Understanding the Properties of Gallium Implanted LGAD Timing Detectors

ATLAS is proposing a High Granularity Timing Detector (HGTD) to be installed in front of the end-cap calorimeters for the upgrade of High Luminosity LHC project with Low Gain Avalanche Detectors (LGAD) chosen as preferred timing detectors. A beam test campaign has been conducted in order to be able to study the properties of these new detectors under severe conditions in June 2018 with a high-energy pion beam of 120 GeV at the H6A line at the CERN SPS. This study is aimed to understand the properties of gallium implanted LGAD timing detectors which was also included in the latest beam test campaign. A simple time reconstruction method of Constant Fraction Discriminator (CFD) was carried out to calculate the time resolution of this sensor. Preliminary studies show that boron implanted sensor, W9LGA35, has a better time resolution ($32.88 \pm 0.08$ ps) than gallium implanted sensor, W6S1021 ($52.93 \pm 0.15$ ps).