Study of the Radiation Hardness of the ATLAS Tile Calorimeter Optical Instrumentation with Run 2 data

TL;DR

This study evaluates the radiation tolerance of the ATLAS Tile Calorimeter's optical components during LHC Run 2, combining data analysis and simulations to understand degradation patterns and predict future performance impacts.

Contribution

It provides the first comprehensive analysis of optical component radiation damage in the ATLAS Tile Calorimeter using Run 2 data and simulation models for future scenario predictions.

Findings

Measured light output loss over Run 2

Modeled degradation as a function of dose and dose rate

Assessed impact on detector response uniformity

Abstract

This paper presents a study of the radiation hardness of the hadronic Tile Calorimeter of the ATLAS experiment in the LHC Run 2. Both the plastic scintillators constituting the detector active media and the wavelength-shifting optical fibres collecting the scintillation light into the photodetector readout are elements susceptible to radiation damage. The dedicated calibration and monitoring systems of the detector (caesium radioactive sources, laser and minimum bias integrator) allow to assess the response of these optical components. Data collected with these systems between 2015 and 2018 are analysed to measure the degradation of the optical instrumentation across Run 2. Moreover, a simulation of the total ionising dose in the calorimeter is employed to study and model the degradation profile as a function of the exposure conditions, both integrated dose and dose rate. The measurement of the relative light output loss in Run 2 is presented and extrapolations to future scenarios are drawn based on current data. The impact of radiation damage on the cell response uniformity is also analysed.