Optimization of the Light Guides for the ATLAS-ZDC

The High Luminosity Zero Degree Calorimeters (HL-ZDCs) will be using tungsten absorbers, radiation-hard fused silica rods as Cherenkov radiators, and Photomultiplier tubes to convert light signals into analog electric signals. The detector will use reflective air light guides (LG) to transport Cherenkov radiation from the radiators to the PMTs. The light guides are being optimized to be efficient and uniform in acceptance. Different surface materials for the LGs and polishing techniques have been considered. The reflectance of the light guides is measured across a wide range of angles and wavelengths across the surface to ensure uniform high reflectivity. The reflectivity data will be used to improve the light transport simulations in the ZDC.