CERN Accelerating science

ATLAS Note
Report number	ATL-ITK-PROC-2024-043
Title	Mitigation strategies for sensor fracturing in the ATLAS ITk strips detector
Author(s)	Tishelman-Charny, Abe (Brookhaven National Laboratory (US))
Corporate Author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Publication	2024
Imprint	31 Oct 2024
Number of pages	6
In:	PoS LHCP2024 (2024) 215
In:	12th Edition of the Large Hadron Collider Physics Conference (LHCP2024), Boston, United States, 3 - 7 Jun 2024, pp.215
DOI	10.22323/1.478.0215
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Abstract	During Long Shutdown 3 of the LHC, the ATLAS detector will undergo substantial upgrades to prepare for data taking at the future HL-LHC. This includes a replacement of its inner detector with a fully silicon tracker called the ITk, composed of pixel and strip sub-detectors. During the pre-production phase of the ITk strips detector, it was discovered that thermal cycling modules after mounting them onto local support structures (staves and petals) 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 pressure points 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.

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