In Situ Measurement of Radiation Damage in Scintillating Fibers

The radiation induced degradation of the optical transmission of the fibers SCSF-38M, SCSF-81M (Kuraray), BCF-60 and BCF-98 (Bicron) with polystyrene core (PS) was studied. During and after irradiation with a 100 kV X-ray source, a ¹³⁷Cs source and a ⁶⁰Co source the effects depend on the fiber type: (1) The permanent damage for BCF-98 (clear PS) is smaller than for the scintillators. (2) The BCF-60 is radiation harder than the other two scintillators but very light sensitive.

Temperature treatments (up to 68°C) of SCSF-38M, without irradiation showed a transmission loss which clearly rises with the increasing temperature. This accelerated ageing phenomenon does not recover and the fiber is permanently damaged. In an additional experiment it was studied whether the transmission damage can be influenced by short illuminations with visible light during and after irradiation. For SCSF-38M a strong reduction of the permanent induced absorption remaining after the end of the recovery process was observed.