The DIRC, the particle identification detector of BaBar

A novel particle identification detector (PID) has been developed for the BABAR experiment which will operate at the PEP-II B factory at SLAC. The principles of this new concept of PID called the DIRC, based on ring imaging $9 Cherenkov techniques, are briefly described. The results obtained with a large scale prototype and pion, kaon and proton beams at CERN are presented. The performances of this prototype are compared to the Monte-Carlo simulations and $9 the BABAR requirements. (4 refs).