Electron beam studies of light collection in a scintillating counter with embedded fibers

The light collection of several fiber configurations embedded in a box-shaped plastic scintillating counter was studied by scanning with minimum ionizing electrons. read out silicon photomultipliers at both ends. yield produced the 855-MeV beam Mainz Microtron showed strong dependence on transverse distance from position to fibers. observations were modeled attributing indirect inside and direct reaching total yield. fibers compared that without These studies carried within development detectors as an active veto system for DarkMESA electron beam-dump experiment will search dark matter particles MeV mass range.