Nuclear-radiation-induced absorption in optical materials

Reactor radiation-induced transient absorption was measured in 7940 fused silica, magnesium fluoride, barium fluoride and sapphire at 257 nm. The fused silica gave the lowest induced transient absorption of all the materials studied. The absorption coefficient per unit dose for fused silica (1.5 cm-1/Mrad) was much more than the value given previously in the literature. The previously measured value was at a temperature of 5000C, suggesting that the induced transient absorption can be greatly reduced by elevating the temperature of the sample. The absorption coefficient per unit dose was also found to be dose rate dependent. 6 figures, 1 table