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T: Fachverband Teilchenphysik

T 11: Silicon trackers 1

T 11.3: Talk

Monday, March 4, 2024, 16:30–16:45, Geb. 30.22: kl. HS B

Measurement of the Thermal Runaway of a 2S Module on a TEDD-like Structure for the CMS Phase-2 Outer Tracker Upgrade — Lutz Feld¹, Katja Klein¹, Martin Lipinski¹, •Vanessa Oppenländer¹, Alexander Pauls¹, Oliver Pooth², and Nicolas Röwert¹ — ¹1. Physikalisches Institut B, RWTH Aachen — ²3. Physikalisches Institut B, RWTH Aachen

The new operating conditions of the future HL-LHC require a replacement of the complete silicon tracking system of the CMS experiment as part of the CMS Phase-2 Upgrade. For the Phase-2 Outer Tracker new silicon strip modules, so-called 2S modules, are being developed that consist of two silicon sensors stacked on top of each other. The radiation conditions of the HL-LHC lead to a high leakage current in the silicon sensors, which is exponentially dependent on the sensor temperature. An evaporative CO₂ cooling system will be used to cool the modules and to ensure a successful operation. In an unstable cooling scenario it is possible that the module enters an uncontrolled self-heating loop called thermal runaway. Therefore it is crucial that the thermal properties and performance of the 2S modules and the cooling structure are tested and characterized. In this talk thermal measurements performed on a small realistic cooling structure similar to the structure foreseen for the endcaps of the CMS Outer Tracker will be presented. The CO₂ temperature at which thermal runaway occurs has been measured. Sufficient margin to the nominal operating CO₂ temperature has been observed.

Keywords: Silicon; Cooling; Thermal runaway