Sodium iodide detector performance detection device and method

Abstract

The invention relates to the technical field of nuclear radiation measurement, in particular to a sodium iodide detector performance detection device and method. The device comprises a constant temperature and humidity test box, a signal acquisition device, a digitizer and an upper computer. The method comprises the steps that the signal acquisition device and the digitizer are powered on for the first time; setting parameters of the sodium iodide detector performance detection device; starting the digitizer; putting the sodium iodide detector to be tested into a constant-temperature and constant-humidity test box for parameter determination; performing energy calibration on the sodium iodide detector to obtain an energy and channel address linear relational expression; measuring the energy linear deviation and the energy resolution of the sodium iodide detector under different temperature and humidity, and comparing the linear deviation, the energy resolution and the detection efficiency according to a measurement result to judge the performance of the detector; and substituting the waveform data of the obtained measurement result into a BP neural network model of MATLAB software for judgment to obtain a classification result. According to the invention, sodium iodide detectors of different interfaces and data acquisition modes of a nuclear power plant can be detected, the maintenance quality and the reliability of equipment are improved, the autonomous overhaul and maintenance capability is enhanced, and safe and effective operation of the equipment in a production cycle is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear radiation measurement, and in particular to a sodium iodide detector performance detection device and method. Background Art

[0002] Sodium iodide detectors have the advantages of high density, high detection efficiency, high luminous efficiency, and good matching of emission spectrum with photomultiplier tube (PMT) absorption spectrum. Sodium iodide detectors are a type of detector widely used in nuclear power plant radiation monitoring equipment. In commercial nuclear power plants, they are mainly used for reactor building air 13 N gas activity monitoring device (hereinafter referred to as N13), low water release specific activity monitoring device (hereinafter referred to as low water release) and steam generator leakage rate monitoring device (hereinafter referred to as N16).

[0003] The above three devices are from different manufacturers. Although the detectors used are the same, different manufacturers have the following differences when assembling sodium iodide detectors. ① The output signal interface method is different: for example, considering that the use environment of N16 is a high temperature environment of 50℃~70℃, the output signal uses a single-core coaxial cable. The local processing device (hereinafter referred to as LPU) supplies high voltage to the detector, and the detector provides signals to LPU. There is only a PMT voltage divider in the detector without a preamplifier (hereinafter referred to as preamplifier). The preamplifier is designed in the LPU; N13 and low-voltage water discharge use separate high-voltage and signal routing. The detector has both a PMT voltage divider and a preamplifier. The power supply of the preamplifier is completed by an external low-voltage module. The low-voltage water discharge uses +15V, while N13 uses -24V. ②The connector models of the cables are also inconsistent: N16 uses TVP 00RW 11-98SF 6-pin female aviation plug, N13 and low-discharge high-voltage connectors use BNC-KY female connectors, N13 output signal and front-end low-voltage power supply also use BNC-KY female connectors, while low-discharge uses FQ14-4-pin aviation plugs. ③The N16 detector has a built-in Pt platinum resistance temperature sensor, while the others do not have temperature sensors.

[0004] In general, the radiation monitoring system of the sodium iodide detector used in nuclear power plants has significant differences in the detector cable connectors and LPU signal data acquisition and processing methods. Although some manufacturers have corresponding test methods for the sodium iodide detectors they produce, third-party inspections are not possible due to closed technology. In addition, in long-term operation, the above-mentioned radiation monitoring system has always had flashing alarms, affecting the safety of nuclear power operation. When a failure occurs, the current solution is to directly replace the entire detector, which is highly dependent on the manufacturer and has basically zero independent maintenance capabilities. Detector Detector Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a sodium iodide detector performance detection device and method, which can detect sodium iodide detectors with different interfaces and data acquisition methods in nuclear power plants, improve the maintenance quality and reliability of equipment, enhance the independent inspection and maintenance capabilities, and ensure the safe and effective operation of the equipment during the production cycle.

[0006] The present invention provides a sodium iodide detector performance detection device, comprising:

[0007] Constant temperature and humidity test chamber, used to place different types of sodium iodide detectors, providing different temperature and humidity environments;

[0008] The signal acquisition device is provided with a plurality of interfaces for connecting different types of sodium iodide detectors respectively, and is used to acquire the pulse signal of the sodium iodide detector and transmit the pulse signal to the digitizer after filtering and amplifying;

[0009] The digitizer filters the pulse signal input from the signal acquisition device and sends it to the host computer for analysis;

[0010] The host computer is used to control the signal acquisition device to provide working high and low voltages for the sodium iodide detector, and read the working high voltage and temperature in real time. The PID is used to adjust the read working high voltage so that the digital-to-analog conversion circuit makes the high voltage value meet the use requirements, presents the energy spectrum and waveform diagram and analyzes various parameters. The collected data is compared and analyzed with the data in the BP neural network classification model to obtain the detection results of the sodium iodide detector.

[0011] In a specific embodiment of the present invention, the host computer is provided with PC setting software, PC digitizer processing software and MATLAB software;

[0012] PC setting software, used to control the signal acquisition device to provide working high and low pressures for the sodium iodide detector, and to read the working high pressure and temperature;

[0013] The digitizer analysis software is used to present the energy spectrum and waveform diagram, and analyze various parameters;

[0014] MATLAB software reads the waveform file data, normalizes the waveform amplitude, and obtains the characteristic vector; MATLAB's BP neural network is used to perform machine learning on the characteristic vector of the sodium iodide detector and establish a classification model;

[0015] The characteristic vector includes pulse width, rise time, fall time, and pulse waveform charge ratio.

[0016] In a specific embodiment of the present invention, the sodium iodide detector includes an N16 detector, an N13 detector and a low water release detector.

[0017] In a specific embodiment of the present invention, the signal acquisition device includes an ARM processor, a digital-to-analog conversion module, an analog-to-digital conversion module, a high-voltage module, a linear voltage regulator module, a DC voltage module, and a filter amplifier module;

[0018] The digital-to-analog conversion module converts the high-voltage value set by the host computer into an analog quantity and then controls the high-voltage module. The high-voltage module outputs a preset working high voltage and provides it to the sodium iodide detector. The high-voltage module reads the output high voltage and converts the analog quantity into a digital quantity through the analog-to-digital conversion module and then transmits it to the ARM processor. The host computer reads the working high voltage of the sodium iodide detector in real time.

[0019] The DC voltage module provides 3.3V working voltage to the host computer and linear voltage regulator module;

[0020] The linear voltage regulator module receives the voltage signal of the 12V voltage input module, converts it into voltage signals of different magnitudes, and provides them to different high-voltage modules to supply different sodium iodide detectors;

[0021] The pulse signal from the sodium iodide detector is processed, filtered, amplified, and then sent to the digitizer;

[0022] Different sodium iodide detectors are matched with different digital-to-analog conversion modules, analog-to-digital conversion modules, high-voltage modules and filter amplifier modules.

[0023] In a specific embodiment of the present invention, after the N16 detector works normally, the signal is input into the charge sensitive preamplifier through the DC blocking capacitor to amplify and improve the signal-to-noise ratio, and then the signal ripple is filtered through the pole-zero cancellation circuit to reduce the signal decay time, and then the counting rate is increased and then the signal enters the programmable amplifier for proportional amplification, and then enters the digitizer through the active filter shaping circuit. After the digitizer analyzes, the energy spectrum and waveform diagram can be displayed by the PC digitizer software;

[0024] After the N13 detector works normally, the signal is input to the isolation amplifier for isolation and amplification. After filtering out high-frequency interference, the signal ripple is filtered through the pole-zero phase cancellation circuit to reduce the signal decay time and increase the counting rate. Then the signal enters the programmable amplifier and is proportionally amplified before entering the digitizer through the active filter shaping circuit. After analysis by the digitizer, the energy spectrum and waveform can be displayed by the PC digitizer software.

[0025] After the low-discharge detector works normally, the signal is input into the reverse amplifier for amplification, high-frequency interference is filtered out, and the signal ripple is filtered through the pole-zero phase cancellation circuit to reduce the signal decay time and increase the counting rate. The signal then enters the programmable amplifier, is amplified in proportion, and then enters the digitizer through the active filter shaping circuit. After analysis by the digitizer, the energy spectrum and waveform can be displayed by the PC digitizer software.

[0026] In a specific embodiment of the present invention, the linear voltage module provides a 3.3V working voltage to the linear voltage regulator module, and then the linear voltage regulator module converts the 12V voltage signal into +10V and -10V voltage signals to provide a working low voltage to the N16 detector;

[0027] The linear voltage regulator module converts the 12V voltage signal into a -24V voltage signal, providing a working low voltage to the N13 detector;

[0028] The linear voltage regulator module converts the 12V voltage signal into a +15V voltage signal, providing a working low voltage to the low-discharge water detector.

[0029] In a specific embodiment of the present invention, the analog-to-digital conversion module also converts the temperature signal of the N16 detector and transmits it to the ARM processor, and the host computer reads the real-time temperature of the N16 detector in real time.

[0030] The present invention provides a method for detecting performance of a sodium iodide detector, comprising the following steps:

[0031] Step 1: Power on the signal acquisition device and digitizer for the first time;

[0032] Step 2: Setting parameters of the sodium iodide detector performance detection device according to any one of claims 1 to 7;

[0033] Step 3: Start the digitizer;

[0034] Step 4: Place the sodium iodide detector to be tested in a constant temperature and humidity test chamber, run it at the set temperature and humidity for more than 4 hours, use the Cs-137 source, adjust the high voltage value of the detection device, so that its 662keV peak position is displayed at around 200 channels in the digitizer spectrum window;

[0035] Step 5: Energy calibration of the sodium iodide detector to obtain a linear relationship between energy and channel address;

[0036] Step 6: Using the Cs-137 source, obtain the actual energy value displayed at the 662keV peak in the digitizer spectrum window, and judge the linearity of the sodium iodide detector according to the deviation; obtain the energy resolution at the 662keV peak in the digitizer spectrum window. If the value is greater than 8%, it means that the energy resolution of the sodium iodide detector does not meet the requirements; if the value is ≤8%, continue with the subsequent steps;

[0037] Step 7: Determine the energy linearity deviation and energy resolution of the sodium iodide detector under different temperatures and humidities, and judge the detector performance by comparing the linearity deviation, energy resolution, and detection efficiency based on the measurement results;

[0038] Step 8: Substitute the waveform data of the obtained measurement results into the BP neural network model of MATLAB software for judgment, obtain the classification result, and thus determine the performance of the sodium iodide detector.

[0039] In a specific embodiment of the present invention, the BP neural network model of the MATLAB software is obtained through training, and the training method is:

[0040] A large number of waveforms are obtained from different detectors using a digitizer at different temperatures. The waveforms obtained by the digitizer are read using MATLAB software to read the waveform file data, and the waveform amplitude is normalized to obtain the characteristic vector; the characteristic vector of the detector is machine-learned using MATLAB's BP neural network to establish a classification model;

[0041] The characteristic vector includes pulse width, rise time, fall time, and pulse waveform charge ratio;

[0042] The MATLAB BP neural network classification model is continuously machine-learned and corrected to further improve its accuracy.

[0043] In a specific embodiment of the present invention, the step 2 specifically includes:

[0044] Use the host computer to set the temperature of the constant temperature and humidity test chamber, the type of sodium iodide detector to be tested, and the high voltage value;

[0045] Set the digitizer sampling channel, signal polarity, baseline, channel number range, discrimination threshold and sampling frequency. Compared with the prior art, the sodium iodide detector performance detection device and method of the present invention can test the detector in the laboratory and obtain key parameters such as the detection efficiency, energy resolution, background level and instability of the sodium iodide detector in a timely and accurate manner. Using one set of this equipment, all testing work for multiple detector types can be completed, and the device also provides a third-party analog output signal test interface, which has good versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram showing a sodium iodide detector performance testing device;

[0047] Figure 2 Represents the overall design drawing. DETAILED DESCRIPTION

[0048] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0049] The embodiment of the present invention discloses a sodium iodide detector performance detection device, such as Figure 1 and Figure 2 As shown, it includes: a constant temperature and humidity test chamber, a signal acquisition device, a digitizer and a host computer;

[0050] The constant temperature and humidity test chamber is used to place different types of sodium iodide detectors and provide different temperature and humidity environments. The energy resolution, detection efficiency, background level and instability of the sodium iodide detector under different temperature and humidity conditions are measured by controlling the temperature and humidity in the constant temperature and humidity test chamber.

[0051] The sodium iodide detectors include N16 detectors, N13 detectors and low-release water detectors;

[0052] The signal acquisition device is provided with a plurality of interfaces for connecting different types of sodium iodide detectors respectively, and is used to acquire the pulse signal of the sodium iodide detector and transmit the pulse signal to the digitizer after filtering and amplifying;

[0053] The signal acquisition device can match the TVP 00RW 11-98 plug on the N16 detector, the FQ aviation plug on the low-discharge detector and the BNC interface on the N13 detector;

[0054] The signal acquisition device includes an ARM processor, a digital-to-analog conversion module, an analog-to-digital conversion module, a high-voltage module, a linear voltage stabilization module, a DC voltage module, and a filtering and amplification module;

[0055] The digital-to-analog conversion module converts the high-voltage value set by the host computer into an analog quantity and then controls the high-voltage module. The high-voltage module outputs a preset working high voltage and provides it to the sodium iodide detector. The high-voltage module reads the output high voltage and converts the analog quantity into a digital quantity through the analog-to-digital conversion module and then transmits it to the ARM processor. The host computer reads the working high voltage of the sodium iodide detector in real time.

[0056] The DC voltage module provides 3.3V working voltage to the host computer and linear voltage regulator module;

[0057] The linear voltage regulator module receives the voltage signal of the 12V voltage input module, converts it into voltage signals of different magnitudes, and provides them to different high-voltage modules to supply different sodium iodide detectors;

[0058] The pulse signal from the sodium iodide detector is processed, filtered, amplified, and then sent to the digitizer;

[0059] Different sodium iodide detectors are matched with different digital-to-analog conversion modules, analog-to-digital conversion modules, high-voltage modules and filter amplifier modules.

[0060] Specifically, the signal acquisition device acquires the pulse signal of the N16 detector, first sets the high voltage value through the PC setting software of the host computer, converts the high voltage value into an analog value through the first digital-to-analog conversion module, and then controls the first high voltage module. The first high voltage module then outputs a preset working high voltage to the N16 detector, and the first high voltage module reads the output high voltage in real time, and then converts the analog value into a digital value through the first analog-to-digital conversion module and transmits it to the ARM processor, and the PC setting software reads the working high voltage of the N16 detector in real time. The DC voltage module provides 3.3V working voltage to the host computer and the linear voltage regulator module, and then the linear voltage regulator module obtains +10V and -10V power supply circuits from +12V to provide working low voltage to the N16 detector. After the N16 detector works normally, the signal is input into the charge sensitive preamplifier through the DC blocking capacitor to amplify and improve the signal-to-noise ratio, and then the signal ripple is filtered through the pole-zero phase cancellation circuit to reduce the signal attenuation time and increase the counting rate. Finally, it enters the programmable amplifier for proportional amplification and enters the digitizer through the active filter shaping circuit. After analysis by the digitizer, the energy spectrum and waveform can be displayed by the PC digitizer software; the temperature signal of the N16 detector enters the fourth analog-to-digital conversion module through the temperature signal amplification circuit to convert the temperature analog quantity into a digital quantity and then transmit it to the ARM processor, and then read through the PC setting software to obtain the real-time temperature value.

[0061] The signal acquisition device acquires the pulse signal of the N13 detector. First, the high voltage value is set through the PC setting software. The second digital-to-analog conversion module converts the digital value of the high voltage value into an analog value and then controls the second high voltage module. The second high voltage module then outputs the preset working high voltage to the N13 detector, and the second high voltage module reads the output high voltage in real time and then transmits the analog value to the digital value after the second analog-to-digital conversion module converts the analog value to a digital value and transmits it to the ARM processor. The PC setting software reads the working high voltage of the N13 detector in real time. The DC voltage module provides a 3.3V working voltage to the host computer and the linear voltage regulator module, and then the linear voltage regulator module obtains a -24V power supply circuit from +12V to provide a working low voltage to the N13 detector. After the N13 detector works normally, the signal is input into the isolation amplifier for isolation and amplification, and high-frequency interference is filtered out. Then, the signal ripple is filtered through the pole-zero phase cancellation circuit to reduce the signal attenuation time and increase the counting rate. Finally, the signal enters the programmable amplifier, is amplified in proportion, and then enters the digitizer through the active filter shaping circuit. After the digitizer analyzes, the energy spectrum and waveform can be displayed by the PC digitizer software.

[0062] The signal acquisition device acquires the pulse signal of the low water discharge detector. First, the high voltage value is set through the PC setting software. The third digital-to-analog conversion module converts the high voltage value into an analog value and then controls the third high voltage module. The third high voltage module then outputs the preset working high voltage to the low water discharge detector. The third high voltage module reads the output high voltage in real time and then transmits it to the ARM processor after the analog value is converted into a digital value by the third analog-to-digital conversion module. The working high voltage of the low water discharge detector is read in real time by the PC setting software. The DC voltage module provides a 3.3V working voltage to the host computer and the linear voltage regulator module, and then the linear voltage regulator module obtains a +15V power supply circuit from +12V to provide a working low voltage to the low water discharge detector. After the low water discharge detector works normally, the signal is input into the reverse amplifier for amplification, high-frequency interference is filtered out, and then the signal ripple is filtered through the pole-zero phase cancellation circuit to reduce the signal attenuation time and increase the counting rate. Finally, it enters the programmable amplifier, is amplified in proportion, and enters the digitizer through the active filter shaping circuit. After the digitizer analyzes, the energy spectrum and waveform can be displayed by the PC digitizer software.

[0063] Since the three types of radiation monitoring detectors use different photomultiplier tubes, the gain and high voltage values ​​are also different. The present invention designs three DC high voltage power supplies to meet the testing requirements of the three probes at the same time. The high voltage value can be set through software. The high voltage module has a built-in high resistance voltage divider circuit. The high voltage signal enters the analog-to-digital conversion module through the circuit and returns to the host computer to obtain the real-time high voltage value. Then, the PID (proportional integral differential) is used to adjust the digital-to-analog conversion module so that the high voltage value meets the use requirements of the device.

[0064] In order to meet the requirements of three types of radiation monitoring equipment for low-voltage power supply and low ripple noise, in view of the N13 detector requiring -24V, the present invention adopts a DC voltage module and a linear voltage regulator module to convert the external input +12V to -24V, and whether the -24V is output can be controlled by software; in view of the low water discharge detector requiring +15, the present invention adopts a DC voltage module and a linear voltage regulator module to convert the external input +12V to +15V, and whether the +15V is output can be controlled by software.

[0065] In order to obtain the temperature signal of the N16 detector, the present invention uses a DC voltage module and a linear voltage regulator module to convert the external input +12V to obtain +10V and -10V power supply circuits. Whether the power supply is output can also be controlled by software; the temperature signal enters the fourth analog-to-digital conversion module through the temperature signal amplification circuit to obtain the real-time temperature value.

[0066] The digitizer filters the pulse signal input from the signal acquisition device and sends it to the host computer for analysis;

[0067] After the digitizer acquires the pulse signal, it can obtain the energy spectrum, energy resolution and counting rate through algorithm processing;

[0068] The host computer is used to control the signal acquisition device to provide working high and low voltages for the sodium iodide detector, and read the working high voltage and temperature in real time. The PID is used to adjust the read working high voltage so that the digital-to-analog conversion circuit makes the high voltage value meet the use requirements, presents the energy spectrum and waveform diagram and analyzes various parameters. The collected data is compared and analyzed with the data in the BP neural network classification model to obtain the detection results of the sodium iodide detector.

[0069] The host computer is provided with PC setting software, PC digitizer processing software and MATLAB software;

[0070] PC setting software, used to control the signal acquisition device to provide working high and low pressures for the sodium iodide detector, and to read the working high pressure and temperature;

[0071] The digitizer analysis software is used to present the energy spectrum and waveform diagram, and analyze various parameters;

[0072] MATLAB software reads the waveform file data, normalizes the waveform amplitude, and obtains the characteristic vector; MATLAB's BP (Back Propagation) neural network is used to perform machine learning on the characteristic vector of the sodium iodide detector and establish a classification model;

[0073] The characteristic vector includes pulse width, rise time, fall time, and pulse waveform charge ratio.

[0074] After the classification model is established, through a large amount of machine learning, the input probe pulse signal can be analyzed to obtain the performance level of the currently used probe and classify it. The more the BP neural network model learns, the more accurate the judgment result it gives.

[0075] The sodium iodide detector performance detection device of the present invention can monitor the energy spectrum and temperature information of the sodium iodide detector in real time; it is internally configured with a high-voltage power supply to achieve voltage adjustment and display; it also realizes data processing of the detector, and has functions such as measuring background counts, energy resolution, and detection efficiency calculation; it also has self-test and fault self-diagnosis functions. By amplifying the output signal of the sodium iodide detector, a digitizer is used for data acquisition, and subsequent processing software is used to test the performance indicators of the detector such as detection efficiency, capacity resolution, background level, and instability, and analyze the parameters, performance, and data to give the fault type. At the same time, through an external constant temperature and humidity test chamber, environmental tests can be performed by changing the working temperature and humidity conditions of the detector, and finally the test conclusions and fault analysis are output, so as to judge the performance of the detector.

[0076] The embodiment of the present invention also discloses a method for detecting the performance of a sodium iodide detector, comprising the following steps:

[0077] Step 1: Power on the signal acquisition device and digitizer for the first time;

[0078] Connect the host computer to the signal acquisition device and digitizer through USB cable and serial port cable respectively, and find the hardware corresponding to the two devices in the host computer device manager, including the sodium iodide detector signal acquisition device and digitizer; set parameters through the host computer high voltage setting software and digitizer processing software to ensure that the software and the device are connected and communicated normally;

[0079] Step 2: Setting parameters of the sodium iodide detector performance detection device described in the above technical solution;

[0080] Specifically include:

[0081] Use the host computer to set the temperature and humidity of the constant temperature and humidity test chamber, the type of sodium iodide detector to be tested, and the high voltage value;

[0082] Set the digitizer sampling channel, signal polarity, baseline, channel range, discrimination threshold and sampling frequency.

[0083] Step 3: Start the digitizer; observe the negative exponential waveform output by the detection device in the digitizer waveform window, and obtain the energy spectrum of the entire device to be detected in the digitizer spectrum window;

[0084] Step 4: Place the sodium iodide detector to be tested in a constant temperature and humidity test chamber, run it at the set temperature and humidity for more than 4 hours, use the Cs-137 source, adjust the high voltage value of the detection device, so that its 662keV peak position is displayed at around 200 channels in the digitizer spectrum window;

[0085] Step 5: Energy calibration of the sodium iodide detector to obtain a linear relationship between energy and channel address;

[0086] Step 6: Using the Cs-137 source, obtain the actual energy value displayed at the 662keV peak in the digitizer spectrum window, and judge the linearity of the sodium iodide detector according to the deviation; obtain the energy resolution at the 662keV peak in the digitizer spectrum window. If the value is greater than 8%, it means that the energy resolution of the sodium iodide detector does not meet the requirements; if the value is ≤8%, continue with the subsequent steps;

[0087] Step 7: Determine the energy linearity deviation and energy resolution of the sodium iodide detector under different temperatures and humidities, and judge the detector performance by comparing the linearity deviation, energy resolution, and detection efficiency based on the measurement results;

[0088] Specifically, change the temperature and humidity values ​​of the constant temperature and humidity test box, keep the temperature and humidity constant for more than 4 hours, repeat step 6, and judge the detector performance by comparing the linear deviation, energy resolution, detection efficiency and other parameters according to the measurement results;

[0089] Step 8: Substitute the waveform data of the obtained measurement results into the BP neural network model of MATLAB software for judgment, obtain the classification result, and thus determine the performance of the sodium iodide detector.

[0090] The BP neural network model of the MATLAB software is obtained through training, and the training method is:

[0091] A large number of waveforms are obtained from different detectors using a digitizer at different temperatures. The waveforms obtained by the digitizer are read using MATLAB software to read the waveform file data, and the waveform amplitude is normalized to obtain the characteristic vector; the characteristic vector of the detector is machine-learned using MATLAB's BP neural network to establish a classification model;

[0092] The characteristic vector includes pulse width, rise time, fall time, and pulse waveform charge ratio;

[0093] The MATLAB BP neural network classification model is continuously machine-learned and corrected to further improve its accuracy.

[0094] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0095] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sodium iodide detector performance detection device, characterized in that: include: Constant temperature and humidity test chamber, used to place different types of sodium iodide detectors, providing different temperature and humidity environments; The signal acquisition device is provided with a plurality of interfaces for connecting different types of sodium iodide detectors respectively, and is used to acquire the pulse signal of the sodium iodide detector and transmit the pulse signal to the digitizer after filtering and amplifying; The digitizer filters the pulse signal input from the signal acquisition device and sends it to the host computer for analysis; The host computer is used to control the signal acquisition device to provide working high and low voltages for the sodium iodide detector, and read the working high voltage and temperature in real time. The PID is used to adjust the read working high voltage so that the digital-to-analog conversion circuit makes the high voltage value meet the use requirements, presents the energy spectrum and waveform diagram and analyzes various parameters. The collected data is compared and analyzed with the data in the BP neural network classification model to obtain the detection results of the sodium iodide detector.

2. The sodium iodide detector performance detection device according to claim 1, characterized in that: The host computer is provided with PC setting software, PC digitizer processing software and MATLAB software; PC setting software, used to control the signal acquisition device to provide working high and low pressures for the sodium iodide detector, and to read the working high pressure and temperature; The digitizer analysis software is used to present the energy spectrum and waveform diagram, and analyze various parameters; MATLAB software reads the waveform file data, normalizes the waveform amplitude, and obtains the characteristic vector; MATLAB's BP neural network is used to perform machine learning on the characteristic vector of the sodium iodide detector and establish a classification model; The characteristic vector includes pulse width, rise time, fall time, and pulse waveform charge ratio.

3. The sodium iodide detector performance detection device according to claim 2, characterized in that: The sodium iodide detectors include N16 detectors, N13 detectors and low water discharge detectors.

4. The sodium iodide detector performance detection device according to claim 3, characterized in that: The signal acquisition device includes an ARM processor, a digital-to-analog conversion module, an analog-to-digital conversion module, a high-voltage module, a linear voltage stabilization module, a DC voltage module, and a filtering and amplification module; The digital-to-analog conversion module converts the high-voltage value set by the host computer into an analog quantity and then controls the high-voltage module. The high-voltage module outputs a preset working high voltage and provides it to the sodium iodide detector. The high-voltage module reads the output high voltage and converts the analog quantity into a digital quantity through the analog-to-digital conversion module and then transmits it to the ARM processor. The host computer reads the working high voltage of the sodium iodide detector in real time. The DC voltage module provides 3.3V working voltage to the host computer and linear voltage regulator module; The linear voltage regulator module receives the voltage signal of the 12V voltage input module, converts it into voltage signals of different magnitudes, and provides them to different high-voltage modules to supply different sodium iodide detectors; The pulse signal from the sodium iodide detector is processed, filtered, amplified, and then sent to the digitizer; Different sodium iodide detectors are matched with different digital-to-analog conversion modules, analog-to-digital conversion modules, high-voltage modules and filter amplifier modules.

5. The sodium iodide detector performance detection device according to claim 4, characterized in that: After the N16 detector works normally, the signal is input to the charge sensitive preamplifier through the DC blocking capacitor to amplify and improve the signal-to-noise ratio, and then the signal ripple is filtered through the pole-zero cancellation circuit to reduce the signal decay time, and then the counting rate is increased and then the signal enters the programmable amplifier for proportional amplification, and then enters the digitizer through the active filter shaping circuit. After the digitizer analyzes, the energy spectrum and waveform diagram can be displayed by the PC digitizer software; After the N13 detector works normally, the signal is input to the isolation amplifier for isolation and amplification. After filtering out high-frequency interference, the signal ripple is filtered through the pole-zero phase cancellation circuit to reduce the signal decay time and increase the counting rate. Then the signal enters the programmable amplifier and is proportionally amplified before entering the digitizer through the active filter shaping circuit. After analysis by the digitizer, the energy spectrum and waveform can be displayed by the PC digitizer software. After the low-discharge detector works normally, the signal is input into the reverse amplifier for amplification, high-frequency interference is filtered out, and the signal ripple is filtered through the pole-zero phase cancellation circuit to reduce the signal decay time and increase the counting rate. The signal then enters the programmable amplifier, is amplified in proportion, and then enters the digitizer through the active filter shaping circuit. After analysis by the digitizer, the energy spectrum and waveform can be displayed by the PC digitizer software.

6. The sodium iodide detector performance detection device according to claim 4, characterized in that: The linear voltage module provides a 3.3V working voltage to the linear voltage regulator module, which then converts the 12V voltage signal into +10V and -10V voltage signals to provide a working low voltage to the N16 detector; The linear voltage regulator module converts the 12V voltage signal into a -24V voltage signal, providing a working low voltage to the N13 detector; The linear voltage regulator module converts the 12V voltage signal into a +15V voltage signal, providing a working low voltage to the low-discharge water detector.

7. The sodium iodide detector performance detection device according to claim 1, characterized in that: The analog-to-digital conversion module also converts the temperature signal of the N16 detector and transmits it to the ARM processor, and the host computer reads the real-time temperature of the N16 detector in real time.

8. A method for detecting performance of a sodium iodide detector, characterized in that: The following steps are involved: Step 1: Power on the signal acquisition device and digitizer for the first time; Step 2: Setting parameters of the sodium iodide detector performance detection device according to any one of claims 1 to 7; Step 3: Start the digitizer; Step 4: Place the sodium iodide detector to be tested in a constant temperature and humidity test chamber, run it at the set temperature and humidity for more than 4 hours, use the Cs-137 source, adjust the high voltage value of the detection device, so that its 662keV peak position is displayed at around 200 channels in the digitizer spectrum window; Step 5: Energy calibration of the sodium iodide detector to obtain a linear relationship between energy and channel address; Step 6: Using the Cs-137 source, obtain the actual energy value displayed at the 662keV peak in the digitizer spectrum window, and judge the linearity of the sodium iodide detector according to the deviation; obtain the energy resolution at the 662keV peak in the digitizer spectrum window. If the value is greater than 8%, it means that the energy resolution of the sodium iodide detector does not meet the requirements; if the value is ≤8%, continue with the subsequent steps; Step 7: Determine the energy linearity deviation and energy resolution of the sodium iodide detector under different temperatures and humidities, and judge the detector performance by comparing the linearity deviation, energy resolution, and detection efficiency based on the measurement results; Step 8: Substitute the waveform data of the obtained measurement results into the BP neural network model of MATLAB software for judgment, obtain the classification result, and thus determine the performance of the sodium iodide detector.

9. The sodium iodide detector performance detection method according to claim 8, characterized in that: The BP neural network model of the MATLAB software is obtained through training, and the training method is: A large number of waveforms are obtained from different detectors using a digitizer at different temperatures. The waveforms obtained by the digitizer are read using MATLAB software to read the waveform file data, and the waveform amplitude is normalized to obtain the characteristic vector; the characteristic vector of the detector is machine-learned using MATLAB's BP neural network to establish a classification model; The characteristic vector includes pulse width, rise time, fall time, and pulse waveform charge ratio; The MATLAB BP neural network classification model is continuously machine-learned and corrected to further improve its accuracy.

10. The sodium iodide detector performance detection method according to claim 8, characterized in that: The step 2 specifically includes: Use the host computer to set the temperature of the constant temperature and humidity test chamber, the type of sodium iodide detector to be tested, and the high voltage value; Set the digitizer sampling channel, signal polarity, baseline, channel range, discrimination threshold and sampling frequency.

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