Münster 2011 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 61: Instrumentierung XII
HK 61.5: Vortrag
Donnerstag, 24. März 2011, 17:30–17:45, HS2
Fully automated calibration of a large-scale scintillating fibre array — •Anselm Esser, Maik Biroth, and Pepe Gülker — Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz
The electron-arm detector of the Kaos spectrometer at the Mainz Microtron MAMI consists of two planes of 18 432 scintillating fibres with 4608 read-out channels. The signal amplitude of different channels varies due to fibre coupling and PMT gain variations and tolerances in the detector building process. To adjust the 144 multi-anode photomultiplier voltages and the 2304 discriminator thresholds, a calibration system was implemented. A 90Sr β-source and a miniature trigger detector are positioned alongside the detector plane by a stepping motor with a precision of 0.1 mm. The operation of the calibration system and the data acquisition and analysis are fully automated. The procedure includes the measurement of the exact position and the signal amplitude of each channel at a fixed PMT voltage. For a subset of channels of every PMT the amplitude is also measured for different voltages to determine the gain curve. The improvement of the data quality by the calibration was demonstrated in beam-tests at MAMI.