Alignment of the ZEUS micro-vertex detector using cosmic tracks

ZEUS Micro-Vertex Detector (MVD) was installed in ZEUS after the HERA upgrade in 2000. MVD is a precise position detector consisting of 712 single-sided silicon strip detectors. The alignment of the barrel MVD has been performed in units of ladders using cosmic tracks. The procedure used is an iterative χ 2 minimization, where χ 2 is defined locally for each ladder. The procedure is numerically stable since it only requires an inversion of 30 6 × 6 matrices and reasonably fast in spite of the iterative approach.