Question from Jaroslav Va'vra (jjv@slac.stanford.edu)
"I am interested in the "radiation" and "UV light" (yellowing) hardness of your optical glues NE 581 and Bicron BC600. Do you have also the transmission measurements ?"

Answer from James A. Crittenden (crittenden@vxdesy.desy.de)
"We have made no measurements of the radiation stability of the optical glues, choosing to accept the statements of the producers. We do not expect aging effects in the glue to contribute significantly to light loss in our optical system, given the following considerations:
1)The radiation level in ZEUS is rather low. In the worst case (near the beam pipe) we expect less than 3 kGy/10 years. For the presampler the dose rate is still smaller.
2)The thickness of glue between scintillator and fiber is less than a few tenths of a millimeter.
3)The amount of UV light during operation is too little to cause significant aging.
We have observed deleterious effects on the light transmission properties of our clear fibers themselves arising from exposure to UV light. So we do take care to protect our optical readout components from external light sources in situ, as we did during fabrication."