A study of the electrical properties and of the signal shapes in the ATLAS Liquid ARgon Accordion Calorimeter using a hardware model

The Milano group realized an apparatus that reproduces a small part of the EM calorimeter barrel. It consists of four electrodes sandwiched among five absorbers, and connected together by summing boards, with the possibility of injecting electrical pulses at the electrode and summing board level, thus allowing to mimic signals produced by EM cascades or injected by the calibration network. This note describes in detail the apparatus and presents first results on the understanding of the signal waveforms and amplitudes, in terms of the characteristic parameters of the apparatus. Electrical models of the detector are also proposed and discussed. The effects of the asymmetry in the ground reference configuration of some back summing boards are also investigated, and prooved to provide a distortion of at most 1.6% on the calibrated signal amplitude.