Sensors capable of detecting single photons are of critical importance for a very wide range of scientific and technical applications in such areas as medical imaging, biotechnology, high energy physics, scientific instrumentation, communication, and homeland security, including, in particular, positron emission tomography, flow cytometry, Cherenkov cosmic ray telescopy, laser ranging, optical time domain reflectometry or beam loss monitoring in particle accelerators and light sources.Silicon Photomultipliers (SiPMs), in particular, are an emerging and very promising technology due to their photon number resolution at room temperature, insensitivity to magnetic fields, compactness and relatively low operating voltages. Furthermore, they are cheap to mass-produce, especially in comparison to conventional photomultiplier tubes. In order to evaluate their potential for a specific application, it is necessary to quantify their fundamental parameters as a particle detector, as well as in combination with scintillators or optical fibers used for signal generation and transport, in detail.In the frame of this Marie Curie IIF project, a comprehensive analytical probabilistic model of the SiPM response shall be developed that will take the specific excess noises of crosstalk and afterpulsing, nonlinearities and saturation effects into account. Based on this model, a full set of analysis, measurement and characterization methods will then be built up. This will allow for selecting an optimum SiPM design and model for a specific application as accelerator, nuclear or medical physics instrumentation and thus contribute to an overall improvement of the respective application. Finally, reliability and mass testing approaches and techniques, applicable for large-scale projects and focused on the balance between accuracy, simplicity and cost efficiency, shall be developed.