Measurement of neutron and gamma-ray intensity distributions with an optical fiber-scintillator detector

On the tip of an optical fiber, a very small amount of ZnS(Ag) scintillator mixed with neutron converter and adhesive paste was painted, which can be inserted into a narrow space and moved by a fiber-driving unit controlled w ith a personal computer. The presented method made it possible to measure n eutron flux distributions in critical assemblies, research reactors or othe r neutron facilities with position resolution of less than 1 mm and in 10 m in or so over a meter. As neutron converter, Li-6 and U-235 are good for th ermal neutrons and Th-232 is useful for fast neutrons. When a neutron conve rter is not used, the method can be applied to the measurement of gamma-ray intensity distribution. (C) 1999 Elsevier Science B.V. All rights reserved .