DIRC, the Internally Reflecting Ring Imaging Cherenkov Detektor for BaBar: Properties of the Quartz Radiators

The DIRC is a Cherenkov imaging detector based on total internal reflection for the BaBar detector at PEP-II. The principles of the DIRC ring imaging Cherenkov technique are explained and its choice for the BaBar detector particle identification system is motivated. The detector design and the status of the R&D are discussed. Results of the measurement of the optical properties and radiation damage of the the radiators, long rectangular bars made of synthetic fused silica, are presented.