| 摘要 |
PURPOSE:To make the gain of a signal amplifying loop constant when a bar-like scintillator, is used for a gamma-ray measuring instrument which measures the level of a fluid or powder by optically connecting an inorganic scintillator having large light emitting energy to the top of a plastic scintillator and irradiating both scintillators with gamma rays, and then controlling the gain of the loop so that optical signals can become constant. CONSTITUTION:An inorganic scintillator 17 is connected to the top of a plastic scintillator 5 and both scintillators 17 and 5 are irradiated with gamma rays from a gamma-ray source 4. Optical signals from both scintillators 17 and 5 are amplified by means of a photomultiplier 6 and amplifier 10 and the signals from the inorganic scintillator 17 are discriminated by means of an energy discriminator 18. Then a second comparator 13 and computing element B14 perform arithmetic operation so that the signals can become constant and control an HV control circuit 16 and high-voltage power source 15 so that level signals can be always amplified constantly. |
