Optical design for a streamer chamber in a quark search experiment

The design of an optical system for a streamer chamber, working in the avalanche mode, which will be used in an experiment searching for fractionally charged particles (CERN 1977), is presented and evaluated. The ability of the optical system and chamber to detect fractionally charged quarks by a measurement of their specific primary ionisation has been investigated by a study of tracks of charged particles obtained in various gases in a small test chamber and a simulation of avalanche formation and detection. The first results obtained in the full size chamber are also presented. (16 refs).