PRECISION TIMING WITH LIQUID IONIZATION CALORIMETERS

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 sigma(tau) is observed to vary inversely with the signal amplitude, which is proportional to the deposited energy E. We measure a resolution of sigma(tau) = 4.15 +/- 0.06 GeV ns/E for a sum of 5 x 5 towers with dimensions 2.7 x 2.5 cm2 each. From this we deduce that the timing resolution for an individual tower is approximately 0.8 GeV ns/E.