Thermal neutron radiation damage on light yield and attenuation length of scintillating fibres

Samples of blue scintillating fibres have been irradiated with thermal neutrons. The light yield and the attenuation length have been measured for a total integrated flux ranging from 3 to 60×1013 neutrons cm−2, and for two different fluxes (3.5 and 35×109 neutrons cm−2 s−1). The long term damage has been investigated for 2 m long samples with uniform irradiation along the fibre. Sizable deteriorations both in light yield and in attenuation length are found even at our lowest integrated neutron flux.