Pulse Shape Characterization of Silicon Diodes for HGCal with data from Beam Test at CERN

The High Luminosity phase of the LHC (starting operation in 2025) will provide unprecedented instantaneous and integrated luminosity, with 25 ns bunch crossing intervals and up to 140 pileup events. A challenge is to provide excellent physics performance in such a harsh environment to fully exploit the HL-LHC potentialities and explore new physics frontiers. In this context, the High Granularity Calorimeter is the detector designed to provide electromagnetic and hadronic energy coverage and reconstruction in the forward direction of the upgraded CMS. In April 2016 and June 2016, a set of 36 diodes were tested in order to understand various characteristics of its performance, in order to use them in the upgraded HG Calorimeter. Here, the silicon diodes were mounted onto a test bench at CERN’s beam test area and exposed to electron showers. Data received from these diodes were acquired and analysed separately. The objective of this report is to show the variation of Time Rise, Time Over Threshold with various parameters such as Signal over Noise Ratio, Irradiation level and Thickness. Time Rise is defined as the time it takes by the signal to increase its intensity from 10% its peak intensity to 90% its peak intensity value. The Time Over Threshold here is defined as the time the signal spends over 50% of its peak intensity value.