Calibration of LHCb RICH detectors with \Lambda \to p\pi decay using data

The LHCb physics programme will focus on high precision studies of CP violation and rare phenomena in B hadron decays. The RICH detectors of LHCb will provide hadron identification over the wide momentum range 1 to 100 GeV/c, and are central to the physics goals of the experiment. An excellent understanding of the hadron identification performance of the RICH detectors is essential. To achieve this goal, calibration strategies have been devised that will enable the performance to be measured from the data themselves. The decay chain $\Lambda \to p \pi$ can be cleanly selected, based on its kinematic signature, without the use of RICH information. These events can be used as an unbiased sample for calibrating the RICH particle identification performance of pions and protons. In this way, the calibration method using the high purity samples of $\Lambda$'s will be described.