Radiation analysis method, radiation analysis device, and computer program

Abstract

The present invention provides a radiation analysis method, a radiation analysis device, and a computer program which are for specifying the amount of an element contained in a sample on the basis of the detected intensity of radiation.　Provided is a radiation analysis method wherein a radiation detector is used to detect radiation produced from a sample, response waves that are included in an output signal outputted from the radiation detector in response to radiation detection are counted to specify a detected intensity of radiation, sum-peak correction is performed to correct, via statistical processing, the detected intensity of radiation which is affected by the overlapping of a plurality of response waves, and the amount of a specific element contained in the sample is calculated on the basis of the detected intensity of radiation that has been corrected by the sum-peak correction.

Description

Radiation analysis method, radiation analysis apparatus, and computer program

[0001] The present invention relates to a radiation analysis method, a radiation analysis apparatus, and a computer program.

[0002] In radiation analysis, radiation generated from a sample is detected, and the amount of an element contained in the sample is estimated based on the intensity of the radiation. For example, the amount of an element is estimated based on the intensity of fluorescent X-rays generated from a sample. Ideally, the detection intensity, which is the intensity of the detected radiation, increases in proportion to the amount of the element. However, in reality, as the amount of the element increases, the rate of increase in the detection intensity of the radiation with respect to the increase in the amount of the element decreases. In a radiation detector, a dead time occurs during which radiation cannot be detected immediately after detection. As the amount of the element increases and the intensity of the radiation incident on the radiation detector increases, the influence of the dead time becomes greater, and the rate of increase in the detection intensity of the radiation with respect to the increase in the amount of the element decreases. Therefore, it is necessary to correct the detection intensity of the radiation according to the dead time. Patent Document 1 discloses an example of a technique for correcting the detection intensity of radiation.

[0003] Japanese Patent No. 7178725

[0004] Even after correcting the detection intensity of the radiation according to the dead time, the rate of increase in the detection intensity of the radiation with respect to the increase in the amount of the element may decrease. When radiation is detected multiple times at very short intervals, pile-up may occur where the multiple detections cannot be separated and are treated as one detection. As the intensity of the radiation incident on the radiation detector increases, the frequency of pile-up increases, and the rate of increase in the detection intensity of the radiation with respect to the increase in the amount of the element decreases. For this reason, the detection intensity of the radiation is not proportional to the amount of the element contained in the sample, and it is difficult to specify the amount of the element based on the detection intensity of the radiation.

[0005] An object of the present invention is to provide a radiation analysis method, a radiation analysis apparatus, and a computer program for specifying the amount of an element contained in a sample based on the detection intensity of the radiation.

[0006] A radiation analysis method according to one embodiment of the present invention is characterized by detecting radiation emitted from a sample using a radiation detector, determining the detected radiation intensity by counting the response waves included in the output signal output from the radiation detector in response to the detection of radiation, performing a sum peak correction to correct the detected radiation intensity affected by the overlap of multiple response waves by statistical processing, and calculating the amount of a specific element contained in the sample based on the detected radiation intensity corrected by the sum peak correction.

[0007] In one embodiment of the present invention, radiation from a sample is detected, a sum-peak correction is applied to the detected radiation intensity, and the amount of a specific element contained in the sample is calculated based on the corrected detected radiation intensity. The detected radiation intensity is determined by counting the response waves included in the output signal from the radiation detector in response to the detection of radiation. The sum-peak correction corrects the detected radiation intensity to correct for the effects of the overlap of multiple response waves that cause sum peaks. By performing the sum-peak correction, the detected radiation intensity is corrected to be approximately proportional to the amount of the element. Based on the corrected detected radiation intensity, it becomes possible to accurately determine the amount of a specific element contained in the sample.

[0008] A radiation analysis method according to one embodiment of the present invention is characterized by generating a first shaped signal by shaping the output signal with a first trapezoidal filter, determining that radiation has been detected by using the first shaped signal to determine that a response wave is included in the output signal, and in the sum peak correction, correcting the detected radiation intensity by calculating the corrected radiation count rate using the time constant of the first trapezoidal filter.

[0009] In one embodiment of the present invention, a first shaped signal is generated by shaping the output signal with a first trapezoidal filter, and it is determined using the first shaped signal whether the response wave is included in the output signal. In the sum peak correction, the time constant of the first trapezoidal filter is used to calculate the detected intensity of the corrected radiation. This makes it possible to correct the detected intensity of radiation affected by the overlap of multiple inseparable response waves to a more appropriate value.

[0010] A radiation analysis method according to one embodiment of the present invention is characterized in that, in the thumb peak correction, the detected intensity of radiation is corrected by calculating ICR' = ICR / exp(-ICR・T1), where ICR is the count rate of radiation before correction by the thumb peak correction, ICR' is the count rate of radiation after correction by the thumb peak correction, and T1 is the time constant of the first trapezoidal filter.

[0011] In one embodiment of the present invention, the radiation count rate after correction by sum peak correction is calculated using a formula that utilizes the time constant of the first trapezoidal filter. By using a formula that includes the time constant of the first trapezoidal filter, sum peak correction can be easily performed.

[0012] A radiation analysis method according to one embodiment of the present invention is characterized by measuring the wave height of the response wave included in the output signal, specifying the detected radiation intensity for each wave height of the response wave, and in the sum peak correction, correcting the detected radiation intensity related to the first wave height based on the detected radiation intensity related to a second wave height obtained due to the overlap of a plurality of response waves including a response wave having a first wave height.

[0013] In one embodiment of the present invention, the wave height of the response wave included in the output signal is measured, and the detected radiation intensity is determined for each wave height. When multiple response waves, including a response wave having a first wave height, overlap, a second wave height, which is the wave height of the response wave generated by the overlapping of the multiple response waves, is measured. In the sum-peak correction, the detected radiation intensity related to the first wave height is corrected based on the detected radiation intensity related to the second wave height. This makes it possible to correct the detected radiation intensity to a value corresponding to the number of detected radiations.

[0014] A radiation analysis method according to one embodiment of the present invention is characterized by performing dead time correction, which corrects the detected radiation intensity according to the dead time, which is a period during which radiation cannot be detected, and the aforementioned sum peak correction.

[0015] In one embodiment of the present invention, dead time correction and sum peak correction are performed according to the dead time. Dead time correction may be performed before sum peak correction. Alternatively, dead time correction and sum peak correction may be performed together by combining the calculations for dead time correction and sum peak correction into a single calculation. By performing dead time correction and sum peak correction, the detected intensity of radiation is corrected to be proportional to the amount of the element.

[0016] A radiation analysis method according to one embodiment of the present invention is characterized by performing dead time correction to correct the detected radiation intensity according to the dead time, which is a period during which radiation cannot be detected, and then correcting the detected radiation intensity corrected by the dead time correction by the sum peak correction.

[0017] In one embodiment of the present invention, dead time correction is performed on the detected radiation intensity, and then a sum peak correction is performed on the detected radiation intensity corrected by the dead time correction. In the dead time correction, the detected radiation intensity is corrected according to the dead time. By performing a sum peak correction after the dead time correction, the detected radiation intensity is corrected to be proportional to the amount of the element.

[0018] A radiation analysis method according to one embodiment of the present invention is characterized by measuring the actual time for detecting radiation and the dead time, and in the dead time correction, the detected radiation intensity is corrected by calculating ICR = OCR・RT / (RT-DT), where the count rate of radiation before correction by the dead time correction is OCR, the count rate of radiation after correction by the dead time correction is ICR, the actual time is RT, and the dead time is DT.

[0019] In one embodiment of the present invention, the actual time and dead time for detecting radiation are measured, and dead time correction is performed using the measured actual time and dead time. The corrected radiation detection intensity is calculated using a formula that utilizes the measured actual time and dead time. Dead time correction can be easily performed by using this formula.

[0020] A radiation analysis method according to one embodiment of the present invention is characterized by calculating the amount of a specific element contained in the sample using a calibration curve that shows the relationship between the detected intensity of radiation corrected by the sum peak correction and the amount of a specific element.

[0021] In one embodiment of the present invention, the amount of a specific element contained in the sample is calculated using a calibration curve, according to the detected radiation intensity corrected by sum peak correction. By using a calibration curve, the amount of a specific element contained in the sample can be easily calculated.

[0022] A radiation analyzer according to one embodiment of the present invention is characterized by comprising: a radiation detector for detecting radiation emitted from a sample; a signal processing unit for determining the detected intensity of radiation by counting response waves included in the output signal output from the radiation detector in response to the detection of radiation; a correction unit for correcting the detected intensity of radiation affected by the overlap of multiple response waves through statistical processing; and an analysis unit for calculating the amount of a specific element contained in the sample based on the detected intensity of radiation corrected by the correction unit.

[0023] In one embodiment of the present invention, a radiation analyzer detects radiation from a sample, performs a sum-peak correction on the detected radiation intensity, and calculates the amount of a specific element contained in the sample based on the corrected detected radiation intensity. In sum-peak correction, the radiation analyzer corrects the detected radiation intensity to correct for the effects of the overlap of multiple response waves. Through sum-peak correction, the detected radiation intensity is corrected to be approximately proportional to the amount of the element. Based on the corrected detected radiation intensity, the radiation analyzer can accurately determine the amount of a specific element contained in the sample.

[0024] A radiation analyzer according to one embodiment of the present invention is further characterized by comprising a transport unit for transporting the sample and an irradiation unit for irradiating the sample with radiation while it is being transported.

[0025] In one embodiment of the present invention, the radiation analyzer irradiates a sample with radiation while transporting it and measures the amount of a specific element contained in the sample. This allows the radiation analyzer to continuously analyze the amount of a specific element contained in multiple locations of the sample.

[0026] A radiation analyzer according to one embodiment of the present invention is characterized in that the sample is in the form of a sheet, and the transport unit transports the sample in a direction along the surface of the sample.

[0027] In one embodiment of the present invention, the sample is in the form of a sheet, and the radiation analyzer irradiates the sample with radiation while transporting it in a direction along the surface of the sample, and measures the amount of a specific element contained in the sample. This allows the radiation analyzer to continuously analyze the amount of a specific element contained in multiple locations on the sheet-like sample.

[0028] A computer program according to one embodiment of the present invention is characterized by causing a computer to perform the following processes: acquire the detection intensity of radiation emitted from a sample; statistically correct the detection intensity of radiation, which is affected by the superposition of multiple response waves included in the output signal output from the radiation detector in response to the detection of radiation; and calculate the amount of a specific element contained in the sample based on the corrected detection intensity of radiation.

[0029] In one embodiment of the present invention, the detected radiation intensity is subjected to a sum peak correction by information processing according to a computer program, and the amount of a specific element contained in the sample is calculated based on the corrected detected radiation intensity. Alternatively, the detected radiation intensity can be corrected by information processing according to a computer program, and the amount of a specific element contained in the sample can be accurately determined based on the corrected detected radiation intensity.

[0030] The present invention offers excellent advantages, such as the ability to determine the amount of elements contained in a sample based on the corrected radiation detection intensity.

[0031] This is a block diagram showing an example of the functional configuration of a radiation analyzer according to Embodiment 1. This is a block diagram showing the functional configuration of the signal processing unit. This is a schematic graph showing an example of an output signal including a response wave. This is a schematic graph showing examples of an output signal, a first shaping signal, and a second shaping signal. This is a schematic graph showing the relationship between the detected intensity of radiation and the concentration of elements contained in the sample. This is a schematic diagram showing an example of a radiation spectrum including a thumb peak. This is a flowchart showing an example of the processing procedure performed by the radiation detector and the signal processing unit. This is a flowchart showing an example of the processing procedure performed by the correction unit and the analysis unit. This is a block diagram showing an example of the functional configuration of a radiation analyzer according to Embodiment 3. This is a block diagram showing an example of the internal configuration of the analysis unit according to Embodiment 3. This is a block diagram showing an example of the functional configuration of a radiation analyzer according to Embodiment 4. This is a block diagram showing an example of the internal configuration of the analysis unit according to Embodiment 4.

[0032] The present invention will now be described in detail based on the drawings illustrating its embodiments. <Embodiment 1> Figure 1 is a block diagram showing an example of the functional configuration of a radiation analyzer 100 according to Embodiment 1. The radiation analyzer 100 includes an irradiation unit 42 that irradiates a sample 5 with radiation and a radiation detector 43 that detects radiation generated from the sample 5. The sample 5 is a long sheet. The sample 5 is placed between a plurality of rollers 45 and is transported in a direction along the surface of the sample 5 by the rotation of the rollers 45. In Figure 1, the direction in which the sample 5 is transported is indicated by white arrows. The rollers 45 are transport units that transport the sample 5. The transport units may include components other than the rollers 45.

[0033] The irradiation unit 42 generates radiation and irradiates the sample 5 during transport. The irradiation unit 42 is constructed, for example, using an X-ray tube. The radiation irradiated onto the sample 5 by the irradiation unit 42 is primary radiation such as X-rays or electron beams. The radiation emitted from the sample 5 is secondary radiation emitted from the sample 5 in response to the irradiation of the sample 5 with primary radiation. The radiation emitted from the sample 5 is, for example, fluorescent X-rays. In Figure 1, the radiation irradiated onto the sample 5 and the radiation emitted from the sample 5 are indicated by arrows.

[0034] The radiation detector 43 has a radiation detection element made of semiconductors. For example, the radiation detector 43 is an SDD (Silicon Drift Detector). The radiation detector 43 is positioned facing the surface of the sample 5. When radiation such as X-rays is irradiated onto the sample 5 from the irradiation unit 42, radiation such as fluorescent X-rays is generated in the sample 5. The radiation generated from the sample 5 is incident on the radiation detector 43. The radiation detector 43 detects the incident radiation and outputs a signal of intensity corresponding to the energy of the detected radiation.

[0035] A signal processing unit 3 is connected to the radiation detector 43. Based on the signal output by the radiation detector 43, the signal processing unit 3 identifies the detected intensity, which is the intensity of the radiation detected by the radiation detector 43. A correction unit 2 is connected to the signal processing unit 3. The correction unit 2 corrects the detected intensity of the radiation. The correction unit 2 is configured using a microcontroller. The correction unit 2 is connected to the analysis unit 1. The analysis unit 1 generates a radiation spectrum and performs analysis processing to calculate the concentration of specific elements contained in the sample 5. The analysis unit 1 is configured using a microcontroller.

[0036] A calibration curve storage unit 46 is connected to the analysis unit 1. The calibration curve storage unit 46 is a non-volatile memory. The calibration curve storage unit 46 stores calibration curve data representing the calibration curve necessary for the analysis processing performed by the analysis unit 1. The irradiation unit 42, signal processing unit 3, correction unit 2, and analysis unit 1 are connected to the control unit 41. A display unit 44, such as a liquid crystal display or an EL display (Electroluminescent Display), is connected to the control unit 41. The display unit 44 displays an image. The control unit 41 controls the operation of the irradiation unit 42, signal processing unit 3, correction unit 2, analysis unit 1, and display unit 44. The control unit 41 may also control the operation of the roller 45. The control unit 41 is configured using a computer that includes an arithmetic unit that performs calculations to control each unit. For example, the control unit 41 is configured using a personal computer. The control unit 41 may be configured to receive user input and control each unit of the radiation analyzer 100 according to the received input.

[0037] Figure 2 is a block diagram showing the functional configuration of the signal processing unit 3. In Figure 2, the signal flow is indicated by arrows. The radiation detector 43 outputs a signal that includes a response wave in response to the detection of radiation. The signal output by the radiation detector 43 is called the output signal. The output signal is a voltage signal. The output signal is continuously output from the radiation detector 43, and the response wave is included in the output signal when the radiation detector 43 detects radiation.

[0038] Figure 3 is a schematic graph showing an example of an output signal including a response wave. In the figure, the horizontal axis represents time, and the vertical axis represents the signal value. Each time radiation enters the radiation detector 43 and an event occurs in which radiation is detected, the radiation detector 43 outputs a response wave, which is a step wave in which the signal value increases in a step-like manner. One response wave is generated in response to one event, in which the signal value increases in a step-like manner. Although Figure 3 shows an example of a response wave in which the signal value increases instantaneously, in reality, a blunted response wave is obtained in which the increase in the signal value takes some time. If multiple events occur, an output signal containing multiple response waves is output. Each time an event occurs, the signal value of the output signal increases. The height of the step in which the signal value increases is defined as the wave height of the response wave. The wave height of the response wave corresponds to the energy of the radiation detected by the radiation detector 43. The radiation analyzer 100 determines the energy of the radiation according to the wave height of the response wave.

[0039] The signal output by the radiation detector 43 is input to the signal processing unit 3. As shown in Figure 2, the signal processing unit 3 includes an A / D (analog-to-digital) conversion unit 31. The A / D conversion unit 31 receives the output signal from the radiation detector 43 and performs A / D conversion on the output signal. The A / D conversion unit 31 receives a continuous output signal, samples the output signal at predetermined time intervals, and performs A / D conversion on the values ​​obtained by the sampling to generate discrete signal values. The A / D conversion unit 31 generates the A / D converted output signal by sequentially generating signal values ​​at predetermined time intervals. The A / D converted output signal is a digital signal consisting of a plurality of discrete signal values.

[0040] The A / D conversion unit 31 is connected to a first trapezoidal filter 32 and a second trapezoidal filter 33. The first trapezoidal filter 32 and the second trapezoidal filter 33 receive the A / D converted output signal from the A / D conversion unit 31. Between the A / D conversion unit 31 and the first trapezoidal filter 32 and the second trapezoidal filter 33, a conversion unit that converts the signal to cancel out waveform distortion due to signal delay and a noise reduction unit that removes noise from the signal may also be connected.

[0041] The first trapezoidal filter 32 and the second trapezoidal filter 33 are digital filters that convert the step-like staircase wave contained in the input signal into a trapezoidal wave, thereby generating a shaped signal from the input signal. That is, the response wave contained in the output signal is converted into a trapezoidal wave. The signal shaped by the first trapezoidal filter 32 is called the first shaped signal, and the signal shaped by the second trapezoidal filter 33 is called the second shaped signal. The first trapezoidal filter 32 and the second trapezoidal filter 33 have defined time constants: a peaking time (PT), which is the period during which the trapezoidal wave rises, and a holding time (HT), which is the period from when the trapezoidal wave rises until the falling edge begins. The PT and HT of the first trapezoidal filter 32 and the second trapezoidal filter 33 are different from each other.

[0042] Figure 4 is a schematic graph showing examples of the output signal, the first shaped signal, and the second shaped signal. The top row shows the output signal including the response wave, the middle row shows the first shaped signal, and the bottom row shows the second shaped signal. In the figure, the horizontal axis represents time, and the vertical axis represents the signal value. The first trapezoidal filter 32 and the second trapezoidal filter 33 shape the output signal by differentiating the output signal. The trapezoidal wave rises in accordance with the rising edge of the response wave, which is a step wave. The trapezoidal wave contained in the first shaped signal and the second shaped signal rises over time PT, maintains its signal value approximately over time HT, and falls over time PT.

[0043] The PT of the first trapezoidal filter 32 is shorter than the PT of the second trapezoidal filter 33, and the HT of the first trapezoidal filter 32 is also shorter than the HT of the second trapezoidal filter 33. Therefore, in response to the response wave, the first shaping signal rises rapidly and falls rapidly. In contrast, the second shaping signal rises more slowly and falls more slowly. Since the first shaping signal rises rapidly, it is suitable for determining the presence or absence of the response wave. Since the second shaping signal rises over a sufficient period of time in response to the response wave, it reflects the characteristics of the response wave more, and the peak value of the second shaping signal becomes a value corresponding to the waveform of the response wave. The signal processing unit 3 measures the peak value of the response wave by measuring the peak value of the second shaping signal. The peak value of the second shaping signal is the peak value of the trapezoidal wave included in the second shaping signal, and is obtained from the signal value of the upper base portion of the trapezoidal wave. The upper base portion of the trapezoidal wave is the period from the time point PT after the rising time point of the trapezoidal wave until the HT has elapsed.

[0044] A determination unit 34 is connected to the first trapezoidal filter 32. The first trapezoidal filter 32 inputs a first shaping signal obtained by shaping the output signal to the determination unit 34. The determination unit 34 uses the first shaping signal to determine whether a response wave is included in the output signal. More specifically, the determination unit 34 compares the first shaping signal with a predetermined threshold value, and determines that a response wave is included in the output signal when the signal value of the first shaping signal exceeds the threshold value. The determination unit 34 determines that the response wave is not included in the output signal when the signal value of the first shaping signal does not exceed the threshold value. For example, the determination unit 34 is composed of an FPGA (Field Programmable Gate Array). When the determination unit 34 determines that a response wave is included in the output signal, the signal processing unit 3 determines that radiation has been detected.

[0045] A wave height measurement unit 35 is connected to the determination unit 34 and the second trapezoidal filter 33. When the determination unit 34 determines that the response wave is included in the output signal, it inputs information indicating that the response wave is included in the output signal to the wave height measurement unit 35. The second trapezoidal filter 33 inputs the second shaped signal, which is the output signal shaped, to the wave height measurement unit 35. When the wave height measurement unit 35 receives information from the determination unit 34 indicating that the response wave is included in the output signal, it measures the wave height of the second shaped signal to measure the wave height of the response wave. The wave height measurement unit 35 obtains a representative value of the upper base portion of the trapezoidal wave included in the second shaped signal and uses the obtained value as the wave height value of the response wave. For example, the wave height measurement unit 35 obtains the maximum value of the signal value included in the upper base portion of the trapezoidal wave as a representative value and uses the obtained value as the wave height value of the response wave. For example, the wave height measurement unit 35 calculates the average or median value of the signal value included in the upper base portion of the trapezoidal wave as a representative value and uses the calculated value as the wave height value of the response wave.

[0046] A counting unit 36 ​​is connected to the wave height measurement unit 35. For example, the counting unit 36 ​​is a multi-channel analyzer. The wave height measurement unit 35 inputs the measured wave height of the response wave to the counting unit 36. The counting unit 36 ​​counts the response waves for each wave height. Specifically, each time the wave height of a response wave is input to the counting unit 36, it increments the count number associated with the input wave height by 1. The counting unit 36 ​​may be configured to count the response waves for all wave heights, or it may be configured to count the response waves only for specific wave heights. In this way, the response waves are counted for each wave height.

[0047] The signal processing unit 3 outputs data indicating the relationship between the wave height of the response wave and the count number counted by the counting unit 36. The count number is the number of times the radiation detector 43 has detected radiation having energy corresponding to the wave height of the response wave, and corresponds to the detection intensity of the radiation having energy corresponding to the wave height of the response wave. By counting the response waves according to the wave height, the detection intensity of the radiation having each energy is specified. The data output by the signal processing unit 3 includes the count number associated with the wave height (energy of the radiation) of the response wave. The correction unit 2 receives the data output by the signal processing unit 3 and performs a process of correcting the detection intensity of the radiation corresponding to the count number included in the data. The content of the process performed by the correction unit 2 will be described later. The correction unit 2 outputs data indicating the relationship between the wave height of the response wave and the corrected detection intensity of the radiation.

[0048] The analysis unit 1 receives the data output by the correction unit 2. The analysis unit 1 performs a process of generating a spectrum of the radiation detected by the radiation detector 43 from the relationship between the wave height of the response wave and the corrected detection intensity of the radiation. The spectrum represents the relationship between the energy of the radiation corresponding to the wave height and the detection intensity of the radiation. The analysis unit 1 further performs an analysis process of calculating the concentration of a specific element contained in the sample 5 that generated the radiation based on the generated spectrum of the radiation. The display unit 44 displays the spectrum generated by the analysis unit 1 and the analysis result by the analysis unit 1.

[0049] The process performed by the correction unit 2 will be described. FIG. 5 is a schematic graph showing the relationship between the detection intensity of the radiation and the concentration of the element contained in the sample 5. In FIG. 5, the horizontal axis represents the concentration of a specific element contained in the sample 5, and the vertical axis represents the detection intensity of the radiation caused by the specific element. The unit of the detection intensity is the number of counts per unit time. In FIG. 5, the ideal graph is shown by a broken line, and the graph actually obtained is shown by a solid line. As shown by the broken line in FIG. 5, ideally, the detection intensity of the radiation increases in proportion to the concentration of the element. However, in reality, as shown by the solid line in FIG. 5, as the concentration of the element increases, the rate of increase in the detection intensity of the radiation with respect to the increase in the concentration of the element becomes smaller, and the detection intensity of the radiation is not proportional to the concentration of the element. The reasons why the detection intensity of the radiation is not proportional to the concentration of the element are dead time and pile-up.

[0050] Dead time is the period immediately following the detection of radiation during which radiation cannot be detected. The signal processing unit 3 measures the amplitude of the response wave by measuring the amplitude of the second shaping signal. Therefore, in order to measure the amplitude of the response wave, the amplitude of the trapezoidal wave included in the second shaping signal must be determined. As shown in Figure 4, at least the sum of the PT and HT of the second trapezoidal filter 33 must elapse from the time the response wave is generated until the amplitude of the trapezoidal wave of the second shaping signal is determined. During this period, the amplitude of other response waves cannot be measured, so this period is dead time.

[0051] The higher the concentration of an element, the greater the intensity of the radiation incident on the radiation detector 43, and the higher the frequency of radiation detection. Since a certain length of dead time occurs each time radiation is detected, the ratio of dead time to real time increases, and the proportion of radiation that cannot be detected due to the effect of dead time increases. For this reason, the detected radiation intensity is affected by the dead time, and as shown by the solid line in Figure 5, the higher the concentration of the element, the smaller the rate of increase in the detected radiation intensity in relation to the increase in element concentration.

[0052] Pile-up is a phenomenon in which multiple response waves overlap. When radiation is detected multiple times at very short intervals, the multiple response waves overlap and are mistakenly treated as a single detection. A first shaped signal containing multiple trapezoidal waves is generated from the output signal containing the multiple overlapping response waves. If radiation is detected multiple times at intervals shorter than the time required to separate the multiple trapezoidal waves contained in the first shaped signal, the multiple trapezoidal waves contained in the first shaped signal cannot be separated and are recognized as a single trapezoidal wave. Therefore, the multiple overlapping response waves are counted as a single response wave, and even though radiation was detected multiple times, the number of times radiation was detected is determined to be only once. As a result, the detected radiation intensity is affected by pile-up and may be underestimated compared to the actual radiation intensity. The time required to separate the multiple trapezoidal waves contained in the first shaped signal is the time constant of the first trapezoidal filter 32, for example, the sum of the PT and HT of the first trapezoidal filter 32.

[0053] The higher the concentration of an element, the greater the intensity of the radiation incident on the radiation detector 43, leading to a higher frequency of radiation detection and a higher frequency of pile-up. Therefore, as shown by the solid line in Figure 5, the higher the concentration of an element, the smaller the rate of increase in radiation detection intensity in response to an increase in element concentration.

[0054] When a pile-up occurs, multiple trapezoidal waves are generated in the second shaping signal, and the wave height of the superimposed trapezoidal wave is measured. In other words, the sum of the wave heights of multiple response waves is measured as the wave height of a single response wave. Therefore, instead of detecting multiple radiations, radiation with an apparent energy equivalent to the sum of the energies of multiple radiations is detected. The radiation spectrum includes not only the peaks of the detected radiation, but also a sum peak, which is the peak of radiation with an energy equivalent to the sum of the energies of multiple radiations.

[0055] Figure 6 is a schematic diagram showing an example of a radiation spectrum including a thumb peak. In Figure 6, the horizontal axis represents the energy of the radiation, and the vertical axis represents the detected intensity of the radiation. In Figure 6, the thumb peak is indicated by an arrow. The thumb peak is only apparent in the radiation spectrum, and radiation with the energy corresponding to the thumb peak is not actually detected. The peaks other than the thumb peak shown in Figure 6 correspond to the radiation that was actually detected. The thumb peak occurs at a position corresponding to an energy higher than that of the radiation that was actually detected. For example, if radiation with the same energy is detected twice at short intervals and a pileup occurs, the thumb peak will occur at a position corresponding to twice the energy of the radiation that was actually detected. In this way, the thumb peak occurs because radiation is detected multiple times at short intervals equal to or less than the time constant of the first trapezoidal filter 32, and multiple response waves overlap.

[0056] The correction unit 2 performs dead time correction, which corrects the detected radiation intensity to correct for the effects of dead time, and sum peak correction, which corrects the detected radiation intensity to correct for the effects of the overlap of multiple response waves. In this embodiment, sum peak correction refers to correcting the detected radiation intensity affected by the overlap of multiple response waves that cause sum peaks to correct for the effects. First, dead time correction will be explained. The number of times radiation is detected per unit time is called the radiation count rate. The number of times radiation is detected per unit time by determining the presence or absence of a response wave using the first shaping signal is defined as the first input count rate. The first input count rate is the count rate after correction by dead time correction and the count rate before correction by sum peak correction.

[0057] The actual time during which radiation detection occurred is denoted by RT, and the dead time by DT. The time obtained by subtracting the dead time from the actual time is called the live time, and the live time is denoted by LT. The live time is expressed as LT = RT - DT. The first input count rate is denoted by ICR, and the number of radiation detections is denoted by N. The first input count rate is approximated by the following equation (1): ICR = N / LT …(1)

[0058] The output count rate is defined as the number of radiation samples detected per unit time by measuring the pulse height of the second shaped signal. The output count rate is the actual count rate obtained, before correction by dead time correction and sum peak correction. The output count rate is expressed as OCR. The output count rate is approximated by the following equation (2): OCR = N / RT …(2)

[0059] Based on equations (1) and (2), the first input count rate ICR can be expressed by the following equation (3) using the output count rate OCR: ICR = OCR・RT / LT = OCR・RT / (RT - DT) ... (3)

[0060] The correction unit 2 performs dead time correction using equation (3). The correction unit 2 acquires real time RT and dead time DT. Real time RT is measured by measuring the time the radiation analyzer 100 operates for radiation detection. The correction unit 2 may measure real time RT, or it may receive the value of real time RT from a measurement unit (not shown). Dead time DT is measured by adding the time spent determining the presence or absence of a response wave and the time spent measuring the wave height each time radiation is detected. Alternatively, dead time DT is measured by starting the measurement of dead time when the process of determining the presence or absence of a response wave begins, and continuing the measurement of dead time until at least one valid wave height is measured. The correction unit 2 may measure dead time DT, or it may receive the value of dead time DT from a measurement unit (not shown).

[0061] The data input to the correction unit 2 from the signal processing unit 3 includes a count corresponding to the detected intensity of radiation. The count per unit time is the output count rate OCR. For example, the correction unit 2 calculates the output count rate OCR by dividing the count included in the data input from the signal processing unit 3 by the real time RT. Alternatively, data containing counts may be periodically input from the signal processing unit 3, and the count included in the data may be used as the output count rate OCR. The correction unit 2 obtains the value of the first input count rate ICR by substituting the values ​​of real time RT, dead time DT, and output count rate OCR into equation (3) and calculating equation (3). Alternatively, the correction unit 2 may measure the live time LT, let the count be the number of radiation detections N, and calculate the value of the first input count rate ICR by substituting the values ​​of live time LT and the number of radiation detections N into equation (1) and calculating equation (1).

[0062] The correction unit 2 performs dead time correction as described above and obtains a first input count rate ICR, which is the count rate after correction by dead time correction. The obtained first input count rate ICR corresponds to the detected radiation intensity corrected by dead time correction. By performing dead time correction, the correction unit 2 corrects the detected radiation intensity so as to adjust the detected radiation intensity affected by dead time to an appropriate value. The correction unit 2 can easily perform dead time correction by using equation (1) or equation (3). The correction unit 2 performs dead time correction on the count obtained for each wave height.

[0063] Next, we will explain the sum-peak correction. Assume that the probability of radiation occurrence follows a statistically Poisson distribution. In a Poisson distribution, the probability that an event that occurs an average of λ times within a given time occurs exactly k times is expressed by the following equation (4): f(X=k)=(λ k / k! )・exp(−λ)…(4)

[0064] Let T1 be the time constant of the first trapezoidal filter 32. For example, T1 is the sum of PT and HT of the first trapezoidal filter 32. The probability that no further radiation is detected within time T1, when radiation is detected, is given by the first input count rate ICR, and since k=0 and λ=ICR・T1 in equation (4), it is expressed by the following equation (5): f(X=0)=exp(-ICR・T1) …(5)

[0065] The second input count rate is obtained by counting all response waves generated by the detection of radiation. All response waves include each of the multiple response waves that overlap due to pile-up. The second input count rate is the count rate after correction by sum-peak correction. The first input count rate (ICR) is approximated by multiplying the second input count rate by the probability that no further radiation is detected within time T1 after the detection of radiation. Therefore, if the second input count rate is ICR', the first input count rate (ICR) can be expressed by equation (6) below using equation (5): ICR = ICR'・exp(-ICR・T1) …(6)

[0066] By rearranging equation (6), the second input count rate ICR' can be expressed by the following equation (7): ICR' = ICR / exp(-ICR・T1) ... (7)

[0067] The correction unit 2 performs a sum peak correction using equation (7). The correction unit 2 stores the value of T1. T1 is the sum of PT and HT of the first trapezoidal filter 32. That is, T1 = PT + HT. T1 may be a longer value. For example, T1 = 2PT + HT, or T1 = PT + HT + α, where α is a predetermined positive value. The correction unit 2 may also receive the value of T1 from outside the correction unit 2.

[0068] The correction unit 2 substitutes the value of T1 and the value of the first input count rate ICR obtained by dead time correction into equation (7) and calculates equation (7) to obtain the value of the second input count rate ICR'. The correction unit 2 performs sum peak correction in this manner. Since equation (7) shows the statistical relationship between the first input count rate ICR and the second input count rate ICR', sum peak correction using equation (7) is a statistical process. The obtained second input count rate ICR' corresponds to the detected intensity of radiation corrected by sum peak correction. By performing sum peak correction, the correction unit 2 corrects the detected intensity of radiation affected by pileup to the value that should be obtained if each of the overlapping response waves is separated and counted. The correction unit 2 performs sum peak correction for each wave height.

[0069] The correction unit 2 outputs data showing the relationship between the wave height of the response wave and the second input counting rate ICR'. The analysis unit 1 receives the data output by the correction unit 2 as input. The radiation spectrum generated by the analysis unit 1 represents the relationship between the energy of the radiation corresponding to the wave height and the detected intensity of the corrected radiation corresponding to the second input counting rate ICR'.

[0070] In the processing of the correction unit 2 described above, the radiation count rate used in the calculation of dead time correction and sum peak correction is obtained from the count number associated with each energy, and dead time correction and sum peak correction are performed for each energy. The correction unit 2 may also perform dead time correction and sum peak correction for the entire energy range. In this case, the radiation count rate used in the calculation of dead time correction and sum peak correction may be the sum of the count numbers associated with the entire energy range. The correction unit 2 may obtain the output count rate OCR from the sum of the count numbers associated with the entire energy range and perform dead time correction and sum peak correction. The correction unit 2 may also calculate the second input count rate ICR' for each energy from the calculated second input count rate ICR' for the entire energy range. For example, the correction unit 2 may calculate the second input count rate ICR' for each energy by changing the output count rate OCR for each energy at the same rate of change as the rate of change from the output count rate OCR for the entire energy range to the second input count rate ICR'.

[0071] The analysis unit 1 further performs an analytical process to calculate the concentration of a specific element contained in the radiation-emitting sample 5. In the analytical process, the analysis unit 1 uses a calibration curve to calculate the concentration of the specific element contained in the sample 5. The concentration of an element corresponds to the amount of that element. The calibration curve shows the relationship between the concentration of the specific element contained in the sample 5 and the value after correcting the detection intensity of the radiation (e.g., fluorescent X-rays) caused by the specific element using dead time correction and sum peak correction. A schematic graph of the calibration curve is similar to the graph shown by the dashed line in Figure 5. The detected intensity of the corrected radiation is approximately proportional to the concentration of the element.

[0072] Calibration curves are created using standard samples whose concentrations of specific elements are known. Radiation is irradiated from the irradiation unit 42, the radiation emitted from the standard sample is detected by the radiation detector 43, the detected radiation intensity is corrected by the correction unit 2, a radiation spectrum is generated, and the corrected detected intensity of the radiation due to the specific element is obtained. Experiments are conducted using multiple standard samples with different concentrations of the specific element to obtain the corrected detected intensity of the radiation for each. Based on the experimental results, a calibration curve is created by creating an approximation formula that approximates the relationship between the concentration of the specific element and the corrected detected intensity of the radiation. The calibration curve may be a straight line or a curve. Calibration curves are created in advance, and the calibration curve storage unit 46 stores calibration curve data representing the calibration curve.

[0073] The following describes the processing flow performed by the radiation analyzer 100. Figure 7 is a flowchart showing an example of the processing procedure performed by the radiation detector 43 and the signal processing unit 3. Hereinafter, steps will be abbreviated as S. The roller 45 transports the sample 5, the control unit 41 operates the irradiation unit 42, and the irradiation unit 42 irradiates the sample 5 with radiation such as X-rays. The sample 5 is irradiated with radiation while being transported. Radiation such as fluorescent X-rays is emitted from the sample 5, and the radiation detector 43 detects the radiation from the sample 5 (S11). The radiation detector 43 generates a response wave having a wave height corresponding to the energy of the detected radiation and outputs an output signal including the response wave. The radiation detector 43 also outputs an output signal even when no radiation is detected.

[0074] The signal processing unit 3 receives the output signal from the radiation detector 43. The A / D conversion unit 31 performs A / D conversion on the input output signal (S12). The A / D converted output signal consists of a plurality of discrete signal values. The A / D conversion unit 31 inputs the A / D converted output signal to the first trapezoidal filter 32 and the second trapezoidal filter 33. The first trapezoidal filter 32 shapes the output signal into a first shaped signal and inputs the first shaped signal to the determination unit 34. The second trapezoidal filter 33 shapes the output signal into a second shaped signal and inputs the second shaped signal to the wave height measurement unit 35.

[0075] The determination unit 34 uses the first shaping signal to determine whether or not the response wave is included in the output signal (S13). In S13, the determination unit 34 determines that the response wave is included in the output signal if the signal value of the first shaping signal exceeds a threshold. The determination unit 34 determines that the response wave is not included in the output signal if the signal value of the first shaping signal does not exceed a threshold. If the response wave is not included in the output signal (S13: NO), the signal processing unit 3 terminates processing without counting the response wave. If the determination unit 34 determines that the response wave is included in the output signal (S13: YES), it inputs information indicating that the response wave is included in the output signal to the wave height measurement unit 35.

[0076] The wave height measurement unit 35 measures the wave height of the response wave when it receives information indicating that the response wave is included in the output signal (S14). In S14, the wave height measurement unit 35 measures the wave height of the response wave by measuring the wave height of the second shaping signal input from the second trapezoidal filter 33. The wave height measurement unit 35 inputs the measured wave height of the response wave to the counting unit 36. The counting unit 36 ​​counts the response waves according to their wave height (S15). After S15 is completed, the signal processing unit 3 terminates its processing. The irradiation unit 42 continues to irradiate with radiation, and the radiation detector 43 and the signal processing unit 3 repeatedly execute the processes from S11 to S15.

[0077] Figure 8 is a flowchart showing an example of the processing procedure performed by the correction unit 2 and the analysis unit 1. The signal processing unit 3 outputs data showing the relationship between the wave height of the response wave and the count number counted by the count unit 36. The data output by the signal processing unit 3 includes a count number corresponding to the detected radiation intensity in relation to the wave height of the response wave. The correction unit 2 acquires the detected radiation intensity by receiving the data output from the signal processing unit 3 (S21).

[0078] The correction unit 2 performs dead time correction (S22) and then sum peak correction (S23) on the detected radiation intensity obtained. The correction unit 2 performs dead time correction and sum peak correction according to the processing method described above. The detected radiation intensity is corrected according to the wave height of the response wave by calculating the second input count rate ICR' according to the wave height of the response wave. The correction unit 2 outputs data showing the relationship between the wave height of the response wave and the second input count rate ICR'. The analysis unit 1 receives the data output by the correction unit 2 as input. The correction unit 2 may execute S22 and S23 together. For example, the correction unit 2 may calculate the second input count rate ICR' using an equation obtained by substituting equation (1) or equation (3) for ICR in equation (7), thereby executing dead time correction and sum peak correction together.

[0079] The analysis unit 1 acquires the corrected detection intensity of radiation originating from a specific element (S24). Based on the data input from the correction unit 2, the analysis unit 1 generates a spectrum of radiation detected by the radiation detector 43. The radiation intensity represented in the spectrum is the detection intensity corrected by dead time correction and sum peak correction. In S24, the analysis unit 1 acquires the corrected detection intensity of radiation originating from a specific element by reading the peak intensity corresponding to the energy of the radiation originating from the specific element from the spectrum. The analysis unit 1 may also acquire the corrected detection intensity of radiation without generating a radiation spectrum by acquiring the detection intensity of radiation associated with a specific wave height from the data input from the correction unit 2.

[0080] The analysis unit 1 calculates the concentration of a specific element contained in the sample 5 based on the corrected radiation detection intensity (S25). In S25, the analysis unit 1 calculates the concentration of a specific element contained in the sample 5 using a calibration curve that shows the relationship between the corrected radiation detection intensity and the concentration of the specific element. More specifically, the analysis unit 1 refers to the calibration curve represented by the calibration curve data stored in the calibration curve storage unit 46 and identifies the concentration of the specific element on the calibration curve that corresponds to the corrected detection intensity of radiation caused by the specific element. In this way, the analysis unit 1 calculates the concentration of a specific element contained in the sample 5. By using the calibration curve, the concentration of a specific element contained in the sample 5 can be easily calculated. After S25 is completed, the analysis unit 1 terminates processing.

[0081] The radiation analyzer 100 continues to transport the sample 5 by the roller 45, repeating the processes S11 to S15 and then S21 to S25. As a result, the concentrations of specific elements contained in multiple locations of the sample 5 are continuously calculated, and the distribution of specific elements within the sample 5 is analyzed. The analysis unit 1 may display an image including the analysis results on the display unit 44.

[0082] As detailed above, the radiation analyzer 100 detects radiation from the sample 5, performs dead time correction and sum peak correction on the detected radiation intensity, and calculates the concentration of a specific element contained in the sample 5 based on the corrected detected radiation intensity. By performing sum peak correction in addition to dead time correction, the corrected detected radiation intensity is approximately proportional to the elemental concentration. Therefore, it is possible to accurately determine the amount of a specific element contained in the sample 5 based on the corrected detected radiation intensity.

[0083] In addition to dead time correction, the radiation analyzer 100 corrects the detected radiation intensity to a more appropriate value by performing sum peak correction, which corrects the detected radiation intensity affected by the overlap of multiple response waves through statistical processing. In sum peak correction, the detected radiation intensity after correction is calculated using the time constant of the first trapezoidal filter 32, thereby correcting the detected radiation intensity affected by the overlap of multiple inseparable response waves.

[0084] Conventionally, in order to determine the amount of elements contained in a sample, radiation measurement conditions were adjusted according to the counting rate, taking into account the occurrence of a sum peak. Therefore, it was not possible to continuously analyze elements contained in multiple locations of a sample without adjusting the measurement conditions. In this embodiment, by performing a sum peak correction, the amount of elements contained in the sample can be accurately determined without adjusting the radiation measurement conditions. Therefore, it is possible to continuously determine the amount of elements without adjusting the measurement conditions. Thus, the amount of elements contained in multiple locations of a sample can be continuously determined while the sample is being transported. In particular, it becomes possible to continuously determine the amount of a specific element contained in a sheet-shaped sample 5 while transporting the sample 5, and the distribution of a specific element within the sheet-shaped sample 5 can be easily analyzed.

[0085] <Embodiment 2> In Embodiment 2, the radiation analyzer 100 performs sum peak correction using a different process than in Embodiment 1. The configuration of the radiation analyzer 100 is the same as in Embodiment 1. In order for the radiation analyzer 100 to analyze the elements contained in the sample 5, the radiation detector 43 and the signal processing unit 3 repeatedly perform the processes S11 to S15, as in Embodiment 1. The correction unit 2 performs the processes S21 to S22, as in Embodiment 1.

[0086] In the sum peak correction in S23, the correction unit 2 corrects the detected intensity of radiation based on the detected intensity of radiation corresponding to the sum peak. When a pileup occurs in which multiple response waves overlap, including a response wave having a first wave height, the wave height of the response wave generated by the overlapping of the multiple response waves is taken as the second wave height. The wave height measurement unit 35 measures the second wave height, and the counting unit 36 ​​performs a count in relation to the second wave height. A sum peak occurs in the radiation spectrum at a position corresponding to the second wave height.

[0087] The second wave height is the sum of the wave heights of the overlapping response waves. The counting unit 36 ​​performs the count in relation to the wave height corresponding to the sum of the wave heights of the overlapping response waves. For example, if two response waves having the first wave height overlap, the second wave height will be twice the first wave height, and the count will be performed in relation to twice the first wave height. For this reason, the second wave height that occurs when other response waves overlap with a response wave having a specific first wave height is known in advance.

[0088] Due to the occurrence of pile-up, the first wave height is not measured, and only the second wave height is measured. As a result, the count number associated with the first wave height decreases compared to the actual number, and the count number associated with the second wave height increases by an amount equivalent to the decrease. Therefore, by adding the count number associated with the second wave height to the count number associated with the first wave height, the count number associated with the first wave height, which was reduced due to pile-up, can be corrected to the number of times a response wave with the first wave height occurred.

[0089] In S23, the correction unit 2 extracts the detection intensity of radiation related to a second wave height, which is known in advance, from the detected radiation intensities after dead time correction for each wave height. The correction unit 2 corrects the detection intensity of radiation related to the first wave height by adding the extracted detection intensity to the detection intensity of radiation related to the first wave height. The corrected radiation detection intensity is obtained by correcting the detection intensity of radiation affected by pile-up to a value corresponding to the number of response waves generated by radiation detection. In this way, the correction unit 2 performs a sum peak correction on the detected radiation intensity after dead time correction.

[0090] After S23 is completed, the correction unit 2 outputs data showing the relationship between the wave height of the response wave and the detected intensity of the corrected radiation, and the analysis unit 1 receives the data output by the correction unit 2. The analysis unit 1 performs the processes of S24 to S25 in the same manner as in Embodiment 1. The radiation analyzer 100 continues to transport the sample 5 by the roller 45 in the same manner as in Embodiment 1, repeating the processes of S11 to S15 and repeating the processes of S21 to S25.

[0091] In Embodiment 2, the radiation analyzer 100 performs dead time correction and sum peak correction, and calculates the concentration of a specific element contained in the sample 5 based on the corrected radiation detection intensity. By performing sum peak correction, the radiation detection intensity can be corrected to a value corresponding to the number of response waves generated by the radiation detection, so the radiation detection intensity becomes more accurate. Based on the more accurate radiation detection intensity, it becomes possible to more accurately determine the amount of a specific element contained in the sample 5.

[0092] <Embodiment 3> Figure 9 is a block diagram showing an example of the functional configuration of a radiation analyzer 100 according to Embodiment 3. In Embodiment 3, the radiation analyzer 100 does not have a calibration curve storage unit 46, and the analysis unit 1 is an information processing device and is composed of a personal computer. The analysis unit 1 may also be composed of a server device. The configuration of the other parts of the radiation analyzer 100 is the same as in Embodiments 1 and 2.

[0093] Figure 10 is a block diagram showing an example of the internal configuration of the analysis unit 1 according to Embodiment 3. The analysis unit 1 comprises a calculation unit 11, a memory 12, a reading unit 13, a storage unit 14, and an operation unit 15. The calculation unit 11 is a processor and is configured using, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a multi-core CPU. The calculation unit 11 may also be configured using a quantum computer. The memory 12 stores temporary data generated in connection with calculations. The memory 12 is, for example, RAM (Random Access Memory).

[0094] The reading unit 13 reads information from the recording medium 10, such as an optical disc or portable memory. The storage unit 14 is non-volatile, for example, a hard disk or non-volatile semiconductor memory. The operation unit 15 receives input of information such as text by receiving operations from the user. The operation unit 15 is for example a touch panel, keyboard, or pointing device. The user inputs various instructions to the analysis unit 1 by operating the operation unit 15. The analysis unit 1 receives the instructions input using the operation unit 15.

[0095] The arithmetic unit 11 causes the reading unit 13 to read the computer program (program product) 141 recorded on the recording medium 10, and stores the read computer program 141 in the storage unit 14. The arithmetic unit 11 executes the necessary processing in the analysis unit 1 according to the computer program 141. Alternatively, the computer program 141 may be stored in the storage unit 14 in advance, or downloaded from outside the analysis unit 1. In this case, the analysis unit 1 does not need to have a reading unit 13.

[0096] The computer program 141 can be deployed on a single computer, at a single site, or distributed across multiple sites and run on multiple computers interconnected by a communication network. That is, the computer program 141 may run on multiple computers connected via a communication network, and the analysis unit 1 may consist of multiple computers connected to each other via a communication network. The analysis unit 1 may also be configured using a cloud server.

[0097] The processing steps described below for executing the information processing method can be performed on multiple computers. The processing steps can also be performed on different computers. The data used during processing may be stored on multiple computers. The processing steps can also be performed using a virtual machine. The processing steps may be performed by multiple arithmetic units. The processing steps may also be performed by different arithmetic units. For example, part of the processing may be performed on one computer, and other parts on other computers.

[0098] The analysis unit 1 is connected to the correction unit 2 and the control unit 41. The analysis unit 1 outputs information necessary for information processing by displaying an image containing information on the display unit 44. The analysis unit 1 receives data output by the correction unit 2 and receives control signals from the control unit 41. In embodiment 3, the storage unit 14 stores calibration curve data.

[0099] In Embodiment 3, the radiation analyzer 100 also analyzes the elements contained in the sample 5. Similar to Embodiment 1 or 2, the radiation detector 43 and the signal processing unit 3 repeatedly execute the processes S11 to S15. The correction unit 2 executes the processes S21 to S23, similar to Embodiment 1 or 2. The correction unit 2 outputs data showing the relationship between the wave height of the response wave and the second input count rate ICR'. The analysis unit 1 receives the data output by the correction unit 2 as input.

[0100] The analysis unit 1 executes the processes S24 to S25. In S24, the calculation unit 11 generates a radiation spectrum based on the data input from the correction unit 2 and obtains the corrected detection intensity of radiation caused by a specific element from the spectrum. The calculation unit 11 may also obtain the corrected detection intensity of radiation from the data input from the correction unit 2. In S25, the calculation unit 11 refers to the calibration curve represented by the calibration curve data stored in the storage unit 14 and uses the calibration curve to calculate the concentration of the specific element contained in the sample 5. After S25 is completed, the analysis unit 1 terminates processing. Similar to Embodiment 1 or 2, the radiation analyzer 100 continues to transport the sample 5 by the roller 45, repeats the processes S11 to S15, and repeats the processes S21 to S25.

[0101] In Embodiment 3, the radiation analyzer 100 performs dead time correction and sum peak correction, and calculates the concentration of a specific element contained in the sample 5 based on the corrected radiation detection intensity. The radiation detection intensity is corrected by the dead time correction and sum peak correction, and based on the corrected radiation detection intensity, it becomes possible to accurately determine the amount of a specific element contained in the sample 5.

[0102] Embodiments 1 and 2 show examples in which the correction unit 2 and the analysis unit 1 are configured using microcontrollers, and the control unit 41 is configured using a personal computer. Embodiment 3 shows an example in which the correction unit 2 is configured using a microcontroller, and the analysis unit 1 and the control unit 41 are configured using a personal computer. The radiation analyzer 100 may have other configurations. For example, the correction unit 2, the analysis unit 1, and the control unit 41 may be configured using microcontrollers, and the display unit 44 may be configured using a personal computer. For example, the correction unit 2, the analysis unit 1, and the control unit 41 may be configured using a personal computer. For example, at least one of the correction unit 2, the analysis unit 1, and the control unit 41 may be configured using a microcontroller, and the others may be configured using a personal computer. The analysis unit 1 and the control unit 41 may be configured using the same computer.

[0103] <Embodiment 4> Figure 11 is a block diagram showing an example of the functional configuration of the radiation analyzer 100 according to Embodiment 4. Figure 12 is a block diagram showing an example of the internal configuration of the analysis unit 1 according to Embodiment 4. The analysis unit 1 is an information processing device and is composed of a personal computer. In Embodiment 4, the radiation analyzer 100 does not have a correction unit 2. The signal processing unit 3 is connected to the analysis unit 1. The configuration of the other parts of the radiation analyzer 100 is the same as in Embodiments 1 to 3.

[0104] In Embodiment 4, the analysis unit 1 also performs the processing performed by the correction unit 2 in Embodiments 1 to 3. The calculation unit 11 performs information processing equivalent to the processing performed by the correction unit 2 in Embodiments 1 to 3, according to the computer program 141. In order for the radiation analyzer 100 to analyze the elements contained in the sample 5, the radiation detector 43 and the signal processing unit 3 repeatedly perform the processing S11 to S15 as in Embodiments 1 to 3, and the analysis unit 1 performs the processing S21 to S25.

[0105] In S21, the analysis unit 1 receives data from the signal processing unit 3 indicating the relationship between the wave height of the response wave and the number of counts counted by the counting unit 36, thereby acquiring the detected radiation intensity. In S22, the analysis unit 1 performs dead time correction on the acquired detected radiation intensity in the same manner as the correction unit 2 in Embodiments 1 to 3. In S23, the analysis unit 1 performs thumb peak correction on the detected radiation intensity after dead time correction in the same manner as the correction unit 2 in Embodiments 1 to 3. The analysis unit 1 may perform S22 and S23 together. Furthermore, the analysis unit 1 performs the processes in S24 to S25 in the same manner as in Embodiments 1 to 3. Similar to Embodiments 1 and 2, the radiation analyzer 100 continues to transport the sample 5 by the roller 45, repeats the processes in S11 to S15, and repeats the processes in S21 to S25.

[0106] In Embodiment 4, the radiation analyzer 100 performs dead time correction and sum peak correction, and calculates the concentration of a specific element contained in the sample 5 based on the corrected radiation detection intensity. The radiation detection intensity is corrected by the dead time correction and sum peak correction, and based on the corrected radiation detection intensity, it becomes possible to accurately determine the amount of a specific element contained in the sample 5.

[0107] The radiation analyzer 100 may also be configured such that the analysis unit 1 implements some or all of the functions of the signal processing unit 3. In this configuration, the calculation unit 11 executes some or all of the processing performed by the signal processing unit 3 in embodiments 1 to 3 according to the computer program 141. For example, the signal processing unit 3 may not have a counting unit 36, and the analysis unit 1 may perform the processing of counting response waves by wave height.

[0108] Embodiments 1 to 4 show examples of calculating the concentration of a specific element contained in the sample 5 using a calibration curve, but the radiation analyzer 100 may also calculate the concentration of an element using a method other than the calibration curve method. For example, the analysis unit 1 may calculate the concentration of a specific element contained in the sample 5 based on a function or table that represents the relationship between the detected intensity of corrected radiation and the concentration of the specific element. The analysis unit 1 may be composed of a microcontroller.

[0109] In embodiments 1 to 4, the sample 5 is shown to be transported by rollers 45, but the radiation analyzer 100 may also be configured to measure the amount of a specific element contained in a fixed sample 5. For example, the radiation analyzer 100 may be equipped with a sample stage, irradiate the sample 5 placed on the sample stage with radiation, and detect the radiation emitted from the sample 5. The sample 5 may have a shape other than a sheet. For example, the sample 5 may have a three-dimensional shape. The radiation analyzer 100 may also be configured without an irradiation unit 42. For example, the radiation analyzer 100 may be configured to detect radiation emitted from a sample 5 containing a radioactive element and calculate the concentration of the radioactive element contained in the sample 5.

[0110] In embodiments 1 to 4, the radiation detector 43 was shown to be a radiation detector having a radiation detection element made of semiconductors. The radiation detector 43 may also be a radiation detector having a radiation detection element other than a radiation detection element made of semiconductors. The radiation detector 43 is not limited to an energy-dispersive type detector. In embodiments 1 to 4, the horizontal axis of the radiation spectrum was shown to be energy, but the radiation analyzer 100 may also be a configuration that handles a spectrum with a value other than energy, such as wavelength or wavenumber, on the horizontal axis.

[0111] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. That is, embodiments obtained by combining technical means that have been appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

[0112] The matters described in each embodiment can be combined with each other. Furthermore, the independent and dependent claims described in the claims can be combined with each other in any combination, regardless of the form of reference. Moreover, although the claims use a form in which claims referencing two or more other claims (multi-claim form), they are not limited to this. A form in which multi-claims referencing at least one multi-claim (multi-multi-claim) may also be used.

[0113] 100 X-ray analyzer 1 Analysis unit 10 Recording medium 11 Calculation unit 14 Storage unit 141 Computer program 2 Correction unit 3 Signal processing unit 42 Irradiation unit 43 Radiation detector 45 Roller (transport unit) 46 Calibration curve storage unit 5 Sample

Claims

1. A radiation analysis method characterized by: detecting radiation emitted from a sample using a radiation detector; determining the detected radiation intensity by counting the response waves included in the output signal output from the radiation detector in response to the detection of radiation; performing a sum peak correction to correct the detected radiation intensity affected by the overlap of multiple response waves through statistical processing; and calculating the amount of a specific element contained in the sample based on the detected radiation intensity corrected by the sum peak correction.

2. The radiation analysis method according to claim 1, characterized in that a first shaped signal is generated by shaping the output signal with a first trapezoidal filter, radiation is detected by determining whether a response wave is included in the output signal using the first shaped signal, and in the sum peak correction, the detected radiation intensity is corrected by calculating the corrected radiation count rate using the time constant of the first trapezoidal filter.

3. The radiation analysis method according to claim 2, characterized in that, in the sum peak correction, the detected intensity of radiation is corrected by calculating ICR' = ICR / exp(-ICR・T1), where ICR is the count rate of radiation before correction by the sum peak correction, ICR' is the count rate of radiation after correction by the sum peak correction, and T1 is the time constant of the first trapezoidal filter.

4. The radiation analysis method according to claim 1, characterized in that the wave height of the response wave included in the output signal is measured, the detected radiation intensity is determined according to the wave height of the response wave, and in the sum peak correction, the detected radiation intensity related to the first wave height is corrected based on the detected radiation intensity related to the second wave height obtained due to the overlap of a plurality of response waves including a response wave having a first wave height.

5. A radiation analysis method according to any one of claims 1 to 4, characterized by performing dead time correction, which corrects the detected radiation intensity according to the dead time, which is a period during which radiation cannot be detected, and the sum peak correction.

6. A radiation analysis method according to any one of claims 1 to 4, characterized in that a dead time correction is performed to correct the detected radiation intensity according to the dead time, which is a period during which radiation cannot be detected, and the detected radiation intensity corrected by the dead time correction is corrected by the sum peak correction.

7. The radiation analysis method according to claim 5 or 6, characterized in that the actual time for detecting radiation and the dead time are measured, and in the dead time correction, the detected radiation intensity is corrected by calculating ICR = OCR・RT / (RT-DT), where OCR is the count rate of radiation before correction by the dead time correction, ICR is the count rate of radiation after correction by the dead time correction, RT is the actual time, and DT is the dead time.

8. A radiation analysis method according to any one of claims 1 to 7, characterized in that the amount of a specific element contained in the sample is calculated using a calibration curve that shows the relationship between the detected intensity of radiation corrected by the sum peak correction and the amount of a specific element.

9. A radiation analyzer comprising: a radiation detector for detecting radiation emitted from a sample; a signal processing unit for determining the detected radiation intensity by counting response waves included in the output signal output from the radiation detector in response to the detection of radiation; a correction unit for correcting the detected radiation intensity affected by the overlap of multiple response waves through statistical processing; and an analysis unit for calculating the amount of a specific element contained in the sample based on the detected radiation intensity corrected by the correction unit.

10. The radiation analyzer according to claim 9, further comprising a transport unit for transporting the sample and an irradiation unit for irradiating the sample with radiation while it is being transported.

11. The radiation analyzer according to claim 10, characterized in that the sample is in the form of a sheet, and the transport unit transports the sample in a direction along the surface of the sample.

12. A computer program characterized by having a computer perform the following processes: acquire the detection intensity of radiation emitted from a sample; statistically correct the detection intensity of radiation, which is affected by the superposition of multiple response waves included in the output signal output from the radiation detector in response to the detection of radiation; and calculate the amount of a specific element contained in the sample based on the corrected detection intensity of radiation.

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