Gamma and Neutron radiation damage studies of optical fibres

An optical data link is under development at CERN for readout of the tracking detectors in the future CMS experiment at the CERN Large Hadron Collider. Radiation doses inside the experiment will be very high, typically ~ 20Mrad and ~10[14]neutrons/cm2 over a 10 year period of operation. The effects of neutron and gamma irradiation on the attenuation in three different types of single mode fibre have been studied at 1550nm wavelength. The Ge-doped fibre was determined to be unsuitable for use inside the tracking volume of the CMS experiment, whereas the two pure silica core fibres were found to be sufficiently radiation resistant.