| 摘要 |
PURPOSE:To lower the intensity of beta-ray source used while increase an output signal of a detector, building up a beta-ray detector with a scintillator for beta rays and a photoelectric multiplier adapted to convert the detection light of the scintillator to electricity and amplify. CONSTITUTION:It is so designed that beta rays radiated from a beta-ray source transmitted through an object to be measured is detected with a beta-ray detector 6 and the thickness of the object being measured is calculated from the detection signal for display. The beta-ray detector 6 is equipped with a scintillator 4 and a photo electric multiplier 5 arranged tight on the back secured in a light shielding case 16. An light admission window 19 is composed of a metal foil such as aluminum foil to transmit beta rays while external light is kept from being incident into the scintillator 4. The scintillator 4 for beta rays is solid and free from the effects of changes in the temperature and atmospheric pressure. A pulse train outputted from the photoelectric multiplier is so stable as to be converted to a DC voltage with a high proportionality. This produces a large output current and can lower the intensity of the beta-ray source used. |
