6-9 July 2015
Moscow, Troitsk
Europe/Moscow timezone
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Contribution talk

STUDIES OF SILICON PHOTOMULTIPLIERS FOR THE CMS HCAL UPGRADE

Speakers

  • Yuri MUSIENKO

Primary authors

  • Yuri MUSIENKO (INR RAS (Moscow)/University of Notre Dame (Notre Dame))

Co-authors

Content

The CMS Barrel (HB) and Endcap (HE) Hadron Calorimeters are scintillator sampling calorimeters with embedded wavelength shifting fibers (WLS) in scintillator tiles. The photo-sensors that are currently used are hybrid photodiodes (HPDs). In 2012 the HCAL Phase I upgrade was approved for the increased luminosity (51034) of SLHC. A key aspect of the HCAL upgrade is to add longitudinal segmentation to improve background rejection, energy resolution and scintillator radiation damage compensation. The increased segmentation can be achieved by replacing the HPDs with silicon photomultipliers (SiPMs)). The SiPMs for the CMS HCAL upgrade have to operate in a very hostile SLHC radiation environment (we expect a maximum total dose of 1012 n/cm2 for an integrated luminosity of 3000 fb-1). They should have good linearity for a wide range of scintillating signals and excellent reliability. During the last years we have successfully completed the R&D for instrumentation of SiPMs for the Phase 1 upgrade of HE/HB in 2017 and 2018. Here we report on the final SiPM parameters of two manufactures considered for the 2015 preproduction run. These candidates Hamamatsu (Japan) and KETEK (Germany) have developed state of the art custom large dynamic range SiPMs with large PDE and small ENC for the CMS HCAL Upgrade project. An overview of all results of our measurements of photon detection efficiency, spectral response, cell recovery time will be reported in this presentation. Results from a study on the radiation hardness of silicon photomultipliers (SiPMs) are also presented. The SiPMs were exposed to hadrons (protons and neutrons) at fluences up to 110^12 hadrons/cm2. The SiPM's main parameters were measured before and after irradiation. The effects of the hadron radiation on breakdown voltage, quenching resistance value, gain, photon detection efficiency, dark current and dark count rate for these devices are shown and discussed.

Author's Institution

INR RAS (Moscow) and University of Notre Dame (Notre Dame, USA)

Co-author's Institution

INR RAS (Moscow) and University of Notre Dame (Notre Dame, USA)