| 摘要 |
PURPOSE:To detect radiation high in the efficiency of transmission to a photomultiplier tube by finishing the surface opposed to the emitting surface of scintillation light among the surfaces of a Bi4Ge3O12 crystal into a rough surface and subjecting the emitting surface and residual surfaces to specular finish. CONSTITUTION:The surface 2a opposed to the emitting surface of scintillation light among the surfaces of a Bi4Ge3O12(BGO) crystal 2 is finished into a rough surface and the emitting surface and the residual surfaces are subjected to specular finish. The surface roughness Ra of the rough surface 2a of the BGO crystal 2 is desirably at least 0.8 mum. When the surface roughness Ra is below 0.8 mum, the quantity of emitted light as a scintillator becomes little. A reflecting layer 3 is desirably provided to the surfaces other than the emitting surfaces of scintillation light of the BGO crystal. Because of this constitution, even when scintillation light is incident to the surface 2a vertically, the light is reflected toward a photomultiplier tube 1 without being transmitted through the surface 2a. The scintillation light incident to side surfaces is totally reflected to reach the photomultiplier tube 1.
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