| 摘要 |
PURPOSE:To enable stable dosage measurement and energy characteristics with low current consumption by providing a voltage dividing resistor which divides a source voltage to set a threshold value and sets the threshold value of a crest value discriminator in case of source voltage variation and an amplitude attenuator. CONSTITUTION:A semiconductor detector 10 converts incident radiation into a pulse signal with a crest value corresponding to the energy level and outputs pulse signals whose number corresponds to the radiation dosage. An amplification part 12 inputs the pulse signals and outputs pulse signals having a specific amplitude level. The pulse signals are inputted to a voltage attenuator 20 and outputted to the crest value discriminator 22. The discriminator 22 discriminates the crest value with a specific threshold value and outputs only pulse signals of crest level higher than the threshold value. The discriminator 22 is provided with voltage dividing resistances R7 and R9 and divides a voltage supplied from a battery power source 24 and when the source voltage varies, an attenuator 20 corresponding to variation in the source voltage attenuates the amplitude level of the pulse signals by the variation in the threshold value.
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