The Large Hadron Collider at CERN is a ring of approximately what circumference?
- A.7 km
- B.17 km
- C.27 km
- D.47 km
Show answer
Explanation
The correct answer is C, 27 km. The Large Hadron Collider occupies a circular tunnel about 27 kilometres around, lying roughly 100 metres below the ground on the Swiss-French border near Geneva, and it is the largest and most powerful particle accelerator ever built; the tunnel was originally dug for an earlier CERN machine, the Large Electron-Positron collider. Option A, 7 km, is far too small and is nearer the size of a medium accelerator ring. Option B, 17 km, is a popular distractor because the number is close, and candidates who remember only that the figure is in the twenties often pick it. Option D, 47 km, is larger than the LHC and is the kind of figure discussed for proposed future colliders, not for the existing machine. Remember the pair 27 km and 100 m deep, and that the protons inside are steered by superconducting magnets cooled with liquid helium.