Local Alignment of the BABAR Silicon Vertex Tracking Detector

Understand

The BABAR Silicon Vertex Tracker (SVT) is a five-layer double-sided silicon detector designed to provide precise measurements of the position and direction of primary tracks, and to fully reconstruct low-momentum tracks produced in e+e- collisions at the PEP-II asymmetric collider at Stanford Linear Accelerator Center.

• This paper describes the design, implementation, performance, and validation of the local alignment procedure used to determine the relative positions and orientations of the 340 SVT wafers.
• This procedure uses a tuned mix of in-situ experimental data and complementary lab-bench measurements to control systematic distortions.
• Wafer positions and orientations are determined by minimizing a chisquared computed using these data for each wafer individually, iterating to account for between-wafer correlations.