Measurements of sensor radiation damage in the ATLAS inner detector using leakage currents

TL;DR

This paper presents measurements and simulations of radiation-induced leakage current in the ATLAS detector's silicon sensors, revealing discrepancies with models and informing future detector design and safety considerations.

Contribution

It provides detailed leakage current measurements across detector layers, highlighting differences from simulations and improving understanding of radiation damage in silicon sensors.

Findings

Stronger |z|-dependence of fluence in innermost layers than in simulations.

Higher than expected fluence on the second innermost layer.

Better simulation agreement at larger radii.

Abstract

Non-ionizing energy loss causes bulk damage to the silicon sensors of the ATLAS pixel and strip detectors. This damage has important implications for data-taking operations, charged-particle track reconstruction, detector simulations, and physics analysis. This paper presents simulations and measurements of the leakage current in the ATLAS pixel detector and semiconductor tracker as a function of location in the detector and time, using data collected in Run 1 (2010-2012) and Run 2 (2015-2018) of the Large Hadron Collider. The extracted fluence shows a much stronger |z|-dependence in the innermost layers than is seen in simulation. Furthermore, the overall fluence on the second innermost layer is significantly higher than in simulation, with better agreement in layers at higher radii. These measurements are important for validating the simulation models and can be used in part to justify safety factors for future detector designs and interventions.