TransPAC Detection of Internally Reflected Cherenkov Light (DIRC), Particle Identification for BaBar The BaBar detector was built at Stanford Linear Accelerator Center to study the millions of B mesons produced by the PEP-II storage ring. The BABAR detector comprises the usual nested set of detector sub-systems to precisely measure the collision point and decay points of the B-meson pairs produced, the momentum and energy of the decay particles, and the nature of the kind of particles in these decays (i.e. electrons, muons, pions, kaons). An important issue in studying CP violation is the ability to tag decays of b-quark versus b-antiquark mesons for particle momenta up to 2.5 GeV/c, and to separate charged pions from charged kaons for momenta up to 4 GeV/c in B decays. The driftchamber provides particle identification (PID) by dE/dx measurements for tracks up to 0.7 GeV/c momentum. Dedicated PID system (DIRC) for higher momenta. The BaBar collaboration consists of around 600 physicists and engineers from 85 institutions in nine countries. Contact Roy Aleksan DAPNIA/SPP Saclay France aleksan@dapnia.cea.fr roy@slac.stanford.edu Collaborators Stanford University Stanford Linear Accelerator Center (SLAC) USA Commissariat a l’Energie Atomic (CEA), DAPNIA-Saclay, Laboratoire de L’Accelerateur Lineaire (LAL) Orsay, LPNHE Paris VI et Paris VII, LPNHE de l’Ecole Polytechnique France Lawrence Berkeley National Laboratory, University of California at Berkeley, Rutgers University, University of California at Santa Barbara, University of Cincinnati USA www.slac.Stanford.edu/BFROOT www-dapnia.cea.fr/Phys/Spp www.SLAC.Stanford.edu
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