Transmission Characteristics of Light Pipers

The transmission characteristics of light pipers used in scintillation counting are very important, especially in situations in which the light piper must be long and thin, as in medical probing counters. This paper discusses several of the important factors involved in the transmission of light through pipers. The superiority of specular reflectors as compared with diffuse reflectors, the superiority of dry reflectors as compared with optically coupled reflectors, and the importance of surface polish are discussed. The use of total-internal-reflection couplers between scintillation crystal and light piper is described. Relative pulse heights obtained with certain crystal-piper-reflector combinations are given, and transmissions as functions of piper length and configuration are shown.