Gamma-Ray To Cerenkov-Light Conversion Efficiency For Pure-Silica-Core Optical Fibers

We have determined experimentally the absolute gamma-ray to Cerenkov-light conversion efficiency for pure-silica-core optical fibers in the vicinity of metallic Compton-converter slabs. To measure the energy dependence of this process, we used 60Co and 24Na radiation sources. The results show how the conversion efficiency varies with Compton-converter material, thickness, angle of the fiber, and fiber-converter distance. We also performed computer calculations of conversion efficiency. This method employs an electron-photon transport code named SANDYL together with analytical calculations of Cerenkov-light generation. We compare the results of these calculations with experimental results.