The photo-detector for the EUSO experiment

Abstract The EUSO experiment is currently under study by ESA for a possible installation on the International Space Station. The experiment is designed to study, by means of a space-based observational apparatus, the Extensive Air Showers produced in the atmosphere by Extreme High-Energy Cosmic Rays. The design of a fast, single-photon sensitive photo-detector in the near UV, covering a large area with a few hundreds thousands pixels, and suitable for 3 years of operation in space is a challenging task. The basic aspects of the current EUSO photo-detector design, based on the presently known requirements and constraints, and the results of the preliminary studies carried on so far will be described.