The Potential of SiPM as Photon Detector in Astroparticle Physics Experiments like MAGIC and EUSO

We discuss the prospects to use a novel photon detector — the so-called SiPM — for the high energy astroparticle physics experiments EUSO and MAGIC. We explain the principle of these photon sensors and present results obtained with some prototypes. Peak photon detection efficiency (PDE) of the devices available is currently about 20%. Already in its existing form Geiger mode APDs offer a very promising replacement candidate for conventional photomultiplier tubes (PMTs) in both experiments, provided some improvements can be achieved.