Mitigation strategies for sensor fracturing in the ATLAS ITk strips detector

During Long Shutdown 3 of the LHC, the ATLAS detector will receive substantial upgrades to prepare for data collection at the High-Luminosity LHC (HL-LHC). These upgrades include replacing the inner detector with a fully silicon-based tracker, known as the ITk, consisting of pixel and strip sub-detectors. During the pre-production phase of the ITk strips detector, it was discovered that thermal cycling of the supports loaded with strips modules induces induces physical cracks in some of the sensors. This phenomenon is understood to be the result of a combination of factors, including the thermomechanical properties of the module mounting glue, and the relative positions of the module’s electric components. These factors combine to create high mechanical stress regions on modules during temperature changes, an effect that must be solved as the detector components must be mechanically robust and able to withstand the planned detector warm-ups and cool-downs during HL-LHC. These proceedings will describe the sensor fracturing mechanism, its signature in electrical test results, and the design and testing of three possible mitigation strategies and their results.