JP2017156172A - Radioactivity measuring device and radioactivity measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the correction accuracy of the summing effect when the quantity of the radioactivity of a sample is determined.SOLUTION: A radioactivity measuring device 10 includes a processing device 15 having a storage unit 16 and a calculation unit 17. The storage unit 16 stores the distribution data related to the frequency distribution in the entire sample of the total absorption peak efficiency of a radioactivity detector 11 associated with an arbitrary position in the sample. The calculation unit 17 calculates the correction detection efficiency by correcting the summing effect for each total absorption peak efficiency associated with the arbitrary position in the sample. The calculation unit 17 calculates the calibration detection efficiency by integrating the correction defection efficiency associated with all the total absorption peak efficiencies included in the distribution data. The calculation unit 17 calculates the quantity of radioactivity included in the sample by using the data of the pulse height distribution data output from a pulse height analysis device 12 when γ rays emitted from the sample is detected by the radioactivity detector 11, and the calibration total absorption peak efficiency associated with the energy of the γ rays of a measurement object.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radioactivity measurement apparatus and a radioactivity measurement method.

Conventionally, when measuring radiation emitted from a sample to quantify the amount of radioactivity in the sample, it is impossible to discriminate temporally the pulse of the desired gamma ray emitted from the sample from the pulse of other radiation. There is known a method of correcting a phenomenon (sum effect) in which a plurality of pulses are added and counted (see, for example, Non-Patent Documents 1 and 2).
Conventionally, when correcting the thumb effect for a volumetric sample such as a volumetric sample filled in a container, a correction coefficient for detection efficiency is calculated using the average detection efficiency of the entire volumetric sample. The method is known (for example, refer nonpatent literature 3).

"Radioactivity measurement series 7 Gamma-ray spectrometry using germanium semiconductor detector", Ministry of Education, Culture, Sports, Science and Technology, 1992, p. 77-87 Noguchi Masayasu, “γ-ray Spectrometry-Experiments and Exercises”, Nikkan Kogyo Shimbun, December 1980, p. 139-146 “Journal of Nuclear and Radiochemical Science”, Vol. 12, No. 1 (2012) p. 5-10 (Journal of Nuclear and Radiochemical Sciences, Vol.12, No.1, pp.5-10, 2012)

  By the way, according to the correction of the sum effect according to the above prior art, the correction coefficient is simply calculated using the average detection efficiency of the entire volume sample, so that the sum effect for each arbitrary position of the volume sample. When the degree of the difference is different, there arises a problem that the correction accuracy of the sum effect cannot be improved.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a radioactivity measurement apparatus and a radioactivity measurement method capable of improving the correction accuracy of the sum effect when quantifying the radioactivity of a sample. Yes.

In order to solve the above problems and achieve the object, the present invention employs the following aspects.
(1) A radioactivity measuring apparatus according to an aspect of the present invention includes a radiation detector that detects radiation emitted from a sample, and a sum effect corresponding to the sample when the detection efficiency of the radiation detector is calibrated. Processing means for correcting, the processing means for storing distribution data related to the frequency distribution of the entire sample of the detection efficiency associated with an arbitrary position in the sample, and the sample The correction detection efficiency is calculated by correcting the sum effect for each of the detection efficiencies associated with an arbitrary position in the position, and the correction detection efficiencies associated with all the detection efficiencies included in the distribution data are integrated. And calculating means for calculating the calibration detection efficiency.

(2) In the radioactivity measurement apparatus according to (1), the characteristic value of the distribution data used by the calculation unit to calculate the calibration detection efficiency is measured using a standard radiation source having a predetermined shape. Calibrated by the detector detection efficiency.

(3) In the radioactivity measurement apparatus according to (1) or (2) above, the distribution data used by the calculation means for calculating the calibration detection efficiency is associated with the crystal shape of the radiation detector.

(4) In the radioactivity measurement apparatus according to any one of (1) to (3) above, the distribution data used by the calculation means for calculating the calibration detection efficiency is associated with the energy of the radiation.

(5) In the radioactivity measurement apparatus according to any one of (1) to (4) above, the distribution data used by the calculation means for calculating the calibration detection efficiency corresponds to an arbitrary position in the sample. It is corrected by the magnitude of the self-absorption of the medium for the applied radiation.

(6) A radioactivity measurement apparatus according to an aspect of the present invention corresponds to a radiation detector that detects radiation emitted from a columnar sample, and the sample when the detection efficiency of the radiation detector is calibrated. Processing means for correcting the sum effect, wherein the processing means stores the detection efficiency data associated with the plurality of samples having different columnar heights, and the detection efficiency data The detection efficiency associated with an arbitrary height position of the columnar shape is calculated based on the correction, and the sum effect is corrected for each detection efficiency associated with the arbitrary height position of the columnar shape. The detection efficiency is calculated, and the corrected detection efficiency associated with all the height positions included from zero to the desired height in the sample in which the height of the columnar shape is a desired height And a calculating means for calculating a calibration detection efficiency by integrating.

(7) In the radioactivity measurement apparatus according to any one of (1) to (6) above, the calculation means uses the wave height distribution data of the output signal pulse of the radiation detector and the calibration detection efficiency. The amount of radioactivity contained in the sample is calculated.

(8) The radioactivity measurement method according to one aspect of the present invention is performed by a processing unit that corrects the sum effect corresponding to the sample when calibrating the detection efficiency of the radiation detector that detects the radiation emitted from the sample. A radioactivity measurement method, wherein the processing means calculates a corrected detection efficiency by correcting the sum effect for each detection efficiency associated with an arbitrary position in the sample; and The processing means is associated with all the detection efficiencies included in the distribution data based on distribution data related to the frequency distribution of the whole of the sample with the detection efficiency associated with an arbitrary position in the sample. And calculating a calibration detection efficiency by integrating the correction detection efficiency.

(9) The radioactivity measurement method according to one aspect of the present invention is a process for correcting the sum effect corresponding to a sample when calibrating the detection efficiency of a radiation detector that detects radiation emitted from a columnar sample. The radioactivity measurement method performed by the means, wherein the processing means is based on the detection efficiency data associated with the plurality of samples having different heights of the columnar shape, and the arbitrary height position of the columnar shape. A first step of calculating the detection efficiency associated with the correction efficiency; and the processing means corrects the sum effect for each detection efficiency associated with an arbitrary height position of the columnar shape. And the processing means corresponds to all the height positions included from zero to the desired height in the sample in which the height of the columnar shape is the desired height. Including a third step of calculating a calibration detection efficiency by integrating the corrected detection efficiency eclipsed.

According to the radioactivity measuring apparatus according to the aspect described in (1) above, the calculation unit corrects the sum effect for each detection efficiency associated with an arbitrary position in the sample. Therefore, it is possible to perform appropriate correction corresponding to different levels of the sum effect, and to calibrate the detection efficiency with high accuracy.
According to the radioactivity measuring apparatus according to the aspect described in (2) above, the characteristic value of the distribution data is calibrated by the detection efficiency of the radiation detector measured with respect to a standard radiation source having a predetermined shape. It is possible to accurately grasp the frequency distribution of detection efficiency associated with an arbitrary position. By improving the accuracy of the distribution data, it is possible to improve the calibration accuracy of the detection efficiency accompanied by the correction of the sum effect.
According to the radioactivity measuring apparatus according to the aspect described in (3) or (4) above, by taking into account the dependence on the crystal shape of the radiation detector or the dependence on the energy of radiation in the distribution data, Accuracy can be improved.
According to the radioactivity measuring apparatus according to the aspect described in (5) above, since the distribution data is corrected for the magnitude of self-absorption of the medium with respect to different radiation for each arbitrary position of the volumetric sample, the accuracy of the distribution data Can be improved.
According to the radioactivity measurement apparatus according to the aspect described in (6) above, the calculation unit corrects the sum effect for each detection efficiency associated with an arbitrary height position in the columnar sample, and thus the columnar shape Appropriate correction can be performed in accordance with the degree of the sum effect that differs for each arbitrary height position in the sample, and the detection efficiency can be accurately calibrated.
According to the radioactivity measuring apparatus according to the aspect described in (7) above, by using the calibration detection efficiency in which the degree of the sum effect that is different for each arbitrary position in the sample is corrected, the amount of radioactivity contained in the sample is determined. Measurement accuracy can be improved.

According to the radioactivity measurement method according to the aspect described in (8) above, the calculation unit corrects the sum effect for each detection efficiency associated with an arbitrary position in the sample. Therefore, it is possible to perform appropriate correction corresponding to different levels of the sum effect, and to calibrate the detection efficiency with high accuracy.
According to the radioactivity measurement method according to the aspect described in (9) above, the calculation unit corrects the sum effect for each detection efficiency associated with an arbitrary height position in the columnar sample. Appropriate correction can be performed in accordance with the degree of the sum effect that differs for each arbitrary height position in the sample, and the detection efficiency can be accurately calibrated.

It is a block diagram of the radioactivity measuring apparatus which concerns on the 1st and 2nd embodiment of this invention. It is sectional drawing of the radiation detector which concerns on the 1st and 2nd embodiment of this invention. It is sectional drawing of the container of the sample which concerns on the 1st Embodiment of this invention. It is a figure which shows typically a standard volume radiation source and radiation detector in case the main shape efficiency data which concern on the 1st Embodiment of this invention are measured. It is a figure which shows an example of the main shape efficiency data which concern on the 1st Embodiment of this invention. It is a figure which shows an example of the main shape efficiency distribution data based on the 1st Embodiment of this invention. It is a figure which shows typically a standard ray source and radiation detector in case the main shape efficiency distribution data based on the 1st Embodiment of this invention are measured. It is a figure which shows typically the several area | region and radiation detector in a main shape in case the main shape efficiency distribution data which concern on the 1st Embodiment of this invention are calculated by simulation. It is a figure which shows the distance from the effective center of the germanium crystal of the radiation detector used for calculating the self-absorption correction coefficient based on the 1st Embodiment of this invention to the arbitrary positions in the main shape. It is a figure which shows an example of the self-absorption correction coefficient distribution data based on the 1st Embodiment of this invention. It is a figure which shows typically the standard ray source and radiation detector in case the sub-shape efficiency data which concern on the 1st Embodiment of this invention are measured. It is a figure which shows typically the maximum value of the total absorption peak efficiency of the main shape efficiency distribution data calibrated by the sub shape efficiency data which concerns on the 1st Embodiment of this invention. It is a figure which shows the main shape efficiency distribution data by which the self-absorption of the sample obtained by making the self-absorption correction coefficient distribution data shown in FIG. 10 act on the main shape efficiency distribution data shown in FIG. It is a figure which shows an example of the decay pattern intrinsic | native to the nuclide of the sample which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the radioactivity measuring apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows typically the sample container and radiation detector which concern on the 2nd Embodiment of this invention. It is a figure which shows typically the several standard volume radiation source and radiation detector from which the height of columnar shape differs when the efficiency data classified by height concerning the 2nd Embodiment of this invention are measured. It is a figure which shows an example of the efficiency data classified by height concerning the 2nd Embodiment of this invention. It is a figure which shows the area | region of thickness (DELTA) h set in the position of arbitrary height h in the columnar sample based on the 2nd Embodiment of this invention. It is a figure which shows the several area | region of thickness (DELTA) h which comprises the sample of the height hs accommodated in the container which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the radioactivity measuring apparatus which concerns on the 2nd Embodiment of this invention.

Hereinafter, a radioactivity measurement apparatus and a radioactivity measurement method according to a first embodiment of the present invention will be described with reference to the accompanying drawings.
The radioactivity measurement apparatus 10 according to the present embodiment includes a radiation detector 11, a pulse height analyzer 12, an input device 13, an output device 14, and a processing device 15, as shown in FIG. . The processing device 15 includes, for example, a storage unit 16 and a calculation unit 17.

  The radiation detector 11 is, for example, a closed end coaxial type germanium semiconductor detector. As shown in FIG. 2, the radiation detector 11 includes a germanium crystal 20, an end cap housing 21, a vacuum region 22 inside the end cap housing 21, and a crystal holder 23 that holds the germanium crystal 20 in the vacuum region 22. And a resin film 24 provided on the crystal holder 23.

The germanium crystal 20 formed in a bottomed cylindrical shape includes a sensitive region 25 for radiation and a surface insensitive layer 26. The germanium crystal 20 held by the crystal holder 23 is accommodated in an end cap housing 21 having, for example, a radiation incident window (not shown). The inside of the end cap housing 21 is in a vacuum state.
The crystal holder 23 is formed in a box shape having an opening. The opening of the crystal holder 23 is closed by the resin film 24 in a state where the germanium crystal 20 is accommodated inside the crystal holder 23. The opening of the crystal holder 23 closed by the resin film 24 is disposed so as to face the incident window of the end cap housing 21.

  The container 30 in which the sample is accommodated is, for example, a so-called marinelli container. As shown in FIG. 3, the container 30 includes a bottomed cylindrical container body 31 and a columnar recess 32 provided on the bottom surface 31 </ b> A of the container body 31 coaxially with the central axis O of the container body 31. Yes. The container 30 can store a sample in the container main body 31. The cylindrical recess 32 of the container 30 is formed so as to accommodate the end cap housing 21 of the radiation detector 11.

  The pulse height analyzer 12 is, for example, a multi-channel analyzer. The wave height analyzer 12 calculates the wave height distribution of the output signal pulse output from the radiation detector 11, that is, the count value for each of a plurality of channels associated with the wave height value. For example, when the radiation detector 11 outputs an output signal pulse having a peak value corresponding to the energy of the radiation, the pulse height analyzer 12 creates an energy spectrum as a pulse height distribution of the output signal pulse of the radiation detector 11.

The input device 13 includes, for example, various switches and a keyboard that output a signal corresponding to an input operation by the operator. The input device 13 outputs various command signals corresponding to the operator's input operation to the processing device 15.
The output device 14 includes, for example, a speaker, a display device, and a printing device. The output device 14 outputs various information output from the processing device 15.

The storage unit 16 of the processing device 15 stores, for example, various types of preset data, various types of data output from the calculation unit 17, data output from the wave height analyzer 12, and the like. The storage unit 16 stores, for example, main shape efficiency data, main shape efficiency distribution data, and self-absorption correction coefficient distribution data.
The main shape efficiency data is data on the energy dependency of the total absorption peak efficiency with respect to γ rays of the radiation detector 11 with respect to the shape (main shape) of the sample accommodated in the container 30. The main shape efficiency data is generated by actually measuring the radiation emitted from the standard volume radiation source 40 by the radiation detector 11. For example, as shown in FIG. 4, the standard volume radiation source 40 has the same shape as the sample accommodated in the container 30. The main shape efficiency data is data indicating the correspondence between the total absorption peak efficiency ε _P of γ rays and the energy E of γ rays, for example, as shown in FIG.
When the standard volume source 40 is regarded as an aggregate of a plurality of point sources, the total absorption peak efficiency of the radiation detector 11 with respect to γ rays emitted from each point source varies depending on the position of each point source. To do. Therefore, the main shape efficiency data generated using the standard volume radiation source 40 is data in which the dependence of the positions of a plurality of point radiation sources is averaged, and the average total absorption in the entire standard volume radiation source 40 is. Data corresponding to peak efficiency.

The main shape efficiency distribution data is data related to the frequency distribution of the total absorption peak efficiency with respect to γ rays of the radiation detector 11. The total absorption peak efficiency of the main shape efficiency distribution data is associated with a minute region Δv set at an arbitrary position in the main shape. For example, as shown in FIG. 6, the main shape efficiency distribution data is a histogram showing the frequency P (ε) of the total absorption peak efficiency ε in the entire main shape, or data of a distribution function based on this histogram. In the main shape efficiency distribution data shown in FIG. 6, the total absorption peak efficiency ε associated with the minute region Δv at an arbitrary position in the main shape is distributed from the minimum value ε _min to the maximum value ε _max .
The main shape efficiency distribution data may be data associated with the energy of γ rays detected by the radiation detector 11 and the shape of the germanium crystal 20 of the radiation detector 11, for example. For example, a plurality of different main shape efficiency distribution data associated with each of a plurality of different γ-ray energies or a plurality of different crystal shapes of the germanium crystal 20 may be stored in the storage unit 16.

The main shape efficiency distribution data is, for example, actual measurement using a relatively small standard source 41 compared to the standard volume source 40, calculation by simulation, or a predetermined distribution shape (for example, Gaussian distribution) set in advance. Generated by.
In actual measurement using the standard radiation source 41, for example, as shown in FIG. 7, γ rays emitted from the standard radiation source 41 arranged at an arbitrary position in the main shape are actually measured by the radiation detector 11. . By calculating the total absorption peak efficiency with respect to γ rays from the data of the wave height distribution with respect to the output signal pulse of the radiation detector 11 for each arbitrary position in the main shape, the frequency distribution of the total absorption peak efficiency in the entire main shape is obtained. Related data is generated.
In the calculation by simulation, when the radiation detector 11 having a crystal having a predetermined shape detects γ rays emitted from the region 42 set at an arbitrary position in the main shape, the transport of radiation is calculated by simulation. Is done. The plurality of regions 42 in the main shape are formed by dividing the main shape into a plurality of parts, for example, as shown in FIG. For each region 42, the data of the wave height distribution for the output signal pulse of the radiation detector 11 is calculated by simulation, and the total absorption peak efficiency for γ rays is calculated from the wave height distribution data, so that the total absorption in the entire main shape is obtained. Data related to the frequency distribution of peak efficiency is generated.

The self-absorption correction coefficient distribution data is data related to the frequency distribution of the self-absorption correction coefficient. The self-absorption correction coefficient is derived from the fact that each medium differs between the radiation source (for example, the standard radiation source 41 and the region 42) used for generating the main shape efficiency distribution data and the sample to be measured. This is a coefficient for correcting the difference in self-absorption for the line. The self-absorption correction coefficient of the self-absorption correction coefficient distribution data is associated with a minute region Δv set at an arbitrary position in the main shape.
The self-absorption correction coefficient is, for example, a self-absorption correction coefficient fs for the source medium and a self-absorption correction coefficient fa for the sample medium. For example, with respect to the total absorption peak efficiency ε _s obtained by measuring the γ rays of the standard source 41, the total absorption peak efficiency ε ₀ corrected for the self-absorption of γ rays by the medium of the standard source 41 is the standard. Ε ₀ = ε _s / fs is described by the self-absorption correction coefficient fs for the medium of the radiation source 41. The total absorption peak efficiency ε _a for the sample of the medium different from the standard source 41 is described as ε _a = ε ₀ × fa = ε _s × (fa / fs) by the self-absorption correction coefficient fa for the sample medium. .

  For example, the self-absorption correction coefficient fa for correcting the self-absorption of the sample contained in the container 30 with respect to the γ-ray is in the main shape from the effective center 20a of the germanium crystal 20 of the radiation detector 11 as shown in FIG. Is expressed as fa = exp (−μd) by the distance d to an arbitrary position and the linear attenuation coefficient μ of the sample medium. The self-absorption correction coefficient distribution data related to the frequency distribution of the entire main shape of the self-absorption correction coefficient fa is, for example, as shown in FIG. 10, a histogram showing the frequency P (fa) of the self-absorption correction coefficient fa, or this For example, distribution function data based on a histogram. In the self-absorption correction coefficient distribution data shown in FIG. 10, the self-absorption correction coefficient fa associated with the minute region Δv at an arbitrary position in the main shape is distributed from the minimum value a (<1) to 1. The self-absorption correction coefficient fa is, for example, the total absorption peak due to the self-absorption of the sample with respect to the total absorption peak efficiency in which the self-absorption is zero by correction so that the self-absorption of the radiation source is canceled out. Used to reflect the decrease in efficiency.

  The storage unit 16 may store auxiliary shape efficiency data for calibrating the main shape efficiency distribution data. The sub-shape efficiency data is used to calibrate characteristic values of main shape efficiency distribution data generated by, for example, calculation by simulation or a predetermined distribution shape (for example, Gaussian distribution) set in advance. The characteristic value of the main shape efficiency distribution data is, for example, the average value of the distribution, the width of the distribution, the minimum value or the maximum value of the distribution, and the like. The sub-shape efficiency data is generated by, for example, actually measuring gamma rays emitted from the standard radiation source 43 having a predetermined shape (sub-shape) arranged at a predetermined position in the main shape by the radiation detector 11. It is the data of the total absorption peak efficiency. The sub-shape efficiency data is obtained by actually measuring the γ-rays emitted from the sub-shape standard radiation source 43 by the radiation detector 11, and calculating the total absorption peak for the γ-ray from the data of the wave height distribution for the output signal pulse of the radiation detector 11. It is generated by calculating the efficiency.

For example, as shown in FIG. 11, the secondary shape efficiency data when the standard radiation source 43 is arranged closest to the germanium crystal 20 of the radiation detector 11 is the maximum of the total absorption peak efficiency ε of the main shape efficiency distribution data. This corresponds to the value ε _max . This sub-shape efficiency data is used to calibrate the maximum value ε _max of the total absorption peak efficiency ε of the main shape efficiency distribution data as shown in FIG. 12, for example. On the other hand, for example, the secondary shape efficiency data when the standard radiation source 43 is arranged farthest from the germanium crystal 20 of the radiation detector 11 calibrates the minimum value ε _min of the total absorption peak efficiency ε of the main shape efficiency distribution data. Used to do.

The calculation unit 17 acquires the main shape efficiency distribution data and the main shape efficiency data from the storage unit 16, and calibrates characteristic values such as an average value of the total absorption peak efficiencies ε of the main shape efficiency distribution data with the main shape efficiency data. . For example, based on the fact that the main shape efficiency data is the data of the total absorption peak efficiency in which the position dependency is averaged over the entire standard volume radiation source 40, the calculation unit 17 calculates the total absorption peak efficiency of the main shape efficiency distribution data. The mean value of ε is calibrated with the main shape efficiency data.
When the sub shape efficiency data is acquired from the storage unit 16, the calculation unit 17 calibrates characteristic values such as the minimum value or the maximum value of the total absorption peak efficiency ε of the main shape efficiency distribution data with the sub shape efficiency data. For example, when the calculation unit 17 acquires sub-shape efficiency data associated with a state in which the standard radiation source 43 is arranged closest to the germanium crystal 20 of the radiation detector 11 as illustrated in FIG. The maximum value ε _max of the total absorption peak efficiency ε of the main shape efficiency distribution data is calibrated with the sub shape efficiency data.

The calculation unit 17 acquires the self-absorption correction coefficient distribution data from the storage unit 16, and in the main shape efficiency distribution data, mutual γ between the radiation source used for generating the main shape efficiency distribution data and the sample to be measured. Correct for differences in self-absorption for lines.
For example, when the self-absorption of the radiation source and the sample is not corrected in the main shape efficiency distribution data, the calculation unit 17 first corrects the self-absorption of the radiation source to cancel the self-absorption by the radiation source. To calculate the main shape efficiency distribution data. The calculation unit 17 causes the self-absorption correction coefficient distribution data related to the frequency distribution of the entire main shape of the self-absorption correction coefficient fs for correcting the self-absorption by the source medium to act on the main shape efficiency distribution data. To calculate the main shape efficiency distribution data in which the self-absorption of the radiation source is corrected. The self-absorption correction coefficient fs is described as fs = exp (−μs · ds), for example, by the passage distance ds of γ rays in the source medium and the linear attenuation coefficient μs of the source medium.

  Next, when the calculation unit 17 corrects the self-absorption of the sample, the total absorption peak efficiency ε of the main shape efficiency distribution data changes so as to be distributed on the decreasing side due to the self-absorption by the sample medium. The main shape efficiency distribution data is calculated. The calculation unit 17 uses the self-absorption correction coefficient distribution data related to the frequency distribution of the main shape of the self-absorption correction coefficient fa for correcting the self-absorption by the sample medium, Main shape efficiency distribution data in which self-absorption of the sample is corrected is calculated by acting on the shape efficiency distribution data. The self-absorption correction coefficient fa is, for example, the γ-ray passing distance in the sample medium (for example, the distance from an arbitrary position in the main shape to the effective center 20a of the germanium crystal 20 of the radiation detector 11) d and the sample medium. Is expressed as fa = exp (−μd). For example, when the main shape efficiency distribution data shown in FIG. 6 is calculated by correcting the self-absorption of the radiation source, the calculation unit 17 adds the self-absorption correction coefficient shown in FIG. 10 to the main shape efficiency distribution data. By operating the distribution data, main shape efficiency distribution data shown in FIG. 13 is calculated.

  For example, when the self-absorption of the radiation source is corrected in the main shape efficiency distribution data, the calculation unit 17 acquires from the storage unit 16 main shape efficiency distribution data that is zeroed by canceling the self-absorption of the source. In this case, the self-absorption of the sample is corrected in the main shape efficiency distribution data. The calculation unit 17 acquires, from the storage unit 16, main shape efficiency distribution obtained from the storage unit 16 as self-absorption correction coefficient distribution data related to the frequency distribution of the main shape of the self-absorption correction coefficient fa for correcting self-absorption by the sample medium. By acting on the data, main shape efficiency distribution data in which self-absorption of the sample is corrected is calculated. In the main shape efficiency distribution data in which the self-absorption of the sample is corrected, the total absorption peak efficiency ε of the main shape efficiency distribution data changes so as to be distributed on the decreasing side due to the self-absorption of the sample.

The computing unit 17 calculates the corrected total absorption peak efficiency by correcting the sum effect for each total absorption peak efficiency ε associated with an arbitrary position in the main shape based on the main shape efficiency distribution data. For each total absorption peak efficiency ε associated with an arbitrary position in the main shape, for example, the calculation unit 17 includes a decay pattern unique to the nuclide of the sample and the total efficiency based on the peak / total ratio of the radiation detector 11. Is used to calculate the sum effect correction coefficient for correcting the sum effect. For example, in the decay pattern from the nuclide NA to the nuclide NB shown in FIG. 14, the first gamma ray γ1 of the two gamma rays (first gamma ray γ1 and second gamma ray γ2) emitted in cascade after beta decay is used as the measurement target. The sum effect correction coefficient g in this case is described as g = (1−ε _T ) by the total efficiency ε _T of the radiation detector 11 with respect to the second gamma ray γ 2. The total efficiency ε _T of the radiation detector 11 for the second gamma ray γ2 is, for example, the peak-to-total ratio PT for the second gamma ray γ2, and the total absorption peak efficiency ε ₍₂₎ of the main shape efficiency distribution data for the second gamma ray γ2. Ε _T = ε ₍₂₎ / PT. The peak-to-total ratio of the radiation detector 11 is generated by, for example, actual measurement using a radiation source that emits single energy γ-rays, calculation by simulation, or empirical formula.
The calculation unit 17 calculates the corrected total absorption peak efficiency by multiplying the total absorption peak efficiency ε by the sum effect correction coefficient for each total absorption peak efficiency ε associated with an arbitrary position in the main shape. The computing unit 17 calculates the calibration total absorption peak efficiency by integrating the corrected total absorption peak efficiencies associated with all the total absorption peak efficiencies ε included in the main shape efficiency distribution data. The calibrated total absorption peak efficiency is the total absorption peak efficiency corrected for self-absorption and sum effects of different samples at any position in the main shape.

  The calculation unit 17 calculates the data of the wave height distribution output from the wave height analyzer 12 when the gamma rays emitted from the sample stored in the container 30 are detected by the radiation detector 11 and the energy of the gamma rays to be measured. The amount of radioactivity contained in the sample is calculated using the calibration total absorption peak efficiency associated with.

  The radioactivity measurement apparatus 10 according to the present embodiment has the above-described configuration. Next, the operation of the radioactivity measurement apparatus 10, that is, the radioactivity measurement method will be described with reference to FIG.

First, the calculating part 17 acquires main shape efficiency data from the memory | storage part 16 (step S01).
Next, the calculating part 17 acquires main shape efficiency distribution data from the memory | storage part 16 (step S02).
Next, when sub shape efficiency data is stored in the storage unit 16, the calculation unit 17 acquires the sub shape efficiency data from the storage unit 16 (step S03).
Next, the computing unit 17 calibrates the characteristic value of the total absorption peak efficiency ε of the main shape efficiency distribution data based on the main shape efficiency data and the sub shape efficiency data (step S04).

Next, the calculation unit 17 acquires self-absorption correction coefficient distribution data, and in the main shape efficiency distribution data, mutual γ rays between the radiation source used for generating the main shape efficiency distribution data and the sample to be measured. The difference in self-absorption with respect to is corrected (step S05).
Next, the computing unit 17 determines whether or not the count value k having an initial value of zero is equal to the number of classifications of the total absorption peak efficiency having different values classified in the main shape efficiency distribution data (step S06). ).
If the determination result is “YES”, the arithmetic unit 17 advances the processing to step S11 described later.
On the other hand, when the determination result is “NO”, the arithmetic unit 17 advances the process to step S07.

Next, the calculation unit 17 calculates the total absorption peak efficiency associated with the same classification number as the count value k among the total absorption peak efficiencies associated with the classification numbers from 1 to the number of classifications in the main shape efficiency distribution data. the epsilon _k obtained from the main shape efficiency distribution data (step S07).
Next, the computing unit 17 calculates the corrected total absorption peak efficiency by correcting the sum effect in the total absorption peak efficiency ε _k associated with the count value k (step S08).
Next, the computing unit 17 calculates the calibration total absorption peak efficiency by integrating the corrected total absorption peak efficiency (step S09).
Next, the computing unit 17 newly sets a value obtained by adding “1” to the count value k as a count value k, and returns the process to step S06 (step S10).
Next, the calculation unit 17 converts the calibration total absorption peak efficiency into the data of the wave height distribution output from the wave height analyzer 12 when γ rays emitted from the sample accommodated in the container 30 are detected by the radiation detector 11. Is used to calculate the amount of radioactivity of the sample. And the calculating part 17 advances a process to an end (step S11).

As described above, according to the radioactivity measurement apparatus 10 according to the present embodiment, the calculation unit 17 corrects the sum effect for each total absorption peak efficiency ε associated with an arbitrary position in the sample. Appropriate correction can be performed in accordance with the degree of the sum effect that differs for each arbitrary position, and the total absorption peak efficiency for the sample can be accurately calibrated.
Furthermore, since the characteristic value of the main shape efficiency distribution data is calibrated by the main shape efficiency data and the sub shape efficiency data, the accuracy of the main shape efficiency distribution data can be improved. By improving the accuracy of the main shape efficiency distribution data, it is possible to improve the calibration accuracy of the total absorption peak efficiency for the sample accompanied by the correction of the sum effect.
Also, the main shape efficiency distribution data is calibrated by the main shape efficiency data and sub shape efficiency data obtained by the calibrated radiation source, so it is generated only once to grasp the shape of the frequency distribution of the total absorption peak efficiency ε. It only has to be done. For example, even when the absolute value of the total absorption peak efficiency ε changes due to repair of the radiation detector 11 or the like, the shape of the frequency distribution of the total absorption peak efficiency ε associated with an arbitrary position in the sample is It can be considered that there is almost no change or little change. Thereby, it is not necessary to repeatedly perform complicated processing for generating main shape efficiency distribution data such as calculation by actual measurement or simulation using the standard radiation source 41, and the processing efficiency can be improved.
Furthermore, by taking into account the dependence on the crystal shape of the radiation detector 11 or the dependence on the energy of radiation in the main shape efficiency distribution data, the accuracy of the main shape efficiency distribution data is improved, and the calibration accuracy of the total absorption peak efficiency is increased. Can be improved.
Furthermore, since the main shape efficiency distribution data is corrected by the self-absorption correction coefficient distribution data, the accuracy of the main shape efficiency distribution data can be improved.
In addition, the accuracy of measurement of the amount of radioactivity contained in the sample can be improved by using a calibrated total absorption peak efficiency that is corrected for the self-absorption of the medium with respect to radiation, and the degree of the sum effect that varies at any position in the sample. Can do.

In the first embodiment described above, the calculation unit 17 integrates the corrected total absorption peak efficiency calculated for each total absorption peak efficiency ε associated with an arbitrary position in the main shape, but is not limited thereto. Not.
For example, when the main shape efficiency distribution data is described by an appropriate function expression, the calculation unit 17 corrects the total absorption peak obtained by multiplying the total absorption peak efficiency ε of the main shape efficiency distribution data by the sum effect correction coefficient. The calibration total absorption peak efficiency may be calculated by integration from the minimum value to the maximum value of the peak efficiency.

In the first embodiment described above, the storage unit 16 stores the self-absorption correction coefficient distribution data, and the calculation unit 17 corrects the main shape efficiency distribution data using the self-absorption correction coefficient distribution data. It is not limited to this.
The storage unit 16 may store main shape efficiency distribution data corrected in advance by self-absorption correction coefficient distribution data.

In the first embodiment described above, the container 30 is a marinade container. However, the container 30 is not limited to this, and may be, for example, another arbitrary shaped container.
In the first embodiment described above, the sample is stored in the container 30, but the present invention is not limited to this, and the container 30 may be omitted and may have an appropriate shape in which the sample is exposed. .

Hereinafter, a radioactivity measurement apparatus and a radioactivity measurement method according to a second embodiment of the present invention will be described with reference to the accompanying drawings.
The radioactivity measurement apparatus 10 according to the present embodiment is similar to the radioactivity measurement apparatus 10 according to the first embodiment described above, the radiation detector 11, the pulse height analysis apparatus 12, the input apparatus 13, and the output apparatus 14. And a processing device 15. The processing device 15 includes, for example, a storage unit 16 and a calculation unit 17.
In the present embodiment, the difference from the first embodiment described above is the storage contents of the storage unit 16 and the operation of the calculation unit 17, and the same points as in the first embodiment described above will be described. Omitted or simplified.

  The container 50 in which the sample is accommodated is, for example, a so-called U-shaped container. The shape of the container 50 is formed in a bottomed cylindrical shape as shown in FIG. The container 50 containing the sample is disposed so as to face the tip of the end cap housing 21 of the radiation detector 11.

The storage unit 16 of the processing device 15 stores, for example, various types of preset data, various types of data output from the calculation unit 17, data output from the wave height analyzer 12, and the like. The storage unit 16 stores, for example, efficiency data by height and self-absorption correction coefficient data.
The efficiency data according to height is data of total absorption peak efficiency with respect to γ rays of the radiation detector 11 associated with a plurality of different heights in the shape (for example, columnar shape) of the sample accommodated in the container 50. The height-dependent efficiency data is generated by actually measuring gamma rays emitted from each of a plurality of standard volume radiation sources 60 having different columnar heights by the radiation detector 11. The plurality of standard volume radiation sources 60 are, for example, five standard volume radiation sources 61,..., 65 having different columnar heights h as shown in FIG. The height h of the first standard volume radiation source 61 is formed to the first height h1. The height h of the second standard volume radiation source 62 is formed to the second height h2 (> h1). The height h of the third standard volume radiation source 63 is formed at the third height h3 (> h2). The height h of the fourth standard volume source 64 is formed to a fourth height h4 (> h4). The height h of the fifth standard volume source 65 is formed at the fifth height h5 (> h5).
The height-dependent efficiency data corresponds to the height h (for example, the first to fifth heights h1,..., H5) of each of the plurality of standard volume radiation sources 60 and each of the plurality of standard volume radiation sources 60. This is data indicating a correspondence relationship with the total absorption peak efficiency ε (for example, first to fifth total absorption peak efficiencies ε1,..., Ε5) attached.

The self-absorption correction coefficient data is different in the self-absorption due to the γ-rays due to the difference in the medium between the standard volume radiation source 60 used for generating the efficiency data by height and the sample to be measured. This is correction coefficient data for correcting the occurrence. The self-absorption correction coefficient data is, for example, data of a self-absorption correction coefficient fs for the medium of the standard volume source 60 and a self-absorption correction coefficient fa for the sample medium.
For example, with respect to the total absorption peak efficiency ε _s obtained by measuring the standard volume source 60, the total absorption peak efficiency ε ₀ corrected for self-absorption by the medium of the standard volume source 60 is the standard volume source 60. Is described as ε ₀ = ε _s / fs. The total absorption peak efficiency ε _a for a sample of a medium different from the standard volume source 60 is described as ε _a = ε ₀ × fa = ε _s × (fa / fs) by the self-absorption correction coefficient fa for the sample medium. The The self-absorption correction coefficient data is generated by, for example, calculations based on simulations of radiation transport in a medium, calculations based on various approximations or assumptions, and the like.

The calculation unit 17 acquires efficiency data according to height from the storage unit 16 and calculates a total absorption peak efficiency (arbitrary height peak efficiency) ε _h0 associated with the standard volume radiation source 60 having an arbitrary height h. To do. For example, as shown in FIG. 18, the calculation unit 17 includes data indicating the correspondence between the height h of each of the plurality of standard volume radiation sources 60 and the reciprocal of the total absorption peak efficiency ε (= 1 / ε). Arbitrary height peak efficiency ε _h0 is calculated by interpolation and extrapolation or appropriate function fitting.

The calculation unit 17 acquires the self-absorption correction coefficient data from the storage unit 16, and the standard volume radiation source 60 used to generate the efficiency data by height at the efficiency data by height or the arbitrary height peak efficiency ε _h0 . The difference in self-absorption with respect to γ rays with the sample to be measured is corrected.
For example, when the self-absorption of the standard volume source 60 and the sample is not corrected in the efficiency data classified by height or the arbitrary height peak efficiency ε _h0 , the calculation unit 17 firstly self-absorbs the standard volume source 60. Correct. Thereby, the calculating part 17 calculates the efficiency data classified by height or the arbitrary height peak efficiency ε _h0 when the self-absorption by the standard volume radiation source 60 is canceled and becomes zero. The calculation unit 17 uses the self-absorption correction coefficient fs for correcting the self-absorption of γ-rays by the medium of the standard volume radiation source 60 to cancel the self-absorption of the standard volume radiation source 60 to zero. Separate efficiency data or arbitrary height peak efficiency ε _h0 is calculated.
Next, the calculation unit 17 corrects the self-absorption of the sample, thereby reducing the total absorption peak efficiency ε or the arbitrary height peak efficiency ε _{h0 of the} efficiency data by height due to self-absorption by the sample medium. The efficiency data classified by height or the arbitrary height peak efficiency ε _h0 is calculated. The calculating unit 17 uses the self-absorption correction coefficient fa for correcting the self-absorption due to the sample medium, the efficiency data classified by height in which the self-absorption of the standard volume source 60 is corrected or the arbitrary height peak efficiency ε _h0. , The height- _dependent efficiency data in which the self-absorption of the sample is corrected or the arbitrary height peak efficiency ε _h0 is calculated.

For example, when the self-absorption of the standard volume source 60 is corrected at the height- _dependent efficiency data or the arbitrary height peak efficiency ε _h0 , that is, the calculation unit 17 cancels out the self-absorption of the standard volume source 60 to zero. When the efficiency data classified by height or the arbitrary height peak efficiency ε _h0 is acquired, the self-absorption of the sample is corrected in the efficiency data classified by height or the arbitrary height peak efficiency ε _h0 . The calculating unit 17 uses the self-absorption correction coefficient fa for correcting the self-absorption due to the sample medium, the efficiency data classified by height in which the self-absorption of the standard volume source 60 is corrected or the arbitrary height peak efficiency ε _h0. , The height- _dependent efficiency data in which the self-absorption of the sample is corrected or the arbitrary height peak efficiency ε _h0 is calculated. In the efficiency data by height or the arbitrary height peak efficiency ε _h0 corrected for the self-absorption of the sample, the total absorption peak efficiency ε or the arbitrary height peak efficiency ε _{h0 of the} efficiency data by height due to the self-absorption of the sample. Changes to decrease.

Based on the arbitrary height peak efficiency ε _h0 associated with the standard volume radiation source 60 having an arbitrary height h, the calculation unit 17 is set at a position of an arbitrary height h as shown in FIG. 19, for example. The total absorption peak efficiency ε _h associated with the region 71 having the thickness Δh is calculated. The thickness Δh is set to, for example, a thickness obtained by dividing the height of the sample accommodated in the container 50 into a predetermined number, which is smaller than the height of the sample accommodated in the container 50.
The computing unit 17 is associated with, for example, an arbitrary height peak efficiency ε _h0 associated with a standard volume radiation source 60 having an arbitrary height h and a standard volume radiation source 60 having an arbitrary height (h + Δh). Based on the difference from the arbitrary height peak efficiency ε _h0 ^′ , the total absorption peak efficiency ε _h associated with the region 71 of the thickness Δh at the position of the arbitrary height _h is calculated.

For example, as illustrated in FIG. 20, the calculation unit 17 regards the sample having the height hs accommodated in the container 50 as an aggregate of the plurality of regions 71, and positions the height h in each of the plurality of regions 71. The corrected total absorption peak efficiency is calculated by correcting the sum effect for each total absorption peak efficiency ε _h associated with. For example, the calculation unit 17 performs, for example, a decay pattern unique to the nuclide of the sample and radiation detection for each total absorption peak efficiency ε _h associated with the position of an arbitrary height h in the shape of the sample accommodated in the container 50. The sum effect correction coefficient for correcting the sum effect is calculated using the total efficiency based on the peak-to-total ratio of the device 11. For example, in the decay pattern from the nuclide NA to the nuclide NB shown in FIG. 14, the first gamma ray γ1 of the two gamma rays (first gamma ray γ1 and second gamma ray γ2) emitted in cascade after beta decay is used as the measurement target. The sum effect correction coefficient g in this case is described as g = (1−ε _T ) by the total efficiency ε _T of the radiation detector 11 with respect to the second gamma ray γ 2. The total efficiency ε _T of the radiation detector 11 for the second gamma ray γ2 is, for example, the peak-to-total ratio PT for the second gamma ray γ2, and the total absorption peak efficiency ε ₍₂₎ of the main shape efficiency distribution data for the second gamma ray γ2. Ε _T = ε ₍₂₎ / PT. The peak-to-total ratio of the radiation detector 11 is generated by, for example, actual measurement using a radiation source that emits single energy γ-rays, calculation by simulation, or empirical formula.
The computing unit 17 multiplies the total absorption peak efficiency ε _h by the sum effect correction coefficient for each total absorption peak efficiency ε _h associated with an arbitrary height h position in the shape of the sample accommodated in the container 50. To calculate the corrected total absorption peak efficiency. The computing unit 17 calculates the calibration total absorption peak efficiency by integrating the corrected total absorption peak efficiency associated with all the regions 71 included in the shape of the sample. The calibrated total absorption peak efficiency is the total absorption peak efficiency corrected for the self-absorption and sum effects of different samples at any height h position in the sample shape.

  The calculation unit 17 calculates the wave height distribution data output from the wave height analyzer 12 and the energy of the gamma ray to be measured when the gamma rays emitted from the sample contained in the container 50 are detected by the radiation detector 11. The amount of radioactivity contained in the sample is calculated using the calibration total absorption peak efficiency associated with.

  The radioactivity measurement apparatus 10 according to the present embodiment has the above-described configuration. Next, the operation of the radioactivity measurement apparatus 10, that is, the radioactivity measurement method will be described with reference to FIG.

First, the calculating part 17 acquires the efficiency data classified by height from the memory | storage part 16 (step S21).
Next, the calculation unit 17 acquires the self-absorption correction coefficient data from the storage unit 16, and in the efficiency data classified by height, the standard volume radiation source 60 used for generating the efficiency data classified by height and the sample to be measured The difference in self-absorption with respect to the mutual γ rays is corrected (step S22).
Next, the computing unit 17 calculates a total absorption peak efficiency (arbitrary peak efficiency) ε _h0 associated with the standard volume radiation source 60 having an arbitrary height h based on the efficiency data classified by height ( Step S23).

Next, the calculation unit 17 determines whether or not the count value k whose initial value is zero is equal to the number of regions (height classification number) of the plurality of regions 71 constituting the sample having the height hs accommodated in the container 50. Is determined (step S24).
If the determination result is “YES”, the computing unit 17 advances the processing to step S29 described later.
On the other hand, when the determination result is “NO”, the arithmetic unit 17 advances the process to step S25.

Next, the calculating part 17 comprises the sample of the height hs accommodated in the container 50, and is the same as the count value k among the some area | regions 71 with which the classification number from 1 to the height classification number is matched. The total absorption peak efficiency ε _hk is calculated for the region 71 associated with the classification number and arranged at the height h _k (step S25).
Next, the computing unit 17 calculates the corrected total absorption peak efficiency by correcting the sum effect in the total absorption peak efficiency ε _hk associated with the count value k (step S26).
Next, the computing unit 17 calculates the calibration total absorption peak efficiency by integrating the corrected total absorption peak efficiency (step S27).
Next, the computing unit 17 newly sets a value obtained by adding “1” to the count value k as the count value k, and returns the process to step S24 (step S28).
Next, the calculation unit 17 calibrates the total absorption peak efficiency to the data of the wave height distribution output from the wave height analyzer 12 when γ rays emitted from the sample accommodated in the container 50 are detected by the radiation detector 11. Is used to calculate the amount of radioactivity of the sample. And the calculating part 17 advances a process to an end (step S29).

As described above, according to the radioactivity measurement apparatus 10 according to the present embodiment, the calculation unit 17 has the total absorption peak efficiency associated with the region 71 set at the position of the arbitrary height h in the columnar sample. Since the sum effect is corrected for each ε _h, it is possible to perform appropriate correction corresponding to the degree of the sum effect that differs for each position of an arbitrary height h. By improving the correction accuracy of the sum effect, the calibration accuracy of the total absorption peak efficiency for the sample accompanied by the correction of the sum effect can be improved.

In the second embodiment described above, the calculation unit 17 calculates each total absorption peak efficiency ε _h associated with the region 71 having a thickness Δh set at a position of an arbitrary height h in the sample. Although the corrected total absorption peak efficiency is integrated, the present invention is not limited to this.
For example, when the total absorption peak efficiency ε _h associated with the position of the height _h is described by an appropriate function formula, the calculation unit 17 multiplies the total absorption peak efficiency ε _h by the sum effect correction coefficient. The calibration total absorption peak efficiency may be calculated by integrating the resulting corrected total absorption peak efficiency from zero to the sample height hs for height h.

In the second embodiment described above, the storage unit 16 stores self-absorption correction coefficient data, and the calculation unit 17 uses the self-absorption correction coefficient data to determine efficiency data according to height or arbitrary height peak efficiency ε _h0. However, the present invention is not limited to this.
The storage unit 16 may store efficiency data classified by height in which self-absorption of the standard volume radiation source 60 and the sample is corrected in advance.

In the second embodiment described above, the container 50 is a U-shaped container. However, the present invention is not limited to this. For example, another bottomed cylindrical container may be used.
In the above-described second embodiment, the sample is stored in the container 50. However, the present invention is not limited to this, and the container 50 may be omitted and may have an appropriate columnar shape with the sample exposed. Good.

  In the first and second embodiments described above, the radiation detector 11 is a germanium semiconductor detector. However, the present invention is not limited to this. For example, other detectors such as a scintillation detector, a dosimeter, and a monitoring post are used. It may be.

DESCRIPTION OF SYMBOLS 10 ... Radioactivity measuring apparatus, 11 ... Radiation detector, 12 ... Wave height analyzer, 15 ... Processing apparatus (processing means), 16 ... Memory | storage part (memory | storage means), 17 ... Calculation part (calculation means), 20 ... Germanium crystal 30 ... Container, 40 ... Standard volume source, 41 ... Standard source, 50 ... Container, 60 ... Standard volume source

Claims (9)

A radiation detector for detecting radiation emitted from the sample, and processing means for correcting the sum effect corresponding to the sample when calibrating the detection efficiency of the radiation detector;
With
The processing means includes
Storage means for storing distribution data related to a frequency distribution in the entire sample with the detection efficiency associated with an arbitrary position in the sample;
The corrected detection efficiency is calculated by correcting the sum effect for each of the detection efficiencies associated with an arbitrary position in the sample, and is associated with all the detection efficiencies included in the distribution data. Calculating means for calculating the calibration detection efficiency by integrating
A radioactivity measurement apparatus comprising: The characteristic value of the distribution data used by the calculation means for calculating the calibration detection efficiency is:
Calibrated by the detection efficiency of the radiation detector measured using a standard source of a predetermined shape;
The radioactivity measuring apparatus according to claim 1. The distribution data used by the calculation means for calculating the calibration detection efficiency is:
Corresponding to the crystal shape of the radiation detector,
The radioactivity measurement apparatus according to claim 1 or claim 2, wherein The distribution data used by the calculation means for calculating the calibration detection efficiency is:
Associated with the energy of the radiation,
The radioactivity measurement apparatus according to any one of claims 1 to 3, wherein The distribution data used by the calculation means for calculating the calibration detection efficiency is:
The magnitude of the self-absorption of the medium for the radiation associated with any position in the sample is corrected,
The radioactivity measuring apparatus according to any one of claims 1 to 4, wherein A radiation detector for detecting radiation emitted from a columnar sample, and processing means for correcting the sum effect corresponding to the sample when calibrating the detection efficiency of the radiation detector;
With
The processing means includes
Storage means for storing data of the detection efficiency associated with the plurality of samples having different heights of the columnar shape;
The detection efficiency associated with an arbitrary height position of the columnar shape is calculated based on the detection efficiency data, and the sum effect is calculated for each detection efficiency associated with an arbitrary height position of the columnar shape. Correction detection efficiency is calculated by correcting, and the correction detection associated with all the height positions included from zero to the desired height in the sample in which the height of the columnar shape is a desired height Arithmetic means for calculating the calibration detection efficiency by integrating the efficiency;
A radioactivity measurement apparatus comprising: The computing means is
Calculate the amount of radioactivity contained in the sample using the pulse height distribution data of the output signal pulse of the radiation detector and the calibration detection efficiency,
The radioactivity measurement apparatus according to claim 1, wherein the radioactivity measurement apparatus is a radioactivity measurement apparatus. A radioactivity measurement method performed by processing means for correcting the sum effect corresponding to a sample when calibrating the detection efficiency of a radiation detector for detecting radiation emitted from the sample,
A first step in which the processing means calculates a corrected detection efficiency by correcting the sum effect for each detection efficiency associated with an arbitrary position in the sample;
The processing means associates with all the detection efficiencies included in the distribution data based on distribution data related to the frequency distribution of the entire sample with the detection efficiency associated with an arbitrary position in the sample. A second step of calculating calibration detection efficiency by integrating the corrected detection efficiency,
including,
The radioactivity measurement method characterized by this. A radioactivity measurement method performed by processing means for correcting the sum effect corresponding to a sample when calibrating the detection efficiency of a radiation detector that detects radiation emitted from a columnar sample,
The processing means calculates the detection efficiency associated with an arbitrary height position of the columnar shape based on the detection efficiency data associated with the plurality of samples having different heights of the columnar shape. 1 step,
A second step in which the processing means calculates a corrected detection efficiency by correcting the sum effect for each detection efficiency associated with an arbitrary height position of the columnar shape;
The processing means integrates the correction detection efficiency associated with all the height positions included from zero to the desired height in the sample in which the height of the columnar shape is a desired height. A third step of calculating calibration detection efficiency;
including,
The radioactivity measurement method characterized by this.

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