Dortmund 2021 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 14: Pixel detectors I
T 14.3: Vortrag
Montag, 15. März 2021, 16:30–16:45, Tn
Study of current, capacity and thermal runaway of hadron-irradiated silicon sensors — Ingo Bloch1, Heiko Lacker2, •Felix Riemer2, and Christian Scharf2 — 1Deutsches Elektronen-Synchrotron DESY — 2Humboldt-Universität zu Berlin
Silicon sensors are widely used in HEP experiments for particle tracking and calorimetry. One of the problems silicon detectors are facing is the increase of leakage current due to radiation damage. Leakage currents generate considerable heat for large detectors. At the same time, the leakage current increases with increasing sensor temperature. Therefore, catastrophic thermal runaway can occur with accumulated radiation damage during service if the cooling performance falls short of the demands. In order to estimate the effects, capacitance and current of irradiated silicon diodes have been measured as a function of particle fluence, temperature, bias voltage, cooling power, and for different pad areas. The diodes were irradiated with 70 MeV/c protons and 1 MeV/c neutrons to equivalent fluences between 1E13 cm−2 and 5E16 cm−2. A parametrization to describe the reverse current of highly irradiated silicon sensors and an analytical model for thermal runaway were used to estimate the critical parameters. A setup was built to confront the model with measurements within its validity range. Runaway was achieved and the existing analytical model was tuned using experimental data. The results can be applied to estimate the change of the heating power of silicon sensors in harsh radiation environments and the cooling infrastructure which is necessary to prevent thermal runaway in future ATLAS operation and other future detectors.