CRISIS detector: The gas system

A low‐pressure, high‐flow, recirculating gas system has been designed and constructed for use on a large volume (250 ft3) ionization sampling drift chamber (CRISIS), which operates at an absolute pressure of less than 1 in. of water relative to atmospheric pressure. The system was also designed to control and monitor the detector gas mixture and to reduce the oxygen level in the detector below 4 ppm. In operation the system demonstrated very stable long and short term stability and also demonstrated the gas cost savings inherent in recirculating systems.