| 摘要 |
PURPOSE:To obtain a title circuit which can simplify apparatus and reduce cost. CONSTITUTION:A radiation detector 10 detects alpha rays and beta rays to output electric signals according to detected amounts, and these electric signals are amplified by a high-speed current type preamplifier 42. An alpha-ray separation filter 44 integrates electric signals outputted from the preamplifier 42, and a first pulse-height discrimination circuit 52 discriminates electric signals outputted from the alpha-ray separation filter 44 and outputs only alpha-ray detection signals. A second pulse-height discrimination circuit 46 discriminates electric signals outputted from the preamplifier 42 and outputs alpha-ray/beta-ray mixture signals which are the mixture of alpha-ray detection signals and beta-ray detection signals, inputs alpha-ray detection signals outputted from the first pulse-height discrimination circuit and alpha-ray/beta-ray mixture signals outputted from the second pulse-height discrimination circuit into a gate circuit 54, so as to subtract alpha-ray detection signals from alpha-ray/beta-ray mixture signals to output only beta-ray detection signals.
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