Some problems of light collection in the long scintillation counters

The question of light losses in very long scintillation counters (4 m) is considered. Using a radioactive β-source and photomultiplier the dependence of the light collection efficiency upon a) the surface quality of the scintillator and of the light guide and b) of the light reflecting characteristic of the material wrapped around the scintillator and the light guide is investigated. Light losses caused by bending and coupling of scintllators are also studied. It is shown that light losses mainly depend on the surface quality. Adiabatic bending does not give remarkable light losses (3 %). The light loss for scintillators coupled without cement (''dry contact'') is of the order of 20 %