Fogging in polyvinyl toluene scintillators used in outdoor environments

It has been observed that large polyvinyl toluene (PVT)-based gamma ray detectors can suffer internal “fogging” when exposed to outdoor environmental conditions over long periods of time. When observed, this change can result in reduced light collection and performance of the PVT. Investigation of the physical cause of these changes has been explored, and a root cause identified. Mitigation procedures and methods are being investigated.