The Spark Chamber
A spark or streamer chamber is a particle detector, a device used in particle physics for detecting electrically charged particles, now superseded by more sophisticated detectors such as drift chambers and silicon detectors, but still useful because of their relative simplicity.
They consist of metal plates placed in a sealed box filled with a gas such as helium, neon or a mixture. As a charged particle travels through the detector, the gas is ionlized. A trigger system is used to apply high voltage to the plates to create an electric field immediately after the particle goes through the chamber, producing sparks on its exact trajectory, similar to a Geiger Muller tube.
Spark chamber detectors are generally less accurate than bubble chamber detectors, but can be made highly selective with the help of auxiliary detectors, making them useful in searching for very rare events.