Radioactivity measuring apparatus using optical fiber

Abstract

An elongated, thinner apparatus is provided so as to measure surface contamination in narrow places and piping. An elongated plate-shaped radioactivity detection section () provided with a scintillator and a radioactivity measuring section () provided with a photomultiplier are provided as independent components and are connected together using a wavelength conversion optical fiber cable (). A measurement signal (optical signal) of α-rays detected by the radioactivity detection section is transmitted to the radioactivity measuring section via the optical fiber cable. The radioactivity detection section is provided with elongated light guides, sets of wavelength conversion optical fibers, each set consisting of two optical fibers, arranged along the light guides in close contact therewith, a scintillator layer and a light-shielding film, and these components are surrounded by a light-shielding frame so that only a detection surface of the light-shielding film is exposed and the optical fibers extend from the radioactivity detection section as the optical fiber cable provided with a light-shielding outer covering.