Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 57: Calorimeters I

T 57.2: Talk

Wednesday, March 17, 2021, 16:15–16:30, Tg

Performance of neutron irradiated SiPM for the CMS HGCAL — •Carmen Victoria Villalba Petro, Erika Garutti, and Joern Schwandt — Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Deutschland

The CMS Collaboration has proposed a high granularity calorimeter (HGCAL) to replace the endcap calorimeter as part of the HL-LHC upgrade. In the region covered by plastic scintillators a fluence of 8x10¹³ neq/cm² is expected. Operating SiPMs in this high radiation environment increases dark count rate and correlated noise, making it not possible to detect single photons anymore. Candidate SiPMs are MPPC S14160-9766 (8480 pixels) and S14160-9768 (17520 pixels), both with pixel size 15µm. The aim of this study is to characterize Light Yield (LY) and Signal-to-Noise Ratio (SNR) of a plastic scintillator tile coupled to the SiPM in response to a MIP. SNR has been calculated as the ratio between the MIP integrated charge and the standard deviation of the pedestal. For LY the MIP integrated charge is normalized to the SiPM gain obtained with low intensity laser light illumination. It is presented a method to record charge spectra illuminating the SiPMs by a pulsed laser and using a beta source. To characterise effects before and after irradiation the analysis of the charge-voltage measurements are performed at different temperatures, irradiation fluences and integration gate lengths. It has been observed that the noise increases and the charge collection efficiency decreases with fluence. Both effects are mitigated by reducing the temperature. To obtain a maximum in SNR gate length and bias voltage can be optimized.