Speaker
Zijin Guo
(Johns Hopkins University)
Description
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 SLAC. This
presentation will describe 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 chi^2 computed using these data
for each wafer individually, iterating to account for between-wafer
correlations. A correction for aplanar distortions of the silicon wafers is
measured and applied. The net effect of residual misalignments on relevant
physical variables is evaluated in special control samples. The BaBar
data-sample collected between November 1999 and April 2008 is used in the
study of the SVT stability.
Authors
Andrei Gritsan
(Johns Hopkins University)
David Brown
(LBNL)
Doug Roberts
(University of Maryland)
Zijin Guo
(Johns Hopkins University)
