Time resolution of the ATLAS barrel liquid argon electromagnetic calorimeter

The time reconstruction performance of the ATLAS electromagnetic calorimeter readout is studied. The contribution of the electronics to the time resolution is estimated to be about 20 ps, thus demonstrating the possibility of achieving a small constant term in the time resolution for particles. The resolution to electromagnetic showers produced by an electron beam is also measured. After correction for the effects due to the calorimeter geometry, a 100 ps constant term is found for a typical cell.