Dresden 2013 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 62: Halbleiterdetektoren: Forschung und Entwicklung 2

T 62.8: Vortrag

Montag, 4. März 2013, 18:35–18:50, GER-007

Simultaneous alignment and Lorentz angle calibration in the CMS silicon tracker using Millepede II. — •Nazar Bartosik, Jörg Behr, Gero Flucke, Gregor Hellwig, Claus Kleinwort, and Rainer Mankel — DESY, Hamburg, Germany

An accurate determination of the positions and orientations of 25 684 sensors of the CMS silicon tracker is crucial for the physics performance of the whole experiment. This is achieved by track-based alignment using the global fit approach of the Millepede II program. About 200 000 parameters are determined simultaneously, including parameters describing sensor curvatures.

The alignment framework has now been extended to treat position sensitive calibration parameters. Of special interest is the Lorentz angle which affects hit positions due to the drift of signal electrons in the magnetic field. The Lorentz angle and its time dependence, induced e.g. by the increasing accumulated radiation dose, have been determined for 2012, making use of data taken with magnetic field switched off.