Aachen 2019 – scientific programme

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T: Fachverband Teilchenphysik

T 67: Detektorsysteme III

T 67.9: Talk

Wednesday, March 27, 2019, 18:00–18:15, S03

Systematic studies of track-based alignment of the CMS tracker — •Josry Metwally — DESY, Hamburg, Germany

The CMS (Compact Muon Solenoid) tracker is the largest silicon tracker in the world, consisting of a large number of pixel (1856) and strip (15148) modules to ensure a precise reconstruction of tracks and vertices. In order to fully exploit the precision of the local reconstruction of the silicon modules, we use a track-based approach to align the modules. The number of alignment parameters is of the order of 100k and its determination is achieved by the means of the linear least-squares method (χ²), while residuals between the hits and the reconstructed track are minimised. Continuous transformations called weak modes corresponding to transformations to which the χ² fit is not very sensitive are one of the major challenges of track-based alignment. In this talk, systematic studies to control weak modes are presented.