THE COSMIC-RAY TRACKING (CRT) DETECTOR SYSTEM

The Cosmic Ray Tracking (CRT) project represents a study on the use of tracking detectors of the time projection chamber type to detect seco ndary cosmic ray particles in extensive air showers, In reconstructing the arrival direction of the primary cosmic ray particles, the CRT de tectors take advantage of the angular correlation of secondary particl es with the cosmic rays leading to these air showers. In this paper, t he detector hardware including the custom-designed electronics system is described in detail, A CRT detector module provides an active area of 2.5 m(2) and allows to measure track directions with a precision of 0.4 degrees. It consists of two circular drift chambers of 1.8 m diam eter with six sense wires each, and a 10 cm thick iron plate between t he two chambers. Each detector has a local electronics box with a read out, trigger, and monitoring system. The detectors can distinguish pen etrating muons from other types of charged secondaries. A large detect or array could be used to search for gamma-ray point sources at energi es above several TeV and for studies of the cosmic-ray composition. Te n detectors are in operation at the site of the HEGRA air shower array .