The ATLAS Forward Proton Time-of-Flight Detector System

Performance studies of the Time-of-Flight (ToF) subdetector of the ATLAS Forward Proton (AFP) detector at the LHC are presented. Efficiencies and resolutions are measured using data samples collected at low and moderate pile-up in 2017. While low efficiencies are observed, of the order of a few percent, the resolutions of the two ToF detectors measured individually are 21 ps and 28 ps, yielding an expected resolution of the longitudinal position of the interaction, zᵥₜₓ in the interaction region. This is in agreement with the observed width of the distribution of the difference between zᵥₜₓ measured independently by the central ATLAS tracker and by the ToF detector, of 6.0 ± 2.0 mm.