High-reflective dielectric foil development with the low UV-cutoff for the light concentrators of the MAGIC-II telescope camera

The light collectors such as Winston Cones are widely used in ground-based gamma-ray astronomy. The highest possible light collection efficiency and low UV-cutoff of the reflective surface are required for the collection of the Cherenkov light. The usage of dielectric materials allows one to reduce absorption and reach almost 100% reflectivity. Here we report about a high-reflective multilayer dielectric foil development with the low UV-cutoff. Developments were done in the collaboration with Fraunhofer-Institut fuer Elektronenstrahl-und Plasmatechnik, Dresden