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T: Fachverband Teilchenphysik

T 15: Halbleiter: Laufende Experimente 1

T 15.8: Talk

Monday, March 9, 2015, 15:45–16:00, K.12.20 (K2)

Simultaneous alignment of the CMS Silicon Tracker using Millepede II — •Nazar Stefaniuk, Rainer Mankel, Matthias Schröder, Claus Kleinwort, and Andrii Gizhko — Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, Hamburg

The CMS tracker is the world's largest silicon detector, consisting of more than 25 000 sensors. A precise knowledge of their positions and orientations is crucial for the physics performance of the whole experiment. Track-based alignment procedure uses minimization of the residuals between the measured and expected hit position in the detector. An accuracy of 10 μm and 10 μrad for the module position and orientation, respectively, is achieved. Both tracks from pp-collision and cosmic-ray data are taken into account. In this way, more than 200 000 alignment parameters, describing the position, rotation and curvature of the sensors are determined simultaneously using the Millepede II program.

In the presentation, results of the CMS-tracker alignment with the data collected in 2012 are presented. The sensitivity of the procedure to a certain misalignment scenario is investigated, and foreseen improvements for the upcoming LHC Run-2 are discussed.