SCINTILLATION-COUNTERS CHARACTERISTICS VERSUS LIGHT COLLECTION CONDITIONS

The effect of the light collection conditions on a scintillation counter's performance have been studied by measuring the characteristics of a counter with a rectangular plastic scintillator surrounded by air, water, and paraffin oil, and those of a counter with trapezium scintillators with angles between side faces of 5.6, 7.5, and 10-degrees. The measurements demonstrate that the time resolution is mainly defined by a number of collected photons. When the refraction index of the environment rises, the effective light propagation velocity towards the PMT rises. It is possible to select an angle between the faces of a trapezium scintillator at which the detected signal amplitude is virtually independent of the scintillation site.