Internal alignement of the SLD vertex detector

The tracking resolution and vertex finding capabilities of the SLD experiment depended upon a precise knowledge of the location and orientation of the elements of the SLD pixel vertex detector (VXD3) in 3D space. At the heart of the procedure described here to align the 96 CCDs is the matrix inversion technique of singular value decomposition (SVD). This tool was employed to unfold the detector geometry corrections from the track data in the VXD3. The algorithm was adapted to perform an optimal Â2 minimization by careful treatment of the track hit residual measurement errors. The tracking resolution obtained with the aligned geometry achieved the design performance. Comments are given on how this method could be used for other trackers.