Signal processing method, computer program, signal processing device, and radiation detection device

Abstract

Provided are a signal processing method, a computer program, a signal processing device, and a radiation detection device for improving the efficiency of detecting radiation.　The signal processing method counts, by wave height, stepped waves that are based on detection of radiation or pulse waves obtained by converting the stepped waves, wherein in order to cancel out a distortion of a waveform caused by a signal delay included in first stepped waves obtained on the basis of detection of radiation, a plurality of signal values constituting signals containing the first stepped waves are converted into a plurality of signal values constituting signals containing second stepped waves, and the second stepped waves or pulse waves obtained by converting the second stepped waves are counted by wave height.

Description

[Technical Field]

[0001] The present invention relates to a signal processing method, a computer program, a signal processing device, and a radiation detection device for processing a signal generated by detecting radiation. [Background technology]

[0002] A radiation detection device that detects radiation such as X-rays includes a radiation detector and a signal processing device that processes a signal output by the radiation detector. The radiation detector is configured using a semiconductor radiation detection element or the like, and outputs a step wave each time radiation is detected. The signal processing device converts the step wave into a pulse wave and measures the height of the pulse wave. The height of the pulse wave corresponds to the energy of the radiation. Patent Document 1 discloses an example of a radiation detection device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6574957 Summary of the Invention [Problem to be solved by the invention]

[0004] A pulse wave spreads with a certain time constant and has a width. Multiple adjacent pulse waves may overlap, causing the pulse wave height to change. When this happens, the wrong radiation energy is measured, and a peak with an incorrect energy, known as a sum peak, appears in the radiation spectrum. To prevent the occurrence of a sum peak, radiation is not counted when multiple pulse waves overlap. Because it is necessary to detect the overlap of multiple pulse waves, the pulse height value is calculated over a time longer than the pulse width. However, when the pulse width is large, the time required to measure the pulse height increases, reducing the efficiency of radiation detection.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a signal processing method, a computer program, a signal processing device, and a radiation detection device that improve the efficiency of detecting radiation. [Means for solving the problem]

[0006] A signal processing method according to the present invention is a signal processing method for counting, by wave height, a step wave in response to the detection of radiation or a pulse wave converted from the step wave, characterized in that a plurality of signal values ​​constituting a signal including a first step wave are converted into a plurality of signal values ​​constituting a signal including a second step wave so as to cancel out waveform distortion due to signal delay contained in a first step wave obtained in response to the detection of radiation, and the second step wave or a pulse wave converted from the second step wave are counted by wave height.

[0007] In one aspect of the present invention, a signal including a first staircase wave is converted into a signal including a second staircase wave, and the second staircase wave or a pulse wave converted from the second staircase wave is counted by wave height. The first staircase wave contains waveform distortion due to signal delay, and the signal including the first staircase wave is converted into a signal including a second staircase wave so as to cancel out the waveform distortion. As a result, the time width of the second staircase wave is shortened, and the pulse width of the pulse wave converted from the second staircase wave is shortened. Because the time width and pulse width of the second staircase wave are shortened, the wave height of the second staircase wave or the pulse wave can be measured in a shorter time.

[0008] The signal processing method according to the present invention is characterized in that the transformed signal value is calculated by using an inverse function of the difference equation representing the signal delay.

[0009] In one aspect of the present invention, a converted signal value is calculated by a calculation using an inverse function of a difference equation that represents a signal delay. The difference equation represents the relationship between a signal value changed by a signal delay and a signal value before the signal delay. The inverse function expresses the signal value before the signal delay as a function of the signal value changed by the signal delay. By calculating using the inverse function, a signal including a first step wave can be restored to the signal before the signal delay, thereby obtaining a signal that does not include distortion due to the signal delay.

[0010] The signal processing method according to the present invention is characterized in that the time constant of the signal delay is calculated by fitting a theoretical equation of the waveform of the first step wave to the first step wave.

[0011] In one embodiment of the present invention, under the assumption that the signal delay is first-order, let t be time and T c The waveform of the first staircase wave is (1-e -t / Tc The time constant of the signal delay is calculated by fitting a theoretical equation for the waveform, such as a theoretical equation expressed as an equation proportional to ), to the first step wave. The obtained time constant can be used to convert the signal value into a signal value in which waveform distortion due to the signal delay is canceled out. Alternatively, by calculating the time constant of the signal delay in real time, an accurate time constant corresponding to the first step wave can be obtained, enabling accurate conversion of the signal value.

[0012] The signal processing method according to the present invention is characterized in that at least one of a signal including a second staircase wave and a signal including a pulse wave converted from the second staircase wave is input to a learning model that outputs information regarding whether or not multiple pulse waves overlap when at least one of a signal including a staircase wave and a signal including a pulse wave converted from the second staircase wave is input, and the second staircase wave or the pulse wave when there is no overlap of the multiple pulse waves is counted according to the information output by the learning model, and the learning model is trained using training data including a signal including a single pulse wave or a signal including a single second staircase wave, and a signal including multiple overlapping pulse waves or a signal including multiple second staircase waves and resulting in multiple overlapping pulse waves converted from the multiple second staircase waves.

[0013] In one embodiment of the present invention, a learning model is used to determine whether or not multiple pulse waves overlap. The learning model is trained using a second staircase wave or a pulse wave converted from the second staircase wave. The time width and pulse width of the second staircase wave are shortened, making the difference between when multiple pulse waves overlap and when they do not become more pronounced. By using the learning model, it is possible to effectively detect overlap of multiple pulse waves.

[0014] The computer program according to the present invention is characterized in that it causes a computer to execute a process of identifying a time constant of a signal delay contained in a first staircase wave obtained in response to detection of radiation, and converting a plurality of signal values ​​constituting a signal including the first staircase wave into a plurality of signal values ​​constituting a signal including a second staircase wave using the time constant so as to cancel out waveform distortion due to the signal delay contained in the first staircase wave.

[0015] In one aspect of the present invention, a signal including a first staircase wave is converted into a signal including a second staircase wave so as to cancel out waveform distortion included in the first staircase wave. The time width of the second staircase wave is shortened. As a result, the pulse wave obtained by converting the second staircase wave has a shortened pulse width, and when the wave height of the second staircase wave or the pulse wave is measured, the measurement can be performed in a shorter time.

[0016] The signal processing device according to the present invention is characterized by comprising: a signal value conversion unit that converts a plurality of signal values ​​constituting a signal including a first staircase wave obtained in response to radiation detection into a plurality of signal values ​​constituting a signal including a second staircase wave so as to cancel out waveform distortion due to signal delay contained in the first staircase wave; and a counting unit that counts the second staircase wave or a pulse wave converted from the second staircase wave by wave height.

[0017] In one aspect of the present invention, a signal processing device converts a signal including a first staircase wave into a signal including a second staircase wave so as to cancel out waveform distortion contained in the first staircase wave, and counts the second staircase wave or a pulse wave converted from the second staircase wave by wave height. The time width of the second staircase wave is shortened, and the pulse width of the pulse wave converted from the second staircase wave is shortened. Because the time width and pulse width of the second staircase wave are shortened, the wave height of the second staircase wave or the pulse wave can be measured in a shorter time.

[0018] The radiation detection device according to the present invention is characterized by comprising: a radiation detector that generates a first staircase wave in response to incidence of radiation and outputs the first staircase wave; a signal value conversion unit that converts a plurality of signal values ​​constituting a signal including the first staircase wave into a plurality of signal values ​​constituting a signal including a second staircase wave so as to cancel out waveform distortion contained in the first staircase wave due to signal delay; a counting unit that counts the second staircase wave or a pulse wave converted from the second staircase wave by wave height; and a spectrum generation unit that generates a spectrum of radiation in accordance with the wave height and count number of the second staircase wave or the pulse wave.

[0019] In one aspect of the present invention, a radiation detection device generates a first step wave in response to incident radiation, converts a signal including the first step wave into a signal including a second step wave so as to cancel out waveform distortion, and counts the second step wave or a pulse wave converted from the second step wave by wave height. The time width of the second step wave is shortened, and the pulse wave converted from the second step wave has a shortened pulse width. Because the time width and pulse width of the second step wave are shortened, measurement of the wave height of the second step wave or the pulse wave can be performed in a shorter time. Since the time required to measure the wave height is shortened and the time required to detect radiation is shortened, efficiency of radiation detection is improved. [Effects of the Invention]

[0020] According to the present invention, the time required to measure the wave height of a step wave or a pulse wave in response to radiation detection is reduced, and since the time required to detect radiation is reduced, the present invention has excellent effects such as improving the efficiency of radiation detection. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a block diagram illustrating an example of the functional configuration of the radiation detection apparatus. [Figure 2] 1 is a block diagram showing the functional configuration of a radiation detector and a signal processing device according to a first embodiment. [Figure 3A] 5A and 5B are schematic characteristic diagrams showing examples of a step wave and a pulse wave. [Figure 3B] 5A and 5B are schematic characteristic diagrams showing examples of a step wave and a pulse wave. [Figure 4A] 10A and 10B are schematic characteristic diagrams showing examples of a step wave and a pulse wave when the interval at which radiation is detected is short. [Figure 4B] 10A and 10B are schematic characteristic diagrams showing examples of a step wave and a pulse wave when the interval at which radiation is detected is short. [Figure 5] 10 is a graph showing an example of a first step wave and a second step wave. [Figure 6] FIG. 2 is a conceptual diagram showing the function of a learning model according to the first embodiment. [Figure 7]4 is a flowchart showing the procedure of processing executed by the signal processing device according to the first embodiment. [Figure 8] FIG. 10 is a block diagram showing the functional configuration of a radiation detector and a signal processing device according to a second embodiment. [Figure 9] FIG. 10 is a block diagram showing the functional configuration of a radiation detector and a signal processing device according to a third embodiment. [Figure 10] FIG. 10 is a conceptual diagram showing the function of a learning model according to the third embodiment. [Figure 11] 10 is a flowchart showing the procedure of processing executed by a signal processing device according to a third embodiment. [Figure 12] FIG. 10 is a block diagram showing the functional configuration of a radiation detector and a signal processing device according to a fourth embodiment. [Figure 13] FIG. 10 is a conceptual diagram showing the function of a learning model according to the fourth embodiment. [Figure 14] 10 is a flowchart showing the procedure of processing executed by a signal processing device according to a fourth embodiment. [Figure 15] FIG. 11 is a block diagram showing the functional configuration of a signal value converter according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will now be described in detail with reference to the drawings showing embodiments thereof. <Embodiment 1> FIG. 1 is a block diagram showing an example of the functional configuration of a radiation detection apparatus 10. The radiation detection apparatus 10 is, for example, an X-ray fluorescence analysis apparatus. The radiation detection apparatus 10 includes an irradiation unit 4 that irradiates a sample 6 with radiation such as an electron beam or X-rays, a sample stage 5 on which the sample 6 is placed, and a radiation detector 1. Radiation is irradiated from the irradiation unit 4 to the sample 6, causing radiation such as fluorescent X-rays to be generated in the sample 6, and the radiation detector 1 detects the radiation generated from the sample 6. In the figure, the radiation is indicated by arrows. Note that the radiation detection apparatus 10 may also be configured to hold the sample 6 by a method other than placing it on the sample stage 5.

[0023] The radiation detector 1 is connected to a signal processing device 2 and a voltage application unit 34 that applies a voltage required for radiation detection to the radiation detection elements included in the radiation detector 1. The signal processing device 2 is connected to an analysis unit 32. The signal processing device 2, analysis unit 32, voltage application unit 34, and irradiation unit 4 are connected to a control unit 31. The control unit 31 controls the operations of the signal processing device 2, analysis unit 32, voltage application unit 34, and irradiation unit 4. The analysis unit 32 is connected to a display unit 33 such as a liquid crystal display or an EL display (Electroluminescent Display). The control unit 31 may be configured to receive user operations and control each unit of the radiation detection device 10 in accordance with the received operations. The control unit 31 and the analysis unit 32 may also be configured as a single computer.

[0024] FIG. 2 is a block diagram showing the functional configuration of a radiation detector 1 and a signal processing device 2 according to the first embodiment. For example, the radiation detection device 10 is an X-ray fluorescence analyzer. The radiation detector 1 includes a radiation detection element 11 and a preamplifier 12. The radiation detection element 11 generates an electric charge according to the energy of incident radiation and outputs a current signal according to the generated electric charge. For example, the radiation detection element 11 is a semiconductor radiation detection element such as an SDD (Silicon Drift Detector). The preamplifier 12 converts the current signal output by the radiation detection element 11 into a voltage signal and generates a staircase wave whose signal value increases stepwise upon radiation detection. The radiation detector 1 outputs a signal including the staircase wave generated by the preamplifier 12.

[0025] The signal output by the radiation detector 1 is input to the signal processing device 2. The signal processing device 2 executes a signal processing method. The signal processing device 2 includes an A / D (analog / digital) conversion unit 21. The A / D conversion unit 21 receives a signal including a step wave from the radiation detector 1 and performs A / D conversion on the signal including the step wave. The A / D conversion unit 21 receives a continuous signal, samples the signal, and A / D converts the value obtained by sampling to generate a discrete signal value.

[0026] The A / D conversion unit 21 is connected to the signal value conversion unit 22. The A / D conversion unit 21 inputs the A / D converted signal to the signal value conversion unit 22. The signal input to the signal value conversion unit 22 contains distortion due to signal delay. The signal is delayed due to the influence of bandwidth caused by the circuits of the radiation detector 1 and the signal processing device 2. The signal value conversion unit 22 performs processing to convert the signal value so as to cancel out the distortion. A step wave included in a signal formed by signal values ​​before conversion is defined as a first step wave, and a step wave included in a signal formed by signal values ​​after conversion is defined as a second step wave. The signal value conversion unit 22 is configured using, for example, a processor and a memory that stores programs and data required for the processor to perform calculations. The signal value conversion unit 22 may be configured using an FPGA (field-programmable gate array). The processing performed by the signal value conversion unit 22 will be described later.

[0027] The signal value converter 22 is connected to the waveform shaping unit 23. The waveform shaping unit 23 receives as input a signal including a second step wave from the signal value converter 22. The waveform shaping unit 23 passes the signal including the second step wave through a predetermined filter to shape the waveform of the signal, thereby converting the signal including the second step wave into a signal including a pulse wave. The filter used by the waveform shaping unit 23 is, for example, a differential filter or a trapezoidal shaping filter. Through processing in the waveform shaping unit 23, the second step wave is converted into a pulse wave, noise contained in the signal is reduced, and predetermined amplification is performed. The waveform shaping unit 23 outputs a signal. The signal output by the waveform shaping unit 23 includes a pulse wave in response to the detection of radiation by the radiation detector 1.

[0028] 3A and 3B are schematic characteristic diagrams showing examples of a step wave and a pulse wave. In the diagrams, the horizontal axis represents time and the vertical axis represents signal value. FIG. 3A shows an example of a signal including a step wave. Each time radiation is detected, the radiation detector 1 outputs a step wave in which the signal value increases in a single step. In response to one radiation detection, one step wave in which the signal value increases in a single step is generated. When the radiation detector 1 detects radiation multiple times, a signal including multiple step waves is output. Each time radiation is detected, the signal value increases. The height of the step in the increasing signal value is defined as the wave height of the step wave. The wave height of the step wave corresponds to the radiation energy.

[0029] FIG. 3B shows a signal obtained by converting the signal shown in FIG. 3A by the waveform shaping unit 23. The step wave is converted into a pulse wave. A pulse wave is a signal in which the signal value rises from a predetermined signal reference, where the signal value is zero, to a peak value, and then falls back to the signal reference. The signal reference is, for example, zero. The height from the signal reference to the peak value is defined as the pulse wave height. The pulse wave height corresponds to the radiation energy.

[0030] 4A and 4B are schematic characteristic diagrams showing examples of step waves and pulse waves when the intervals at which radiation is detected are short. In the diagrams, the horizontal axis represents time, and the vertical axis represents signal value. In the example shown in FIG. 4A, the intervals at which radiation is detected multiple times by the radiation detector 1 are short, and the intervals between the multiple step waves are short, compared to the example shown in FIG. 3A. FIG. 4B shows a signal obtained by converting the signal shown in FIG. 4A using the waveform shaping unit 23. The intervals between the multiple pulse waves are short, and a superimposed wave is formed in which the multiple pulse waves overlap. The height of the superimposed wave is different from the height of a single pulse wave, and an erroneous measurement of radiation energy will occur depending on the height of the superimposed wave.

[0031] The waveform shaping unit 23 is connected to the processing unit 24 and the pulse detection unit 25. The waveform shaping unit 23 inputs a signal containing a pulse wave to the processing unit 24 and the pulse detection unit 25. The pulse detection unit 25 receives the signal from the waveform shaping unit 23 and detects the pulse wave contained in the signal. For example, the pulse detection unit 25 determines that a pulse wave has been detected when the signal value exceeds a predetermined threshold. The pulse detection unit 25 is connected to the processing unit 24. When the pulse detection unit 25 detects a pulse wave, it inputs information indicating that a pulse wave has been detected to the processing unit 24.

[0032] The processing unit 24 receives a signal including a pulse wave from the waveform shaping unit 23 and receives information indicating that a pulse wave has been detected from the pulse detection unit 25. The processing unit 24 is configured using elements that perform calculations. The processing unit 24 includes a learning model 241 for determining whether or not multiple pulse waves overlap. For example, the learning model 241 is configured using an FPGA. For example, the learning model 241 is trained so that, when multiple signal values ​​are input, the learning model 241 outputs information indicating whether or not the signal includes multiple overlapping pulse waves. When a pulse wave is detected, the processing unit 24 uses the learning model 241 to determine whether or not the signal includes multiple overlapping pulse waves.

[0033] A pulse-height measuring unit 26 is connected to the waveform shaping unit 23 and the processing unit 24. The waveform shaping unit 23 inputs a signal including a pulse wave to the pulse-height measuring unit 26. The processing unit 24 inputs information indicating whether or not multiple pulse waves overlap to the pulse-height measuring unit 26. When multiple pulse waves do not overlap, the pulse-height measuring unit 26 measures the pulse height of the pulse wave included in the signal input from the waveform shaping unit 23. For example, the pulse-height measuring unit 26 determines the maximum signal value among multiple signal values ​​constituting the signal including the pulse wave to be the pulse height. The pulse-height measuring unit 26 may measure the pulse height by integrating the signal or accumulating the signal values. When multiple pulse waves overlap, the pulse-height measuring unit 26 does not measure the pulse height of the pulse wave included in the signal input from the waveform shaping unit 23.

[0034] The counting unit 27 is connected to the pulse height measuring unit 26. The pulse height measuring unit 26 inputs the measured pulse wave height to the counting unit 27. The counting unit 27 counts the pulse waves for each pulse height. For example, the counting unit 27 is a multi-channel analyzer. The counting unit 27 may be configured to count pulse waves for all pulse heights, or may be configured to count pulse waves only for a specific pulse height. The signal processing device 2 outputs data indicating the relationship between the pulse wave height and the count number counted by the counting unit 27. The count number corresponds to the number of times that the radiation detector 1 has detected radiation having energy corresponding to the pulse wave height.

[0035] When multiple pulse waves overlap, the pulse-height measuring unit 26 does not measure the height of the pulse waves, and therefore the signal processing device 2 does not count the overlapping pulse waves. Note that the pulse-height measuring unit 26 may be configured to measure the height of overlapping pulse waves but not input the measured wave height to the counting unit 27. The pulse-height measuring unit 26 may be configured to input the height of overlapping pulse waves to the counting unit 27, and the counting unit 27 may not count overlapping pulse waves. The pulse-height measuring unit 26 may be configured to input the height of overlapping pulse waves to the counting unit 27, and the counting unit 27 may count overlapping pulse waves separately from non-overlapping pulse waves.

[0036] The analysis unit 32 is composed of a computer such as a personal computer. The analysis unit 32 receives the data output by the signal processing device 2. The analysis unit 32 performs processing to generate a spectrum of the radiation detected by the radiation detector 1 from the relationship between the pulse wave height and the count number of the pulse wave. The analysis unit 32 corresponds to the spectrum generation unit. The analysis unit 32 may further perform further processing, such as elemental analysis of the radiation source, based on the generated spectrum of the radiation. For example, the radiation detector 1 detects fluorescent X-rays, and the analysis unit 32 performs qualitative analysis or quantitative analysis of the elements contained in the sample based on the spectrum of the fluorescent X-rays. The display unit 33 displays the spectrum generated by the analysis unit 32 and the analysis results by the analysis unit 32. The signal processing device 2 may also have a function to generate a spectrum of the radiation.

[0037] If overlapping pulse waves are erroneously counted as a single pulse wave and an incorrect radiation energy is measured, the radiation spectrum will contain a sum peak, which is a peak having an incorrect energy. If elemental analysis is performed based on a spectrum containing a sum peak, there is a risk of erroneously detecting an element that does not exist according to the sum peak. Alternatively, there is a risk that the sum peak will overlap with the peak of a present element, resulting in an excessive detection of the amount of that element.

[0038] The following describes the processing performed by the signal value converter 22. The signal value converter 22 converts a plurality of signal values ​​constituting a signal including a first staircase wave into a plurality of signal values ​​constituting a signal including a second staircase wave so as to cancel out waveform distortion contained in the first staircase wave due to signal delay.

[0039] A signal delay occurs during signal generation and signal processing before the signal is input to the signal value conversion unit 22, and distortion due to the signal delay is included in the signal input to the signal value conversion unit 22. The signal delay occurs due to the influence of the bandwidth caused by the characteristics of electronic components included in the circuits of the radiation detector 1 and the signal processing device 2. The characteristics of the electronic components that affect the signal delay are, for example, the parasitic capacitance of the electrodes included in the radiation detection element 11, the bandwidth of the preamplifier 12, or the electrostatic capacitance of the capacitor included in the A / D conversion unit 21.

[0040] When radiation is incident on the radiation detection element 11, electric charges are generated, and the group of charges spreads rapidly due to statistical effects. Then, due to the effect of the electric field formed inside the radiation detection element 11, the group of charges reaches an electrode provided in the radiation detection element 11. A current signal corresponding to the charges that have reached the electrode is output from the radiation detection element 11, and a step wave corresponding to the current signal is obtained. The step wave has a width due to the spread of the group of electric charges. If it is assumed that the spread of the group of electric charges is uniform in all directions, the width of the step wave follows a Gaussian. When the aforementioned signal delay is further applied to the step wave having a width according to a Gaussian, it becomes a first step wave.

[0041] When a low-pass filter using an RC circuit is applied to a signal containing a step wave with a vertical rise, a waveform similar to the first step wave is obtained. That is, as a result of signal delay caused by the bandwidth effect due to the circuit, the first step wave has a waveform equivalent to the waveform of a signal obtained by applying a virtual low-pass filter to a step wave with a Gaussian width. If a step wave before applying the virtual low-pass filter is obtained, the obtained step wave should not contain distortion due to signal delay. Therefore, if the signal containing the first step wave is inversely converted to a signal before applying the virtual low-pass filter, the inversely converted signal will not contain distortion due to signal delay. The signal value conversion unit 22 converts the signal value of the signal containing the first step wave to a signal before applying the virtual low-pass filter. This cancels out the waveform distortion contained in the first step wave. Furthermore, the signal containing the second step wave corresponds to the signal before applying the virtual low-pass filter.

[0042] Assume that the signal delay is first-order. The signal value before conversion by the signal value converter 22 (the signal value changed by the signal delay) is y, and the signal value after conversion (the signal value before being changed by the signal delay) is X. Let n be an integer, and the nth signal value before conversion is y n , the nth transformed signal value is X n The original signal value without signal delay is X n and the signal value Xn is the signal value y n The sampling interval by the A / D converter 21 is Δt, and the time constant of the first-order lag is T c The differential equation for the first-order lag is expressed as the following equation (1). T c dy / dt+y=X …(1) A differential equation in a continuous space is approximated by a difference equation in a discrete space. Equation (1) is approximated by the following difference equation, equation (2). T c (y n -y n-1 ) / Δt+y n =X n …(2) By rearranging equation (2), we obtain the following equation (3). y n =αy n-1 +(1-α)X n …(3) Here, α is expressed by the following equation (4). α=1 / (1+Δt / T c ) …(4) Equation (3) is a difference equation that represents a first-order signal delay. The inverse function of equation (3) is expressed by the following equation (5). X n =(y n -αy n-1 ) / (1-α) …(5) Equation (5) expresses the converted signal value (the signal value before it is changed by the signal delay) as a function of the pre-conversion signal value (the signal value changed by the signal delay). By using equation (5), the converted signal value X n can be calculated.

[0043] The signal consisting of a plurality of signal values ​​y before conversion is a signal including a first staircase wave. The signal consisting of a plurality of signal values ​​X after conversion is a signal including a second staircase wave. FIG. 5 is a graph showing examples of the first staircase wave and the second staircase wave. The horizontal axis of FIG. 5 represents time, and the vertical axis represents signal strength. The units of the horizontal and vertical axes are arbitrary units. In FIG. 5, the signal including the first staircase wave is shown by a dashed line, and the signal including the second staircase wave is shown by a solid line. The signal including the second staircase wave shown in FIG. 5 is a signal obtained by converting the signal including the first staircase wave using equation (5).

[0044] While the first staircase wave contains waveform distortion due to signal delay, the second staircase wave cancels out this waveform distortion. As a result, the second staircase wave has a more vertical rise compared to the first staircase wave, and the time it takes for the signal strength to stabilize after rising is shorter. This shortens the time width of the staircase wave, which corresponds to the time it takes for the signal value to rise in a single step.

[0045] Signal delay time constant T c is determined by the characteristics of the electronic components included in the circuits of the radiation detector 1 and the signal processing device 2, and is a constant specific to the radiation detection device 10. That is, for all the first step waves generated by the radiation detection device 10, the signal delay time constant T c are the same. The signal delay time constant T c can be estimated from a signal containing the first staircase wave. Assuming that the signal delay is first-order lag, the theoretical formula for the waveform of the first staircase wave from the rising of the signal value until the rising of the signal value ends is (1-e -t / Tc ) is proportional to the time constant T c By fitting the theoretical equation of the waveform including c The signal value converter 22 calculates the time constant T c is stored in advance.

[0046] The signal value converter 22 may convert the signal value so as to cancel out waveform distortion caused by signal delays other than first-order lag. The difference equation representing the first-order signal delay shown in equation (3) can be more generally expressed by the following equation (6). y n =aX n +by n-1 …(6) The inverse function of equation (6) is expressed by the following equation (7). X n =(1 / a)y n -(b / a)y n-1 …(7) As shown in equations (3) and (4), the coefficients in equation (7) include the time constant of the first-order signal delay. Similarly, the difference equation representing the signal delay including the second-order delay is expressed by equation (8) below, and the inverse function is expressed by equation (9) below. y n =aX n +by n-1 +cy n-2 …(8) X n =(1 / a)y n -(b / a)y n-1 -(c / a)y n-2 …(9) The difference equation representing the signal delay including the third-order delay is expressed by the following equation (10), and the inverse function is expressed by the following equation (11). y n =aX n +by n-1 +cy n-2 +dy n-3 …(10) X n =(1 / a)y n -(b / a)y n-1 -(c / a)y n-2 -(d / a)y n-3 …(11) The coefficients in equation (9) include the time constants of the signal delays of the first order lag and the second order lag. The coefficients in equation (11) include the time constants of the signal delays of the first order lag, the second order lag, and the third order lag.

[0047] The signal value converter 22 converts the signal value X by using equation (9) so as to cancel out the distortion of the waveform due to the signal delay including the second-order delay. n In this case, the signal value converter 22 calculates the time constant T c Alternatively, the signal value converter 22 may use the equation (11) to convert the signal value X n In this case, the signal value converter 22 calculates the time constant T c In addition to the above, the signal value converter 22 uses the time constant of the second-order delay and the time constant of the third-order delay in addition to the above. Similarly to the equations (7), (9), and (11), the signal value converter 22 uses the inverse function of the difference equation representing the signal delay including the fourth-order or higher delay to convert the signal value X n may be calculated.

[0048] The signal value conversion unit 22 further applies a predetermined filter to the converted signal to reduce noise contained in the signal. The signal value conversion unit 22 sequentially inputs the converted signal values ​​with reduced noise to the waveform shaping unit 23, thereby inputting the signal containing the second step wave to the waveform shaping unit 23. Note that the process of reducing noise contained in the converted signal does not have to be performed by the signal value conversion unit 22, and may be performed before the waveform of the signal is shaped by the waveform shaping unit 23.

[0049] The waveform shaping unit 23 shapes the signal including the second step wave, thereby converting the signal including the second step wave into a signal including a pulse wave. Since the time width of the second step wave is shortened, the pulse wave obtained by converting the second step wave has a shorter pulse width than the pulse wave obtained by converting the first step wave. The waveform shaping unit 23 inputs the signal including the pulse wave obtained by converting the signal including the second step wave to the processing unit 24, the pulse detection unit 25, and the pulse height measurement unit 26. The processing unit 24, the pulse detection unit 25, and the pulse height measurement unit 26 process the pulse wave obtained by converting the second step wave. In other words, the processing unit 24, the pulse detection unit 25, and the pulse height measurement unit 26 process the pulse wave with the shortened pulse width.

[0050] A method for determining whether or not there is overlap of multiple pulse waves in the processing unit 24 will be described. FIG. 6 is a conceptual diagram showing the function of the learning model 241 according to the first embodiment. A signal including a pulse wave is input to the learning model 241. More specifically, a plurality of signal values ​​constituting the signal including a pulse wave are input to the learning model 241. The learning model 241 is trained in advance so that when a signal including a pulse wave is input, the learning model 241 outputs information indicating whether or not there is overlap of multiple pulse waves.

[0051] For example, the learning model 241 is configured with a neural network. A plurality of signal values ​​constituting a signal including a pulse wave are input to a plurality of nodes including an input layer, calculations are performed in one or more intermediate layers, and information indicating whether or not a plurality of pulse waves overlap is output from an output layer. The learning model 241 may be configured with a fully connected neural network, a convolutional neural network (CNN), or a recurrent neural network (RNN).

[0052] Learning of the learning model 241 is performed using a computer. The computer performs learning using training data including a pulse wave signal including a single pulse wave and a superimposed wave signal including multiple overlapping pulse waves. The pulse wave signal is a signal including a pulse wave converted from a second step wave. The superimposed wave signal is a signal including multiple overlapping pulse waves converted from the second step wave. The training data includes multiple pulse wave signals and multiple superimposed wave signals. The pulse wave signal is associated with information indicating that the multiple pulse waves do not overlap, and the superimposed wave signal is associated with information indicating that the multiple pulse waves overlap.

[0053] The learning model 241 receives input of multiple signal values ​​constituting a pulse wave signal or multiple signal values ​​constituting a superimposed wave signal, and outputs information indicating whether or not multiple pulse waves overlap. An error in the information is calculated using an error function whose variables are information associated with the input pulse wave signal or superimposed wave signal and information output from the learning model 241, and the parameters of the operation of each node in the learning model 241 are adjusted to minimize the error. That is, the parameters are adjusted so that when a pulse wave signal is input, information indicating no overlap of multiple pulse waves is output, and when a superimposed wave signal is input, information indicating an overlap of multiple pulse waves is output. For example, the parameters are adjusted using the error backpropagation method.

[0054] Machine learning of the learning model 241 is performed by repeating the process of adjusting parameters using a plurality of pulse wave signals and a plurality of superimposed wave signals. The trained learning model 241 is generated by generating trained data that records the final adjusted parameters. The learning model 241 included in the processing unit 24 is manufactured based on the trained data. For example, the learning model 241 is manufactured by storing in the processing unit 24 a program and data for realizing the parameters recorded in the trained data. For example, the learning model 241 is manufactured by configuring a logic circuit of an FPGA included in the processing unit 24 to realize the parameters recorded in the trained data.

[0055] Next, the processing executed by the signal processing device 2 will be described. FIG. 7 is a flowchart showing the procedure of the processing executed by the signal processing device 2 according to the first embodiment. Hereinafter, step will be abbreviated as S. When radiation is incident on the radiation detection element 11, the radiation detector 1 generates a step wave according to the energy of the radiation and outputs a signal including the step wave. The signal processing device 2 receives the signal including the step wave from the radiation detector 1 (S101). The A / D conversion unit 21 A / D converts the input signal (S102). The A / D conversion unit 21 inputs the A / D converted signal to the signal value conversion unit 22.

[0056] The signal value conversion unit 22 converts the time constant T c In S103, the signal value converter 22 determines the time constant T c By reading out the time constant T c When the signal input from the A / D converter 21 includes a first step wave, the signal value converter 22 determines the time constant T c By calculating the time constant T c For example, the signal value conversion unit 22 may determine the time constant T of the signal delay by fitting the first step wave included in the input signal to a theoretical equation of the first step wave, which assumes that the signal delay is a first-order lag. c Calculate the time constant T of the signal delay in real time. c By calculating the time constant T c is obtained, enabling accurate conversion of signal values.

[0057] The signal value converter 22 calculates the signal delay time constant T c (S104). In S104, the signal value converter 22 converts the signal values ​​by performing calculations based on equation (5). In S104, signal values ​​are sequentially input, and the signal value converter 22 sequentially converts the input signal values. When a signal including a first staircase wave is input from the A / D converter 21, the signal value converter 22 converts the input signal into a signal including a second staircase wave. The signal value converter 22 further performs processing to apply a filter to the signal to reduce noise contained in the converted signal. The signal value converter 22 inputs the signal made up of the converted signal values ​​and after applying the filter to the waveform shaping unit 23. The signal value converter 22 may convert the signal values ​​so as to cancel out waveform distortion caused by signal delays including second-order or higher delays by performing calculations based on equations (9) or (11), etc. In this embodiment, the signal value converter 22 specifies a time constant for a delay of second order or higher in advance in S103.

[0058] The waveform shaping unit 23 shapes the waveform of the input signal (S105). By shaping the waveform, the waveform shaping unit 23 converts the second step wave included in the signal into a pulse wave. The waveform shaping unit 23 inputs the signal including the pulse wave to the processing unit 24, the pulse detection unit 25, and the pulse height measurement unit 26.

[0059] The pulse detection unit 25 determines whether or not a pulse wave contained in the input signal has been detected (S106). In S106, for example, the pulse detection unit 25 determines that a pulse wave contained in the signal has been detected if the signal value exceeds a predetermined threshold. The threshold is stored in advance in the pulse detection unit 25. If a pulse wave has not been detected (S106: NO), the pulse detection unit 25 repeats the process of S106.

[0060] If a pulse wave contained in the signal is detected (S106: YES), the pulse detection unit 25 inputs information indicating that a pulse wave has been detected to the processing unit 24, and the processing unit 24 inputs the signal including the pulse wave to the learning model 241 (S107). In response to the input of the signal, the learning model 241 performs a process of outputting information indicating whether or not there is overlap of multiple pulse waves. The processing unit 24 inputs the information indicating whether or not there is overlap of multiple pulse waves output by the learning model 241 to the pulse height measurement unit 26.

[0061] The pulse-height measuring unit 26 determines whether or not there is overlap of multiple pulse waves based on the information input from the processing unit 24 (S108). If information indicating that there is no overlap of multiple pulse waves is input and there is no overlap of multiple pulse waves (S108: NO), the pulse-height measuring unit 26 measures the height of the pulse wave included in the input signal (S109). The pulse-height measuring unit 26 inputs the measured pulse height to the counting unit 27.

[0062] The counting unit 27 counts the pulse waves for each pulse height input from the pulse-height measuring unit 26 (S110) and ends the process. If information indicating that multiple pulse waves overlap is input to the pulse-height measuring unit 26 and multiple pulse waves overlap (S108: YES), the pulse-height measuring unit 26 does not measure the height of the multiple overlapping pulse waves, and the signal processing device 2 ends the process. As a result, the counting unit 27 does not count the multiple overlapping pulse waves. If multiple pulse waves overlap, the pulse wave heights are incorrect, and by not counting, the occurrence of a sum peak is prevented. The signal processing device 2 repeatedly executes the processes of S101 to S110 individually.

[0063] The signal processing device 2 outputs data indicating the relationship between the pulse wave height and the number of counts counted by the counting unit 27. The analysis unit 32 receives the data output by the signal processing device 2 and generates a spectrum of the radiation detected by the radiation detector 1 based on the data.

[0064] As described above in detail, in this embodiment, the signal processing device 2 converts a signal including a first step wave into a signal including a second step wave and counts the pulse wave obtained by converting the second step wave by wave height. The first step wave contains waveform distortion due to signal delay, and the signal processing device 2 converts the signal including the first step wave into a signal including a second step wave so as to cancel out the waveform distortion. As a result, the time width of the second step wave is shortened, and the pulse wave obtained by converting the second step wave has a shortened pulse width. Because the pulse width is shortened, the detection of the pulse wave by the pulse detection unit 25 and the measurement of the wave height of the pulse wave by the wave height measurement unit 26 can be performed in a shorter time. The time required to measure the wave height is shortened, and the time required to detect radiation is also shortened, thereby improving the efficiency of radiation detection.

[0065] Furthermore, because the pulse width is shortened, the difference between a single pulse wave and multiple overlapping pulse waves becomes more apparent. The learning model 241 is trained using pulse waves with a shortened pulse width, and can clearly distinguish between a single pulse wave and multiple overlapping pulse waves. By using the learning model 241, it is possible to effectively detect the overlap of multiple pulse waves. This can prevent erroneous measurement of radiation energy due to overlapping pulse waves and prevent the occurrence of sum peaks in the radiation spectrum. This can improve the accuracy of elemental analysis based on spectra.

[0066] Furthermore, since the pulse width is shortened, multiple pulse waves are less likely to overlap with each other. This reduces the number of pulse waves that are not counted due to multiple pulse waves overlapping, and increases the chances of counting pulse waves. This increases the number of times radiation can be detected per unit time, improving the efficiency of radiation detection.

[0067] Although the present embodiment shows a configuration in which the learning model 241 is used, the signal processing device 2 may be configured to detect overlapping of pulse waves without using the learning model 241. For example, the processing unit 24 may be configured to detect a pulse width and compare the pulse width with a predetermined threshold value to determine whether or not overlapping of pulse waves occurs.

[0068] <Embodiment 2> 8 is a block diagram showing the functional configuration of the radiation detector 1 and the signal processing device 2 according to the second embodiment. The configuration and functions of the portions of the radiation detection device 10 other than the signal processing device 2 are the same as those of the first embodiment. The processing unit 24 is connected to the signal value conversion unit 22 and the waveform shaping unit 23. The processing unit 24 receives as input the signal including the second step wave from the signal value conversion unit 22 and the signal including the pulse wave from the waveform shaping unit 23.

[0069] The learning model 241 is pre-trained to output information indicating whether or not multiple pulse waves overlap when a signal including a second step wave and a signal including a pulse wave are input. The learning model 241 receives multiple signal values ​​constituting the signal including the second step wave in addition to multiple signal values ​​constituting the signal including the pulse wave. Training data for training the learning model 241 includes a pulse wave signal containing a single pulse wave, a superimposed wave signal containing multiple overlapping pulse waves, a signal containing a single second step wave, and a signal containing multiple second step waves converted into multiple overlapping pulse waves by conversion in the waveform shaping unit 23. The signal containing multiple second step waves is a signal in which multiple pulse waves obtained by converting the multiple second step waves overlap. The configuration of the signal processing device 2 other than the signal value conversion unit 22 and the processing unit 24 is the same as that of the first embodiment.

[0070] The signal processing device 2 executes the processes of S101 to S106, as in the first embodiment. In S107, the processing unit 24 inputs to the learning model 241 a plurality of signal values ​​constituting the signal including the pulse wave input from the waveform shaping unit 23 and a plurality of signal values ​​constituting the signal including the second step wave input from the signal value conversion unit 22. In response to the input of the signal, the learning model 241 executes a process of outputting information indicating whether or not there is overlap of a plurality of pulse waves. The signal processing device 2 executes the processes of S108 to S110, as in the first embodiment. The signal processing device 2 outputs data indicating the relationship between the pulse wave height and the count number, and the analysis unit 32 receives the data output by the signal processing device 2 and generates a spectrum of the radiation detected by the radiation detector 1.

[0071] As described above in detail, in the second embodiment as well, the signal processing device 2 converts a signal including a first step wave into a signal including a second step wave, and counts the pulse waves obtained by converting the second step wave by wave height. The time width of the second step wave is shortened, and the pulse width of the pulse wave is shortened. Detection of the pulse wave and measurement of the wave height of the pulse wave can be performed in a shorter time, and multiple pulse waves are less likely to overlap with each other. This improves the efficiency of radiation detection. Furthermore, in the second embodiment, overlapping of multiple pulse waves can be effectively detected by detecting overlapping of pulse waves using a signal including the second step wave in addition to a signal including a pulse wave.

[0072] The signal processing device 2 may be configured to detect overlapping of multiple pulse waves using a signal including a second step wave instead of a signal including a pulse wave. In this configuration, the learning model 241 is pre-trained to output information indicating whether or not multiple pulse waves overlap when a signal including a second step wave is input. The learning model 241 is trained using training data including a signal including a single second step wave and a signal including multiple second step waves converted into multiple overlapping pulse waves. In S107, the signal processing device 2 does not input a signal including a pulse wave to the learning model 241, but inputs a signal including the second step wave to the learning model 241. Because the time width of the second step wave is shortened, the difference between the single second step wave and multiple second step waves resulting from the overlapping of multiple pulse waves becomes significant. This allows the signal processing device 2 to effectively detect overlapping of multiple pulse waves.

[0073] <Embodiment 3> In the third embodiment, a learning model 241 is used to determine the presence or absence of a pulse wave. FIG. 9 is a block diagram showing the functional configuration of a radiation detector 1 and a signal processing device 2 according to the third embodiment. The configuration and functions of the radiation detection device 10 other than the signal processing device 2 are the same as those in the first embodiment. The signal processing device 2 includes an A / D conversion unit 21, a signal value conversion unit 22, a waveform shaping unit 23, a processing unit 24, a pulse height measurement unit 26, and a counting unit 27. The processing unit 24 receives as input at least one of a signal including a second step wave from the signal value conversion unit 22 and a signal including a pulse wave from the waveform shaping unit 23. The processing unit 24 inputs information regarding the number of pulse waves to the pulse height measurement unit 26.

[0074] FIG. 10 is a conceptual diagram illustrating the function of the learning model 241 according to the third embodiment. The learning model 241 is trained so as to output information regarding the number of pulse waves contained in a signal when a signal including a pulse wave and / or a second step wave is input. For example, the learning model 241 outputs information indicating that the signal does not include a pulse wave, information indicating that the signal includes only one pulse wave, or information indicating that the signal includes multiple overlapping pulse waves. The learning model 241 is trained using training data including a signal that does not include a pulse wave or a second step wave, a signal that includes a single pulse wave and / or a single second step wave, and a signal that includes multiple pulse waves and / or a signal that includes multiple second step waves.

[0075] 11 is a flowchart showing the procedure of processing executed by the signal processing device 2 according to embodiment 3. The signal processing device 2 receives a signal including a step wave from the radiation detector 1 (S21), and the A / D conversion unit 21 A / D converts the signal (S22). The A / D conversion unit 21 inputs the A / D converted signal to the signal value conversion unit 22.

[0076] The signal value conversion unit 22 converts the time constant T c The signal value converter 22 determines the time constant T cThe signal value converter 22 converts a plurality of signal values ​​constituting the signal input from the A / D converter 21 using the above (S24). When a signal including a first staircase wave is input from the A / D converter 21, the signal value converter 22 converts the input signal into a signal including a second staircase wave in S24. The signal value converter 22 may convert the signal values ​​so as to cancel out waveform distortion caused by signal delays including second-order or higher delays. The signal value converter 22 inputs a signal consisting of the converted signal values ​​to the waveform shaping unit 23.

[0077] The waveform shaping unit 23 shapes the waveform of the input signal (S25). By waveform shaping, the second step wave is converted into a pulse wave. The waveform shaping unit 23 inputs the signal including the pulse wave to the pulse height measuring unit 26.

[0078] The processing unit 24 receives the signal from the signal value conversion unit 22 and / or the signal from the waveform shaping unit 23 as input, and inputs the input signal to the learning model 241 (S26). In response to the input signal, the learning model 241 outputs information regarding the number of pulse waves contained in the signal. The processing unit 24 inputs the information regarding the number of pulse waves contained in the signal to the pulse-height measurement unit 26.

[0079] Based on the input information, the pulse-height measurement unit 26 determines whether the signal contains one pulse wave (S27). If the number of pulse waves is one (S27: YES), the pulse-height measurement unit 26 measures the height of the pulse wave contained in the input signal (S28). The pulse-height measurement unit 26 inputs the measured pulse wave height to the counting unit 27. The counting unit 27 counts the pulse waves by height (S29) and ends the processing. If the signal does not contain a pulse wave or contains multiple overlapping pulse waves (S27: NO), the pulse-height measurement unit 26 does not measure the pulse height, and the signal processing device 2 ends the processing. As a result, the counting unit 27 does not count the multiple overlapping pulse waves. The signal processing device 2 repeatedly executes the processing of S21 to S29.

[0080] The signal processing device 2 outputs data indicating the relationship between the pulse wave height and the number of counts counted by the counting unit 27. The analysis unit 32 receives the data output by the signal processing device 2 and generates a spectrum of the radiation detected by the radiation detector 1 based on the data.

[0081] In the third embodiment as well, the efficiency of detecting radiation is improved by counting the pulse waves converted from the second step wave by wave height. Also in the third embodiment as well, by using the learning model 241, it is possible to effectively detect the overlap of multiple pulse waves and suppress the occurrence of sum peaks in the radiation spectrum.

[0082] <Embodiment 4> In the fourth embodiment, a form is shown in which the wave height is determined using a learning model 241. FIG. 12 is a block diagram showing the functional configuration of a radiation detector 1 and a signal processing device 2 according to the fourth embodiment. The configuration and function of the parts of the radiation detection device 10 other than the signal processing device 2 are the same as those in the first embodiment. The signal processing device 2 includes an A / D conversion unit 21, a signal value conversion unit 22, a processing unit 24, and a counting unit 27. The signal value conversion unit 22 inputs a signal including a second step wave to the processing unit 24.

[0083] FIG. 13 is a conceptual diagram illustrating the function of a learning model 241 according to the fourth embodiment. The learning model 241 is trained so that, when a signal including a second step wave is input, it outputs information regarding the number and height of the second step waves included in the signal. For example, the learning model 241 outputs information indicating zero height if the signal does not include a second step wave, outputs information indicating the height if the signal includes only one second step wave, and outputs information indicating the presence of multiple second step waves if the signal includes multiple overlapping second step waves. The learning model 241 is trained using training data including a signal without a second step wave, a signal including a single second step wave, and a signal including multiple second step waves.

[0084] 14 is a flowchart showing the procedure of processing executed by the signal processing device 2 according to the fourth embodiment. The signal processing device 2 receives a signal including a step wave from the radiation detector 1 (S31), and the A / D conversion unit 21 A / D converts the signal (S32). The A / D conversion unit 21 inputs the A / D converted signal to the signal value conversion unit 22. The signal value conversion unit 22 converts the signal into a digital signal by using a time constant T c The signal value converter 22 determines the time constant T c The signal value converter 22 converts the multiple signal values ​​constituting the signal input from the A / D converter 21 using the above (S34). When a signal including a first staircase wave is input from the A / D converter 21, the signal value converter 22 converts the input signal into a signal including a second staircase wave in S24. The signal value converter 22 may convert the signal values ​​so as to cancel out waveform distortion caused by signal delays including second-order or higher delays. The signal value converter 22 inputs a signal consisting of the converted signal values ​​to the processing unit 24.

[0085] The processing unit 24 inputs the input signal to the learning model 241 (S35). In response to the input signal, the learning model 241 outputs information regarding the number and wave heights of second step waves included in the signal. The processing unit 24 inputs the information regarding the number and wave heights of second step waves included in the signal to the counting unit 27.

[0086] The counting unit 27 determines whether the number of second staircase waves is one or not based on the input information (S36). For example, if information indicating a wave height is input, the counting unit 27 determines that the number of second staircase waves is one. If the number of staircase waves is one (S36: YES), the counting unit 27 counts the staircase waves by wave height (S37) and ends the process. If the number of second staircase waves is a number other than one (S37: NO), the counting unit 27 does not count, and the signal processing device 2 ends the process. As a result, the second staircase waves in the case where multiple pulse waves overlap are not counted. The signal processing device 2 repeatedly executes the processes of S31 to S37.

[0087] The signal processing device 2 outputs data indicating the relationship between the wave height of the second step wave and the number of counts counted by the counting unit 27. The analysis unit 32 receives the data output by the signal processing device 2 and generates a spectrum of the radiation detected by the radiation detector 1 based on the data.

[0088] In the fourth embodiment, the efficiency of detecting radiation is improved by counting the second step wave by wave height. Also in the fourth embodiment, by using the learning model 241, it is possible to effectively detect the overlap of multiple pulse waves and suppress the occurrence of sum peaks in the radiation spectrum.

[0089] <Embodiment 5> FIG. 15 is a block diagram showing the functional configuration of the signal value converter 22 according to the fifth embodiment. The signal value converter 22 has a calculation unit 221 and a memory 222. The calculation unit 221 is configured using, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a multi-core CPU. The calculation unit 221 may be configured using a quantum computer. The memory 222 is a non-volatile memory. The memory 222 stores a computer program 223. The computer program 223 is read from a recording medium 220, such as an optical disk or portable memory, that stores the computer program 223 by a recording device (not shown), and written to the memory 222, thereby being stored in the memory 222. The calculation unit 221 executes processing required for the signal value converter 22 in accordance with the computer program 223. The memory 222 stores a time constant T c may be stored.

[0090] The calculation unit 221 executes information processing in accordance with the computer program 223, thereby performing the processing required for the signal value conversion unit 22 in the first to fourth embodiments. In this way, the signal value conversion unit 22 in the first to fourth embodiments is realized. The configurations and functions of the parts of the radiation detection device 10 other than the signal processing device 2 are the same as those in the first to fourth embodiments. The configurations and functions of the parts of the signal processing device 2 other than the signal value conversion unit 22 are the same as those in the first to fourth embodiments. The signal processing device 2 and the radiation detection device 10 execute the same processing as those in the first to fourth embodiments.

[0091] In the fifth embodiment as well, the efficiency of detecting radiation is improved by counting the second step wave or the pulse wave converted from the second step wave by wave height. Also in the fifth embodiment as well, by using the learning model 241, it is possible to effectively detect the overlap of multiple pulse waves and suppress the occurrence of sum peaks in the radiation spectrum.

[0092] In the first to fifth embodiments, the processing for acquiring the wave height of the second step wave or pulse wave is entirely performed inside the signal processing device 2, but the signal processing device 2 may be configured to execute part of the processing outside the signal processing device 2. For example, the signal processing device 2 may be configured to execute the processing using the learning model 241 in a cloud outside the signal processing device 2.

[0093] In the first to fifth embodiments, radiation is irradiated onto the sample 6 and radiation generated from the sample 6 is detected. However, the radiation detection device 10 may be configured to detect radiation that has passed through or been reflected by the sample 6. The radiation detection device 10 may be configured to scan the sample 6 with radiation by changing the direction of the radiation. The radiation detection device 10 may be configured to irradiate a moving sample with radiation. The radiation detection device 10 may be configured not to include the irradiation unit 4, the sample stage 5, or the display unit 33.

[0094] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. In other words, embodiments obtained by combining technical means modified appropriately within the scope of the claims are also included in the technical scope of the present invention. [Explanation of symbols]

[0095] 1. Radiation detector 10 Radiation detection equipment 11 Radiation detection element 2. Signal Processing Device 21 A / D conversion section 22 Signal value conversion unit 220 Recording Media 223 Computer Programs 23 Waveform shaping section 24 Processing section 241 Learning Model 25 Pulse detection unit 26 Wave height measurement section 27 Counting section 32 Analysis Department

Claims

1. 1. A signal processing method for counting step waves generated in response to radiation detection or pulse waves converted from the step waves, by wave height, comprising: converting a plurality of signal values ​​constituting a signal including a first staircase wave into a plurality of signal values ​​constituting a signal including a second staircase wave so as to cancel out waveform distortion due to signal delay contained in the first staircase wave obtained in response to radiation detection; Counting the second step wave or the pulse wave converted from the second step wave by wave height. A signal processing method comprising:

2. calculating a transformed signal value by using an inverse function of the difference equation representing the signal delay; 2. The signal processing method according to claim 1, wherein:

3. Calculating the time constant of the signal delay by fitting a theoretical equation of the waveform of the first step wave to the first step wave.

3. The signal processing method according to claim 2, wherein:

4. inputting at least one of a signal including a second staircase wave and a signal including a pulse wave converted from the second staircase wave into a learning model that outputs information regarding whether or not a plurality of pulse waves overlap when at least one of a signal including a staircase wave and a signal including a pulse wave converted from the staircase wave is input; counting the second step wave or the pulse wave when there is no overlap of the plurality of pulse waves according to the information output by the learning model; The learning model is trained using training data including a signal including a single pulse wave or a signal including a single second step wave, and a signal including a plurality of overlapping pulse waves or a signal including a plurality of second step waves and resulting in a plurality of overlapping pulse waves obtained by converting the plurality of second step waves.

4. A signal processing method according to claim 1, wherein:

5. Identifying a time constant of a signal delay included in a first step wave obtained in response to the detection of radiation; Using the time constant, a plurality of signal values ​​constituting a signal including the first step wave are converted into a plurality of signal values ​​constituting a signal including a second step wave so as to cancel out waveform distortion due to signal delay contained in the first step wave. A computer program that causes a computer to execute a process.

6. a signal value conversion unit that converts a plurality of signal values ​​constituting a signal including a first staircase wave into a plurality of signal values ​​constituting a signal including a second staircase wave so as to cancel out waveform distortion due to signal delay contained in the first staircase wave obtained in response to radiation detection; a counting unit that counts the second step wave or the pulse wave converted from the second step wave according to wave height; A signal processing device comprising:

7. a radiation detector that generates a first step wave in response to incidence of radiation and outputs the first step wave; a signal value conversion unit that converts a plurality of signal values ​​constituting a signal including the first staircase wave into a plurality of signal values ​​constituting a signal including a second staircase wave so as to cancel out waveform distortion contained in the first staircase wave by signal delay; a counting unit that counts the second step wave or the pulse wave converted from the second step wave according to wave height; a spectrum generating unit that generates a spectrum of radiation according to the wave height and count number of the second step wave or the pulse wave; A radiation detection device comprising:

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