Particle identification for the BaBar experiment Detection of Internally Reflected Cherenkov light (DIRC)

We describe a new type of detector for particle identification which will be used in the BaBar experiment at the SLAC B factory (PEP-II). This detector, used in the barrel region of BaBar, is called the DIRC which is an acronym for Detection of Internally Reflected Cherenkov light. Similar to other Cherenkov ring imaging devices, the DIRC provides high resolution determination of the Cherenkov angle for pions and kaons but is also particularly well-matched to the momentum range and angular distribution of CP-violating final states in asymmetric B factories.