Large-area SiPMs for the CMS hadron outer calorimeter

We report on the measurement of pulse shape, gain, leakage current, and photon detection efficiency in 4–9 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> state-of-the-art silicon photomultipliers (SiPMs) obtained recently from the Center of Perspective Technology and Appa- ratus (CPTA) in Russia, Center for Scientific and Technological Research (ITC-irst) in Italy, and Hamamatsu Corporation in Japan. The CPTA and IRST SiPMs were used to read out a hodoscope of scintillators designed for the outer layer of the hadron calorimeter of the Compact Muon Solenoid (CMS) with muon and pion beams at CERN. A direct comparison with CMS production hybrid photodiodes (HPDs) show that the SiPMs give an order of magnitude improvement in the signal to noise for single minimum ionizing particles (MIPs) and that the dynamic range is sufficient to detect up to 450 MIPs for use as a tail-catcher for late-developing hadronic showers in CMS.