Comparison of BCF-10, BCF-12, and BCF-20 Scintillating Fibers for Use in a 1-Dimensional Linear Sensor

Abstract

One-dimensional fiber-bundle arrays may prove useful in a number of radiation sensing applications where radiation detection over large areas is needed. Tests have been performed to evaluate the light generation and transmission characteristics of 15-meter long, 10-fiber bundles of BCF-10, BCF-12, and BCF-20 scintillating fibers (Saint Gobain) exposed to collimated gamma-ray sources. The test set-up used one R9800 (Hamamatsu) photomultiplier tube (PMT) at each end, with a high-speed waveform digitizer to collect data. Time constraints were imposed on the waveform data to perform time-of-flight analysis of the events in the fiber bundles, eliminating spurious noise pulses in the high gain PMTs and also allowing 1-dimensional localization of interactions along the lengths of the fiber bundles. Measurements show that the spatial response of these three fibers is linear over at least 15-m lengths and that, with the equipment used here, the spatial resolution for events irradiating 1 cm of fiber (using a collimated source) ranges from 50 cm to 60 cm over the entire length of the bundles. The efficiency for detecting events varies along the length of the arrays, with the sensitivity at the midpoint (half of the distance) of an array ranging from ~ 2X to ~ 3X the efficiency at the ends, depending on the length of the fiber-bundle array and the self-absorption factor for each fiber's scintillation light. Compared to prior work, a 20-fold improvement in detection sensitivity has been shown for this technique, most likely due to improved optical coupling and improved signal analysis.