Light guide production for LBNE and the effects of UV exposure on VUV waveshifter efficiency

The Long-Baseline Neutrino Experiment (LBNE) Project is expected to provide facilities that will enable a program in neutrino physics that can measure fundamental physical parameters, explore physics beyond the Standard Model and better elucidate the nature of matter and anti-matter. The LBNE Photon Detection subsystem is primarily designed to detect the scintillation photons produced at 128 nm as ionizing particles traverse the liquid argon. The LBNE reference design for the photon detector subsystem uses adiabatic light guides consisting of cast acrylic bars whose surface is embedded with waveshifter to convert the VUV 128 nm photons into the sensitive optical range of silicon photomultipliers (SiPMs). In this investigation we first describe our methods for manufacturing light guides. We then describe our testing program to determine the effects of UV radiation on the waveshifter efficiency. We find that UV radiation from fluorescent lights does not degrade waveshifter efficiency significantly in 96 hours of exposure, but that waveshifter quickly deteriorates when exposed to the UV radiation in sunlight.