SPARK CHAMBER

radiation detector useful for the investigation of subatomic particles in high-energy particle physics. It consists of a series of thin metal plates, parallel to each other, separated by small gaps, and enclosed in a container filled with neon or another inert gas. A very high potential drop, or voltage, is applied as a brief pulse across the two sets of alternate plates. Sparks are produced between the plates along the paths of charged subatomic particles that enter or are produced within the spark chamber because the particles leave a trail of ionized gas molecules that conduct a current. The paths of ionization remain in the chamber for about a millionth of a second, a sufficient time interval for a logic circuit to identify whether the particles that have emerged are of interest and consequently whether the high voltage pulse be sent to the plates and the resultant spark pattern be photographed for later analysis.