Liquid ionization calorimetry with time-sampled signals

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Abstract

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 (∼ 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 × 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%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 ∈ can be expressed as (c)2 + σcal2, 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 σcal.

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This research was supported in part by the National Science Foundation the U.S. Department of Energy under contract DE-AC02-76CH 00016, and TNRLC under grants RGFY92–109 and RGFY93–208.

Corresponding author. Tel. +1 (516) 282 4266, fax: +1 (516) 282 3000.