MEASURING DEVICE OF RADIOACTIVITY NUCLEAR SPECIES

PURPOSE:To calculate accurately the amount of radioactivity in a sample by making corrections on the basis of the relation previously found as to a total counting rate and a death time and the variation found by performing counting at every unit time by utilizing a multiple counting rate. CONSTITUTION:A multiple counting system 16 calculates the variation in total counting rate during a measurement of the sample 11. Namely, when the measurement of the sample is started, only the detection signal of gamma rays is supplied to a multiple counting circuit 162. Then, the total counting rate N in the sample measurement is found at every unit time and written in a process memory 163. A multiple crest value analysis system 17, on the other hand, calculates the peak counting rate of the gamma rays from gamma-ray radiating nuclear species. When the measurement is completed, a computer 18 for data analysis reads data out of process memories 163 and 172 and obtains information on the correction coefficient of the death time from the memory 163. Further, peak counting rates by nuclear species are obtained from the memory 172. Then, the correction coefficient is calculated from the variation in total counting rate. Thus, the correction coefficient is calculated to make corrections, thereby calculating accurately the amount of radioactivity in the sample.