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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Experimentelle Elementarteilchenphysik

Nukri Komin (2000)

Time Calibration of the Outer Tracker at HERA-B

Diplom Thesis, Humboldt Universität zu Berlin.

HERA-B is a fixed target experiment designed to study CP violation. A proton-
nucleon interaction rate of up to 40 MHz leads to a high number of charged tracks
and requires a powerful tracking system. The Outer Tracker, the outer part of the
tracking system, uses about 115000 honeycomb drift cells for track measurement.
    An accurate drift distance measurement can only be achieved if a proper time
calibration of the single channels is done.
    In this thesis three different calibration approaches are described. A first hard-
ware based method uses a test pulse system. In a second calibration approach the
drift time spectra of beam events are described by an analytical function. The refer-
ence times are determined from a fit of the function to the drift time spectra of the
single channels. The third method uses the mean value of the drift time spectra.
    Additionally, a technique for calculating track residuals is introduced. Track
residuals are used to compare the different calibrations. The calibration methods
considered lead to similar results. Residual resolutions (RMS) between 365 µm and
389 µm are achieved.