Bubble chamber

A particle detector that records charged particles as trails of bubbles in a superheated liquid. Its photographs reveal particle paths and interactions.

Superheated liquid: A liquid heated above its boiling point while remaining liquid because it lacks suitable nucleation sites. The chamber’s liquid is poised to boil when a charged particle leaves ionization behind.
Ionization: The creation of charged atoms or molecules by removing or adding electrons. Charged particles leave ionization along their paths, triggering bubble formation.
Donald A. Glaser: An American physicist who invented the bubble chamber and received the 1960 Nobel Prize in Physics. His invention established the detector principle that this page describes.
Neutrino: A neutral, weakly interacting elementary particle that comes in three known flavors. Neutrino interactions were inferred from the charged particles they produced inside large chambers.
Bubble nucleation: The formation of gas bubbles at sites where vapor can begin growing within a liquid. Ionized molecules provide nucleation sites that let the superheated liquid form a particle track.
Charged particle: A particle with nonzero electric charge that responds to electromagnetic fields. Only charged particles directly produce the ionization trails recorded in a bubble chamber.
Nobel Prize in Physics 1960: The 1960 physics Nobel awarded to Donald A. Glaser for inventing the bubble chamber. The prize recognized the invention’s impact on observing subatomic particles.
Gargamelle: A large CERN bubble chamber used in neutrino experiments during the 1970s. Gargamelle’s tracks provided evidence for weak neutral currents.
Stopping power: A measure of the energy a particle loses per unit distance while traveling through matter. Energy loss along the path determines how densely the liquid is ionized and where bubbles form.
Particle track: A visible or reconstructed path marking a particle’s movement through a detector. A string of bubbles is the chamber’s direct record of a particle track.

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