Beam-test evaluation of pre-production Low Gain Avalanche Detectors for the ATLAS High Granularity Timing Detector

TL;DR

This paper reports on beam-test evaluations of pre-production LGAD sensors for the ATLAS HGTD, demonstrating they meet performance requirements even after neutron irradiation, supporting their deployment in the HL-LHC upgrade.

Contribution

It provides the first beam-test results of pre-production LGAD sensors for the ATLAS HGTD, including post-irradiation performance assessments.

Findings

LGAD sensors meet charge collection, time resolution, and efficiency requirements

Sensors maintain performance after neutron irradiation up to HL-LHC conditions

Results support deployment of LGADs in the ATLAS HGTD for HL-LHC

Abstract

The High Granularity Timing Detector (HGTD) will be installed in the ATLAS experiment as part of the Phase-II upgrade for the High Luminosity-Large Hadron Collider (HL-LHC). It will mitigate pile-up effects in the forward region, and measure per bunch luminosity. The design of HGTD is based on Low Gain Avalanche Detector (LGAD) sensors. This paper presents the results of beam-test campaigns conducted at CERN and DESY in 2023 and 2024 on single LGADs from HGTD pre-production test structures, before and after neutron irradiation up to fluences of $2.5 \times 10^{15}~\mathrm{n_{eq}/cm^2}$. The tested LGADs can meet HGTD requirements in terms of charge collection, time resolution, and hit efficiency, even under HL-LHC end-of-life conditions, supporting their deployment in the final detector.