Dear Linear Collider Colleagues, Those of you arriving at the Michigan Linear Collider Workshop early on Thursday are invited to attend a seminar given by Bob Wilson of Colorado State on the BaBar Cerenkov Imaging system. The seminar will be held at 4:00 Thursday March 25 in 335 West Hall (same building the workshop will be held in). An abstract is appended below. Please let me know if you have any questions. Keith Riles The DIRC Particle ID System at BaBar Robert J. Wilson Colorado State University The BaBar experiment at the SLAC PEP-II B-factory will begin taking data in May 1999. A unique feature of the experiment is the use of a DIRC (Detection of Internally Reflected Cerenkov light) for particle identification. This is the first implementation of this novel Cerenkov ring-imaging technique in a full-scale experiment. I will describe first the physics motivation for a DIRC and the basic principles of the device. Next, I will show the implementation for the BaBar experiment including results from a recent cosmic ray run just prior to installation. Finally, I will present some ideas for future DIRCs involving the use of UV-sensitive Avalanche Photodiode pixel arrays to form a compact, magnetic field insensitive readout.