LIQUID IONIZATION CALORIMETRY WITH TIME-SAMPLED SIGNALS

We present the results of a study of amplitude and timing measurements made in a liquid krypton electromagnetic calorimeter, using multiply sampled signals of the shaped waveform. The measurements were designed to emulate the type of data that will be available from a calorimeter operating at future hadron-hadron colliders with short (approximately 20 ns) spacing between bunch crossings. Data have been collected with 18 ns sample spacing on waveforms from individual calorimeter sections with a shaping time of 40 ns and from 5 x 5 tower analog sums with a shaping time of 50 ns. The amplitude was measured using the analog sum signal, and the timing was measured using the signal from the individual sections. The data were processed using the method of optimal filtering, and a reduction in the noise of about a factor of two over that for a single sample is seen when using multiple samples for determining the amplitude. We find an energy resolution of 6.7%/square-root E, in agreement with the resolution measured for the same calorimeter using a single sample measured at the peak of the waveform. The timing resolution for a section of a calorimeter tower with deposited energy epsilon can be expressed as square-root (c/epsilon)2 + sigma(cal)2, with a value of c of 0.38 GeV ns for the front section (the first 6 radiation lengths) and 0.70 GeV ns for the back section, and a value of 0.15 ns for sigma(cal).