Everyone has heard of the Large Hadron Collider, but how many have stopped to think how it gets cleaned? Or even suspected it required cleaning? Sarah Charley tells us how it works [symmetrymagazine.org]:
The inside of the beam pipes need to be spotless, which is why the LHC is thoroughly cleaned every year before it ramps up its summer operations program.
It's not dirt or grime that clogs the LHC. Rather, it's microscopic air molecules.
"The LHC is incredibly cold and under a strong vacuum, but it's not a perfect vacuum," says LHC accelerator physicist Giovanni Rumolo. "There's a tiny number of simple atmospheric gas molecules and even more frozen to the beam pipes' walls."
Protons racing around the LHC crash into these floating air molecules, detaching their electrons. The liberated electrons jump after the positively charged protons but quickly crash into the beam pipe walls, depositing heat and liberating even more electrons from the frozen gas molecules there.
This process quickly turns into an avalanche, which weakens the vacuum, heats up the cryogenic system, disrupts the proton beam and dramatically lowers the efficiency and reliability of the LHC.