Reconstruction and PID performance of the LHCb RICH detectors

Particle identification in the LHCb experiment is provided by two RICH detectors, covering a momentum range of approximately 1–100 GeV/c. To maintain the integrity of the LHCb physics performance, it is essential to measure and monitor the particle identification efficiency and misidentification fraction over time. To achieve this, the unique decay kinematics associated with KS0, Λ and φ decays are exploited to obtain high purity samples of pions, protons and kaons through the use of tracking information alone. Such calibration samples then allow for an unbiased assessment of the performance of the RICH detectors. Given the high production rates of KS0, Λ and φ mesons at the LHC, monitoring of the RICH detectors performance is possible both “on-line” during running and “off-line” after full-reconstruction of the data. Following analysis of the first LHC collisions, the performance of the LHCb RICH detectors will be presented based on a preliminary alignment of the detector. Identification and mis-identification probabilities as a function of track momentum will be shown.