Evolution of the electrical characteristics of the ATLAS18 ITk strip sensors with HL-LHC radiation exposure range

TL;DR

This study evaluates how ATLAS18 ITk strip sensors' electrical performance evolves under HL-LHC radiation exposure, confirming their suitability for long-term operation in high-radiation environments through comprehensive testing.

Contribution

It provides the first full-size sensor irradiation results across a wide radiation range, validating sensor performance against specifications for HL-LHC conditions.

Findings

Sensors meet ATLAS specifications after irradiation

Detailed characterization of capacitance and resistance changes

Insights into sensor behavior at high radiation doses

Abstract

The objective of the study is to evaluate the evolution of the performance of the new ATLAS Inner-Tracker (ITk) strip sensors as a function of radiation exposure, to ensure the proper operation of the upgraded detector during the lifetime of the High-Luminosity Large Hadron Collider (HL-LHC). Full-size ATLAS ITk Barrel Short-Strip (SS) sensors with final layout design, ATLAS18SS, have been irradiated with neutrons and gammas, to confirm the results obtained with prototypes and miniature sensors during the development phase. The irradiations cover a wide range of fluences and doses that ITk will experience, going from 1e13 neq/cm2 and 0.49 Mrad, to 1.6e15 neq/cm2 and 80 Mrad. The split irradiation enables a proper combination of fluence and dose values of the HL-LHC, including a 1.5 safety factor. A complete electrical characterization of the key sensor parameters before and after irradiation is presented, studying the leakage current, bulk capacitance, single-strip and inter-strip characteristics. The results confirm the fulfilment of the ATLAS specifications throughout the whole experiment. The study of a wide range of fluences and doses also allows to obtain detailed results, such as the frequency dependence of the bulk capacitance measurements for highly irradiated sensors, or the evolution of the punch-through protection and inter-strip resistance with radiation.