Precision timing with liquid ionization calorimeters

Abstract We present timing measurements performed with a liquid krypton electromagnetic accordion calorimeter, measured in an electron beam over an energy range of 5–20 GeV. A novel discriminator with an amplitude-independent timing response was used to extract the inherently accurate timing information from the calorimeter. As expected, the timing resolution σ τ is observed to vary inversely with the signal amplitude, which is proportional to the deposited energy E . We measure a resolution of σ τ = 4.15±0.06 GeV ns/ E for a sum of 5×5 towers with dimensions 2.7×2.5 cm 2 each. From this we deduce that the timing resolution for an individual tower is approximately 0.8 GeV ns/ E .