  Detectors based on polystyrene scintillator strips with WLS fiber readout are
widely used to register charged particles in many high-energy physics
experiments. The fibers are placed into grooves or holes along the strip. The
detection efficiency of these devices can be significantly increased by
improving the optical contact between the scintillator and the fiber by adding
an optical filler into the groove/hole.
  This work is devoted to the study of the light yield of a 5-m-long
scintillator strip with a 1.2-mm-diameter Kuraray Y11(200)~MC WLS fiber
inserted into the strip's co-extruded hole filled with synthetic silicon resin
SKTN-MED(E). The light yield was studied using cosmic muons and a $^{60}$Co
radioactive source.
  Radiation hardness study of viscous fillers and short strip samples were
performed on the IBR-2 pulsed research reactor of fast neutrons at JINR.
