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.Comment: 4 pp. Contributed to the 7th ICFA School on Instrumentation in
Elementary Particle Physics, Leon, Guanajuato, Mexico, 7-19 Jul 199
