Radiation measurement adjustment device, radiation measurement system, and radiation measurement method

Abstract

To automatically measure radiation more accurately than before.SOLUTION: According to an embodiment, a radiation measurement system 200 includes a radiation detector 1, a preamplifier 2, and a radiation measurement adjustment device 100. The radiation measurement adjustment device 100 includes a high-speed waveform shaping amplifier 111, a pulse height discriminator 112 that discriminates a high-speed waveform signal and outputs a high-level signal, a trigger generator 113 that outputs a trigger signal after a predetermined delay time from the output of the high-level signal, a low-speed waveform shaping amplifier 121, a sample-and-hold device 122 that outputs an instantaneous value of a low-speed waveform signal at the time of the output of the trigger signal as a sample value, and an AD converter 123. This device is provided with a delay time adjusting part 130 for deriving the dependent characteristics of a digital sample value on a delay time, selecting an optimum delay time and defining it as the delay time of a trigger generator 113.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a radiation measurement adjustment device, a radiation measurement system, and a radiation measurement method. [Background technology]

[0002] Generally, radiation measurement systems that measure radiation use a method called energy analysis to obtain radiation energy information. In energy analysis, the charge of the pulse-like electrical signal generated when a radiation detector detects radiation is converted into a voltage, and the peak value of the converted signal is measured and converted into the energy loss in the detector.

[0003] As an example of such a radiation measurement system, a sample-and-hold type radiation energy measurement device is known.

[0004] FIG. 9 is a block diagram showing an example of the configuration of a conventional radiation measurement system using a sample-and-hold method.

[0005] The radiation measurement system includes a radiation detector 1 , a preamplifier 2 , a high-speed waveform shaping amplifier 111 , a pulse height discriminator 112 , a trigger generator 113 , a low-speed waveform shaping amplifier 121 , a sample-and-hold device 122 , and an analog-to-digital converter 123 .

[0006] Fig. 10 is a graph showing signal processing in a conventional radiation measurement system. The horizontal axis represents time, and the vertical axis represents the output of each component. That is, Fig. 10 shows the change over time in the output of each component of the radiation measurement system when a single ray of radiation is incident on the radiation detector 1, in other words, the waveform of the output of each component.

[0007] The operation of a conventional sample-and-hold type radiation energy measuring device will be described below with reference to FIGS.

[0008] When the radiation detector 1 detects one radiation, it outputs one impulse-shaped current signal (detector signal A). The preamplifier 2 receives the detector signal A and outputs a pseudo-step voltage signal (preamplifier signal B). The preamplifier signal B is input to the high-speed waveform shaping amplifier 111 and the low-speed waveform shaping amplifier 121.

[0009] The high-speed waveform shaping amplifier 111 passes the preamplifier signal B through a filter circuit with a relatively fast time constant to convert it into a relatively short pulse-like signal (high-speed waveform signal C). The high-speed waveform signal C is input to the pulse height discriminator 112. The pulse height discriminator 112 compares the high-speed waveform signal C with a discrimination threshold value, and if the high-speed waveform signal C is large, outputs a high-level signal D as a discriminated pulse signal D. H The trigger generator 113 outputs a trigger signal E, which is a logic signal, after a predetermined delay time Td from the generation of the discrimination pulse signal D.

[0010] On the other hand, the slow waveform shaping amplifier 121 passes the preamplifier signal B from the preamplifier 2 through a filter circuit with a relatively slow time constant, and converts it into a relatively long pulse-like signal (slow waveform signal F).

[0011] The sample and hold device 122 receives the trigger signal E and the slow waveform signal F, holds the voltage of the slow waveform signal F when a pulse of the trigger signal E occurs, and outputs it as a sample value. Furthermore, the analog-to-digital converter 123 converts the sample value into a digital value, which is output as a measurement value.

[0012] Here, the delay time Td is adjusted and set in advance so as to coincide with the timing at which the peak value of the slow waveform signal F occurs. If the delay time Td is adjusted and set in this way, the sample value will indicate the peak value of the slow waveform signal F. Conversely, if the delay time Td is not set correctly, the timing will not coincide with the appearance of the peak value, and the peak value of the slow waveform signal F cannot be obtained. As described above, the delay time Td is an important parameter in the sample and hold method.

[0013] The simplest method for setting the delay time Td is to use a device that measures signal waveforms, such as an oscilloscope, to visually check the signal waveforms of the trigger signal E and the slow waveform signal F, and adjust the timing based on the results (conventional adjustment method 1).

[0014] Alternatively, as a more precise adjustment method, the energy spectrum is measured for multiple delay times Td, and the Td at which the spectrum value is maximized is adopted as the set value (conventional adjustment method 2).

[0015] Furthermore, instead of using a signal generated by detecting radiation (a signal whose magnitude varies with each detection), there is also a method in which an electrical signal of a fixed magnitude generated by a signal generator or the like is input and adjustment is made based on the signal waveform (conventional adjustment method 3).

[0016] As a configuration that does not require strict timing adjustment, there is a technique called a peak hold method as opposed to the sample hold method, but the cases in which it can be applied are limited. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Japanese Patent Publication No. 2021-143993 [Patent Document 2] Patent No. 7093083 Summary of the Invention [Problem to be solved by the invention]

[0018] The above-described adjustment method for the delay time Td has the following problems (1) to (3). (1) Conventional adjustment method 1 refers only to the signal waveform, and it is not possible to strictly confirm that the measured value actually captures the peak of the signal waveform.

[0019] (2) Conventional adjustment method 2 requires measuring the energy spectrum and then performing analytical evaluation, which makes the adjustment process complicated and increases the workload.

[0020] (3) In conventional adjustment method 3, it is difficult to precisely match the shape of the impulse-shaped current signal output by the radiation detector upon detection of radiation with the shape of an electrical signal artificially generated by a signal generator or the like. As a result, it may not be possible to obtain a delay time equivalent to that of the signal upon radiation detection. Furthermore, when attempting to perform adjustment using the signal from the radiation detector instead of the electrical signal, it is not possible to obtain a signal of a consistent magnitude because the energy absorbed by the radiation detector varies each time. Therefore, adjustment using this method is difficult.

[0021] A common problem in the above adjustment methods (1) to (3) is the effect of changes in each component over time.

[0022] As described above, there has been a demand for a method that enables confirmation and adjustment of the delay time Td using an actual radiation detector signal. Furthermore, in such a method, it is desirable that normal measurements can be performed in a state where the delay time Td can be automatically confirmed and adjusted. In other words, there is a demand for a method that automatically enables more accurate radiation measurement than conventional methods.

[0023] An object of the present invention is to provide a radiation measurement adjustment device, a radiation measurement system, and a radiation measurement method that enable more accurate radiation measurement to be performed automatically than conventional methods. [Means for solving the problem]

[0024] In order to achieve the above-mentioned object, the radiation measurement adjustment device of this embodiment is a radiation measurement adjustment device that receives a voltage signal from a preamplifier that converts a current signal from a radiation detector into a voltage signal and acquires the energy level of the radiation, and is characterized by comprising: a slow waveform shaping amplifier that receives the voltage signal and generates a slow waveform signal; a high-speed waveform shaping amplifier that receives the voltage signal and generates a high-speed waveform signal; a pulse height discriminator that discriminates the pulse height value of the high-speed waveform signal and outputs a high-level signal while the pulse height value of the high-speed waveform signal exceeds a discrimination threshold; a trigger generator that outputs a trigger signal after a predetermined delay time from the time point at which the high-level signal is output; a sample and hold device that acquires the instantaneous value of the slow waveform signal at the time point at which the trigger signal is output and outputs it as a sample value; an analog-to-digital converter that digitizes the sample value and outputs a digital sample value; and a delay time adjustment unit that generates a valid signal when the output time width of the high-level signal is common for a plurality of the high-speed waveform signals, derives a dependency characteristic of the digital sample value on the delay time, and selects an optimal delay time from the delay times based on the dependency characteristic and sets it as the delay time of the trigger generator. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a block diagram showing the configuration of a radiation measurement system according to a first embodiment. [Figure 2] 4 is a graph showing output waveforms of each part of the radiation measurement system according to the first embodiment. [Figure 3] 1 is a flowchart showing the procedure of a radiation measurement method according to a first embodiment. [Figure 4] 4 is a graph showing an ideal form of a dependency characteristic derived by the radiation measurement system according to the first embodiment. [Figure 5] 4 is a graph showing an example of a dependency characteristic derived in the radiation measurement system according to the first embodiment. [Figure 6] 4 is a graph showing an example of a dependency characteristic obtained as a result of filtering in the radiation measurement system according to the first embodiment. [Figure 7] FIG. 10 is a block diagram showing the configuration of a radiation measurement system according to a second embodiment. [Figure 8] FIG. 10 is a flowchart showing the procedure of a radiation measurement method according to a second embodiment. [Figure 9] FIG. 1 is a block diagram showing an example of the configuration of a conventional radiation measurement system. [Figure 10] 10 is a graph showing signal processing in a conventional radiation measurement system. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, a radiation measurement adjustment device, a radiation measurement system, and a radiation measurement method according to embodiments of the present invention will be described with reference to the drawings. Hereinafter, identical or similar parts will be denoted by common reference numerals, and overlapping descriptions will be omitted.

[0027] [First embodiment] Fig. 1 is a block diagram showing the configuration of a radiation measurement system 200 according to the first embodiment. Fig. 2 is a graph showing output waveforms of each unit of the radiation measurement system 200 according to the first embodiment.

[0028] <Explanation of the configuration of the radiation measurement system 200> The radiation measurement system 200 includes a radiation detector 1 , a preamplifier 2 , and a radiation measurement adjustment device 100 .

[0029] The radiation detector 1 is a pulse-type radiation detector. The radiation detector 1 outputs an impulse-like detector signal A every time radiation strikes it. The time integral value of the detector signal A of the radiation detector 1 corresponds to an electric charge proportional to the energy imparted by a single radiation quantum.

[0030] The preamplifier 2 receives the detector signal A from the radiation detector 1, converts it into a pseudo-step voltage signal, and outputs it as the preamplifier signal B. After passing its peak, the preamplifier signal B slowly decays exponentially with a fixed time constant. The preamplifier 2 functions, for example, as a capacitor. Therefore, the peak value of the preamplifier signal B is proportional to the total charge of the detector signal A, which is a current signal. In other words, the peak value of the preamplifier signal B, which is a voltage signal, is proportional to the energy of the incident radiation.

[0031] The radiation measurement adjustment device 100 includes a high-speed processing unit 110, a low-speed processing unit 120, a delay time adjustment unit 130, a human-machine interface (HMI) 140, and a storage unit 150. The radiation measurement adjustment device 100 is, for example, a computer system. Alternatively, it may be a collection of individual devices. The high-speed processing unit 110 and the low-speed processing unit 120 are similar to the conventional sample-and-hold system described with reference to FIG. 9, but will be described again in this embodiment.

[0032] The high-speed processing unit 110 includes a high-speed waveform shaping amplifier 111 , a pulse height discriminator 112 , and a trigger generator 113 .

[0033] The high-speed waveform shaping amplifier 111 receives the preamplifier signal B from the preamplifier 2, passes it through a filter circuit with a relatively fast time constant, and converts it into a relatively short pulse-shaped voltage signal, a high-speed waveform signal C. Here, the peak value of the high-speed waveform signal C, which is a voltage signal, is proportional to the energy of the radiation.

[0034] The pulse height discriminator 112 compares the peak value of the received high-speed waveform signal C with a discrimination threshold value Pth, and outputs a discrimination pulse signal D, which is a logic signal. Specifically, when the peak value of the high-speed waveform signal C is greater than the discrimination threshold value Pth, a high-level signal D is output. H When the discrimination threshold Pth is greater than the peak value of the high-speed waveform signal C, the low-level signal D L are output as discrimination pulse signals D.

[0035] The trigger generator 113 generates a high level signal D as the discrimination pulse signal D. H The trigger generator 113 outputs a trigger signal E, which is a logical signal, at a time point that is a predetermined delay time Td after the issuance of the trigger signal G. However, the trigger generator 113 outputs the trigger signal E only when there is a valid signal G from the TOT determiner 131, which will be described later.

[0036] The low-speed processing unit 120 includes a low-speed waveform shaping amplifier 121 , a sample-and-hold device 122 , and an analog-to-digital converter (AD converter) 123 .

[0037] The slow waveform shaping amplifier 121 passes the preamplifier signal B from the preamplifier 2 through a filter circuit (not shown) with a relatively slow time constant, and converts it into a slow waveform signal F, which is a relatively long pulse-like signal.

[0038] The sample and hold device 122 receives the trigger signal E from the trigger generator 113 and the slow waveform signal F from the slow waveform shaping amplifier 121. The sample and hold device 122 acquires the voltage value of the slow waveform signal F when a pulse of the trigger signal E occurs, and outputs this voltage value as a sample value.

[0039] An analog-to-digital converter (AD converter) 123 converts the sample value generated by the sample-and-hold device 122 into a digital sample value (ADC value), and outputs this as a measurement value.

[0040] The delay time adjustment unit 130 performs the following functions. First, it selects the target of subsequent signal processing. Specifically, the delay time adjustment unit 130 selects a high-level signal D from the plurality of high-speed waveform signals C. H The trigger generator 113 selects a case where the TOT value, which is the time duration during which the trigger signal is output, is within a predetermined range and outputs a valid signal G. The delay time adjustment unit 130 derives the dependency characteristic of the ADC value on the delay time Td by changing the delay time Td. The delay time adjustment unit 130 selects an optimal delay time (optimum Td value) from the delay times Td based on this dependency characteristic, and replaces the delay time Td of the trigger generator 113 with this optimal Td value.

[0041] For this purpose, the delay time adjustment unit 130 includes a TOT determiner 131 , an average value calculator 132 , a dependency characteristic deriving unit 133 , a filter 134 , a delay time selector 135 , a delay time setter 136 , and a progress controller 137 .

[0042] The TOT determiner 131 determines whether the high-level signal D is a discrimination pulse signal D from the pulse height discriminator 112. H The TOT determiner 131 measures the time width (TOT value) during which the TOT signal is issued. Here, TOT is an abbreviation for timeover threshold. The TOT determiner 131 determines whether the TOT value is within a predetermined range. Here, the predetermined range is a range within a reference width including a reference TOT value. Specifically, for example, it is a range of a reference value Ttot, which is the reference TOT value, plus or minus a predetermined width dtot. If it is determined that the TOT value is within the reference width dtot including the reference TOT value, the TOT determiner 131 outputs a valid signal G. Here, the reference TOT value and the reference width dtot are received as external inputs via the HMI 140, for example.

[0043] As described above, the peak value of the high-speed waveform signal C is proportional to the radiation energy. That is, the TOT value has a one-to-one correspondence with the radiation energy. Therefore, the determination of the TOT value by the TOT determiner 131 means a determination of whether or not the signal is a radiation signal within a certain energy level range. Therefore, the valid signal G is output only when the signal is a radiation signal within a certain energy level range.

[0044] When the trigger generator 113 is set to a predetermined delay time Td, the above-mentioned signal processing is performed each time radiation is detected. Only when a valid signal G is output from the TOT determiner 131 during this process, the AD converter 123 performs AD conversion of the sample value and outputs a digitized sample value (ADC value). In other words, for multiple radiation detections, an ADC value is output only when a valid signal G is output. The average value calculator 132 averages the multiple ADC values ​​output from the AD converter 123 and outputs an average sample value (average ADC value).

[0045] The dependency characteristic deriving unit 133 derives the relationship between the average ADC value and the delay time Td, i.e., the dependency characteristic of the average ADC value on the delay time Td, based on the average ADC value obtained for each delay time while changing the delay time Td.

[0046] The filter 134 smoothes the average ADC value by filtering in relation to the dependency of the average ADC value on the delay time Td.

[0047] The delay time selector 135 selects the Td value that gives the maximum value of the average ADC value in the dependency characteristic of the average ADC value on the Td value, and outputs it as the optimum delay time (optimum Td value).

[0048] The delay time setter 136 outputs the optimum Td value selected by the delay time selector 135 to the trigger generator 113 to instruct the change. Based on this instruction, the trigger generator 113 changes the value of the delay time Td to the accepted optimum Td value.

[0049] The progress controller 137 controls the progress of processing in the high-speed processing unit 110, the low-speed processing unit 120, and the delay time adjustment unit 130. The progress controller 137 starts and progresses the radiation measurement operation by the radiation measurement adjustment device 100 in response to a command received from the outside by a human-machine interface (HMI) 140. The progress controller 137 may be, for example, a controller such as an FPGA (Field Programmable Gate Array). Alternatively, it may be a computer program having such a function. The specific contents of the progress controller 137 will be described later with reference to FIG. 3.

[0050] The human-machine interface (HMI) 140 receives, as external inputs, instructions to adjust the delay time Td, an initial setting value for the delay time Td, and various other parameters required for adjusting the delay time Td. The human-machine interface (HMI) 140 also displays information related to the processing status of the radiation measurement adjustment device 100.

[0051] The storage unit 150 stores external inputs received by the HMI 140 and processing results of each unit in the radiation measurement adjustment device 100 .

[0052] <Explanation of the procedure and effects of radiation measurement method> FIG. 3 is a flowchart showing the procedure of the radiation measurement method according to the first embodiment.

[0053] The progression between steps in the following procedure is controlled by the progression controller 137 unless otherwise specified.

[0054] First, when the HMI 140 receives a command to execute adjustment, the progress controller 137 performs initialization (step S01). Specifically, the HMI 140 receives external inputs such as an initial value Td0 of the delay time Td, the minimum value Tmin and maximum value Tmax of the delay time Td, the survey interval ΔT of the delay time Td, the reference value Ttot of the TOT, a predetermined width dtot centered on the reference value Ttot, and the discrimination threshold value Pth of the pulse-height discriminator 112. Next, the progress controller 137 sets the delay time Td to the minimum value Tmin and the value of the judgment criterion in the TOT determiner 131 to the reference value Ttot and the predetermined width dtot. For example, if the delay time Td is to be varied in 5-nanosecond increments within a range from 10 nanoseconds to 100 nanoseconds, the minimum value Tmin is set to 10 nanoseconds, the survey interval ΔT to 5 nanoseconds, and the maximum value Tmax to 100 nanoseconds.

[0055] The progress controller 137 changes the value of the delay time Td used by the trigger generator 113 to the initial value Td0 accepted by the HMI 140 (step S02). Note that if the delay time Td already exists and there is no need to change the delay time Td to the initial value Td0, this step may be skipped.

[0056] Subsequently, the following steps S03, S04, S10 and S20 are steps in which the delay time Td is changed, the average ADC value for each delay time Td is calculated, and the dependency of the average ADC value on the delay time Td is derived.

[0057] Next, the process branches depending on whether the preamplifier 2 has received the detector signal A (step S03). If the preamplifier 2 has not received the detector signal A (step S03 NO), step S03 is repeated. Note that this reception refers to the operation of the radiation detector 1 detecting radiation through its normal function and outputting the detector signal A, and the preamplifier 2 receiving the detector signal A. In other words, step S03 means waiting until the radiation detector 1 detects radiation.

[0058] When the preamplifier 2 receives the detector signal A (YES in step S03), the preamplifier 2 converts the detector signal A into a pseudo-step voltage signal as shown in FIG.

[0059] The radiation measurement method then includes a sample value acquisition step S10 and an optimum Td value setting step S20.

[0060] The sample value acquisition step S10 will be described in detail below.

[0061] First, the high-speed waveform shaping amplifier 111 generates a high-speed shaped pulse signal (step S11). That is, the high-speed waveform shaping amplifier 111 receives the preamplifier signal B and generates a high-speed waveform signal C as shown in FIG.

[0062] Next, the pulse height discriminator 112 compares the high-speed waveform signal C with the discrimination threshold value Pth to generate a discrimination pulse signal D (step S12). That is, if the level of the high-speed waveform signal C is greater than the discrimination threshold value Pth, the pulse height discriminator 112 generates a high-level signal D as the discrimination pulse signal D. H Output.

[0063] Next, the TOT determiner 131 determines whether the TOT value is the TOT reference value (step S13). Here, "the TOT value is the TOT reference value" means, as described above, that the TOT value is within a predetermined width dtot centered on the reference value Ttot. As described above, the TOT value being the TOT reference value means that the radiation energy is within a certain range of levels, in other words, at approximately the same level. By selecting and narrowing down the signals in this way, the dependency characteristics described below can be made significant.

[0064] If the TOT determiner 131 does not determine that the TOT value is the TOT reference value (NO in step S13), steps S03 to S13 are repeated.

[0065] When the TOT determiner 131 determines that the TOT value is equal to the TOT reference value (YES in step S13), a high-level signal D is output as the discrimination pulse signal D. H After a delay time Td has elapsed since the trigger generator 113 outputs the trigger signal E.

[0066] Meanwhile, in parallel with step S11, the low-speed waveform shaping amplifier 121 generates a low-speed waveform signal F (step S15).

[0067] After steps S14 and S15, at the timing when trigger signal E is input, sample and hold device 122 acquires the instantaneous value of the voltage of low-speed waveform signal F and outputs it as a sample value (step S16).

[0068] Next, the optimum Td value setting step S20 will be described in detail.

[0069] First, the AD converter 123 performs AD conversion on the sample value and outputs a digital sample value (ADC value) (step S21).

[0070] Next, the average value calculator 132 receives the ADC value from the AD converter 123, performs averaging processing, and outputs an average sample value (average ADC value) (step S22).

[0071] Next, the relationship between the Td value and the average ADC value, i.e., the dependency characteristic of the average ADC value on the Td value, is derived (step S23). In detail, first, the combined data of the Td value and the average ADC value obtained in steps S04 to S22 is stored in the storage unit 150. Next, the dependency characteristic derivation unit 133 derives the dependency characteristic of the average ADC value on the Td value based on the combined data of the Td value and the average ADC value.

[0072] Next, the progress controller 137 determines whether the delay time Td value is equal to or greater than Tmax (step S24). If it is determined that the delay time Td value is not equal to or greater than Tmax (step S24 NO), the progress controller 137 sets the delay time Td value to (Td+ΔT) (step S25) and returns to step S03.

[0073] If it is determined that the delay time Td value is equal to or greater than Tmax (YES in step S24), the filter 134 performs filtering processing on the average ADC value (step S26).

[0074] Here, the smoothing process by filtering in step S26 will be described with reference to Figures 4 to 6. The horizontal axis of the graphs shown in Figures 4 to 6 is the delay time Td (nanoseconds), and the vertical axis is the average ADC value (relative value).

[0075] Fig. 4 is a graph showing an ideal form of the dependency characteristic derived by the radiation measurement system according to the first embodiment. The graph shown in Fig. 4 should be obtained along the time axis direction of the slow waveform signal F for radiation of a certain energy. In other words, it is identical to a portion of the slow waveform signal F during a certain time period. Therefore, ideally, it should be a smooth curve as shown in Fig. 4.

[0076] 5 is a graph showing an example of a dependency characteristic derived by the radiation measurement system 200 according to the first embodiment. That is, it is a dependency characteristic curve derived by the dependency characteristic derivation unit 133 in step S23. Since there is statistical variation in the data sequence of the average ADC values, the dependency characteristic curve may not have a simple mountain-like shape as in the example shown in FIG.

[0077] FIG. 6 is a graph showing an example of a dependency characteristic obtained as a result of filtering in the radiation measurement system 200 according to the first embodiment. That is, this is a dependency characteristic curve obtained by smoothing processing by filtering using the filter 134 in step S26. As shown, the curve is smooth and has a clear peak position. The smoothing processing by filtering is performed, for example, by serializing the average ADC value with the average ADC value (n) in the increasing direction of the delay time Td (n=1 to N, N is the number of delay times Td on the horizontal axis). The filtering method is not particularly limited as long as it maintains the delay time Td that gives the peak value of the dependency characteristic curve, that is, does not cause a deviation in the delay time (a deviation in the horizontal axis direction in FIG. 6). For example, a moving average type of filtering may be used as an easy method.

[0078] Next, the delay time selector 135 selects the optimum Td value (step S27). A smooth dependency characteristic curve with a clear peak position is obtained by the filtering process in step S26. As a result, the delay time selector 135 can easily obtain the delay time Td that gives the average ADC value. The delay time selector 135 outputs the delay time Td that gives the average ADC value as the optimum Td value.

[0079] Next, the delay time setter 136 sets the optimum Td value output by the delay time selector 135 in step S27 as the delay time Td used in the trigger generator 113 (step S28). As a result, the delay time Td of the trigger generator 113 is rewritten to the optimum Td value.

[0080] <Effects> The radiation incident on the radiation detector 1 has various energies. Therefore, although the slow waveform signal changes over time in the same way, the signal magnitude also takes on various values. In such a situation, it is difficult to grasp the dependency characteristics.

[0081] In this embodiment, only signals corresponding to radiation with a certain range of energy are extracted by the TOT determiner 131, and the dependency characteristic is derived based on these signals. As a result, a meaningful dependency characteristic curve can be obtained.

[0082] Furthermore, by averaging by the average value calculator 132 and smoothing by the filter 134, it is possible to derive a clearer dependency characteristic.

[0083] Furthermore, the progress controller 137 can automatically generate the dependency characteristics, derive the optimum delay time, and reflect the result in the delay time Td used by the trigger generator 113.

[0084] As described above, the radiation measurement system and radiation measurement method according to this embodiment automatically checks and adjusts the delay time for capturing the peak of the signal waveform using the actual signal from the radiation detector, thereby enabling more accurate automatic radiation measurement than conventional methods.

[0085] [Second embodiment] 7 is a block diagram showing the configuration of a radiation measurement system 200a according to the second embodiment. This embodiment is a modification of the first embodiment. In this embodiment, the output of the TOT determiner 131 is output to an average value calculator 132, not to the trigger generator 113. In other respects, this embodiment is the same as the first embodiment.

[0086] 8 is a flowchart showing the procedure of the radiation measurement method according to the second embodiment. In the flowchart, the order of TOT determination by the TOT determiner 131 differs from that of the first embodiment.

[0087] In this embodiment, instead of step S13 of TOT determination in the first embodiment, step S29 of TOT determination by a TOT determiner 131 is provided between step S21 and step S22.

[0088] In this embodiment, as in the first embodiment, only signals corresponding to radiation with a certain range of energy are extracted by the TOT determiner 131, and the dependency characteristics are derived based on these signals. Therefore, the same effects as in the first embodiment are achieved.

[0089] In this embodiment, the extraction by the TOT determiner 131 is performed after AD conversion by the AD converter 123. That is, in this embodiment, AD conversion is performed on all signals. The detector signal A of the radiation detector 1 may be processed for purposes other than grasping the energy level. In such cases, it may be necessary to perform AD conversion on all detector signals A. This embodiment is useful in such cases.

[0090] According to the embodiments described above, it is possible to provide a radiation measurement adjustment device, a radiation measurement system, and a radiation measurement method that enable more accurate radiation measurement to be performed automatically than conventional methods.

[0091] [Other embodiments] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. Furthermore, the embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0092] 1...radiation detector, 2...preamplifier, 100, 100a...radiation measurement adjustment device, 110...high-speed processing unit, 111...high-speed waveform shaping amplifier, 112...pulse height discriminator, 113...trigger generator, 120...low-speed processing unit, 121...low-speed waveform shaping amplifier, 122...sample and hold device, 123...analog-to-digital converter (AD converter), 130...delay time adjustment unit, 131...TOT judgement unit, 132...average value calculator, 133...dependence characteristic derivation unit, 134...filter, 135...delay time selector, 136...delay time setter, 137...progress controller, 140...human-machine interface (HMI), 150...memory unit, 200...radiation measurement system

Claims

1. A radiation measurement adjustment device that receives a voltage signal from a preamplifier that converts a current signal from a radiation detector into a voltage signal and measures radiation, a high-speed waveform shaping amplifier that receives the voltage signal and generates a high-speed waveform signal; a peak-height discriminator that discriminates the peak value of the high-speed waveform signal and outputs a high-level signal while the peak value exceeds a discrimination threshold; a trigger generator that outputs a trigger signal after a predetermined delay time from the time when the high-level signal is output; a slow waveform shaping amplifier that receives the voltage signal and generates a slow waveform signal; a sample-and-hold device that acquires an instantaneous value of the low-speed waveform signal at the time when the trigger signal is output and outputs the instantaneous value as a sample value; an analog-to-digital converter that digitizes the sample values ​​and outputs digital sample values; a delay time adjusting unit that selects a valid signal when a TOT value, which is a time duration during which the high-level signal is output from the plurality of high-speed waveform signals, is within a predetermined range, derives a dependency characteristic of the digital sample value on the delay time by changing the delay time, selects an optimal delay time from the delay times based on the dependency characteristic, and replaces the delay time of the trigger generator with the optimal delay time; A radiation measurement and adjustment device comprising:

2. The delay time adjustment unit a TOT determiner for determining the TOT value by assuming that the predetermined range is within a reference width including a reference TOT value; a dependency characteristic acquisition unit that acquires the dependency characteristic of the digital sample value on the delay time by changing the delay time; a delay time selector for selecting the optimum delay time that gives the maximum value of the digital sample value in the dependency characteristic; a delay time setter that sets the optimum delay time as the delay time of the trigger generator; a progress controller for controlling the progress of the process in the delay time adjustment unit; 2. The radiation measurement adjustment device according to claim 1, further comprising:

3. the delay time adjustment unit further includes an average value calculator that calculates an average sample value of the digital sample values ​​obtained for each of the plurality of voltage signals obtained by detecting the radiation a plurality of times; 3. The radiation measurement adjustment device according to claim 2, wherein the average sample value is used as the dependency characteristic.

4. 4. The radiation measurement adjustment device according to claim 3, wherein the delay time adjustment unit further includes a filter that smooths the average sample value in the dependency characteristic by filtering.

5. 2. The radiation measurement adjustment device according to claim 1, wherein the trigger generator outputs the trigger signal only when the valid signal is output.

6. 2. The radiation measurement adjustment device according to claim 1, wherein the delay time adjustment unit derives the dependency characteristic only for the digital sample values ​​obtained when the valid signal is output, among the digital sample values.

7. a radiation detector that detects radiation and outputs a current signal; a preamplifier that converts the current signal into a voltage signal; a radiation measurement adjustment device that receives the voltage signal and measures the radiation; A radiation measurement system comprising: The radiation measurement and adjustment device is a high-speed waveform shaping amplifier that receives the voltage signal and generates a high-speed waveform signal; a peak-height discriminator that discriminates the peak value of the high-speed waveform signal and outputs a high-level signal while the peak value exceeds a discrimination threshold; a trigger generator that outputs a trigger signal after a predetermined delay time from the time when the high-level signal is output; a slow waveform shaping amplifier that receives the voltage signal and generates a slow waveform signal; a sample-and-hold device that acquires an instantaneous value of the low-speed waveform signal at the time when the trigger signal is output and outputs the instantaneous value as a sample value; an analog-to-digital converter that digitizes the sample values ​​and outputs digital sample values; a delay time adjusting unit that selects a valid signal when a TOT value, which is a time duration during which the high-level signal is output from the plurality of high-speed waveform signals, is within a predetermined range, derives a dependency characteristic of the digital sample value on the delay time by changing the delay time, selects an optimal delay time from the delay times based on the dependency characteristic, and replaces the delay time of the trigger generator with the optimal delay time; A radiation measurement system comprising:

8. A radiation measurement method for measuring radiation by receiving a voltage signal from a preamplifier that converts a current signal from a radiation detector into a voltage signal, the voltage signal being received, the method comprising: a first step in which a high-speed waveform shaping amplifier receives the voltage signal and generates a high-speed waveform signal; a second step in which a peak value discriminator discriminates the peak value of the high-speed waveform signal and outputs a high-level signal while the peak value exceeds a discrimination threshold; a third step in which a TOT determiner of a delay time adjusting unit selects a valid signal when a TOT value, which is a time duration during which the high-level signal is output from the pulse height discriminator, is within a predetermined range; and a fourth step in which a trigger generator outputs a trigger signal after a predetermined delay time from the time when the high-level signal is output; a fifth step in which a slow waveform shaping amplifier receives the voltage signal and generates a slow waveform signal in parallel with the first step to the fourth step; a sixth step in which a sample-and-hold device acquires an instantaneous value of the low-speed waveform signal at the time when the trigger signal is output and outputs the sampled value; a seventh step in which an analog-to-digital converter digitizes the sample values ​​and outputs digital sample values; an eighth step in which the first step to the seventh step are repeated, and the delay time adjustment unit derives a dependency characteristic of the digital sample value on the delay time by detecting the radiation a plurality of times, and selects an optimal delay time from the delay times based on the dependency characteristic, and sets the optimal delay time as the delay time of the trigger generator; A radiation measurement method comprising:

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