Göttingen 2012 – scientific programme

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T: Fachverband Teilchenphysik

T 64: Halbleiterdetektoren: Forschung und Entwicklung 2

T 64.6: Talk

Tuesday, February 28, 2012, 18:00–18:15, ZHG 001

Pixel sensors capacitance determination with PixCap chip — •Miroslav Havranek, Fabian Hügging, Hans Krüger, and Norbert Wermes — Physikalisches Institut, Universität Bonn

The innermost layers of the ATLAS experiment are occupied by a pixel detector, which plays an essential role in the ATLAS tracking system. After years of operation, the sensors and the read-out electronics of the pixel detector will degrade due to the radiation damage. Also, due to the planned LHC luminosity upgrades, the pixel detector will have to cope with higher hit rates and therefore will need an upgrade. Currently three competing sensor technologies exist: silicon planar, silicon 3D and diamond sensors. One of the key parameters of a sensor is the capacitance it couples to the read-out electronics, which determines the noise performance. Knowledge of the pixel capacitance for each sensor type allows a direct comparison of the various sensor technologies. Since the expected pixel capacitance is in order of hundreds femtofarads, a precise capacitance measurement of the fine pitch ATLAS pixel sensors can not be easily achieved by conventional methods. To resolve this problem, we developed the PixCap chip which directly interfaces with sensor pixels and thus performs precise on-sensor capacitance measurement with an accuracy of a few femtofarads. In this presentation, the PixCap design will be introduced and capacitance measurement results with various ATLAS sensor types will be discussed.