WO2019181065A1 - Signal processing device, analysis device, and signal processing method - Google Patents

Signal processing device, analysis device, and signal processing method Download PDF

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Publication number
WO2019181065A1
WO2019181065A1 PCT/JP2018/043125 JP2018043125W WO2019181065A1 WO 2019181065 A1 WO2019181065 A1 WO 2019181065A1 JP 2018043125 W JP2018043125 W JP 2018043125W WO 2019181065 A1 WO2019181065 A1 WO 2019181065A1
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signal
output signal
radiation detector
signal processing
electrodes
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PCT/JP2018/043125
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French (fr)
Japanese (ja)
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佑多 齋藤
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株式会社島津製作所
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
    • G01N23/223—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/18—Measuring radiation intensity with counting-tube arrangements, e.g. with Geiger counters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
    • H01J47/06—Proportional counter tubes

Definitions

  • the present invention relates to a signal processing device that processes an output signal from a radiation detector, an analysis device including the signal processing device, and a signal processing method.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 7-167805
  • Patent Document 1 describes a window range of a wave height sorter for wave height sorting of an X-ray detection pulse output from a radiation detector which is a proportional counter, and a peak of a target element. The technique of setting according to is disclosed.
  • the present disclosure has been made in order to solve the above-described problem, and an object of the present disclosure is to easily determine the occurrence of a discharge abnormality of a radiation detector by using a signal that has been ignored in the past. It is to provide a possible signal processing device, analysis device and signal processing method.
  • the signal processing device processes an output signal from the radiation detector.
  • the radiation detector includes a pair of electrodes to which a predetermined voltage is applied and a gas that exists between the pair of electrodes and can be ionized when receiving radiation.
  • the output signal has a peak value corresponding to the energization amount between the pair of electrodes.
  • the signal processing device has a pair of discriminators for discriminating the output signal as an abnormal signal, and a pair of abnormal signals.
  • a determination unit for determining whether or not a discharge abnormality occurs between the electrodes.
  • the first threshold is an upper limit value that can be taken by the peak value of the output signal when the gas receives the radiation to be detected.
  • the peak value of the output signal of the radiation detector is higher than the peak value of the output signal of the radiation detector when the X-ray to be detected is incident.
  • an abnormal signal is discriminated from the output signal utilized in order to determine the X-ray dose which injected into the radiation detector, and the presence or absence of generation
  • the abnormal signal has a peak value that exceeds the upper limit of the peak value of the output signal when receiving the radiation to be detected, and has been conventionally ignored. Accordingly, it is possible to easily determine whether or not a discharge abnormality has occurred based on an abnormality signal that has been ignored in the past without separately providing a device for determining whether or not there is a discharge abnormality.
  • the determination unit determines that a discharge abnormality has occurred when the number of abnormal signal counts per unit time exceeds a predetermined value. According to said structure, the presence or absence of discharge abnormality generation can be easily determined by counting an abnormal signal.
  • the determination unit determines that a discharge abnormality has occurred when the peak value of the abnormal signal exceeds the second threshold value.
  • the second threshold value is larger than the first threshold value.
  • the determination unit determines that a discharge abnormality has occurred when a time during which the intensity of the abnormal signal exceeds the first threshold exceeds a predetermined time.
  • a time during which the intensity of the abnormal signal exceeds the first threshold exceeds a predetermined time.
  • the determination unit notifies the presence / absence of occurrence of the discharge abnormality based on the determination result of the occurrence of discharge abnormality.
  • the user can grasp
  • an analyzer includes the signal processing device described above and a radiation detector. Also with the above configuration, it is possible to easily determine whether or not a discharge abnormality has occurred based on an abnormality signal that has been ignored in the past.
  • the signal processing method is a method for processing an output signal from a radiation detector.
  • the radiation detector includes a pair of electrodes to which a predetermined voltage is applied and a gas that exists between the pair of electrodes and can be ionized when receiving radiation.
  • the output signal has a peak value corresponding to the energization amount between the pair of electrodes.
  • the signal processing method includes a step of discriminating the output signal as an abnormal signal when the peak value of the output signal received from the radiation detector exceeds a threshold value, and a discharge abnormality between the pair of electrodes based on the abnormal signal. And determining whether or not it has occurred.
  • the threshold value is an upper limit value that can be taken by the peak value of the output signal when the gas receives predetermined radiation. Also with the above configuration, it is possible to easily determine whether or not a discharge abnormality has occurred based on an abnormality signal that has been ignored in the past.
  • FIG. 1 is a schematic configuration diagram of a wavelength dispersive X-ray fluorescence spectrometer equipped with a signal processing device according to Embodiment 1.
  • FIG. It is a figure which shows schematic structure of a radiation detector. An example of the output signal (output signal derived from X-rays) from the radiation detector when X-rays enter the gas is shown. An example of an output signal (output signal derived from discharge) from a radiation detector when a discharge abnormality occurs between a pair of electrodes is shown. It is a figure which shows the wave height distribution of the output signal from a radiation detector. It is a block diagram which shows the internal structure of a signal processing apparatus.
  • ⁇ Embodiment 1> (Configuration of analyzer) An example of an analysis apparatus provided with the signal processing apparatus according to Embodiment 1 will be described. Hereinafter, a wavelength dispersion type fluorescent X-ray analyzer will be described as an example of the analyzer. However, the analyzer is not limited to the wavelength dispersive X-ray fluorescence analyzer, and any analyzer that has a function of detecting radiation may be used.
  • FIG. 1 is a schematic configuration diagram of a wavelength dispersive X-ray fluorescence spectrometer 100 including a signal processing device 7 according to the first embodiment.
  • the wavelength dispersive X-ray fluorescence analyzer 100 includes an X-ray tube 1, solar slits 3 and 5, a spectral crystal 4, a radiation detector 6, a signal processing device 7, and a display. Part 8.
  • the X-ray tube 1 emits primary X-rays to the sample 2.
  • the X-ray tube 1 includes, for example, a target that is an anode and a filament that is a cathode, which are arranged inside a housing, and collides thermal electrons radiated from the filament with the end surface of the target.
  • the generated primary X-ray is generated.
  • the X-ray tube 1 generates MnK ⁇ rays generated from 55 Fe at 5.9 keV as primary X-rays.
  • Sample 2 that has received the primary X-rays emits fluorescent X-rays.
  • the solar slit 3 removes components that are not parallel from the fluorescent X-rays emitted from the sample 2 and heading toward the spectroscopic crystal 4, thereby improving the parallelism of the fluorescent X-rays.
  • the solar slit 5 removes non-parallel components from the X-rays diffracted by the spectroscopic crystal 4 and improves the parallelism of the X-rays.
  • the radiation detector 6 is an X-ray detector using a proportional counter, detects X-rays diffracted by the spectroscopic crystal 4, and performs signal processing on an output signal S0 having a peak value corresponding to the detected X-ray energy. Output to device 7.
  • the signal processing device 7 processes the output signal S0 from the radiation detector 6, determines the X-ray dose incident on the radiation detector 6, and determines the occurrence of discharge abnormality in the radiation detector 6.
  • the signal processing device 7 displays the determination result on the display unit 8.
  • the display unit 8 is configured by a liquid crystal display or the like.
  • FIG. 2 is a diagram showing a schematic configuration of the radiation detector 6.
  • the radiation detector 6 includes a pair of electrodes 61 and 62, a gas 63 existing between the pair of electrodes 61 and 62, and a voltage generation that applies a voltage between the pair of electrodes 61 and 62.
  • a circuit 65 and an amplifier circuit 67 are included.
  • the electrode 61 is a metal formed in a tubular shape.
  • the electrode 61 is formed with a window 66 through which X-rays can enter.
  • the electrode 61 is connected to the ground.
  • the electrode 62 is a metal wire and is disposed on the axis of the tubular electrode 61 by an insulator 64.
  • a predetermined voltage (for example, 2 kV) is applied to the electrode 62 by the voltage generation circuit 65.
  • the gas 63 is accommodated inside the tubular electrode 61.
  • the gas is, for example, Ar, and is ionized into electrons and ions by incident X-rays.
  • the amplification circuit 67 is connected to the electrode 62, generates a peak value output signal S 0 corresponding to the amount of current flowing between the electrodes 61, 62, and outputs it to the signal processing device 7.
  • the discharge abnormality is a phenomenon in which the gas 63 breaks down because the applied voltage between the electrodes 61 and 62 is too high, even though the gas 63 does not receive X-rays having a specific wavelength to be detected. That is.
  • the output signal S0 generated by ionizing the gas 63 that has received X-rays having a specific wavelength to be detected is referred to as an “X-ray-derived output signal S0”.
  • the output signal S0 generated when the discharge abnormality occurs is referred to as “discharge-derived output signal S0”.
  • the output signal S0 from the radiation detector 6 includes a signal derived from electrical noise.
  • FIG. 3 shows an example of an output signal S0 (output signal derived from X-rays) from the radiation detector 6 when X-rays having a specific wavelength to be detected enter the gas 63.
  • FIG. 4 shows an example of an output signal S0 (output signal derived from discharge) from the radiation detector 6 when a discharge abnormality occurs between the pair of electrodes 61 and 62.
  • the output signal S0 is indicated by a change with time of the intensity indicated by the voltage value.
  • the peak value of the output signal S0 is the intensity (voltage value) (that is, the maximum intensity) at the peak of the output signal S0.
  • the peak value V2 for example, 1.8 V
  • the peak value V1 for example, 1 V
  • the X-ray dose is determined based on the output signal S0 from the radiation detector 6, and the presence or absence of occurrence of discharge abnormality in the radiation detector 6 is determined. Therefore, it is necessary to discriminate between the output signal S0 derived from X-rays, the output signal S0 derived from electrical noise, and the output signal S0 derived from discharge. Therefore, the range that the peak value of the output signal S0 can take when the gas 63 receives X-rays of a specific wavelength to be detected is set as a normal range.
  • the lower limit (for example, 0.5 V) that the peak value of the output signal S0 can take when the gas 63 receives X-rays having a specific wavelength to be detected is the output signal S0 derived from the X-rays and the electricity.
  • the upper limit value (for example, 1.3 V) that the peak value of the output signal S0 can take is the X-ray-derived output signal S0 and the discharge-derived output.
  • Th_U for discrimination from the signal S0. That is, a range between the threshold Th_L and the threshold Th_U is set as the normal range. Note that the threshold Th_L and the threshold Th_U are appropriately set according to the wavelength of the X-ray to be detected.
  • FIG. 6 is a block diagram showing an internal configuration of the signal processing device 7. As shown in FIG. 6, the signal processing device 7 includes a discrimination unit 71 and a determination unit 76.
  • the discriminator 71 discriminates the output signal S0 as a normal signal when the peak value of the output signal S0 received from the radiation detector 6 is within the normal range, and determines the peak value of the output signal S0 received from the radiation detector 6. When the threshold value Th_U is exceeded, the output signal S0 is discriminated as an abnormal signal.
  • the discrimination unit 71 includes a first comparison circuit 72, a second comparison circuit 73, a first pulse signal output circuit 74, and a second pulse signal output circuit 75.
  • the first comparison circuit 72 compares the intensity (voltage value) of the output signal S0 from the radiation detector 6 with the threshold value Th_L, and outputs a signal S1 indicating the comparison result.
  • the first comparison circuit 72 outputs a high level signal S1 when the intensity of the output signal S0 is smaller than the threshold value Th_L, and the low level signal S1 when the intensity of the output signal is equal to or greater than the threshold value Th_L. Is output.
  • the second comparison circuit 73 compares the intensity of the output signal S0 from the radiation detector 6 with the threshold value Th_U, and outputs a signal S2 indicating the comparison result.
  • the second comparison circuit 73 outputs a high level signal S2 when the intensity of the output signal S0 is equal to or less than the threshold value Th_U, and outputs a low level signal S2 when the intensity of the output signal S0 exceeds the threshold value Th_U. Is output.
  • the second pulse signal output circuit 75 outputs the one-pulse signal P2 at the timing when the period in which the signal S2 is continuously at the low level is completed.
  • the case where the signal S2 is at a low level means that the peak value of the output signal S0 received from the radiation detector 6 exceeds the threshold value Th_U. That is, the signal P2 is output when the output signal S0 received from the radiation detector 6 is an abnormal signal.
  • the discriminating unit 71 is configured by, for example, an FPGA (Field-Programmable Gate Array).
  • Each of the first comparison circuit 72 and the second comparison circuit 73 includes a comparator.
  • Each of the first pulse signal output circuit 74 and the second pulse signal output circuit 75 includes a logic circuit that receives signals output from the first comparison circuit 72 and the second comparison circuit 73.
  • FIG. 7 is a diagram illustrating an example of signals S1, S2, P1, and P2 that are output when the X-ray-derived output signal S0 is received.
  • the peak value of the X-ray-derived output signal S0 is not less than the threshold value Th_L and not more than the threshold value Th_U.
  • the signal S1 becomes low level during a period from time t1 to time t2 when the intensity of the output signal S0 becomes equal to or higher than the threshold Th_L, and becomes high level during other periods.
  • the signal S2 is always at a high level.
  • the first pulse signal output circuit 74 outputs one pulse signal P1 at time t2 when the signal S2 changes from low level to high level.
  • the second pulse signal output circuit 75 does not output the signal P2.
  • FIG. 8 is a diagram illustrating an example of signals S1, S2, P1, and P2 that are output when the output signal S0 derived from discharge is received.
  • the peak value of the discharge-derived output signal S0 exceeds the threshold value Th_U.
  • the signal S1 becomes low level during a period from time t3 to time t6 when the intensity of the output signal S0 becomes equal to or higher than the threshold Th_L, and becomes high level during other periods.
  • the signal S2 becomes low level during a period from time t4 to time t5 when the intensity of the output signal S0 exceeds the threshold Th_U, and becomes high level during other periods.
  • the time t3 is before the time t4, and the time t6 is after the time t5.
  • the signal S2 becomes low level during a part of the period from time t3 to time t6 when the signal S1 is low level (period from time t4 to time t5). Therefore, the first pulse signal output circuit 74 does not output the signal P1 at time t6 when the signal S2 changes from the low level to the high level.
  • the second pulse signal output circuit 75 outputs a one-pulse signal P2 at time t5 when the signal S2 changes from the low level to the high level.
  • the determination unit 76 determines the X-ray dose incident on the gas 63 based on the signal P ⁇ b> 1, and determines whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62 based on the signal P ⁇ b> 2. judge.
  • the signal P1 means that a normal signal whose peak value is within the normal range of the threshold value Th_L or more and the threshold value Th_U or less is received from the radiation detector 6.
  • the determination unit 76 determines the X-ray dose incident on the gas 63 based on the signal P1.
  • the determination unit 76 determines the X-ray dose incident on the gas 63 by counting the number of signals P1 output from the first pulse signal output circuit 74.
  • the signal P2 means that an abnormal signal whose peak value exceeds the threshold Th_U has been received from the radiation detector 6.
  • the determination unit 76 determines whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62 based on the signal P2. For example, the determination unit 76 may determine that a discharge abnormality has occurred between the pair of electrodes 61 and 62 when receiving the signal P2. Alternatively, the determination unit 76 counts the number of signals P2 output from the second pulse signal output circuit 75 per unit time, and sets a predetermined value Th1 (for example, 2 to 3 cps) in which the count number is set in advance. When exceeding, you may determine with the discharge abnormality having generate
  • Th1 for example, 2 to 3 cps
  • the determination unit 76 displays (outputs) the determination result on the display unit 8. For example, when it is determined that a discharge abnormality has occurred between the pair of electrodes 61, 62, the determination unit 76 indicates that a discharge abnormality has occurred and determines the voltage applied between the pair of electrodes 61, 62. A screen that prompts a decrease is displayed on the display unit 8.
  • the signal processing device 7 determines whether or not the peak value of the output signal S0 from the radiation detector 6 is greater than or equal to the threshold value Th_L (step S11). If the peak value of output signal S0 is not equal to or greater than threshold value Th_L (NO in S11), the process returns to step S11.
  • the signal processing device 7 determines whether or not the peak value of the output signal S0 is equal to or less than the threshold value Th_U (step S12). ).
  • the signal processing device 7 When the peak value of the output signal S0 is equal to or less than the threshold value Th_U (YES in S12), the signal processing device 7 generates a signal P1 indicating that the output signal S0 is a normal signal (step S13). Thereafter, the signal processing device 7 increases the count number of the signal P1 by 1, determines the X-ray dose detected by the radiation detector 6 based on the count number of the signal P1, and displays the determined X-ray dose on the display unit 8. Displayed (step S14).
  • the signal processing device 7 When the peak value of the output signal S0 exceeds the threshold value Th_U (NO in S12), the signal processing device 7 generates a signal P2 indicating that the output signal S0 is an abnormal signal (step S15). That is, when the peak value of the output signal S0 received from the radiation detector 6 exceeds the threshold value Th_U, the signal processing device 7 discriminates the output signal S0 as an abnormal signal.
  • the signal processing device 7 discriminates the output signal S0 as an abnormal signal.
  • the discriminating part 71 is provided.
  • the signal processing device 7 includes a determination unit 76 that determines whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62 based on the abnormality signal.
  • the threshold value Th_U is an upper limit value that can be taken by the peak value of the output signal S0 when the gas 63 receives X-rays to be detected.
  • an abnormal signal is discriminated from the output signal S0 used for determining the X-ray dose incident on the radiation detector 6, and the pair of electrodes 61, It is determined whether or not a discharge abnormality between 62 occurs. That is, it is not necessary to separately provide a device (such as an ammeter) for determining whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62. Therefore, it is possible to easily determine the occurrence of discharge abnormality of the radiation detector 6.
  • the determination unit 76 determines that a discharge abnormality has occurred when the count number of abnormal signals per unit time (that is, the count number of the signal P2) exceeds a predetermined value Th1. Therefore, by appropriately setting the predetermined value Th1, the determination unit 76 does not determine that a discharge abnormality has occurred simply by receiving the output signal S0 that suddenly exceeds the threshold value Th_U for some reason. As a result, the frequency of erroneous determination by the determination unit 76 can be reduced.
  • the determination unit 76 outputs a determination result of occurrence of discharge abnormality to the display unit 8. Thereby, the user can grasp
  • FIG. The user can suppress deterioration of the radiation detector 6 by appropriately implementing measures such as reducing the applied voltage between the pair of electrodes 61 and 62.
  • the applied voltage between the pair of electrodes 61 and 62 is too high, an abnormal discharge occurs, and even when the gas 63 receives X-rays having a specific wavelength to be detected, the avalanche is higher than expected. As a result, a large current may flow between the electrodes 61 and 62. Even when a large current flows between the electrodes 61 and 62 due to the electron avalanche exceeding the assumption, the determination unit 76 determines that a discharge abnormality has occurred, and the applied voltage between the electrodes 61 and 62 decreases. Can be displayed on the display unit 8. Accordingly, the user can appropriately take measures such as reducing the applied voltage between the electrodes 61 and 62.
  • the determination unit 76 determines that a discharge abnormality has occurred when the count number of the signal P2 per unit time exceeds a predetermined value Th1.
  • the determination part 76 determines with the discharge abnormality having generate
  • the threshold value Th_U2 is larger than the threshold value Th_U that is the upper limit value of the normal range.
  • cosmic rays may enter the radiation detector 6. Since the energy of cosmic rays is higher than the energy of X-rays, when the cosmic rays enter the radiation detector 6, an output signal S0 having a large peak value is output. For this reason, in the first embodiment, the output signal S0 having a large peak value may be erroneously determined as the output signal S0 derived from discharge.
  • FIG. 10A is a diagram showing an output signal S0 derived from discharge.
  • FIG. 10B is a diagram showing an output signal S0 derived from cosmic rays. As shown in FIGS. 10A and 10B, the peak value of the cosmic ray-derived output signal S0 exceeds the threshold Th_U, but is generally lower than the peak value of the discharge-derived output signal S0.
  • the determination unit 76 of the second embodiment is larger than a threshold value Th_U that is an upper limit value that the peak value of the output signal S0 can take when the gas 63 receives X-rays of a specific wavelength to be detected. It is determined that a discharge abnormality has occurred using the threshold value Th_U2. Specifically, the determination unit 76 determines that a discharge abnormality has occurred when the peak value of the abnormal signal discriminated by the discriminating unit 71 exceeds the threshold value Th_U2. Thereby, the influence of the output signal S0 derived from the cosmic ray having a peak value lower than the threshold value Th_U2 can be suppressed, and the determination unit 76 can accurately determine whether or not the discharge abnormality has occurred in the radiation detector 6. .
  • the time T2 when the intensity (voltage value) of the output signal S0 derived from cosmic rays exceeds the threshold Th_U is generally the intensity of the output signal S0 derived from X-rays. Is shorter than the time T1 when the threshold value Th_U is exceeded. Therefore, the determination unit 76 according to the third embodiment, when the time when the intensity of the output signal S0 exceeds the threshold value Th_U exceeds a predetermined time Th2 (for example, 80 ns) set in advance, the pair of electrodes 61, It is determined that a discharge abnormality has occurred between 62. Thereby, the influence of the output signal S0 derived from the cosmic ray having a short time width is suppressed, and the determination unit 76 can accurately determine whether or not the discharge abnormality has occurred in the radiation detector 6.
  • a predetermined time Th2 for example, 80 ns
  • the signal processing device 7 provided in the wavelength dispersive X-ray fluorescence analyzer 100 has been described.
  • the signal processing device 7 may be applied to an analysis device that analyzes radiation other than X-rays.
  • the radiation detector 6 detects radiation other than X-rays.
  • the threshold values Th_L, Th_U, Th_U2, the predetermined value Th1, and the predetermined time Th2 set in the signal processing device 7 are appropriately set according to the radiation to be detected.
  • the determination unit 76 may output a determination result of occurrence of discharge abnormality to an indicator lamp. For example, the determination unit 76 lights the indicator lamp in green when no discharge abnormality has occurred, and lights the indicator lamp in red when a discharge abnormality has occurred. Or the determination part 76 may output the sound which shows a determination result from a speaker or a buzzer.
  • the signal processing device 7 processes the output signal S0 from the radiation detector 6 using a proportional counter.
  • the signal processing device 7 may perform the same processing as described above on the output signal from the semiconductor detector or the scintillation detector.
  • a program for causing the signal processing device 7 to execute the above-described operation may be provided.
  • Such a program is recorded on a computer-readable recording medium such as a flexible disk attached to the computer, a CD-ROM (Compact Disk-Read Only Memory), a ROM, a RAM, and a memory card, and provided as a program product. You can also.
  • the program can be provided by being recorded on a recording medium such as a hard disk built in the computer.
  • a program can also be provided by downloading via a network.
  • the provided program product is installed in a program storage unit such as a hard disk and executed.
  • the program product includes the program itself and a recording medium on which the program is recorded.

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Abstract

A signal processing device (7) processes an output signal (S0) from a radiation detector (6). The radiation detector (6) comprises a pair of electrodes to which a prescribed voltage has been applied and a gas that is present in between the pair of electrodes and that can be ionized when radiation is received. The output signal (S0) includes a peak value corresponding to the quantity of the current passing between the pair of electrodes. The signal processing device (7) comprises: a discernment unit (71) for discerning the output signal (S0) as an abnormal signal in a case where the peak value of the output signal (S0) received from the radiation detector (6) exceeds a threshold value; and a determination unit (76) for determining on the basis of the abnormal signal whether a discharge abnormality has occurred in between the pair of electrodes. The threshold value is the maximum value that the peak value of the output signal (S0) can reach when the gas has received radiation to be detected.

Description

信号処理装置、分析装置および信号処理方法Signal processing apparatus, analysis apparatus, and signal processing method
　本発明は、放射線検出器からの出力信号を処理する信号処理装置、当該信号処理装置を備えた分析装置、および信号処理方法に関する。 The present invention relates to a signal processing device that processes an output signal from a radiation detector, an analysis device including the signal processing device, and a signal processing method.
　従来、試料に含まれる元素を分析するために、当該試料から放出される蛍光Ｘ線を検出することが行なわれている。たとえば、特開平７－１６７８０５号公報（特許文献１）には、比例計数管である放射線検出器から出力されるＸ線検出パルスを波高選別する波高選別器の窓の範囲を、目的元素のピークに応じて設定する技術が開示されている。 Conventionally, in order to analyze elements contained in a sample, detection of fluorescent X-rays emitted from the sample has been performed. For example, Japanese Patent Application Laid-Open No. 7-167805 (Patent Document 1) describes a window range of a wave height sorter for wave height sorting of an X-ray detection pulse output from a radiation detector which is a proportional counter, and a peak of a target element. The technique of setting according to is disclosed.
特開平７－１６７８０５号公報Japanese Unexamined Patent Publication No. 7-167805
　比例計数管などの放射線検出器は、高電圧を印加して使用される。そのため、印加される電圧が高すぎる場合または放射線検出器の製造上の不具合がある場合に放電異常が発生し得る。放電異常が発生した状態で使用し続けると、放射線検出器が早期に劣化し、放射線検出器の交換が必要となる。 Radiation detectors such as proportional counters are used with high voltage applied. Therefore, discharge abnormality may occur when the applied voltage is too high or when there is a manufacturing defect of the radiation detector. If it continues to be used in a state where discharge abnormality has occurred, the radiation detector will deteriorate early, and the radiation detector will need to be replaced.
　放電異常時に流れる電流を検出する電流計によって放電異常の発生を判定することが考えられるが、当該電流計を放射線検出器に別途設ける必要があった。 It is conceivable to determine the occurrence of discharge abnormality with an ammeter that detects the current flowing when discharge is abnormal, but it is necessary to separately provide the ammeter in the radiation detector.
　さらに、従来、放射線検出器から出力される信号のうち所定の正常範囲外の信号は、すべてノイズとして無視されており、有効に利用されていなかった。 Furthermore, conventionally, signals outside the predetermined normal range among signals output from the radiation detector are all ignored as noise and have not been used effectively.
　本開示は、上記の課題を解決するためになされたものであって、その目的は、従来無視されていた信号を利用することにより、放射線検出器の放電異常の発生を容易に判定することが可能な信号処理装置、分析装置および信号処理方法を提供することである。 The present disclosure has been made in order to solve the above-described problem, and an object of the present disclosure is to easily determine the occurrence of a discharge abnormality of a radiation detector by using a signal that has been ignored in the past. It is to provide a possible signal processing device, analysis device and signal processing method.
　本開示のある局面によれば、信号処理装置は、放射線検出器からの出力信号を処理する。放射線検出器は、所定電圧が印加された一対の電極と、一対の電極間に存在し、放射線を受けたときに電離可能なガスとを備える。出力信号は、一対の電極間の通電量に応じた波高値を有する。信号処理装置は、放射線検出器から受ける出力信号の波高値が第１のしきい値を超える場合に、当該出力信号を異常信号として弁別するための弁別部と、異常信号に基づいて、一対の電極間の放電異常の発生の有無を判定するための判定部とを備える。第１のしきい値は、ガスが検出対象の放射線を受けたときの出力信号の波高値が取り得る上限値である。 According to an aspect of the present disclosure, the signal processing device processes an output signal from the radiation detector. The radiation detector includes a pair of electrodes to which a predetermined voltage is applied and a gas that exists between the pair of electrodes and can be ionized when receiving radiation. The output signal has a peak value corresponding to the energization amount between the pair of electrodes. When the peak value of the output signal received from the radiation detector exceeds the first threshold value, the signal processing device has a pair of discriminators for discriminating the output signal as an abnormal signal, and a pair of abnormal signals. A determination unit for determining whether or not a discharge abnormality occurs between the electrodes. The first threshold is an upper limit value that can be taken by the peak value of the output signal when the gas receives the radiation to be detected.
　一対の電極間に放電異常が発生したときに放射線検出器の出力信号の波高値は、検出対象のＸ線が入射したときの放射線検出器の出力信号の波高値よりも高くなる。上記の構成によれば、放射線検出器に入射されたＸ線量を判定するために利用される出力信号から異常信号が弁別され、当該異常信号に基づいて放電異常の発生の有無が判定される。異常信号は、検出対象の放射線を受けたときの出力信号の波高値が取り得る上限値を超える波高値を有し、従来無視されていた信号である。これにより、放電異常の有無を判定するための機器を別途設けることなく、従来無視されていた異常信号に基づいて、放電異常の発生の有無を容易に判定することができる。 When the discharge abnormality occurs between the pair of electrodes, the peak value of the output signal of the radiation detector is higher than the peak value of the output signal of the radiation detector when the X-ray to be detected is incident. According to said structure, an abnormal signal is discriminated from the output signal utilized in order to determine the X-ray dose which injected into the radiation detector, and the presence or absence of generation | occurrence | production of discharge abnormality is determined based on the said abnormal signal. The abnormal signal has a peak value that exceeds the upper limit of the peak value of the output signal when receiving the radiation to be detected, and has been conventionally ignored. Accordingly, it is possible to easily determine whether or not a discharge abnormality has occurred based on an abnormality signal that has been ignored in the past without separately providing a device for determining whether or not there is a discharge abnormality.
　好ましくは、判定部は、単位時間当たりの異常信号のカウント数が所定の値を超える場合に、放電異常が発生していると判定する。上記の構成によれば、異常信号をカウントすることにより、放電異常の発生の有無を容易に判定することができる。 Preferably, the determination unit determines that a discharge abnormality has occurred when the number of abnormal signal counts per unit time exceeds a predetermined value. According to said structure, the presence or absence of discharge abnormality generation can be easily determined by counting an abnormal signal.
　好ましくは、判定部は、異常信号の波高値が第２のしきい値を超える場合に、放電異常が発生していると判定する。第２のしきい値は、第１のしきい値よりも大きい。上記の構成によれば、異常信号の波高値と第２のしきい値とを比較することにより、第２のしきい値よりも低い波高値の宇宙線由来の信号の影響を抑制でき、放電異常の発生の有無を精度良く判定することができる。 Preferably, the determination unit determines that a discharge abnormality has occurred when the peak value of the abnormal signal exceeds the second threshold value. The second threshold value is larger than the first threshold value. According to said structure, by comparing the peak value of an abnormal signal with a 2nd threshold value, the influence of the signal derived from the cosmic ray of the peak value lower than a 2nd threshold value can be suppressed, and discharge It is possible to accurately determine whether or not an abnormality has occurred.
　好ましくは、判定部は、異常信号の強度が第１のしきい値を超えている時間が所定の時間を超える場合に、放電異常が発生していると判定する。上記の構成によれば、異常信号の強度が第１のしきい値を超えている時間を計ることにより、時間幅の短い宇宙線由来の信号の影響を抑制でき、放電異常の発生の有無を精度良く判定することができる。 Preferably, the determination unit determines that a discharge abnormality has occurred when a time during which the intensity of the abnormal signal exceeds the first threshold exceeds a predetermined time. According to the above configuration, by measuring the time during which the intensity of the abnormal signal exceeds the first threshold, it is possible to suppress the influence of a signal derived from a cosmic ray having a short time width, and to determine whether or not a discharge abnormality has occurred. It can be determined with high accuracy.
　好ましくは、判定部は、放電異常の発生の判定結果に基づいて、前記放電異常の発生の有無を報知する。上記の構成によれば、ユーザは、放電異常が発生していることを把握でき、メンテナンス等の適切な対応を実行することができる。 Preferably, the determination unit notifies the presence / absence of occurrence of the discharge abnormality based on the determination result of the occurrence of discharge abnormality. According to said structure, the user can grasp | ascertain that the discharge abnormality has generate | occur | produced and can perform appropriate measures, such as a maintenance.
　本発明の別の局面によれば、分析装置は、上記の信号処理装置と、放射線検出器とを備える。上記の構成によっても、従来無視されていた異常信号に基づいて、放電異常の発生の有無を容易に判定することができる。 According to another aspect of the present invention, an analyzer includes the signal processing device described above and a radiation detector. Also with the above configuration, it is possible to easily determine whether or not a discharge abnormality has occurred based on an abnormality signal that has been ignored in the past.
　本発明の別の局面によれば、信号処理方法は、放射線検出器からの出力信号を処理するための方法である。放射線検出器は、所定電圧が印加された一対の電極と、一対の電極間に存在し、放射線を受けたときに電離可能なガスとを備える。出力信号は、一対の電極間の通電量に応じた波高値を有する。信号処理方法は、放射線検出器から受ける出力信号の波高値がしきい値を超える場合に、当該出力信号を異常信号として弁別するステップと、異常信号に基づいて、一対の電極間の放電異常の発生の有無を判定するステップとを備える。しきい値は、ガスが所定放射線を受けたときの前記出力信号の波高値が取り得る上限値である。上記の構成によっても、従来無視されていた異常信号に基づいて、放電異常の発生の有無を容易に判定することができる。 According to another aspect of the present invention, the signal processing method is a method for processing an output signal from a radiation detector. The radiation detector includes a pair of electrodes to which a predetermined voltage is applied and a gas that exists between the pair of electrodes and can be ionized when receiving radiation. The output signal has a peak value corresponding to the energization amount between the pair of electrodes. The signal processing method includes a step of discriminating the output signal as an abnormal signal when the peak value of the output signal received from the radiation detector exceeds a threshold value, and a discharge abnormality between the pair of electrodes based on the abnormal signal. And determining whether or not it has occurred. The threshold value is an upper limit value that can be taken by the peak value of the output signal when the gas receives predetermined radiation. Also with the above configuration, it is possible to easily determine whether or not a discharge abnormality has occurred based on an abnormality signal that has been ignored in the past.
　本開示によれば、従来無視されていた異常信号に基づいて、放射線検出器の放電異常の発生を容易に判定することができる。 According to the present disclosure, it is possible to easily determine the occurrence of the discharge abnormality of the radiation detector based on the abnormality signal that has been conventionally ignored.
実施の形態１に係る信号処理装置を備えた波長分散型蛍光Ｘ線分析装置の概略構成図である。1 is a schematic configuration diagram of a wavelength dispersive X-ray fluorescence spectrometer equipped with a signal processing device according to Embodiment 1. FIG. 放射線検出器の概略的構成を示す図である。It is a figure which shows schematic structure of a radiation detector. ガス中にＸ線が入射した場合における放射線検出器からの出力信号（Ｘ線由来の出力信号）の一例を示す。An example of the output signal (output signal derived from X-rays) from the radiation detector when X-rays enter the gas is shown. 一対の電極間に放電異常が発生した場合における放射線検出器からの出力信号（放電由来の出力信号）の一例を示す。An example of an output signal (output signal derived from discharge) from a radiation detector when a discharge abnormality occurs between a pair of electrodes is shown. 放射線検出器からの出力信号の波高分布を示す図である。It is a figure which shows the wave height distribution of the output signal from a radiation detector. 信号処理装置の内部構成を示すブロック図である。It is a block diagram which shows the internal structure of a signal processing apparatus. Ｘ線由来の出力信号を受けたときに出力される信号Ｓ１，Ｓ２，Ｐ１，Ｐ２の一例を示す図である。It is a figure which shows an example of signal S1, S2, P1, P2 output when the output signal derived from an X-ray is received. 放電由来の出力信号を受けたときに出力される信号Ｓ１，Ｓ２，Ｐ１，Ｐ２の一例を示す図である。It is a figure which shows an example of signal S1, S2, P1, P2 output when the output signal derived from discharge is received. 信号処理装置の処理の流れを示すフローチャートである。It is a flowchart which shows the flow of a process of a signal processing apparatus. 放電由来の出力信号を示す図である。It is a figure which shows the output signal derived from discharge. 宇宙線由来の出力信号を示す図である。It is a figure which shows the output signal derived from a cosmic ray.
　本発明の実施の形態について、図面を参照しながら詳細に説明する。なお、図中の同一または相当部分については、同一符号を付してその説明は繰返さない。また、以下で説明する各実施の形態または変形例は、適宜組み合わされてもよい。 Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated. Each embodiment or modification described below may be combined as appropriate.
　＜実施の形態１＞
　（分析装置の構成）
　実施の形態１に係る信号処理装置を備えた分析装置の一例について説明する。以下では、分析装置の一例として、波長分散型蛍光Ｘ線分析装置を説明する。ただし、分析装置は、波長分散型蛍光Ｘ線分析装置に限定されるものではなく、放射線を検出する機能を有するものであればよい。 <Embodiment 1>
(Configuration of analyzer)
An example of an analysis apparatus provided with the signal processing apparatus according to Embodiment 1 will be described. Hereinafter, a wavelength dispersion type fluorescent X-ray analyzer will be described as an example of the analyzer. However, the analyzer is not limited to the wavelength dispersive X-ray fluorescence analyzer, and any analyzer that has a function of detecting radiation may be used.
　図１は、実施の形態１に係る信号処理装置７を備えた波長分散型蛍光Ｘ線分析装置１００の概略構成図である。図１に示されるように、波長分散型蛍光Ｘ線分析装置１００は、Ｘ線管１と、ソーラースリット３，５と、分光結晶４と、放射線検出器６と、信号処理装置７と、表示部８とを備える。 FIG. 1 is a schematic configuration diagram of a wavelength dispersive X-ray fluorescence spectrometer 100 including a signal processing device 7 according to the first embodiment. As shown in FIG. 1, the wavelength dispersive X-ray fluorescence analyzer 100 includes an X-ray tube 1, solar slits 3 and 5, a spectral crystal 4, a radiation detector 6, a signal processing device 7, and a display. Part 8.
　Ｘ線管１は、一次Ｘ線を試料２に出射する。Ｘ線管１は、たとえば、筐体の内部に配置された陽極であるターゲットと陰極であるフィラメントとを含み、フィラメントから放射された熱電子をターゲットの端面に衝突させることで、ターゲットの端面で発生した一次Ｘ線を生成する。たとえば、Ｘ線管１は、５５Ｆｅから５．９ｋｅＶにて生成されるＭｎＫα線を一次Ｘ線として生成する。一次Ｘ線を受けた試料２は、蛍光Ｘ線を放出する。 The X-ray tube 1 emits primary X-rays to the sample 2. The X-ray tube 1 includes, for example, a target that is an anode and a filament that is a cathode, which are arranged inside a housing, and collides thermal electrons radiated from the filament with the end surface of the target. The generated primary X-ray is generated. For example, the X-ray tube 1 generates MnKα rays generated from 55 Fe at 5.9 keV as primary X-rays. Sample 2 that has received the primary X-rays emits fluorescent X-rays.
　ソーラースリット３は、試料２から放出され、分光結晶４に向かう蛍光Ｘ線から平行ではない成分を除去し、蛍光Ｘ線の平行性を高める。 The solar slit 3 removes components that are not parallel from the fluorescent X-rays emitted from the sample 2 and heading toward the spectroscopic crystal 4, thereby improving the parallelism of the fluorescent X-rays.
　分光結晶４は、ソーラースリット３を通過した蛍光Ｘ線を波長分散させ、分析対象となる元素に対応した特定波長のＸ線を放射線検出器６の方向に回折する。分光結晶４から放射線検出器６の方向に回折されるＸ線の波長は、分光結晶４に入射する蛍光Ｘ線と分光結晶４の結晶格子面とのなす角度θによって決定される。 The spectroscopic crystal 4 wavelength-disperses the fluorescent X-rays that have passed through the solar slit 3 and diffracts X-rays having a specific wavelength corresponding to the element to be analyzed in the direction of the radiation detector 6. The wavelength of X-rays diffracted from the spectral crystal 4 in the direction of the radiation detector 6 is determined by the angle θ formed by the fluorescent X-rays incident on the spectral crystal 4 and the crystal lattice plane of the spectral crystal 4.
　ソーラースリット５は、分光結晶４により回折されたＸ線から平行ではない成分を除去し、Ｘ線の平行性を高める。 The solar slit 5 removes non-parallel components from the X-rays diffracted by the spectroscopic crystal 4 and improves the parallelism of the X-rays.
　放射線検出器６は、比例計数管を用いたＸ線検出器であり、分光結晶４により回折されたＸ線を検出し、検出したＸ線のエネルギーに応じた波高値の出力信号Ｓ０を信号処理装置７へ出力する。 The radiation detector 6 is an X-ray detector using a proportional counter, detects X-rays diffracted by the spectroscopic crystal 4, and performs signal processing on an output signal S0 having a peak value corresponding to the detected X-ray energy. Output to device 7.
　信号処理装置７は、放射線検出器６からの出力信号Ｓ０を処理し、放射線検出器６に入射したＸ線量を判定するとともに、放射線検出器６における放電異常の発生を判定する。信号処理装置７は、判定結果を表示部８に表示させる。表示部８は、液晶ディスプレイ等により構成される。 The signal processing device 7 processes the output signal S0 from the radiation detector 6, determines the X-ray dose incident on the radiation detector 6, and determines the occurrence of discharge abnormality in the radiation detector 6. The signal processing device 7 displays the determination result on the display unit 8. The display unit 8 is configured by a liquid crystal display or the like.
　（放射線検出器の構成）
　図２は、放射線検出器６の概略的構成を示す図である。図２に示されるように、放射線検出器６は、一対の電極６１，６２と、一対の電極６１，６２間に存在するガス６３と、一対の電極６１，６２間に電圧を印加する電圧生成回路６５と、増幅回路６７とを含む。 (Configuration of radiation detector)
FIG. 2 is a diagram showing a schematic configuration of the radiation detector 6. As shown in FIG. 2, the radiation detector 6 includes a pair of electrodes 61 and 62, a gas 63 existing between the pair of electrodes 61 and 62, and a voltage generation that applies a voltage between the pair of electrodes 61 and 62. A circuit 65 and an amplifier circuit 67 are included.
　電極６１は、管状に形成された金属である。電極６１には、Ｘ線が入射可能な窓６６が形成される。電極６１は、グランドに接続される。 The electrode 61 is a metal formed in a tubular shape. The electrode 61 is formed with a window 66 through which X-rays can enter. The electrode 61 is connected to the ground.
　電極６２は、金属線であり、絶縁体６４によって管状の電極６１の軸上に配置される。電極６２には電圧生成回路６５により所定電圧（たとえば２ｋＶ）が印加される。 The electrode 62 is a metal wire and is disposed on the axis of the tubular electrode 61 by an insulator 64. A predetermined voltage (for example, 2 kV) is applied to the electrode 62 by the voltage generation circuit 65.
　ガス６３は、管状の電極６１の内部に収容される。ガスは、たとえばＡｒであり、入射されたＸ線により電子とイオンとに電離される。 The gas 63 is accommodated inside the tubular electrode 61. The gas is, for example, Ar, and is ionized into electrons and ions by incident X-rays.
　増幅回路６７は、電極６２に接続され、電極６１，６２間の通電量に応じた波高値の出力信号Ｓ０を生成し、信号処理装置７へ出力する。 The amplification circuit 67 is connected to the electrode 62, generates a peak value output signal S 0 corresponding to the amount of current flowing between the electrodes 61, 62, and outputs it to the signal processing device 7.
　電極６１，６２間が通電する場合には、検出対象となる特定波長のＸ線を受けたガス６３が電離することによって電極６１，６２間に電荷が発生した場合と、電極６１，６２間に放電異常が発生した場合とが含まれる。ここで、放電異常とは、検出対象となる特定波長のＸ線をガス６３が受けていないにもかかわらず、電極６１，６２間の印加電圧が高すぎるためにガス６３が絶縁破壊する現象のことである。以下では、検出対象となる特定波長のＸ線を受けたガス６３が電離することによって生成される出力信号Ｓ０を「Ｘ線由来の出力信号Ｓ０」という。放電異常が生じることによって生成される出力信号Ｓ０を「放電由来の出力信号Ｓ０」という。さらに、放射線検出器６からの出力信号Ｓ０には、電気的なノイズ由来の信号も含まれる。 When the electrodes 61 and 62 are energized, a charge 63 is generated between the electrodes 61 and 62 due to ionization of the gas 63 that has received X-rays having a specific wavelength to be detected, and between the electrodes 61 and 62. The case where a discharge abnormality occurs is included. Here, the discharge abnormality is a phenomenon in which the gas 63 breaks down because the applied voltage between the electrodes 61 and 62 is too high, even though the gas 63 does not receive X-rays having a specific wavelength to be detected. That is. Hereinafter, the output signal S0 generated by ionizing the gas 63 that has received X-rays having a specific wavelength to be detected is referred to as an “X-ray-derived output signal S0”. The output signal S0 generated when the discharge abnormality occurs is referred to as “discharge-derived output signal S0”. Further, the output signal S0 from the radiation detector 6 includes a signal derived from electrical noise.
　図３は、ガス６３中に検出対象となる特定波長のＸ線が入射した場合における放射線検出器６からの出力信号Ｓ０（Ｘ線由来の出力信号）の一例を示す。図４は、一対の電極６１，６２間に放電異常が発生した場合における放射線検出器６からの出力信号Ｓ０（放電由来の出力信号）の一例を示す。出力信号Ｓ０は、電圧値で示される強度の経時変化によって示されする。出力信号Ｓ０の波高値は、出力信号Ｓ０のピークにおける強度（電圧値）（つまり最大強度）である。図３および図４に示されるように、放電由来の出力信号Ｓ０の波高値Ｖ２（たとえば１．８Ｖ）は、Ｘ線由来の出力信号Ｓ０の波高値Ｖ１（たとえば１Ｖ）よりも大きい。 FIG. 3 shows an example of an output signal S0 (output signal derived from X-rays) from the radiation detector 6 when X-rays having a specific wavelength to be detected enter the gas 63. FIG. 4 shows an example of an output signal S0 (output signal derived from discharge) from the radiation detector 6 when a discharge abnormality occurs between the pair of electrodes 61 and 62. The output signal S0 is indicated by a change with time of the intensity indicated by the voltage value. The peak value of the output signal S0 is the intensity (voltage value) (that is, the maximum intensity) at the peak of the output signal S0. As shown in FIGS. 3 and 4, the peak value V2 (for example, 1.8 V) of the output signal S0 derived from the discharge is larger than the peak value V1 (for example, 1 V) of the output signal S0 derived from the X-ray.
　図５は、放射線検出器６からの出力信号Ｓ０の波高分布を示す図である。図５において、横軸は出力信号Ｓ０の波高値を示し、縦軸は、波高値ごとの出力信号Ｓ０のカウント数を示す。図５に示されるように、電気的なノイズ由来の出力信号Ｓ０の波高値は低い。放電由来の出力信号Ｓ０の波高値は高く、比較的狭い範囲に含まれる。Ｘ線由来の出力信号Ｓ０の波高値は、電気的なノイズ由来の出力信号Ｓ０の波高値と、放電由来の出力信号Ｓ０の波高値との間であり、比較的広い範囲に含まれる。 FIG. 5 is a diagram showing the wave height distribution of the output signal S0 from the radiation detector 6. As shown in FIG. In FIG. 5, the horizontal axis indicates the peak value of the output signal S0, and the vertical axis indicates the count number of the output signal S0 for each peak value. As shown in FIG. 5, the peak value of the output signal S0 derived from electrical noise is low. The peak value of the discharge-derived output signal S0 is high and included in a relatively narrow range. The peak value of the output signal S0 derived from X-rays is between the peak value of the output signal S0 derived from electrical noise and the peak value of the output signal S0 derived from discharge, and is included in a relatively wide range.
　本実施の形態１では、放射線検出器６からの出力信号Ｓ０に基づいて、Ｘ線量を判定するとともに、放射線検出器６における放電異常の発生の有無を判定する。そのため、Ｘ線由来の出力信号Ｓ０と、電気的なノイズ由来の出力信号Ｓ０と、放電由来の出力信号Ｓ０とを弁別する必要がある。そこで、ガス６３が検出対象となる特定波長のＸ線を受けたときに出力信号Ｓ０の波高値のとり得る範囲が、正常範囲として設定される。具体的には、ガス６３が検出対象となる特定波長のＸ線を受けたときに出力信号Ｓ０の波高値のとり得る下限値（たとえば０．５Ｖ）が、Ｘ線由来の出力信号Ｓ０と電気的なノイズ由来の出力信号Ｓ０との弁別のためのしきい値Ｔｈ_Ｌとして設定される。さらに、ガス６３が検出対象となる特定波長のＸ線を受けたときに出力信号Ｓ０の波高値のとり得る上限値（たとえば１．３Ｖ）が、Ｘ線由来の出力信号Ｓ０と放電由来の出力信号Ｓ０との弁別のためのしきい値Ｔｈ_Ｕとして設定される。つまり、しきい値Ｔｈ_Ｌ以上しきい値Ｔｈ_Ｕ以下の範囲が、正常範囲として設定される。なお、しきい値Ｔｈ_Ｌおよびしきい値Ｔｈ_Ｕは、検出対象となるＸ線の波長に応じて適宜設定される。 In the first embodiment, the X-ray dose is determined based on the output signal S0 from the radiation detector 6, and the presence or absence of occurrence of discharge abnormality in the radiation detector 6 is determined. Therefore, it is necessary to discriminate between the output signal S0 derived from X-rays, the output signal S0 derived from electrical noise, and the output signal S0 derived from discharge. Therefore, the range that the peak value of the output signal S0 can take when the gas 63 receives X-rays of a specific wavelength to be detected is set as a normal range. Specifically, the lower limit (for example, 0.5 V) that the peak value of the output signal S0 can take when the gas 63 receives X-rays having a specific wavelength to be detected is the output signal S0 derived from the X-rays and the electricity. Is set as a threshold value Th_L for discrimination from an output signal S0 derived from noise. Furthermore, when the gas 63 receives X-rays of a specific wavelength to be detected, the upper limit value (for example, 1.3 V) that the peak value of the output signal S0 can take is the X-ray-derived output signal S0 and the discharge-derived output. It is set as a threshold value Th_U for discrimination from the signal S0. That is, a range between the threshold Th_L and the threshold Th_U is set as the normal range. Note that the threshold Th_L and the threshold Th_U are appropriately set according to the wavelength of the X-ray to be detected.
　（信号処理装置の構成）
　図６は、信号処理装置７の内部構成を示すブロック図である。図６に示されるように、信号処理装置７は、弁別部７１と判定部７６とを備える。 (Configuration of signal processing device)
FIG. 6 is a block diagram showing an internal configuration of the signal processing device 7. As shown in FIG. 6, the signal processing device 7 includes a discrimination unit 71 and a determination unit 76.
　弁別部７１は、放射線検出器６から受ける出力信号Ｓ０の波高値が正常範囲内である場合に当該出力信号Ｓ０を正常信号として弁別し、放射線検出器６から受ける出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｕを超える場合に当該出力信号Ｓ０を異常信号として弁別する。 The discriminator 71 discriminates the output signal S0 as a normal signal when the peak value of the output signal S0 received from the radiation detector 6 is within the normal range, and determines the peak value of the output signal S0 received from the radiation detector 6. When the threshold value Th_U is exceeded, the output signal S0 is discriminated as an abnormal signal.
　弁別部７１は、第１比較回路７２と、第２比較回路７３と、第１パルス信号出力回路７４と、第２パルス信号出力回路７５とを含む。 The discrimination unit 71 includes a first comparison circuit 72, a second comparison circuit 73, a first pulse signal output circuit 74, and a second pulse signal output circuit 75.
　第１比較回路７２は、放射線検出器６からの出力信号Ｓ０の強度（電圧値）としきい値Ｔｈ_Ｌとを比較し、比較結果を示す信号Ｓ１を出力する。第１比較回路７２は、出力信号Ｓ０の強度がしきい値Ｔｈ_Ｌよりも小さい場合にハイレベルの信号Ｓ１を出力し、出力信号の強度がしきい値Ｔｈ_Ｌ以上である場合にローレベルの信号Ｓ１を出力する。 The first comparison circuit 72 compares the intensity (voltage value) of the output signal S0 from the radiation detector 6 with the threshold value Th_L, and outputs a signal S1 indicating the comparison result. The first comparison circuit 72 outputs a high level signal S1 when the intensity of the output signal S0 is smaller than the threshold value Th_L, and the low level signal S1 when the intensity of the output signal is equal to or greater than the threshold value Th_L. Is output.
　第２比較回路７３は、放射線検出器６からの出力信号Ｓ０の強度としきい値Ｔｈ_Ｕとを比較し、比較結果を示す信号Ｓ２を出力する。第２比較回路７３は、出力信号Ｓ０の強度がしきい値Ｔｈ_Ｕ以下である場合にハイレベルの信号Ｓ２を出力し、出力信号Ｓ０の強度がしきい値Ｔｈ_Ｕを超える場合にローレベルの信号Ｓ２を出力する。 The second comparison circuit 73 compares the intensity of the output signal S0 from the radiation detector 6 with the threshold value Th_U, and outputs a signal S2 indicating the comparison result. The second comparison circuit 73 outputs a high level signal S2 when the intensity of the output signal S0 is equal to or less than the threshold value Th_U, and outputs a low level signal S2 when the intensity of the output signal S0 exceeds the threshold value Th_U. Is output.
　第１パルス信号出力回路７４は、信号Ｓ１が連続してローレベルである期間中において信号Ｓ２が常にハイレベルであった場合に、当該期間が終了したタイミングで１パルスの信号Ｐ１を出力する。信号Ｓ１が連続してローレベルである期間中において信号Ｓ２が常にハイレベルである場合とは、放射線検出器６から受けた出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｌ以上しきい値Ｔｈ_Ｕ以下の正常範囲内であることを意味する。つまり、信号Ｐ１は、放射線検出器６から受けた出力信号Ｓ０が正常信号である場合に出力される。 The first pulse signal output circuit 74 outputs a one-pulse signal P1 at the end of the period when the signal S2 is always at a high level during the period in which the signal S1 is continuously at a low level. When the signal S2 is always at a high level during a period in which the signal S1 is continuously at a low level, the peak value of the output signal S0 received from the radiation detector 6 is not less than the threshold Th_L and not more than the threshold Th_U. Means within normal range. That is, the signal P1 is output when the output signal S0 received from the radiation detector 6 is a normal signal.
　第２パルス信号出力回路７５は、信号Ｓ２が連続してローレベルである期間が終了したタイミングで１パルスの信号Ｐ２を出力する。信号Ｓ２がローレベルである場合とは、放射線検出器６から受けた出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｕを超えることを意味する。つまり、信号Ｐ２は、放射線検出器６から受けた出力信号Ｓ０が異常信号である場合に出力される。 The second pulse signal output circuit 75 outputs the one-pulse signal P2 at the timing when the period in which the signal S2 is continuously at the low level is completed. The case where the signal S2 is at a low level means that the peak value of the output signal S0 received from the radiation detector 6 exceeds the threshold value Th_U. That is, the signal P2 is output when the output signal S0 received from the radiation detector 6 is an abnormal signal.
　弁別部７１は、たとえばＦＰＧＡ（Field-Programmable　Gate　Array）により構成される。第１比較回路７２および第２比較回路７３の各々は、コンパレータにより構成される。第１パルス信号出力回路７４および第２パルス信号出力回路７５の各々は、第１比較回路７２および第２比較回路７３から出力された信号を受ける論理回路により構成される。 The discriminating unit 71 is configured by, for example, an FPGA (Field-Programmable Gate Array). Each of the first comparison circuit 72 and the second comparison circuit 73 includes a comparator. Each of the first pulse signal output circuit 74 and the second pulse signal output circuit 75 includes a logic circuit that receives signals output from the first comparison circuit 72 and the second comparison circuit 73.
　図７は、Ｘ線由来の出力信号Ｓ０を受けたときに出力される信号Ｓ１，Ｓ２，Ｐ１，Ｐ２の一例を示す図である。図７に示されるように、Ｘ線由来の出力信号Ｓ０の波高値は、しきい値Ｔｈ_Ｌ以上しきい値Ｔｈ_Ｕ以下である。信号Ｓ１は、出力信号Ｓ０の強度がしきい値Ｔｈ_Ｌ以上となる時刻ｔ１から時刻ｔ２までの期間においてローレベルとなり、それ以外の期間でハイレベルとなる。一方、信号Ｓ２は、常にハイレベルとなる。 FIG. 7 is a diagram illustrating an example of signals S1, S2, P1, and P2 that are output when the X-ray-derived output signal S0 is received. As shown in FIG. 7, the peak value of the X-ray-derived output signal S0 is not less than the threshold value Th_L and not more than the threshold value Th_U. The signal S1 becomes low level during a period from time t1 to time t2 when the intensity of the output signal S0 becomes equal to or higher than the threshold Th_L, and becomes high level during other periods. On the other hand, the signal S2 is always at a high level.
　第１パルス信号出力回路７４は、信号Ｓ２がローレベルからハイレベルに変化する時刻ｔ２において、１パルスの信号Ｐ１を出力する。第２パルス信号出力回路７５は、信号Ｐ２を出力しない。 The first pulse signal output circuit 74 outputs one pulse signal P1 at time t2 when the signal S2 changes from low level to high level. The second pulse signal output circuit 75 does not output the signal P2.
　図８は、放電由来の出力信号Ｓ０を受けたときに出力される信号Ｓ１，Ｓ２，Ｐ１，Ｐ２の一例を示す図である。図８に示されるように、放電由来の出力信号Ｓ０の波高値は、しきい値Ｔｈ_Ｕを超える。信号Ｓ１は、出力信号Ｓ０の強度がしきい値Ｔｈ_Ｌ以上となる時刻ｔ３から時刻ｔ６までの期間でローレベルとなり、それ以外の期間でハイレベルとなる。信号Ｓ２は、出力信号Ｓ０の強度がしきい値Ｔｈ_Ｕを超える時刻ｔ４から時刻ｔ５までの期間でローレベルとなり、それ以外の期間でハイレベルとなる。時刻ｔ３は、時刻ｔ４よりも前であり、時刻ｔ６は、時刻ｔ５よりも後である。 FIG. 8 is a diagram illustrating an example of signals S1, S2, P1, and P2 that are output when the output signal S0 derived from discharge is received. As shown in FIG. 8, the peak value of the discharge-derived output signal S0 exceeds the threshold value Th_U. The signal S1 becomes low level during a period from time t3 to time t6 when the intensity of the output signal S0 becomes equal to or higher than the threshold Th_L, and becomes high level during other periods. The signal S2 becomes low level during a period from time t4 to time t5 when the intensity of the output signal S0 exceeds the threshold Th_U, and becomes high level during other periods. The time t3 is before the time t4, and the time t6 is after the time t5.
　信号Ｓ１がローレベルである時刻ｔ３から時刻ｔ６までの期間中の一部の期間（時刻ｔ４から時刻ｔ５までの期間）において信号Ｓ２がローレベルとなる。そのため、第１パルス信号出力回路７４は、信号Ｓ２がローレベルからハイレベルに変化する時刻ｔ６において信号Ｐ１を出力しない。第２パルス信号出力回路７５は、信号Ｓ２がローレベルからハイレベルに変化する時刻ｔ５において、１パルスの信号Ｐ２を出力する。 The signal S2 becomes low level during a part of the period from time t3 to time t6 when the signal S1 is low level (period from time t4 to time t5). Therefore, the first pulse signal output circuit 74 does not output the signal P1 at time t6 when the signal S2 changes from the low level to the high level. The second pulse signal output circuit 75 outputs a one-pulse signal P2 at time t5 when the signal S2 changes from the low level to the high level.
　図６に戻って、判定部７６は、信号Ｐ１に基づいて、ガス６３に入射したＸ線量を判定するとともに、信号Ｐ２に基づいて、一対の電極６１，６２間の放電異常の発生の有無を判定する。 Returning to FIG. 6, the determination unit 76 determines the X-ray dose incident on the gas 63 based on the signal P <b> 1, and determines whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62 based on the signal P <b> 2. judge.
　信号Ｐ１は、波高値がしきい値Ｔｈ_Ｌ以上しきい値Ｔｈ_Ｕ以下の正常範囲内である正常信号を放射線検出器６から受けたことを意味する。判定部７６は、信号Ｐ１に基づいて、ガス６３に入射したＸ線量を判定する。判定部７６は、第１パルス信号出力回路７４から出力された信号Ｐ１の個数をカウントすることにより、ガス６３に入射したＸ線量を判定する。 The signal P1 means that a normal signal whose peak value is within the normal range of the threshold value Th_L or more and the threshold value Th_U or less is received from the radiation detector 6. The determination unit 76 determines the X-ray dose incident on the gas 63 based on the signal P1. The determination unit 76 determines the X-ray dose incident on the gas 63 by counting the number of signals P1 output from the first pulse signal output circuit 74.
　信号Ｐ２は、波高値がしきい値Ｔｈ_Ｕを超える異常信号を放射線検出器６から受けたことを意味する。判定部７６は、信号Ｐ２に基づいて、一対の電極６１，６２間の放電異常の発生の有無を判定する。たとえば、判定部７６は、信号Ｐ２を受けたときに、一対の電極６１，６２間に放電異常が発生していると判定してもよい。もしくは、判定部７６は、単位時間当たりに第２パルス信号出力回路７５から出力された信号Ｐ２の個数をカウントし、当該カウント数が予め設定された所定の値Ｔｈ１（たとえば、２～３ｃｐｓ）を超える場合に、一対の電極６１，６２間に放電異常が発生していると判定してもよい。 The signal P2 means that an abnormal signal whose peak value exceeds the threshold Th_U has been received from the radiation detector 6. The determination unit 76 determines whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62 based on the signal P2. For example, the determination unit 76 may determine that a discharge abnormality has occurred between the pair of electrodes 61 and 62 when receiving the signal P2. Alternatively, the determination unit 76 counts the number of signals P2 output from the second pulse signal output circuit 75 per unit time, and sets a predetermined value Th1 (for example, 2 to 3 cps) in which the count number is set in advance. When exceeding, you may determine with the discharge abnormality having generate | occur | produced between a pair of electrodes 61 and 62. FIG.
　判定部７６は、判定結果を表示部８に表示（出力）する。たとえば、一対の電極６１，６２間に放電異常が発生している判定した場合、判定部７６は、放電異常が発生している旨を示すとともに、一対の電極６１，６２間への印加電圧の低下を促す画面を表示部８に表示する。 The determination unit 76 displays (outputs) the determination result on the display unit 8. For example, when it is determined that a discharge abnormality has occurred between the pair of electrodes 61, 62, the determination unit 76 indicates that a discharge abnormality has occurred and determines the voltage applied between the pair of electrodes 61, 62. A screen that prompts a decrease is displayed on the display unit 8.
　判定部７６は、たとえばＣＰＵ（Central　Processing　Unit）と、ＲＯＭ（Read　Only　Memory）と、ＲＡＭ（Random　Access　Memory）とによって構成される。なお、これらの部位は、内部バスを介して互いに接続される。ＣＰＵは、ＲＯＭに格納されているプログラムをＲＡＭなどに展開して実行する。ＲＯＭに格納されるプログラムは、判定部７６の処理方法が記されたプログラムである。 The determination unit 76 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). These parts are connected to each other via an internal bus. The CPU executes the program stored in the ROM by expanding it in the RAM or the like. The program stored in the ROM is a program in which the processing method of the determination unit 76 is described.
　（信号処理装置の処理の流れ）
　次に、図９を参照して、信号処理装置７の処理の流れについて説明する。図９は、信号処理装置７の処理の流れを示すフローチャートである。 (Processing flow of signal processor)
Next, a processing flow of the signal processing device 7 will be described with reference to FIG. FIG. 9 is a flowchart showing a processing flow of the signal processing device 7.
　まず、信号処理装置７は、放射線検出器６からの出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｌ以上であるか否か判定する（ステップＳ１１）。出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｌ以上ではない場合（Ｓ１１でＮＯ）、処理はステップＳ１１に戻される。 First, the signal processing device 7 determines whether or not the peak value of the output signal S0 from the radiation detector 6 is greater than or equal to the threshold value Th_L (step S11). If the peak value of output signal S0 is not equal to or greater than threshold value Th_L (NO in S11), the process returns to step S11.
　出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｌ以上である場合（Ｓ１１でＹＥＳ）、信号処理装置７は、出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｕ以下であるか否かを判定する（ステップＳ１２）。 When the peak value of the output signal S0 is equal to or greater than the threshold value Th_L (YES in S11), the signal processing device 7 determines whether or not the peak value of the output signal S0 is equal to or less than the threshold value Th_U (step S12). ).
　出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｕ以下である場合（Ｓ１２でＹＥＳ）、信号処理装置７は、出力信号Ｓ０が正常信号である旨を示す信号Ｐ１を生成する（ステップＳ１３）。その後、信号処理装置７は、信号Ｐ１のカウント数を１だけ増やし、信号Ｐ１のカウント数に基づいて、放射線検出器６によって検出されたＸ線量を決定し、決定したＸ線量を表示部８に表示する（ステップＳ１４）。 When the peak value of the output signal S0 is equal to or less than the threshold value Th_U (YES in S12), the signal processing device 7 generates a signal P1 indicating that the output signal S0 is a normal signal (step S13). Thereafter, the signal processing device 7 increases the count number of the signal P1 by 1, determines the X-ray dose detected by the radiation detector 6 based on the count number of the signal P1, and displays the determined X-ray dose on the display unit 8. Displayed (step S14).
　出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｕを超える場合（Ｓ１２でＮＯ）、信号処理装置７は、出力信号Ｓ０が異常信号である旨を示す信号Ｐ２を生成する（ステップＳ１５）。すなわち、信号処理装置７は、放射線検出器６から受ける出力信号Ｓ０の波高値がしきい値Ｔｈ_Ｕを超える場合に、当該出力信号Ｓ０を異常信号として弁別する。 When the peak value of the output signal S0 exceeds the threshold value Th_U (NO in S12), the signal processing device 7 generates a signal P2 indicating that the output signal S0 is an abnormal signal (step S15). That is, when the peak value of the output signal S0 received from the radiation detector 6 exceeds the threshold value Th_U, the signal processing device 7 discriminates the output signal S0 as an abnormal signal.
　次に、信号処理装置７は、異常信号に基づいて、一対の電極６１，６２間の放電異常の発生の有無を判定する。具体的には、信号処理装置７は、信号Ｐ２のカウント数を１だけ増やし、単位時間当たりの信号Ｐ２のカウント数が所定の値Ｔｈ１を超えるか否かを判定する（ステップＳ１６）。単位時間当たりの信号Ｐ２のカウント数が所定の値Ｔｈ１を超える場合（Ｓ１６でＹＥＳ）、信号処理装置７は、放射線検出器６が備える一対の電極６１，６２間に放電異常が発生していると判定し、その判定結果を表示部８に表示する（ステップＳ１７）。 Next, the signal processing device 7 determines whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62 based on the abnormality signal. Specifically, the signal processing device 7 increases the count number of the signal P2 by 1, and determines whether or not the count number of the signal P2 per unit time exceeds a predetermined value Th1 (step S16). When the count number of the signal P2 per unit time exceeds the predetermined value Th1 (YES in S16), the signal processing device 7 has a discharge abnormality between the pair of electrodes 61 and 62 provided in the radiation detector 6. And the determination result is displayed on the display unit 8 (step S17).
　ステップＳ１４，Ｓ１７の後、処理は終了する、単位時間当たりの信号Ｐ２のカウント数が所定の値Ｔｈ１を超えない場合（Ｓ１６でＮＯ）も、処理は終了する。 After steps S14 and S17, the process ends. When the count number of the signal P2 per unit time does not exceed the predetermined value Th1 (NO in S16), the process also ends.
　以上のように、信号処理装置７は、放射線検出器６から受ける出力信号Ｓ０の波高値がしきい値（第１のしきい値）Ｔｈ_Ｕを超える場合に、当該出力信号Ｓ０を異常信号として弁別する弁別部７１を備える。さらに、信号処理装置７は、異常信号に基づいて、一対の電極６１，６２間の放電異常の発生の有無を判定する判定部７６を備える。ここで、しきい値Ｔｈ_Ｕは、ガス６３が検出対象となるＸ線を受けたときの出力信号Ｓ０の波高値が取り得る上限値である。 As described above, when the peak value of the output signal S0 received from the radiation detector 6 exceeds the threshold value (first threshold value) Th_U, the signal processing device 7 discriminates the output signal S0 as an abnormal signal. The discriminating part 71 is provided. Furthermore, the signal processing device 7 includes a determination unit 76 that determines whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62 based on the abnormality signal. Here, the threshold value Th_U is an upper limit value that can be taken by the peak value of the output signal S0 when the gas 63 receives X-rays to be detected.
　上記の実施の形態１によれば、放射線検出器６に入射されたＸ線量を判定するために利用される出力信号Ｓ０から異常信号が弁別され、当該異常信号に基づいて、一対の電極６１，６２間の放電異常の発生の有無が判定される。つまり、一対の電極６１，６２間の放電異常の発生の有無を判定するための機器（たとえば電流計など）を別途設ける必要がない。そのため、放射線検出器６の放電異常の発生を容易に判定することができる。 According to the first embodiment, an abnormal signal is discriminated from the output signal S0 used for determining the X-ray dose incident on the radiation detector 6, and the pair of electrodes 61, It is determined whether or not a discharge abnormality between 62 occurs. That is, it is not necessary to separately provide a device (such as an ammeter) for determining whether or not a discharge abnormality has occurred between the pair of electrodes 61 and 62. Therefore, it is possible to easily determine the occurrence of discharge abnormality of the radiation detector 6.
　たとえば、判定部７６は、単位時間当たりの異常信号のカウント数（つまり、信号Ｐ２のカウント数）が所定の値Ｔｈ１を超える場合に、放電異常が発生していると判定する。そのため、所定の値Ｔｈ１を適宜設定することにより、何等かの原因により突発的にしきい値Ｔｈ_Ｕを超える出力信号Ｓ０を受けただけでは、判定部７６は、放電異常が発生したとは判定しない。その結果、判定部７６の誤判定の頻度を低下させることができる。 For example, the determination unit 76 determines that a discharge abnormality has occurred when the count number of abnormal signals per unit time (that is, the count number of the signal P2) exceeds a predetermined value Th1. Therefore, by appropriately setting the predetermined value Th1, the determination unit 76 does not determine that a discharge abnormality has occurred simply by receiving the output signal S0 that suddenly exceeds the threshold value Th_U for some reason. As a result, the frequency of erroneous determination by the determination unit 76 can be reduced.
　判定部７６は、放電異常の発生の判定結果を表示部８に出力する。これにより、ユーザは、放射線検出器６において放電異常の発生の有無を把握することができる。ユーザは、一対の電極６１，６２間の印加電圧を低下させるなどの対応を適宜実施することで、放射線検出器６の劣化を抑制することができる。 The determination unit 76 outputs a determination result of occurrence of discharge abnormality to the display unit 8. Thereby, the user can grasp | ascertain the presence or absence of generation | occurrence | production of discharge abnormality in the radiation detector 6. FIG. The user can suppress deterioration of the radiation detector 6 by appropriately implementing measures such as reducing the applied voltage between the pair of electrodes 61 and 62.
　なお、一対の電極６１，６２間の印加電圧が高すぎる場合には、放電異常が発生するとともに、検出対象となる特定波長のＸ線をガス６３が受けたときにも、想定以上の電子なだれによって、電極６１，６２間に大きな電流が流れる可能性がある。このような想定以上の電子なだれによって電極６１，６２間に大きな電流が流れた場合にも、判定部７６は、放電異常が発生していると判定し、電極６１，６２間の印加電圧の低下を促す画面を表示部８に表示させることができる。これにより、ユーザは、電極６１，６２間の印加電圧を低下させるなどの対応を適宜実施することができる。 If the applied voltage between the pair of electrodes 61 and 62 is too high, an abnormal discharge occurs, and even when the gas 63 receives X-rays having a specific wavelength to be detected, the avalanche is higher than expected. As a result, a large current may flow between the electrodes 61 and 62. Even when a large current flows between the electrodes 61 and 62 due to the electron avalanche exceeding the assumption, the determination unit 76 determines that a discharge abnormality has occurred, and the applied voltage between the electrodes 61 and 62 decreases. Can be displayed on the display unit 8. Accordingly, the user can appropriately take measures such as reducing the applied voltage between the electrodes 61 and 62.
　＜実施の形態２＞
　上記の実施の形態１では、判定部７６は、単位時間当たりの信号Ｐ２のカウント数が所定の値Ｔｈ１を超える場合に、放電異常が発生していると判定する。これに対し、本実施の形態２では、判定部７６は、異常信号の波高値がしきい値（第２のしきい値）Ｔｈ_Ｕ２を超える場合、放電異常が発生していると判定する。しきい値Ｔｈ_Ｕ２は、正常範囲の上限値であるしきい値Ｔｈ_Ｕよりも大きい。 <Embodiment 2>
In the first embodiment, the determination unit 76 determines that a discharge abnormality has occurred when the count number of the signal P2 per unit time exceeds a predetermined value Th1. On the other hand, in this Embodiment 2, the determination part 76 determines with the discharge abnormality having generate | occur | produced, when the peak value of an abnormal signal exceeds threshold value (2nd threshold value) Th_U2. The threshold value Th_U2 is larger than the threshold value Th_U that is the upper limit value of the normal range.
　放射線検出器６には、試料２が放出した蛍光Ｘ線の他に、宇宙線が入射する可能性がある。宇宙線のエネルギーはＸ線のエネルギーよりも高いため、宇宙線が放射線検出器６に入射すると、波高値の大きい出力信号Ｓ０が出力される。そのため、上記の実施の形態１では、当該波高値の大きい出力信号Ｓ０が放電由来の出力信号Ｓ０として誤判定される可能性がある。 In addition to the fluorescent X-rays emitted from the sample 2, cosmic rays may enter the radiation detector 6. Since the energy of cosmic rays is higher than the energy of X-rays, when the cosmic rays enter the radiation detector 6, an output signal S0 having a large peak value is output. For this reason, in the first embodiment, the output signal S0 having a large peak value may be erroneously determined as the output signal S0 derived from discharge.
　図１０Ａは、放電由来の出力信号Ｓ０を示す図である。図１０Ｂは、宇宙線由来の出力信号Ｓ０を示す図である。図１０Ａおよび図１０Ｂに示されるように、宇宙線由来の出力信号Ｓ０の波高値は、しきい値Ｔｈ_Ｕを超えるものの、一般的に放電由来の出力信号Ｓ０の波高値よりも低い。 FIG. 10A is a diagram showing an output signal S0 derived from discharge. FIG. 10B is a diagram showing an output signal S0 derived from cosmic rays. As shown in FIGS. 10A and 10B, the peak value of the cosmic ray-derived output signal S0 exceeds the threshold Th_U, but is generally lower than the peak value of the discharge-derived output signal S0.
　そこで、本実施の形態２の判定部７６は、ガス６３が検出対象の特定波長のＸ線を受けたときに出力信号Ｓ０の波高値のとり得る上限値であるしきい値Ｔｈ_Ｕよりも大きいしきい値Ｔｈ_Ｕ２を用いて、放電異常が発生していると判定する。具体的には、判定部７６は、弁別部７１によって弁別された異常信号の波高値がしきい値Ｔｈ_Ｕ２を超える場合に放電異常が発生していると判定する。これにより、しきい値Ｔｈ_Ｕ２よりも低い波高値の宇宙線由来の出力信号Ｓ０の影響を抑制でき、判定部７６は、放射線検出器６における放電異常の発生の有無を精度良く判定することができる。 Therefore, the determination unit 76 of the second embodiment is larger than a threshold value Th_U that is an upper limit value that the peak value of the output signal S0 can take when the gas 63 receives X-rays of a specific wavelength to be detected. It is determined that a discharge abnormality has occurred using the threshold value Th_U2. Specifically, the determination unit 76 determines that a discharge abnormality has occurred when the peak value of the abnormal signal discriminated by the discriminating unit 71 exceeds the threshold value Th_U2. Thereby, the influence of the output signal S0 derived from the cosmic ray having a peak value lower than the threshold value Th_U2 can be suppressed, and the determination unit 76 can accurately determine whether or not the discharge abnormality has occurred in the radiation detector 6. .
　＜実施の形態３＞
　図１０Ａおよび図１０Ｂに示されるように、宇宙線由来の出力信号Ｓ０の強度（電圧値）がしきい値Ｔｈ_Ｕを超えている時間Ｔ２は、一般的に、Ｘ線由来の出力信号Ｓ０の強度がしきい値Ｔｈ_Ｕを超えている時間Ｔ１よりも短い。そこで、実施の形態３の判定部７６は、出力信号Ｓ０の強度がしきい値Ｔｈ_Ｕを超えている時間が予め設定された所定の時間Ｔｈ２（たとえば８０ｎｓ）を超える場合に、一対の電極６１，６２間に放電異常が発生していると判定する。これにより、時間幅の短い宇宙線由来の出力信号Ｓ０の影響が抑制され、判定部７６は、放射線検出器６における放電異常の発生の有無を精度良く判定することができる。 <Embodiment 3>
As shown in FIGS. 10A and 10B, the time T2 when the intensity (voltage value) of the output signal S0 derived from cosmic rays exceeds the threshold Th_U is generally the intensity of the output signal S0 derived from X-rays. Is shorter than the time T1 when the threshold value Th_U is exceeded. Therefore, the determination unit 76 according to the third embodiment, when the time when the intensity of the output signal S0 exceeds the threshold value Th_U exceeds a predetermined time Th2 (for example, 80 ns) set in advance, the pair of electrodes 61, It is determined that a discharge abnormality has occurred between 62. Thereby, the influence of the output signal S0 derived from the cosmic ray having a short time width is suppressed, and the determination unit 76 can accurately determine whether or not the discharge abnormality has occurred in the radiation detector 6.
　＜変形例＞
　上記の各実施の形態では、波長分散型蛍光Ｘ線分析装置１００に備えられる信号処理装置７について説明した。しかしながら、信号処理装置７は、Ｘ線以外の放射線を分析する分析装置に適用されてもよい。この場合、放射線検出器６は、Ｘ線以外の放射線を検出する。信号処理装置７に設定されるしきい値Ｔｈ_Ｌ，Ｔｈ_Ｕ，Ｔｈ_Ｕ２、所定の値Ｔｈ１および所定の時間Ｔｈ２は、検出対象となる放射線に応じて適宜設定される。 <Modification>
In each of the above embodiments, the signal processing device 7 provided in the wavelength dispersive X-ray fluorescence analyzer 100 has been described. However, the signal processing device 7 may be applied to an analysis device that analyzes radiation other than X-rays. In this case, the radiation detector 6 detects radiation other than X-rays. The threshold values Th_L, Th_U, Th_U2, the predetermined value Th1, and the predetermined time Th2 set in the signal processing device 7 are appropriately set according to the radiation to be detected.
　判定部７６は、放電異常の発生の判定結果を、表示灯に出力してもよい。たとえば、判定部７６は、放電異常が発生していない場合には表示灯を緑色に点灯させ、放電異常が発生している場合には表示灯を赤色に点灯させる。あるいは、判定部７６は、判定結果を示す音をスピーカーまたはブザーから出力してもよい。 The determination unit 76 may output a determination result of occurrence of discharge abnormality to an indicator lamp. For example, the determination unit 76 lights the indicator lamp in green when no discharge abnormality has occurred, and lights the indicator lamp in red when a discharge abnormality has occurred. Or the determination part 76 may output the sound which shows a determination result from a speaker or a buzzer.
　上記の各実施の形態では、信号処理装置７は、比例計数管を用いた放射線検出器６からの出力信号Ｓ０を処理するものとした。しかしながら、信号処理装置７は、半導体検出器またはシンチレーション検出器からの出力信号に対しても、上記の同様の処理を行なってもよい。 In each of the above embodiments, the signal processing device 7 processes the output signal S0 from the radiation detector 6 using a proportional counter. However, the signal processing device 7 may perform the same processing as described above on the output signal from the semiconductor detector or the scintillation detector.
　上述した動作（図９に示すステップＳ１１～ステップＳ１７）を信号処理装置７に実行させるためのプログラムが提供されてもよい。このようなプログラムは、コンピュータに付属するフレキシブルディスク、ＣＤ－ＲＯＭ（Compact　Disk-Read　Only　Memory）、ＲＯＭ、ＲＡＭおよびメモリカードなどのコンピュータ読み取り可能な記録媒体にて記録させて、プログラム製品として提供することもできる。あるいは、コンピュータに内蔵するハードディスクなどの記録媒体にて記録させて、プログラムを提供することもできる。また、ネットワークを介したダウンロードによって、プログラムを提供することもできる。 A program for causing the signal processing device 7 to execute the above-described operation (steps S11 to S17 shown in FIG. 9) may be provided. Such a program is recorded on a computer-readable recording medium such as a flexible disk attached to the computer, a CD-ROM (Compact Disk-Read Only Memory), a ROM, a RAM, and a memory card, and provided as a program product. You can also. Alternatively, the program can be provided by being recorded on a recording medium such as a hard disk built in the computer. A program can also be provided by downloading via a network.
　提供されるプログラム製品は、ハードディスクなどのプログラム格納部にインストールされて実行される。なお、プログラム製品は、プログラム自体と、プログラムが記録された記録媒体とを含む。 The provided program product is installed in a program storage unit such as a hard disk and executed. The program product includes the program itself and a recording medium on which the program is recorded.
　今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は、上記した説明ではなく、請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
　１　Ｘ線管、２　試料、３，５　ソーラースリット、４　分光結晶、６　放射線検出器、７　信号処理装置、８　表示部、６１，６２　電極、６３　ガス、６４　絶縁体、６５　電圧生成回路、６６　窓、６７　増幅回路、７１　弁別部、７２　第１比較回路、７３　第２比較回路、７４　第１パルス信号出力回路、７５　第２パルス信号出力回路、７６　判定部、１００　波長分散型蛍光Ｘ線分析装置。 1 X-ray tube, 2 sample, 3, 5 solar slit, 4 spectral crystal, 6 radiation detector, 7 signal processing device, 8 display unit, 61, 62 electrode, 63 gas, 64 insulator, 65 voltage generation circuit, 66 Window, 67 amplifier circuit, 71 discriminator, 72 first comparator circuit, 73 second comparator circuit, 74 first pulse signal output circuit, 75 second pulse signal output circuit, 76 determination unit, 100 wavelength dispersive X-ray fluorescence analysis apparatus.

Claims (7)

  1. 　放射線検出器からの出力信号を処理する信号処理装置であって、
    　前記放射線検出器は、所定電圧が印加された一対の電極と、前記一対の電極間に存在し、放射線を受けたときに電離可能なガスと、を備え、
    　前記出力信号は、前記一対の電極間の通電量に応じた波高値を有し、
    　前記信号処理装置は、
    　前記放射線検出器から受ける出力信号の波高値が第１のしきい値を超える場合に、当該出力信号を異常信号として弁別するための弁別部と、
    　前記異常信号に基づいて、前記一対の電極間の放電異常の発生の有無を判定するための判定部と、を備え、
    　前記第１のしきい値は、前記ガスが検出対象の放射線を受けたときの前記出力信号の波高値が取り得る上限値である信号処理装置。     A signal processing device for processing an output signal from a radiation detector,
    The radiation detector includes a pair of electrodes to which a predetermined voltage is applied, and a gas that exists between the pair of electrodes and that can be ionized when receiving radiation,
    The output signal has a peak value corresponding to an energization amount between the pair of electrodes,
    The signal processing device includes:
    A discriminator for discriminating the output signal as an abnormal signal when the peak value of the output signal received from the radiation detector exceeds a first threshold;
    A determination unit for determining presence or absence of occurrence of discharge abnormality between the pair of electrodes based on the abnormality signal;
    The signal processing apparatus, wherein the first threshold value is an upper limit value that can be taken by a peak value of the output signal when the gas receives radiation to be detected.
  2. 　前記判定部は、単位時間当たりの前記異常信号のカウント数が所定の値を超える場合に、前記放電異常が発生していると判定する、請求項１に記載の信号処理装置。 The signal processing device according to claim 1, wherein the determination unit determines that the discharge abnormality has occurred when a count number of the abnormal signal per unit time exceeds a predetermined value.
  3. 　前記判定部は、前記異常信号の波高値が第２のしきい値を超える場合に、前記放電異常が発生していると判定し、
    　前記第２のしきい値は、前記第１のしきい値よりも大きい、請求項１に記載の信号処理装置。     The determination unit determines that the discharge abnormality has occurred when a peak value of the abnormal signal exceeds a second threshold value,
    The signal processing apparatus according to claim 1, wherein the second threshold value is larger than the first threshold value.
  4. 　前記判定部は、前記異常信号の強度が前記第１のしきい値を超えている時間が所定の時間を超える場合に、前記放電異常が発生していると判定する、請求項１に記載の信号処理装置。 The said determination part determines that the said discharge abnormality has generate | occur | produced, when the intensity | strength of the said abnormal signal exceeds the said 1st threshold value exceeds predetermined time. Signal processing device.
  5. 　前記判定部は、前記放電異常の発生の有無の判定結果に基づいて、前記放電異常の発生の有無を報知する、請求項１～４のいずれか１項に記載の信号処理装置。 5. The signal processing apparatus according to claim 1, wherein the determination unit notifies the presence / absence of occurrence of the discharge abnormality based on the determination result of occurrence / non-occurrence of the discharge abnormality.
  6. 　請求項１～５のいずれか１項に記載の信号処理装置と、
    　前記放射線検出器と、を備える分析装置。     A signal processing device according to any one of claims 1 to 5;
    An analyzer comprising the radiation detector.
  7. 　放射線検出器からの出力信号を処理する信号処理方法であって、
    　前記放射線検出器は、所定電圧が印加された一対の電極と、前記一対の電極間に存在し、放射線を受けたときに電離可能なガスとを備え、
    　前記出力信号は、前記一対の電極間の通電量に応じた波高値を有し、
    　前記信号処理方法は、
    　前記放射線検出器から受ける出力信号の波高値がしきい値を超える場合に、当該出力信号を異常信号として弁別するステップと、
    　前記異常信号に基づいて、前記一対の電極間の放電異常の発生の有無を判定するステップと、を備え、
    　前記しきい値は、前記ガスが検出対象の放射線を受けたときの前記出力信号の波高値が取り得る上限値である信号処理方法。     A signal processing method for processing an output signal from a radiation detector,
    The radiation detector includes a pair of electrodes to which a predetermined voltage is applied, and a gas that is present between the pair of electrodes and can be ionized when receiving radiation,
    The output signal has a peak value corresponding to an energization amount between the pair of electrodes,
    The signal processing method includes:
    Discriminating the output signal as an abnormal signal when the peak value of the output signal received from the radiation detector exceeds a threshold value;
    Determining whether or not a discharge abnormality has occurred between the pair of electrodes based on the abnormality signal, and
    The signal processing method, wherein the threshold value is an upper limit value that can be taken by a peak value of the output signal when the gas receives radiation to be detected.
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JPS54107791A (en) * 1978-02-13 1979-08-23 Matsushita Electric Ind Co Ltd Radiation exposure detector
JPH0527040A (en) * 1991-07-17 1993-02-05 Toshiba Corp Radiation ray measuring device
JPH07248383A (en) * 1994-03-14 1995-09-26 Toshiba Corp Radiation monitor device and natural radiation calculating method
JP2012007928A (en) * 2010-06-23 2012-01-12 Rigaku Corp X-ray analysis apparatus and emission analyzer
JP2013113648A (en) * 2011-11-28 2013-06-10 Mitsubishi Electric Corp Radiation measuring device

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Publication number Priority date Publication date Assignee Title
JPS54107791A (en) * 1978-02-13 1979-08-23 Matsushita Electric Ind Co Ltd Radiation exposure detector
JPH0527040A (en) * 1991-07-17 1993-02-05 Toshiba Corp Radiation ray measuring device
JPH07248383A (en) * 1994-03-14 1995-09-26 Toshiba Corp Radiation monitor device and natural radiation calculating method
JP2012007928A (en) * 2010-06-23 2012-01-12 Rigaku Corp X-ray analysis apparatus and emission analyzer
JP2013113648A (en) * 2011-11-28 2013-06-10 Mitsubishi Electric Corp Radiation measuring device

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