can worry about something dangerous created in particle collisions. Unknown particles may destroy or a mini black hole suck the planet in. Again, I’m no expert, but I know that scientists checked that is impossible to the best of our knowledge.