PHY6040 Particle Detectors Dr C N Booth

Bubble Chambers

In a superheated liquid, bubbles start to form on nucleation centres - surface irregularities, dirt or positive ions - in the liquid.  Bubbles can therefore form along the track of a charged particle, and make it visible.  This was the principle exploited by Glaser in 1952 in the first bubble chamber, which proved of great importance in particle physics experiments for many years.

Features of bubble chambers include



Picture from the Stanford 1 m hydrogen bubble chamber, exposed to 8.8 GeV/c antiprotons.

A careful study of this photograph reveals the reaction to be  ,  where

  • the slow proton is identifed by its heavier ionisation,
  • the K0 subsequently decays into a pair of charged pions,
  • the antineutron annihilates with a proton a short distance downstream from the primary interaction, to produce three charged pions,
  • the neutral pion decays into two photons, which (unusually for a hydrogen chamber) both convert into e+e pairs,
  • (external particle detectors were used to identify the charged kaon).


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