  Photoelectron yields of extruded scintillation counters with titanium dioxide
coating and embedded wavelength shifting fibers read out by silicon
photomultipliers have been measured at the Fermilab Test Beam Facility using
120\,GeV protons. The yields were measured as a function of transverse,
longitudinal, and angular positions for a variety of scintillator compositions
and reflective coating mixtures, fiber diameters, and photosensor sizes. Timing
performance was also studied. These studies were carried out by the Cosmic Ray
Veto Group of the Mu2e collaboration as part of their R\&D program.
