International audienceEUSO-Balloon is a balloon borne mission operated by CNES during a one-night flight in August 2014 over the Ontario forest, in Canada, at 38 km altitude. The payload is a technological demonstrator for the Extreme Universe Space Observatory (JEM-EUSO) aiming at the detection of Extensive Air Showers (EAS) induced by Ultra High Energy Cosmic Rays (UHECR) from the International Space Station (ISS). The photon detection module of EUSO-Balloon consists in a square assembly of 36 Multi-Anodes Photomultiplier Tubes for a total of 2,304 pixels. The characterization at the single photoelectron level in laboratory has been processed before flight in a dedicated black box. After-flight calibration to check possible decrease of gain and efficiency of PMTs has been also carried out. Finally we discuss the upgrade of the detector module to improve the gain and the signal to noise ratio as well as the dynamic range of the readout electronics. The significant progresses made on these aspects represent a first milestone for the R&D of future EUSO-like missions
