Bonn 2010 – scientific programme
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T: Fachverband Teilchenphysik
T 68: Detektorsysteme II
T 68.4: Talk
Wednesday, March 17, 2010, 14:45–15:00, HG ÜR 1
Determination of the ATLAS Pixel Detector Timing from Collision Data* — Peter Buchholz1, •Iskander Ibragimov1, and Michael Köhler2 — 1Universität Siegen — 2Universität Freiburg
The ATLAS Pixel Detector is the innermost tracking detector of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN. It is built using a hybrid silicon pixel detector technology and consists of 1744 identical modules with in total 80 million readout channels. The detector must distinguish signal hits from two subsequent bunch crossings with the time interval of 25 ns (or 1 BC) at the full LHC luminosity. Because of the timewalk effect in the FE electronics the phase of the clock in each module has to be properly adjusted within this time window to sample collision data without losing efficiency. This can be achieved using hit information from particle tracks together with the precise knowledge of timing behavior and charge calibration from the dedicated calibration measurements.
The Pixel Detector modules were preliminary adjusted using measured propagation delays in the clock and trigger distribution circuitry. The overall detector timing adjustment within 5 BC was verified using the 2008 cosmic-ray data. With the collision data, which is the actual reference for the adjustment, the sub-BC timing can be determined with a few nanoseconds precision. In the talk the algorithm for the timing determination will be explained and the results with the first collision data will be presented.
* This work was supported in part by BMBF