Hamburg 2016 – scientific programme

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T: Fachverband Teilchenphysik

T 94: Kalorimeter III (SiPM)

T 94.5: Talk

Thursday, March 3, 2016, 17:45–18:00, VMP6 HS E

Dark noise rates in irradiated silicon photomultiplier arrays — Sebastian Bachmann, Albert Comerma, •David Gerick, Xiaoxue Han, Stephanie Hansmann-Menzemer, Matthieu Kecke, Blake Leverington, José Mazorra de Cos, Dominik Mitzel, Max Neuner, and Ulrich Uwer for the LHCb collaboration — Physikalisches Institut, Universität Heidelberg

The planned downstream tracking system - the Scintillating Fibre Tracker - for the LHCb upgrade uses silicon photomultiplier (SiPM) arrays of 128 channels to read out mats made of 250 µm diameter scintillating fibres. In the LHCb environment the neutron flux degrades the silicon detectors to the edge of an acceptable performance in terms of DCR. Studies have shown that the dark count rate (DCR) of the SiPMs increases linearly with the neutron flux. Towards the end of the designed lifetime of the experiment the DCR per SiPM channel operated at T = −40^∘C is expected to reach a few MHz after partial annealing.
To reduce the impact of the DCR - while at the same time provide efficient hit reconstruction - a clustering algorithm is developed to separate signal from noise. A brief introduction into the custom designed read-out ASIC and the cluster algorithm will be presented along with the studies of the dark count cluster rate dependency on the neutron flux, the DCR per channel and the effects of the applied signal thresholds for the clustering algorithm.