Scintillation detector failures

[CLAUDE A. FLORY <FLORYCA@GWSMTP.NU.COM>]

I need to justify use of an LED in lieu of an ionizing radiation source to
source check some scintillation detectors.  Although the primary sensor, the
scintillator, is not tested by the LED the use may be justified because the
chance of the scintillator failing between 18 month calibrations is extremely
remote.

Does anybody have any experience with scintillator failure such as decoupling
from the light pipe or scintillator degradation?  Manufacturers claim that
newer designs are more reliable because of the epoxy used to cement the
scintillator and light pipe.

We have two types of scintillation detectors, a 10 mil thick plastic
scintillator and a 1.5" by 1" NaI.  I have more confidence in the plastic
scintillator not failing between calibrations than I do in the NaI.

Any help would be greatly appreciated.

Claude Flory
Northeast Utilities