A PROPOSAL FOR THE ALIGNMENT OF THE LHCB RICH DETECTOR

The strict requirements in Cherenkov angle resolution combined with the size and complexity of the LHCb RICH2 detector will pose a challenge in the quality and alignment of the mirrors. There are 28 spherical and 20 planar mirror segments in each half of RICH2, and the required Cherenkov angle resolution is below 0.6 mrad. We have studied extensively the mirror misalignment effect on Cherenkov angle resolution and particle identification performance, and to what extent alignment with data can compensate for mirror misalignment. Our results show that the initial mirror alignment must be better than 1 mrad to achieve a negligible effect of the alignment on the total Cherenkov angle resolution.