| 摘要 |
PURPOSE:To obtain high detection efficiency even when a scintillator of crystal which contains air bubbles is used, by disposing the growth axis of the crystal and the axis of a photodetector in a position intersecting at right angles. CONSTITUTION:Photoelectric tubes 21 and 22 have three axes (x), (y), and (z) to a scintillator 20, and radiation may be incident in those axial directions. If the scintillator 20 contains air bubbles, the scintillator emits light by radiation, but light is reflected by the air bubbles and light detected by the photoelectric tubes varies in accordance with the directions of the photoelectric tubes. For this purpose, the crystal growth axis of the scintillator and the axes of the photoelectric tubes are disposed in a position interrecting at right angles, this scintillator has a detection rate similar to that of a scintillator of crystal which does not contain any air bubble. |
