PRECISION TIMING WITH LIQUID IONIZATION CALORIMETERS

We present timing measurements performed with a liquid krypton electro magnetic accordion calorimeter, measured in an electron beam over an e nergy range of 5-20 GeV. A novel discriminator with an amplitude-indep endent timing response was used to extract the inherently accurate tim ing information from the calorimeter. As expected, the timing resoluti on sigma(tau) is observed to vary inversely with the signal amplitude, which is proportional to the deposited energy E. We measure a resolut ion of sigma(tau) = 4.15 +/- 0.06 GeV ns/E for a sum of 5 x 5 towers w ith 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.