Radiation damage effect on avalanche photodiodes

Avalanche photodiodes have been chosen as photon sensors for the electromag netic calorimeter of the CMS experiment at the LHC, These sensors should op erate in the 4 T magnetic field of the experiment. Because of the high neut ron radiation in the detector extensive studies have been done by the CMS c ollaboration on the APD neutron radiation damage. The characteristics of th ese devices after irradiation have been analyzed, with particular attention to the quantum efficiency and the dark current. The recovery of the radiat ion-induced dark current has been studied carefully at room temperature and at slightly lower and higher temperatures. The temperature dependence of t he annealing has been evaluated. (C) 1999 Elsevier Science B.V. All rights reserved.