| 摘要 |
PROBLEM TO BE SOLVED: To correct influence of radon existing in the natural world and exactly judge the presence of radiation contamination even if the influence of natural radiation is not estimated otherwise by correcting the measuring value of aβray by the value of theβray which a natural radioactive nuclide emits, and using it for contamination judgement. SOLUTION: Anαray and aβray which a natural radioactive nuclide emits can be separated and measured with discrimination circuits 5a, 5b and the emission ratio of the measuredαray andβray due to the natural radioactive nuclide can be calculated previously. Next, a radiation emitted from a specimen is detected with a radiation detector 20, and the a ray and theβray are separated and measured from the detected signal. The value of theβray due to the natural radioactive nuclide contained in the measured value of theβray is found, the value of theβray due to the natural radioactive nuclide is corrected to be deducted from the measured value of theβray. Accordingly, contamination judgement can be performed with theβray measured value of high reliability in which the influence of theβray due to the natural radioactive nuclide is eliminated.
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