Investigation of the impact of mechanical stress on the properties of silicon strip sensors

Abstract

Over the next few years the luminosity of the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN), will be increased to accumulate a higher number of collisions to gain access to rare processes. It is planned to reach an instantaneous luminosity of L=7.5⋅1034cm−2s−1 in the year 2026 at the High Luminosity Large Hadron Collider (HL-LHC). Due to the resulting higher radiation level, the requirements on the components of the ATLAS detector increase. The ATLAS Inner Detector is foreseen to be replaced with the ATLAS Inner Tracker, consisting of a pixel tracker and a strip tracker. The upgraded strip tracker will consist of 18,000 silicon strip detector modules, each consisting of silicon sensors, circuit boards and readout chips. Adhesives are used to connect the modular components thermally and mechanically. Due to different coefficients of thermal expansion of the various involved materials, temperature changes between construction (22 °C) and operation (−30 °C) lead to the exertion of mechanical stress on the sensor. This publication shows measurements quantifying the impact of mechanical stress on the properties of silicon strip sensors.