Neutron irradiation studies of avalanche photodiodes using californium-252

Californium-252 is a convenient and copious source of neutrons of energies around 1 MeV, and provides many advantages over reactors for neutron irradiation studies of detector components. We describe here an experimental setup at Oak Ridge National Laboratory which has been constructed to study the performance of avalanche photodiodes in neutron fluences up to 1013 neutrons/cm2, similar to what is expected in parts of the CMS detector at the LHC. An irradiation study of some avalanche photodiodes is discussed, followed by a brief summary of results obtained.