Application of multi-pixel avalanche photodiodes operating in Geiger mode for scintillator pad detector read-out

Details of application of Si avalanche photodiode read-out for scintillator pad detector are discussed. The detection of charged particles using scintillator pads read-out with embedded WLS fiber is explored in many HEP experiments. The 12 cm×12 cm and 4 cm×4 cm scintillator counter design developed for LHC-b experiment [LHC-b Calorimeters Technical Design Report, CERN/LHCC/, 2000-0036] is being explored for the “OKA” experiment (Protvino) [V.F. Obraztsov, OKA: the experimental program with RF-separated K+-beam, KAON-05, Evanston, 2005, 〈http://www.oka.ihep.su〉] aimed to K-meson rare decays study. Recently developed multi-pixel avalanche photodiodes operating in Geiger mode have definitive advantages with respect to conventional multi-anode PMT, i.e. larger quantum efficiency, compact detector design and small light losses, lower supply voltage. All this allows one to achieve a high light response of more than 100 photo-electrons per MIP with a simple and economical detector design. s paper we describe characteristics of 3 batches of MRS APD, produced by the CPTA, Moscow [Center of Perspective Technologies and Apparatus (CPTA), Moscow; Photonique SA, Geneva 〈http://www.photonique.ch〉]. We tested 3 types of photodiodes with a sensitive area of 1 mm2 with 556 pixels, defining the noise counting rate and detection efficiency as a function of electronics threshold.