Characterization of avalanche photodiodes for calorimetry applications

Silicon avalanche photodiodes (APDs) have been studied extensively as photosensor candidates for the electromagnetic calorimeter of the CMS detector at LHC. This work presents the measurements of APDs from Hamamatsu and EG&G, with particular emphasis on multiplication factor, spectral response, excess noise factor as well as their dependence on wavelength. The results are compared to the theoretical predictions. Results on the stability of APD gain to bias and temperature drift are also presented.