Radiation energy measuring device

Abstract

To provide a radioactivity measuring device that can improve the accuracy and reliability of measurements for radioactive volume samples. [Solution] The radioactivity measuring device 10 comprises a radiation detector 13, a state detection unit 12, and a processing device 15. The radiation detector 13 detects the energy of radiation emitted from the sample 11 and outputs a pulse signal corresponding to the energy. The state detection unit 12 detects the state of the sample 11, including at least its shape and dimensions, and outputs a state detection signal. The processing device 15 obtains a predetermined variable h related to the shape and dimensions of the sample 11 based on the detection signal output from the state detection unit 12. The processing device 15 obtains the counting efficiency ε of the radiation detector 13 for the sample 11 by associating the pulse signal output from the radiation detector 13 with the predetermined variable h.

Description

Technical Field

[0001] The present invention relates to a radioactive substance measurement device.

Background Art

[0002] Conventionally, for example, in the quantification of radioactive substances in a radioactive volume sample such as an environmental sample like soil, information on the energy dependence of the counting efficiency (so-called efficiency curve) is obtained in advance for each filling height of the sample in the measurement container, enabling rapid quantification. Conventionally, regarding methods for grasping the filling height of a sample, for example, a method of detecting the liquid level of a liquid sample in a container by irradiating it with X-rays (see, for example, Patent Document 1) or a method of obtaining the average filling height by visually reading the scale of a measuring stick applied to the surface of a transparent container (see, for example, Non-Patent Document 1) are known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in the quantitative determination of radioactive materials in volumetric samples, there is a need to improve the accuracy and reliability of counting efficiency. For example, when detecting the liquid surface of a liquid sample, as in the conventional technique described above, there is a risk that it may not be possible to adequately handle solid samples that are unevenly distributed within the container. Also, when obtaining the average filling height by visual inspection, as in the conventional technique described above, there is a problem in that reliability cannot be improved.

[0006] The present invention aims to provide a radioactivity measuring device that can improve the accuracy and reliability of measurements for radioactive volumetric samples. [Means for solving the problem]

[0007] In order to solve the above problems and achieve the above objectives, the present invention employs the following embodiments. (1) A radioactivity measuring device (10) according to one aspect of the present invention includes a radiation detector (13) that detects the energy of radiation emitted from a sample (11) and outputs a pulse signal corresponding to the energy; a state detection unit (12, 42) that detects the state of the sample, including at least its shape and dimensions, and outputs a state detection signal; and a processing unit (15) that acquires predetermined variables related to the shape and dimensions based on the detection signal output from the state detection unit, and associates the pulse signal output from the radiation detector with the predetermined variables.

[0008] (2) In the radioactivity measuring device described in (1) above, the processing unit may obtain the counting efficiency of the radiation detector for the sample using the predetermined variable.

[0009] (3) The radioactivity measuring device described in (2) above includes a pulse height analyzer (14) that generates pulse height distribution data having counts associated with each of a plurality of channels based on the pulse height value of the pulse signal, and the processing unit may acquire the counting efficiency corresponding to the predetermined variable based on the pulse height distribution data output from the pulse height analyzer.

[0010] (4) The radioactivity measuring device described in any one of (1) to (3) above may include a shielding body (20) that shields against radiation and in which the radiation detector and the state detection unit are arranged.

[0011] (5) The radioactivity measuring device described in any one of (1) to (3) above includes an exchanger (31) for exchanging the sample to be detected by the radiation detector from a plurality of samples, and the state detection unit may detect the state of the sample selected by the exchanger.

[0012] (6) In the radioactivity measuring device described in (2) above, the processing unit may obtain the counting efficiency of the radiation detector for the total volume of the sample by summing up the efficiencies of the partial volumes of the sample according to the predetermined variable.

[0013] (7): In the radioactivity measuring device described in (6) above, the processing unit may obtain the counting efficiency ε of the radiation detector for the sample based on the following formula (1), which is described by n predetermined variables h(k) obtained by dividing the maximum value of the predetermined variable by a predetermined natural number n, and which are arbitrary natural numbers k (=1,...,n) up to the predetermined natural number n, n partial volumes V(k) corresponding to the n predetermined variables h(k) that constitute the volume V of the containment space inside the container (21) in which the sample is contained, and n counting efficiencies ε(k) corresponding to the n partial volumes V(k).

[0014]

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[0015] (8) In the radioactivity measuring device described in (7) above, the processing unit may obtain the counting efficiency ε based on the following formula (2), which is described by the n packing rates r(k) corresponding to the n partial volumes V(k).

[0016]

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[0017] (9): In the radioactive ray measurement device according to the above (7) or (8), the processing unit may use the predetermined variable as the distance from the radiation detector along the direction from the radiation detector toward the sample.

Advantages of the Invention

[0018] According to the above (1), by providing a state detection unit that detects at least the shape and dimensions of the sample, the accuracy and reliability of quantification for a volumetric sample can be improved.

[0019] In the case of the above (2), the accuracy and reliability of the counting efficiency for a volumetric sample can be improved.

[0020] In the case of the above (3), by providing a pulse height analyzer, it is possible to suppress a decrease in work efficiency and an increase in work time when obtaining the counting efficiency.

[0021] In the case of the above (4), the detection of the state of the sample by the state detection unit and the detection of the radioactive rays by the radiation detector can be collectively performed inside the shield, and the workability of the quantification of radioactive substances can be improved.

[0022] In the case of the above (5), for example, it is not necessary to provide a space for arranging the state detection unit inside the shield, and the space efficiency can be improved.

[0023] In the case of the above (6) or (7), regardless of the shape and dimensions of the sample, a good counting efficiency can be obtained.

[0024] In the case of the above (8), for example, even when the sample is unevenly distributed in the container, a good counting efficiency can be obtained based on the filling rate r(k).

[0025] In the case of (9) above, it is possible to suppress the cumbersome or complicated process of obtaining efficiency in partial volumes and to facilitate the acquisition of counting efficiency by summation. [Brief explanation of the drawing]

[0026] [Figure 1] A block diagram showing the functional configuration of a radioactivity measuring device according to an embodiment of the present invention. [Figure 2] A cross-sectional view showing an example of the arrangement of the state detection unit, radiation detector, and container of a radioactivity measuring device according to an embodiment of the present invention. [Figure 3] A figure showing an example of a partial volume corresponding to a predetermined variable when the counting efficiency is obtained by a radioactivity measuring device according to an embodiment of the present invention. [Figure 4] A flowchart illustrating the operation of a radioactivity measuring device according to an embodiment of the present invention. [Figure 5] A block diagram showing the functional configuration of a radioactivity measuring device according to a first modified embodiment of the present invention. [Figure 6] A figure showing an example of a sample unevenly distributed within a container when the counting efficiency is obtained by a radioactivity measuring device according to a second modified embodiment of the present invention. [Figure 7] A plan view showing an example of the arrangement of the state detection unit, radiation detector, and container of a radioactivity measuring device according to a third modified embodiment of the present invention. [Modes for carrying out the invention]

[0027] Hereinafter, an embodiment of the radioactivity measuring device of the present invention will be described with reference to the attached drawings. The radioactivity measuring device of the embodiment measures the radioactivity of a sample that emits radiation such as gamma rays, X-rays, beta rays, alpha rays, and neutron rays. Figure 1 is a block diagram showing the functional configuration of the radioactivity measuring device 10 according to an embodiment. Figure 2 is a cross-sectional view showing an example of the arrangement of the state detection unit 12, radiation detector 13, and container 21 of the radioactivity measuring device 10 according to an embodiment. In the following, the directions of the X, Y, and Z axes, which are mutually orthogonal in three-dimensional space, are parallel to each other. For example, the Z-axis direction is parallel to the vertical direction of the radioactivity measuring device 10, the Y-axis direction is parallel to the left-right direction of the radioactivity measuring device 10, and the X-axis direction is parallel to the front-back direction of the radioactivity measuring device 10.

[0028] As shown in Figures 1 and 2, the radioactivity measuring device 10 of the embodiment includes, for example, a state detection unit 12 for detecting the state of a sample 11, a radiation detector 13, a multi-wave height analyzer 14, a processing unit 15, an input unit 16 and an output unit 17, a shielding body 20, and a container 21 in which the sample 11 is contained.

[0029] The state detection unit 12 is a sensor that emits light such as laser light, electromagnetic waves such as radio waves, or sound waves such as ultrasound, and detects reflection or scattering by an object. The state detection unit 12 is arranged, for example, inside the shielding body 20, which will be described later. The state detection unit 12 detects the state of the sample 11, including at least its shape and dimensions, by scanning the sample 11 inside the container 21, which will be described later, along a predetermined direction such as the vertical direction of the shielding body 20. The state detection unit 12 outputs a detection signal that includes information about the state of the sample 11 (state information).

[0030] The radiation detector 13 detects various types of radiation, such as gamma rays, X-rays, beta rays, and alpha rays. The radiation detector 13 may be a semiconductor detector made of a semiconductor such as germanium, silicon, or compound semiconductor (such as GaAs and CdTe), or a scintillation detector made of various scintillators such as organic, inorganic, liquid, or gaseous materials. The radiation detector 13 in this embodiment is, for example, a germanium semiconductor detector equipped with a vertical cryostat. An end cap housing having a radiation incidence window is provided at the tip of the cryostat. A germanium crystal sensitive to radiation is held in the vacuum region inside the end cap housing. The sensitive part of the radiation detector 13 is, for example, located inside the shielding body 20, which will be described later.

[0031] The multi-channel height analyzer 14 is an MCA (Multi-Channel Analyzer). The multi-channel height analyzer 14 calculates the height distribution of the output signal pulses (detection data) output from the radiation detector 13, that is, the count values ​​for each of the multiple channels that correspond to the height values. For example, when the radiation detector 13 outputs an output signal pulse with a height value corresponding to the energy of the radiation, the multi-channel height analyzer 14 creates an energy spectrum (spectral data) as the height distribution of the output signal pulses of the radiation detector 13.

[0032] The processing unit 15 is, for example, an information processing device such as a personal computer, a smartphone, or a tablet terminal. Part of the processing unit 15 includes a software function unit that functions when a predetermined program is executed by a processor such as a CPU (Central Processing Unit). The software function unit is an ECU (Electronic Control Unit) that includes a processor such as a CPU, a ROM (Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and electronic circuits such as a timer. Part of the processing unit 15 may also include an integrated circuit such as an LSI (Large Scale Integration).

[0033] The processing unit 15 comprehensively controls the operation of various components, such as the state detection unit 12, the radiation detector 13, the multi-wave height analyzer 14, and auxiliary equipment such as a sample changer. Based on the energy spectrum of the radiation generated by the multi-wave height analyzer 14, the processing unit 15 performs processes such as calibration and inspection of the radiation detector 13 and the multi-wave height analyzer 14, spectral analysis, and nuclide analysis. The processing unit 15 includes, for example, an input unit 16 such as a touch panel, various switches, or a keyboard that outputs signals corresponding to the operator's input. The processing unit 15 also includes, for example, an output unit 17 such as a display device that displays various information and data, and a speaker that outputs various sounds.

[0034] The shielding body 20 has an external shape that is, for example, a box shape that surrounds the sensitive area of ​​the radiation detector 13 and the object to be detected. The object to be detected, such as the container 21 that contains the sample 11, is placed, for example, at a predetermined position appropriately away from the sensitive area of ​​the radiation detector 13. The shielding body 20 is made of a radiation-shielding material such as lead or tungsten. The container 21 is a variety of containers, such as a so-called Marinelli container, a so-called U8 container for single use, or a sample dish sealed with various films. For example, the outer shape of the container 21 shown in Figure 2 is cylindrical. For example, the container 21 is positioned above the radiation detector 13 with its central axis parallel to the vertical direction.

[0035] The operation of the radioactivity measuring device 10 of this embodiment will be described below. The processing unit 15 obtains a predetermined variable h related to the shape and dimensions of the sample 11 in the container 21, for example, based on the detection signal output from the state detection unit 12. The predetermined variable h is, for example, the distance from the radiation detector 13 along the direction from the radiation detector 13 toward the sample 11. For example, as shown in Figure 2, when the container 21 is positioned above the radiation detector 13 equipped with a vertical cryostat, the predetermined variable h is the distance from the radiation detector 13 in the vertical direction, and is related, so to speak, to the filling height of the sample 11 in the vertical direction within the container 21.

[0036] The processing unit 15 obtains the counting efficiency ε of the radiation detector 13 for the sample 11 by, for example, associating the pulse signal output from the radiation detector 13 with a predetermined variable h. The processing unit 15 also obtains the counting efficiency ε corresponding to the predetermined variable h based on the pulse height distribution data output from the multi-pulse height analyzer 14 based on the pulse height value of the pulse signal.

[0037] Figure 3 shows an example of a partial volume V(k) corresponding to a predetermined variable h(k) when the counting efficiency ε is obtained by the radioactivity measuring device 10 according to the embodiment. As shown in Figure 3, the processing unit 15 obtains the counting efficiency ε of the radiation detector 13 for the entire volume of the sample 11 by, for example, summing up the counting efficiencies ε(k) at partial volumes V(k) of the sample 11 corresponding to a predetermined variable h(k). Hereafter, the counting efficiency ε(k) will be simply referred to as efficiency ε(k).

[0038] Any natural number k is, for example, any natural number from 1 to a predetermined natural number n. The predetermined variable h(k) is, for example, any of the n predetermined variables h(1), ..., h(n) obtained by dividing the maximum value of the predetermined variable h by the predetermined natural number n. The partial volume V(k) corresponding to any predetermined variable h(k) is, for example, any of the n partial volumes V(1), ..., V(n) obtained by dividing the volume V of the containment space inside the container 21 in which the sample 11 is contained by the predetermined natural number n. The volume V of the containment space inside the container 21 is the sum of the n partial volumes V(1), ..., V(n), and is the volume of the containment space corresponding to the maximum value of the predetermined variable h.

[0039] For example, the external shape of a partial volume V(k) is a plate-like shape perpendicular to the direction related to the setting of a predetermined variable h, i.e., the vertical direction. For example, n partial volumes V(1), ..., V(n) are obtained by sequentially cutting the storage space of the container 21 with a plane perpendicular to the vertical direction (i.e., the XY plane perpendicular to the Z-axis), corresponding to each of the n predetermined variables h(1), ..., h(n). For example, in the case of a cylindrical container 21, the external shape of a partial volume V(k) is a disc-like shape with a predetermined thickness in the vertical direction.

[0040] The processing device 15, for example, uses the appropriate volume V of the containment space within the container 21. L The volume V of the first containment space s and the volume V of the second containment space x If it is the sum of, then volume V L Efficiency ε L Efficiency ε at volume Vs s and volume V x Efficiency ε x Set it as shown in formula (3) below.

[0041]

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[0042] The processing device 15, for example, obtains the counting efficiency ε at the volume V of the containment space inside the container 21 based on the above formula (3) by integrating the efficiencies ε(k) at partial volumes V(k), as shown in the following formula (4). The efficiency ε(k) at partial volumes V(k) is obtained, for example, based on efficiency measurements using an appropriate radiation source or efficiency calculations by simulation.

[0043]

number

[0044] Figure 4 is a flowchart showing the operation of the radioactivity measuring device 10 according to the embodiment. As shown in Figure 4, first, the processing device 15, for example, by controlling a sample changer, places the container 21 containing the sample 11 in a predetermined position within the shielding body 20 as the target for detection by the radiation detector 13 (step S01). Next, the processing device 15 detects the state of the sample 11 in the container 21 using the state detection unit 12 (step S02). Next, the processing unit 15 acquires state information of the sample 11 based on the detection signal output from the state detection unit 12 (step S03). Next, the processing unit 15 obtains the counting efficiency ε of the radiation detector 13 for the sample 11 by associating the pulse signal output from the radiation detector 13 with a predetermined variable h (step S04). Then, the processing unit 15 proceeds to the end of the process.

[0045] As described above, the radioactivity measuring device 10 of the embodiment includes a state detection unit 12 that detects the state of the sample 11, including at least its shape and dimensions, thereby improving the accuracy and reliability of quantitative analysis for volumetric samples. By obtaining the counting efficiency ε of the radiation detector 13 for the sample 11 using a predetermined variable h, the accuracy and reliability of the counting efficiency ε for volumetric samples can be improved.

[0046] By incorporating a multi-wave height analyzer 14, it is possible to suppress the decrease in work efficiency and the increase in work time when acquiring the counting efficiency ε. By positioning the state detection unit 12 inside the shielding body 20, the detection of the state of the sample 11 by the state detection unit 12 and the detection of radiation by the radiation detector 13 can be performed simultaneously inside the shielding body 20, thereby improving the efficiency of quantitative analysis of radioactive materials.

[0047] By summing the efficiencies ε(k) at partial volumes V(k) of the sample 11, the counting efficiency ε of the radiation detector 13 for the entire volume of the sample 11 can be obtained, thereby enabling the acquisition of a highly accurate counting efficiency ε regardless of the shape and dimensions of the sample 11. By defining the predetermined variable h as the distance from the radiation detector 13 along the direction from the radiation detector 13 toward the sample 11 (for example, the vertical direction), it is possible to suppress the complexity or difficulty of obtaining the efficiency ε(k) at a partial volume V(k) and to facilitate the acquisition of the counting efficiency ε by summation.

[0048] (modified version) Modified examples of the embodiments are described below. Note that parts identical to those in the embodiments described above are denoted by the same reference numerals, and their descriptions are omitted or simplified. In the embodiment described above, the state detection unit 12 is positioned inside the shielding body 20, but this is not the only option. For example, the state detection unit 12 may be positioned outside the shielding body 20. Figure 5 is a block diagram showing the functional configuration of the radioactivity measuring device 10A according to the first modified embodiment. As shown in Figure 5, the first modified radioactivity measuring device 10A differs from the radioactivity measuring device 10 of the above-described embodiment in that it is equipped with a detection target exchanger 31, and the state detection unit 12 is provided on the detection target exchanger 31.

[0049] The detection target exchanger 31 is, for example, a so-called sample changer and includes a transport mechanism such as a belt conveyor for transporting multiple containers 21, an exchange mechanism such as a robot arm for selecting and exchanging a container 21 containing a sample 11 to be detected from among the multiple containers 21, and an opening and closing mechanism for opening and closing the opening and closing door of the shielding body 20. The detection target exchanger 31 operates automatically, for example, in response to control by the processing device 15. The state detection unit 12 detects the state of the sample 11 inside the container 21 when the container 21 to be detected is replaced by the detection target exchanger 31.

[0050] In the first modified example, the state detection unit 12 is located outside the shielding body 20, so the state detection unit 12 detects the state of the sample 11 before the container 21 of the sample 11 is placed inside the shielding body 20. For example, in the flowchart shown in Figure 4 of the above-described embodiment, steps S02 and S03 may be executed prior to the execution of step S01 or before the container 21 is placed inside the shielding body 20 in the process of step S01. Then, step S04 may be executed after the process of step S01. According to the first modified example, for example, it is possible to eliminate the need for space to place the state detection unit 12 inside the shielding body 20.

[0051] In the first modified example described above, the state detection unit 12 is provided on the detection target exchanger 31, but it is not limited to this and may be located elsewhere. The location elsewhere may be, for example, inside the shielding body 20 as in the embodiment described above, or at an appropriate location outside the shielding body 20. In this case, for example, in the functional configuration diagram of the radioactivity measuring device 10A in the first modified example shown in Figure 5, the state detection unit 12 may be located adjacent to the sample 11 or around the sample 11.

[0052] In the embodiments and first modifications described above, the state detection unit 12 is positioned inside or outside the shielding body 20, but this is not limited to this. For example, multiple state detection units 12 may be positioned in one location or multiple locations. Multiple locations include, for example, inside and outside the shielding body 20, and locations adjacent to or surrounding other equipment such as the target exchange 31. Multiple state detection units 12 may be, for example, sensors of the same type, or a combination of different types of sensors.

[0053] In the embodiments described above, the processing apparatus 15 obtains the counting efficiency ε using the partial volume V(k) and efficiency ε(k) as shown in formula (4) above, but is not limited to this. For example, as shown in formula (5) below, the processing apparatus 15 may obtain the counting efficiency ε using the partial volume V(k), efficiency ε(k), and packing rate r(k). The packing rate r(k) corresponding to any predetermined variable h(k) is the packing rate of the sample 11 in the partial volume V(k).

[0054]

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[0055] Figure 6 shows an example of the uneven distribution of the sample 11 within the container 21 when the counting efficiency ε is obtained by the radioactivity measuring device 10 according to the second modified embodiment. As shown in Figure 6, the packing rate r(k) is, for example, the packing rate of the sample 11 on a predetermined surface set for a partial volume V(k). The predetermined surface is, for example, a surface perpendicular to the direction related to the setting of a predetermined variable h, i.e., the vertical direction, and is the top surface of the partial volume V(k). For example, the total area S(k) of the predetermined surface of the partial volume V(k) is described by the sum of the area Sa(k) of the region where the sample 11 exists and the area Sb(k) of the region where the sample 11 does not exist. In this case, the packing rate r(k) is described by the ratio of the total area S(k) to the area Sa(k) of the region where the sample 11 exists, as shown in formula (5) above. According to the second modification, for example, even if the sample 11 is unevenly distributed within the container 21, a highly accurate counting efficiency ε can be obtained by the packing rate r(k).

[0056] In the embodiment described above, the state detection unit 12 scans the sample 11 inside the container 21 along a predetermined direction, such as the vertical direction, which is related to the setting of a predetermined variable h. However, it is not limited to this. For example, detection may be performed at multiple positions along the perimeter of the container 21 for the same position in the vertical direction, where the distance from the radiation detector 13 is the same.

[0057] Figure 7 is a plan view showing an example of the arrangement of the state detection unit 42, radiation detector 13, and container 21 of the radioactivity measuring device 10B according to a third modified example of the embodiment. As shown in Figure 7, the radioactivity measuring device 10B according to the third modified example may include, for example, a rotation mechanism 41 that rotates the container 21 around the Z-axis. The radioactivity measuring device 10B according to the third modified example may also include, for example, a state detection unit 42 that rotates around the container 21 around the Z-axis, and a guide member 43 that guides the rotational movement of the state detection unit 42. According to the third modification, the state of the sample 11 can be understood in more detail by detecting the state of the sample 11 at multiple positions along the perimeter of the container 21. Furthermore, even when understanding the average state of the sample 11 based on detection at multiple positions, for example, the detection accuracy can be improved.

[0058] In the embodiments described above, the state detection unit 12 is a sensor that detects reflection or scattering of radiated waves by an object, such as a so-called finder, radar device, and sonar, but it is not limited to this. The state detection unit 12 may be, for example, an imaging device for the visible light region and infrared region, a sensor that detects the transmission of electromagnetic waves such as X-rays through an object, or a sensor that detects changes in capacitance without contact, such as a so-called capacitive proximity sensor.

[0059] The state of the sample 11, including its shape and dimensions, detected by the state detection unit 12 is not limited to the external shape of the sample 11, but may also include the internal state of the sample 11, for example, when voids and cavities are formed inside the sample 11. Furthermore, the state detection unit 12 is not limited to the state of the sample 11 including its shape and dimensions, but may also detect the state of the sample 11 including its components, for example, when the sample 11 has a layered structure composed of multiple different components. Sample 11 may include, for example, airborne dust, fallout, freshwater (such as tap water and freshwater), soil, seabed sediment, polished rice, raw or ashed vegetables and tea leaves, milk, seawater, raw or ashed seafood and everyday food, and timely precipitation. Furthermore, the state detection unit 12 may also perform detection on the container 21 even when it does not contain any sample 11.

[0060] In the embodiments described above, the outer shape of the container 21 is cylindrical and the central axis of the container 21 is parallel to the vertical direction, but it is not limited to these. For example, the shape of the container 21 may be other than cylindrical, and the orientation of the container 21 may be set as appropriate. In the embodiment described above, the predetermined variable h was defined as the distance from the radiation detector 13 along the direction toward the sample 11 (for example, the vertical direction), but it is not limited to this. For example, the predetermined variable h may be the distance from an appropriate position set along a direction other than the direction toward the sample 11 toward the radiation detector 13 to the sample 11.

[0061] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0062] 10, 10A, 10B...Radioactivity measuring device, 11...Sample, 12...State detection unit, 13...Radiation detector, 14...Multiple pulse height analyzer, 15...Processing device, 16...Input unit, 17...Output unit, 20...Shielding body, 21...Container, 41...Rotation mechanism, 42...State detection unit, 43...Guide member.

Claims

1. A radiation detector that detects the energy of radiation emitted from a sample and outputs a pulse signal corresponding to the energy, A state detection unit detects the state of the sample, including at least its shape and dimensions, and outputs a state detection signal. A processing unit acquires predetermined variables related to the shape and dimensions based on the detection signal output from the state detection unit, and associates the pulse signal output from the radiation detector with the predetermined variables. A radioactivity measuring device equipped with the following features.

2. The processing unit acquires the counting efficiency of the radiation detector for the sample using the predetermined variable. The radioactivity measuring device according to claim 1.

3. The system includes a pulse height analyzer that generates pulse height distribution data having counts associated with each of a plurality of channels based on the pulse height values ​​of the pulse signal, The processing unit acquires the counting efficiency corresponding to the predetermined variable based on the wave height distribution data output from the wave height analyzer. The radioactivity measuring device according to claim 2.

4. The system includes a shielding body that blocks radiation and in which the radiation detector and the state detection unit are arranged. A radioactivity measuring device according to any one of claims 1 to 3.

5. The device includes an exchanger for exchanging the sample to be detected by the radiation detector from among a plurality of the aforementioned samples, The state detection unit detects the state of the sample selected by the exchanger. A radioactivity measuring device according to any one of claims 1 to 3.

6. The aforementioned processing unit, The counting efficiency of the radiation detector for the entire volume of the sample is obtained by summing the efficiencies of partial volumes of the sample according to the predetermined variable. The radioactivity measuring device according to claim 2.

7. The aforementioned processing unit, The maximum value of the predetermined variable is divided by a predetermined natural number n, and n predetermined variables h(k) are obtained by any natural number k (=1, ..., n) up to the predetermined natural number n, The n partial volumes V(k) corresponding to the n predetermined variables h(k) constitute the volume V of the storage space inside the container in which the sample is contained, The n counting efficiencies ε(k) corresponding to the n partial volumes V(k) and The counting efficiency ε of the radiation detector for the sample is obtained based on the following formula (1) described by [formula]. The radioactivity measuring device according to claim 6. [Math 1]

8. The aforementioned processing unit, The counting efficiency ε is obtained based on the following formula (2), which is described by the n packing rates r(k) corresponding to the n partial volumes V(k) mentioned above. The radioactivity measuring device according to claim 7. [Math 2]

9. The aforementioned processing unit, The predetermined variable is defined as the distance from the radiation detector along the direction from the radiation detector towards the sample. The radioactivity measuring device according to claim 7 or claim 8.

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