Author/Authors :
Antunovic، نويسنده , , Z. and Deiters، نويسنده , , K. and Dzelalija، نويسنده , , M. and Godinovic، نويسنده , , David N. and Ingram، نويسنده , , Q. and Musienko، نويسنده , , Y. and Puljak، نويسنده , , I. and Renker، نويسنده , , D. and Soric، نويسنده , , I.، نويسنده ,
Abstract :
The photodetectors which read out the scintillation light generated in the lead tungstate crystals in the barrel part of the Compact Muon Solenoid (CMS) electromagnetic calorimeter are avalanche photodiodes (APDs). Scanning the APDʹs active area with a collimated light spot, the spatial uniformity of their quantum efficiency and gain has been measured at four different operating gains. Details of the APD surface structure are examined by scanning with a fine light spot. These details help to explain the difference between the bias voltage for a given gain when the full APD area is illuminated and when only the central part is illuminated.
Keywords :
Silicon avalanche photodiodes , Calorimetry , GAIN , Quantum efficiency , Uniformity
