International audienceJEM-EUSO [1] is intended to be a space-borne fruorescence telescope onboard of JEM/EF(Japanese Experimental Modeul/Exposure Facility) on the International Space Station (ISS). Themain goal of the JEM-EUSO project is to detect the Extensive Air Showers (EAS) produced bythe Extreme Energy Cosmic Rays (EECRs) with energies above 1019eV from the extragalacticobjects. As a pathfinder, the JEM-EUSO collaboration is currently developing a balloon-bornefluorescence telescope experiment, called EUSO-Balloon, funded by CNES, the French spaceagency. It will perform end-to-end tests of the JEM-EUSO subsystems and instrumental concept,and measure the UV background for space-based EECR detectors. It involves several French institutes(LAL, APC and IRAP) as well as several key institutes of the JEM-EUSO collaboration.The EUSO-Balloon instrument consists of an UV telescope and an infrared camera. The UVtelescope will be operated at an altitude of 40 km to observe the background and possibly signalphotons in the fluorescence UV range (290-430 nm), which are emitted along shower tracks generatedby ultra high energy cosmic rays with energies above 1018eV interacting with the earth’satmosphere. The balloon experiment will be equipped with electronics and acquisition systems,as close as possible to the ones designed for the UV telescope of main JEM-EUSO instrument.The past years have been devoted to the design, the fabrication and the tests of the prototypeboards of the PDM, of the digital processor, and the flight models of optics, electronics and theIR camera for EUSO-Balloon.Here we focus on the PDM, the core element of the JEM-EUSO focal surface. We first describeall key items of the PDM, from the photodetectors to the FPGA board, the first stage of the dataprocessing (DP). We then report on the tests carried out on the integration to assess their functionalityand their suitability for a balloon mission
