Karlsruhe 2011 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 72: Detektorsysteme II
T 72.2: Vortrag
Donnerstag, 31. März 2011, 17:05–17:20, 30.36: 011
Low noise readout system for the characterisation of DEPFET minimatrices — •Christian Oswald1,3, Ján Scheirich1,4, Peter Kodyš1, Andreas Wassatsch2, and DEPFET collaboration5 — 1Charles University, Prague — 2MPI für Physik - Halbleiterlabor, München — 3MPI für Physik, München — 4Czech Technical University, Prague — 5International
The innermost two layers of the Belle II vertex detector will be made of DEPFET pixel detectors. This type of detector shows an excellent signal to noise ratio with a first stage of amplification already integrated in the pixels.
A test system for the readout of big matrices is already available. However, its high frame rate does not allow detailed studies of the detector noise. Measurements of single pixel structures in contrast miss effects such as charge sharing between neighbouring pixels. This gap should be bridged by test structures of an intermediate size of 12x8 pixels, so called minimatrices. We developed a dedicated low noise readout system comprising a sequencer unit, switcher electronics and preamplifiers. The flexible sequencer unit allows the programming of user-defined steering sequences (e.g. correlated double sampling, where the pedestal current is measured directly after the signal current). A further strength of the system is the continuous acquisition of the entire waveform of the signal at the preamplifier output. Therefore, not only the pixel signal itself is accessible, but also full information about what happens between the evaluation of the signal, for example reactions of the system to the steering pulses.