A radiation monitoring method and device for mixed radiation field

Abstract

The present invention discloses a radiation monitoring method and device for a mixed radiation field, the radiation monitoring method comprising the following steps: detecting and receiving neutron gamma radiation signals of the mixed radiation field; preprocessing the neutron gamma radiation signals and converting the neutron gamma radiation signals into corresponding digital signals; performing signal discrimination processing on the digital signals using PSD technology; displaying and calculating the digital signals after discrimination processing to achieve radiation monitoring. The monitoring device comprises a CLYC detector, a photomultiplier tube, a preamplifier, a mixed radiation field radiation monitoring prototype and a host computer. The method uses PSD technology to perform signal discrimination processing on the preprocessed digital signals, improves the accuracy of long and short gate integration and peak finding, and can more accurately and quickly distinguish and extract neutron gamma ray signals.

Description

Technical Field

[0001] The present invention relates to the field of radiation monitoring technology, and in particular to a radiation monitoring method and device for a mixed radiation field. Background Art

[0002] In nuclear power plants and other nuclear-related workplaces, the rays produced by the decay of nuclear materials are complex in type and widely distributed in energy, with typical mixed radiation field characteristics. The strong penetrating rays are mainly neutron gamma rays, and neutrons and gamma rays always exist together and are difficult to distinguish. Radiation monitoring of mixed radiation fields, identifying neutron gamma rays and displaying neutron and gamma fluxes in real time has become a very important part of nuclear radiation technology. Traditional waveform identification is based on analog electronic technology and requires dedicated nuclear instrument plug-ins or the use of microcomputer automatic measurement and control systems. Although real-time identification can be achieved, the instrument is complex, the system is large, the pulse count rate is low, the stability is poor, and the identification method is single and the identification efficiency is low.

[0003] The existing patent CN114488265A discloses a beta spectrometer for calibration laboratory, including a detection module and an energy spectrum data processing module. The detection module is placed in a copper shell with an incident window in the center. The detection module includes a Si detector and a CZT detector. The Si detector and the CZT detector are used to measure the received rays. The energy spectrum data processing module is used to output the events captured on the Si detector according to the events, perform energy calibration on the Si detector and the CZT detector, obtain the deposited energy of each event, and obtain the total beta energy spectrum after judging the event compliance.

[0004] The existing patent CN115079240A discloses a thunderstorm high-energy radiation detection system, which belongs to the field of thunderstorm physical characteristics detection technology. The system uses a high-energy radiation detection device arranged at the observation point with different range detection channels, and online identifies thunderstorm high-energy radiation events based on the law of radioactive statistical fluctuations, collects, stores and uploads thunderstorm high-energy radiation data and time location information, and uses a remote control terminal to control system operation and data management.

[0005] In summary, the above two existing patents have not solved the problems in the prior art that the radiation monitoring instruments are complex, the system is bulky, the pulse counting rate is low, the stability is poor, and the identification efficiency is low. Summary of the invention

[0006] Based on the above technical problems, the present invention proposes a radiation monitoring method and device for a mixed radiation field to solve the problems in the prior art of complex radiation monitoring instruments, bulky systems, low pulse counting rate, poor stability, and low identification efficiency.

[0007] To achieve the above object, the present invention proposes a radiation monitoring method for a mixed radiation field.

[0008] A radiation monitoring method for a mixed radiation field, comprising:

[0009] Detect and receive neutron gamma radiation signals from the mixed radiation field;

[0010] Preprocessing the neutron gamma radiation signal to convert the neutron gamma radiation signal into a corresponding digital signal;

[0011] Use PSD technology to perform signal identification processing on digital signals;

[0012] The digital signal after screening and processing is displayed and calculated to achieve radiation monitoring.

[0013] Further, the neutron gamma radiation signal is preprocessed to convert the neutron gamma radiation signal into a corresponding digital signal, including:

[0014] Amplify the neutron gamma radiation signal;

[0015] converting the amplified neutron gamma radiation signal into a differential signal;

[0016] The differential signal is sampled, quantized, and encoded to be converted into a digital signal.

[0017] Furthermore, the PSD technology is used to perform signal identification processing on the digital signal, including:

[0018] Perform SK filtering on digital signals;

[0019] Smoothing the digital signal after SK filtering;

[0020] According to the smoothed digital signal, the corresponding baseline threshold is determined by a peak-finding algorithm, and the baseline zeroing operation is performed on the digital signal;

[0021] According to the digital signal after the baseline zeroing operation, the corresponding long gate integral and short gate integral are calculated respectively;

[0022] Perform secondary smoothing on the digital signal after SK filtering, and perform peak search and nuclear pulse signal counting based on the result of secondary smoothing;

[0023] Digital signals are identified based on long gate integration, short gate integration, peak finding and nuclear pulse signal counting.

[0024] Furthermore, the digital signal after screening is displayed and calculated, including:

[0025] The quality factor is determined by using formula 1, and the discrimination effect of the digital signal is quantified by the quality factor. Formula 1: Among them, FOM is the quality factor, S represents the distance between the highest peaks of the gamma peak and the neutron peak, FWHM γ Indicates the half-width of the gamma peak, FWHM n represents the half-width at half-height of the neutron peak.

[0026] Furthermore, the digital signal is subjected to SK filtering, including:

[0027] According to formula 2, the digital signal is processed by SK filtering. Formula 2: Among them, y i Represents the digital signal after SK filtering. Δt is the sampling period of ADC, RC is the product of the resistance and capacitance of the first-order RC low-pass filter circuit, D represents the gain of SK filter, x i Indicates the sample value of ADC.

[0028] Furthermore, the digital signal after the SK filtering is smoothed, including:

[0029] According to formula 3, the digital signal after SK filtering is smoothed. Formula 3, B (i) =B (i-1) +m*[x i -B (i-1) ], where B (i) is the output value of the i-th sample value after first-order RC filtering, B (i-1) is the output value of the i-1th sample value after first-order RC filtering, x i is the sampling value of ADC.

[0030] Further, according to the digital signal after the baseline zeroing operation, the corresponding long gate integral and short gate integral are calculated respectively, including:

[0031] Based on the digital signal after the baseline zeroing operation, the corresponding long gate integral and short gate integral are calculated respectively by formula 4. Formula 4: Among them, Z b is the long gate integral or short gate integral, i represents the i-th signal sampling point counted from the time when the nuclear pulse signal is detected, b is the long gate value or short gate value, x i is the sampling value of ADC.

[0032] Furthermore, based on long gate integration, short gate integration, peak finding and nuclear pulse signal counting, the digital signal is identified, including:

[0033] Based on the long gate integral and the short gate integral, the functional spectral density value corresponding to the digital signal is determined by formula 5. Formula 5: Among them, Q longrepresents the Nagato integral, Q short is the short gate integration, PSD is the functional spectral density value of the neutron pulse signal or the gamma pulse signal;

[0034] Generate a PSD depth map based on the functional spectral density value, peak search and nuclear pulse signal count;

[0035] The digital signal is identified through the PSD depth map.

[0036] Furthermore, the digital signal after the SK filtering process is subjected to Gaussian quadratic smoothing. The calculation formula of Gaussian quadratic smoothing is Formula 6. Formula 6:

[0037]

[0038] Where w[i] is the impulse response function, n represents the position of the sampling point from left to right in the window, N is the window size, x[ni] is the sampling value of the ADC, and y[n] is the signal output value after Gaussian quadratic smoothing.

[0039] Based on the above technical solution, a radiation monitoring method for a mixed radiation field of the present invention has at least the following beneficial effects:

[0040] 1. A radiation monitoring method for a mixed radiation field of the present invention utilizes PSD technology to perform signal identification processing on the pre-processed digital signal, specifically including SK filtering, Gaussian quadratic smoothing filtering, baseline zeroing, and long-short gate integral calculation. This method can reduce the probability of pulse accumulation, increase the pulse counting rate, and improve the accuracy of long-short gate integral and peak finding, thereby more accurately and quickly distinguishing and extracting neutron gamma-ray signals.

[0041] In order to achieve the same purpose as the above method, the present invention also proposes a radiation monitoring device for a mixed radiation field, the radiation monitoring device is used to perform the above radiation monitoring method, and the radiation monitoring device comprises:

[0042] CLYC detector, used to detect and receive neutron gamma radiation signals from the mixed radiation field;

[0043] A photomultiplier tube, which is connected to the CLYC detector and is used to convert neutron gamma radiation signals into corresponding electrical signals;

[0044] A preamplifier is used to receive and amplify electrical signals;

[0045] The hybrid radiation field radiation monitoring prototype is used to identify and process the amplified electrical signals;

[0046] The host computer is connected to the mixed radiation field radiation monitoring prototype and is used to display and calculate the electrical signals after screening and processing to realize radiation monitoring.

[0047] Furthermore, the hybrid radiation field radiation monitoring prototype includes a main electronic board daughter board, a main electronic board mother board, an HMI display screen, an uninterruptible power supply UPS and an industrial computer containing host computer software, and the main electronic board daughter board is connected to the main electronic board mother board through an FMC connector.

[0048] Furthermore, the main electronics board sub-board includes: an analog signal conditioning module and an ADC sampling module, the analog signal conditioning module is used to condition the electrical signal processed by the preamplifier and convert the electrical signal into a differential signal; the ADC sampling module is used to sample, quantize and encode the differential signal and convert the differential signal into a digital signal.

[0049] Furthermore, the main electronic board motherboard includes a ZYNQ chip, and the ZYNQ chip is used to identify and process the digital signal.

[0050] Based on the above technical solution, the radiation monitoring device of a mixed radiation field of the present invention has at least the following beneficial effects:

[0051] 1. The hybrid radiation field monitoring device of the present invention includes a CLYC detector, a photomultiplier tube, a preamplifier, a hybrid radiation field radiation monitoring prototype and a host computer. By embedding a ZYNQ chip as a core processing chip on the main electronic board motherboard of the hybrid radiation field radiation monitoring prototype, the PSD discrimination algorithm in the ZYNQ chip can more accurately and quickly distinguish and extract neutron gamma ray signals. The signal processing method implemented by the ZYNQ chip is highly flexible, and can realize precise energy measurement and dose calculation as well as real-time monitoring of environmental radiation, which is more suitable for industrial applications.

[0052] 2. The hybrid radiation field monitoring device of the present invention adopts a CLYC detector for signal detection. The detector has the advantages of high energy resolution, efficient detection and strong radiation resistance, so that the present invention can better detect low-intensity radiation signals and also has good detection performance in high-radiation environments.

[0053] 3. The present invention embeds the Linux system inside the ZYNQ chip to realize local detection of neutron gamma discrimination data, and realizes remote data monitoring function through reserved network port communication, which can overcome the shortcomings of the traditional waveform discrimination device with large size, realize low power consumption and small size design, and make the mixed radiation field monitoring device more portable and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0055] Figure 1 A flow chart of a radiation monitoring method for a mixed radiation field according to an embodiment of the present invention;

[0056] Figure 2 A logic diagram of using PSD technology to perform signal discrimination processing on a digital signal in one embodiment of the present invention;

[0057] Figure 3 A circuit diagram for Sallen-Key;

[0058] Figure 4 A signal diagram of a neutron pulse and a gamma pulse and a position for selecting long and short gate integration according to an embodiment of the present invention;

[0059] Figure 5 A PSD depth map determined by signal identification using a Cf252 radiation source in a specific embodiment of the present invention;

[0060] Figure 6 A PSD depth map determined by signal screening using an AmBe radiation source in a specific embodiment of the present invention;

[0061] Figure 7 A schematic diagram of a radiation monitoring device for a mixed radiation field according to an embodiment of the present invention;

[0062] Figure 8 This is a diagram showing the results of a gamma energy resolution experiment conducted on a mixed radiation field radiation monitoring prototype using a Cs137 radiation source in a specific embodiment of the present invention.

[0063] The above drawings include the following reference numerals:

[0064] 1. CLYC detector; 2. Photomultiplier tube; 3. Preamplifier; 4. Mixed radiation field radiation monitoring prototype; 5. Host computer. DETAILED DESCRIPTION

[0065] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0066] The present invention is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed by the present invention.

[0067] Example

[0068] In order to solve the problems in the prior art of complex radiation monitoring instruments, bulky systems, low pulse counting rate, poor stability and low identification efficiency, the present invention proposes a radiation monitoring method and device for a mixed radiation field.

[0069] To achieve the above object, the present invention proposes a radiation monitoring method for a mixed radiation field.

[0070] like Figure 1 FIG. 4 is a flow chart of a method for monitoring radiation in a mixed radiation field according to an embodiment of the present invention. The method comprises the following steps:

[0071] S1, detects and receives neutron gamma radiation signals from the mixed radiation field.

[0072] In this step, the neutron gamma radiation signal of the mixed radiation field can be detected by a detector. In this embodiment, a CLYC detector is used for detection.

[0073] S2, preprocessing the neutron gamma radiation signal, and converting the neutron gamma radiation signal into a corresponding digital signal.

[0074] Further, the neutron gamma radiation signal is preprocessed to convert the neutron gamma radiation signal into a corresponding digital signal, including:

[0075] S201, amplifying the neutron gamma radiation signal.

[0076] S202, converting the amplified neutron gamma radiation signal into a differential signal.

[0077] S203, sampling, quantizing, and encoding the differential signal into a digital signal.

[0078] In this embodiment, a preamplifier is used to amplify the neutron gamma radiation signal. After the signal detected by CLYC enters the preamplifier, the input current signal is converted into a voltage signal through the first stage circuit of the preamplifier, and then the signal is output through the second stage shaping circuit containing baseline adjustment. The signal output by the preamplifier is transmitted to the main electronic board sub-board of the hybrid radiation monitoring prototype, and the signal from the preamplifier is converted into a differential signal through the functional module in the main electronic board sub-board, and the differential signal is sampled, quantized, and encoded into a digital signal.

[0079] S3, using PSD technology to perform signal identification processing on digital signals.

[0080] The principle of the PSD technology (Pulse Shape Discriminator) is as follows: the difference in waveform shape of nuclear pulse signals formed by neutrons and gamma rays incident on the detector is used as a basis for particle discrimination. This method is an important method for radiation monitoring in mixed radiation fields.

[0081] like Figure 2 The figure shows the logic diagram of using PSD technology to perform signal discrimination processing on digital signals. Figure 2 As shown, the process is mainly divided into the following steps:

[0082] S301, performing SK filtering processing on the digital signal.

[0083] After the neutron gamma radiation signal is pre-processed in step S2, it is first subjected to SK filtering to filter out the noise jitter on the signal and improve the accuracy of the tail integral of the signal. When setting parameters, it is necessary to avoid excessive filtering that causes the signal to become Gaussian, thereby causing the tail characteristics of the neutron gamma signal to disappear. Furthermore, SK filtering is derived from the Sallen-Key filter, which is an active filter circuit. The present invention digitizes it and uses it in actual engineering. A circuit principle of Sallen-Key is as follows Figure 3 As shown, Figure 3 V i is the sampling point of the ADC input, V O is the output after SK filtering, R 1 , R 2 , R 3 , R 4 Represents the resistance in the circuit, C 1 , C 2 represents the capacitance in the circuit; the sampling period of the ADC is Δt. 1 =R 2 =R,C 1 =C 2 =C, D = (R 3 +R 4 ) / R 3 , when k = RC / Δt, the digital formula is Formula 2: In this embodiment, the digital signal is subjected to SK filtering according to Formula 2, where y i Represents the digital signal after SK filtering. Δt is the sampling period of ADC, RC is the product of the resistance and capacitance of the first-order RC low-pass filter circuit, D represents the gain of SK filter, x iRepresents the sampling value of ADC. After debugging and analysis, the present invention can reduce noise and improve the accuracy of signal tail integration when k=0.5 and D=1.1 without changing the signal tail characteristics.

[0084] S302, smoothing the digital signal after the SK filtering process.

[0085] Furthermore, in this embodiment, the digital signal after SK filtering is smoothed according to Formula 3. Formula 3, B (i) =B (i-1) +m*[x i -B (i-1) ], where B (i) is the output value of the i-th sample value after first-order RC filtering, B (i-1) is the output value of the i-1th sample value after first-order RC filtering, x i is the ADC sampling value. In a specific embodiment of the present invention, after actual application debugging, the m value is selected as 1 / 32.

[0086] S303, determining a corresponding baseline threshold through a peak finding algorithm according to the smoothed digital signal, and performing a baseline zeroing operation on the digital signal.

[0087] Trigger_Threshold (trigger threshold) is used to trigger the peak-finding algorithm to start PSD value calculation and nuclear pulse counting. When the signal amplitude is greater than Trigger_Threshold (trigger threshold), the peak-finding algorithm module considers that the signal received at this moment is a nuclear pulse signal. At this time, the peak-finding algorithm will first look forward for a fixed length of sampling points and discard them. The fixed length of sampling points is a fixed value set by the host computer according to the characteristics of the nuclear pulse signal. The purpose is to eliminate the influence of the nuclear pulse signal before the trigger threshold. Subsequently, the peak-finding algorithm looks forward for the Baseline length sampling point, accumulates and averages these Baseline sampling points, and calculates the baseline threshold. The Baseline length sampling point is a value preset by the host computer. The purpose is to reduce the influence of noise on the baseline threshold by accumulating and averaging multiple points.

[0088] Furthermore, the baseline threshold is the differential value of the nuclear pulse signal, and its value is generally greater than the differential value of the baseline. When the signal is differentiated and its differential value is found to be greater than the baseline threshold, the signal at this time is considered to be a nuclear pulse signal, and the baseline freezing stage is entered. When entering the baseline freezing stage, the baseline of the nuclear pulse signal will not be recalculated, but the current signal value will be subtracted from the baseline threshold calculated before the baseline is frozen, that is, the baseline is reset to zero and sent to the RAM buffer area to prevent the baseline of the nuclear pulse signal from affecting the long gate and short gate calculations. In the baseline freezing stage, if it is detected that the differential value of the signal is greater than the baseline threshold again, it is considered to be a pile-up signal, and the baseline freezing time will be extended to prevent the baseline calculation error during pile-up from causing the long gate and short gate calculation error, thereby affecting the FOM value calculation.

[0089] S304, respectively calculating the corresponding long gate integral and short gate integral according to the digital signal after the baseline zeroing operation.

[0090] Further, according to the digital signal after the baseline zeroing operation, the corresponding long gate integral and short gate integral are calculated respectively, including:

[0091] Based on the digital signal after the baseline zeroing operation, the corresponding long gate integral and short gate integral are calculated respectively by formula 4. Formula 4: Among them, Z b is the long gate integral or short gate integral, i represents the i-th signal sampling point counted from the time when the nuclear pulse signal is detected, b is the long gate value or short gate value, x i is the amplitude of the signal sampled.

[0092] like Figure 4 The schematic diagram of neutron pulse and gamma pulse signals and the long and short gate pulse signals are shown in FIG. 1 , wherein the dotted line Neutron represents the neutron pulse signal and the solid line Gamma represents the gamma pulse signal. Figure 4 The two square wave signals above are short gate and long gate respectively. The high pulse time of short gate and long gate indicates the position points selected by the long and short gate integration.

[0093] S305, performing secondary smoothing processing on the digital signal after the SK filtering processing, and performing peak search and core pulse signal counting based on the result after the secondary smoothing processing.

[0094] Based on a large number of experiments and simulations, the following conclusions are drawn: the peak value of the pulse waveform of different particle pulses after Gaussian quadratic smoothing function nuclear pulse shaping does not change much with the change of the tailing of the detector output signal, and the peak value of the pulse after shaping is not much offset from the position of the original pulse peak value, and the algorithm can separate the accumulated signal, thereby improving the accuracy of the counting rate and the accuracy of the peak search, thereby improving the system energy resolution and the calculation accuracy of the dose rate. In this embodiment, the calculation formula for the secondary smoothing of the digital signal after SK filtering is Formula 6,

[0095]

[0096] Where w[i] is the impulse response function, n represents the position of the sampling point from left to right in the window, N is the window size, x[ni] is the sampling value of the ADC, and y[n] is the signal output value after Gaussian quadratic smoothing.

[0097] The x[ni] can be determined according to the following formula 7, wherein:

[0098]

[0099] Where x[n] represents the sampling value of the ADC, N is the window size, n represents the position of the sampling point from left to right in the window; k represents the linear baseline slope, c is a fixed constant, H is the nuclear pulse amplitude, τ 0 is the exponential decay constant.

[0100] After performing peak search and core pulse signal counting based on the result after the secondary smoothing process, this embodiment packages the long gate integral and short gate integral determined in step S304 and the peak search and core pulse signal counting in step S305 to the PS end, embeds the Linux system in the PS end, determines the functional spectral density value corresponding to the digital signal through the Linux system, and identifies the digital signal. The specific process is shown in step S306.

[0101] S306, based on the long gate integration, the short gate integration, the peak search and the nuclear pulse signal count, the digital signal is identified.

[0102] Furthermore, based on the long gate integration, the short gate integration, the peak finding and the nuclear pulse signal count, the digital signal is identified, including the following sub-steps:

[0103] S3061, determining a functional spectral density value corresponding to the digital signal based on the long gate integral and the short gate integral.

[0104] Specifically, the functional spectral density value corresponding to the digital signal is determined by formula 5. Formula 5: Among them, Qlong represents the Nagato integral, Q short is the short gate integration, and PSD is the functional spectral density value of the neutron pulse signal or the gamma pulse signal.

[0105] S3062, generating a PSD depth map according to the functional spectral density value, peak search condition and nuclear pulse signal count.

[0106] S3063, identifying the digital signal through the PSD depth map.

[0107] like Figure 5 This is a PSD depth map determined by signal identification using a Cf252 radiation source in a specific embodiment of the present invention. Figure 6 The PSD depth map is determined by using an AmBe radiation source to perform signal screening in a specific embodiment of the present invention. Figure 5 , Figure 6 The horizontal axis is the ADC channel address, and the vertical axis is the PSD value. The ADC channel address is the maximum value of the nuclear pulse signal found during peak search or the maximum value obtained by the five-point average as the ADC channel address. Figure 5 , Figure 6 As shown in the figure, the PSD depth map determined by signal identification for the two radioactive sources is divided into two upper and lower areas. Since the PSD value of the neutron signal is usually smaller than the PSD value of the gamma signal, it is considered that Figure 5 Area A in Figure 6 The region A' in is the gamma signal, Figure 5 Region B in Figure 6 Region B' in the graph is the neutron signal.

[0108] S4, displays and calculates the digital signal after screening and processing to achieve radiation monitoring.

[0109] Furthermore, the digital signal after screening is displayed and calculated, including:

[0110] The quality factor is determined by using formula 1, and the discrimination effect of the digital signal is quantified by the quality factor. Formula 1: Among them, FOM is the quality factor, S represents the distance between the highest peaks of the gamma peak and the neutron peak, FWHM γ Indicates the half-width of the gamma peak, FWHM n represents the half-width at half-height of the neutron peak.

[0111] The above formula is used to determine the above Figure 5 , Figure 6 The quality factor FOM values ​​corresponding to the corresponding embodiments are 2.3889 and 2.1765 respectively, both reaching the specified index (FOM>2). Therefore, it can be determined that the method has a good signal discrimination effect and can distinguish neutron signals from gamma signals.

[0112] In summary, it can be seen from the above description that the above-mentioned embodiment of the radiation monitoring method for a mixed radiation field of the present invention can achieve the following technical effects:

[0113] 1. A radiation monitoring method for a mixed radiation field of the present invention utilizes PSD technology to perform signal identification processing on the pre-processed digital signal, specifically including SK filtering, Gaussian quadratic smoothing filtering, baseline zeroing, and long-short gate integral calculation. This method can reduce the probability of pulse accumulation, increase the pulse counting rate, and improve the accuracy of long-short gate integral and peak finding, thereby more accurately and quickly distinguishing and extracting neutron gamma-ray signals.

[0114] A radiation monitoring device for a mixed radiation field, the radiation monitoring device is used to execute the above-mentioned radiation monitoring method.

[0115] like Figure 7 Schematic diagram of a radiation monitoring device for a mixed radiation field according to an embodiment of the present invention is shown, wherein the radiation monitoring device comprises: a CLYC detector 1, a photomultiplier tube 2, a preamplifier 3, a mixed radiation field radiation monitoring prototype 4 and a host computer 5.

[0116] Specifically, the CLYC detector 1 is used to detect and receive the neutron gamma radiation signal of the mixed radiation field. The energy resolution of the detector is <3.8%, and it has the advantages of high resolution, high efficiency, low background noise and good energy resolution. The photomultiplier tube 2 is connected to the CLYC detector and is used to convert the neutron gamma radiation signal into a corresponding electrical signal. The preamplifier 3 is used to receive the electrical signal and amplify the electrical signal to enhance the amplitude of the input signal, improve the signal-to-noise ratio, reduce interference, and then transmit the signal through the second-stage shaping circuit containing baseline adjustment.

[0117] The rapid development of FPGA technology and high-performance ADC has opened up a new space for waveform identification, making it possible to replace analog plug-ins with digital instruments. Digital, portable, and real-time waveform identification can be effectively embedded in digital-based nuclear physics electronics systems. Compared with traditional analog methods, it saves a lot of hardware parts, reduces the system scale, and makes the identification method more flexible, greatly improving the speed and accuracy of waveform identification, which is of great significance. The present invention embeds a ZYNQ chip in the hybrid radiation monitoring prototype 4, and uses the PSD algorithm and other functional modules in the ZYNQ chip to achieve signal identification.

[0118] Specifically, the hybrid radiation field radiation monitoring prototype 4 is used to identify and process the electrical signal after amplification. The hybrid radiation field radiation monitoring prototype 4 is an embedded industrial touch-screen all-in-one computer, which is mounted on a movable industrial computer cabinet. For the convenience of power supply, an uninterruptible power supply (UPS) is configured inside the cabinet. The working power supply of the prototype is mainly provided by the adapter. At the same time, in order to facilitate the debugging of the board, an external power supply interface is reserved on the circuit board for powering the board through a DC regulated power supply. Furthermore, the hybrid radiation field radiation monitoring prototype 4 includes a main electronic board motherboard, a main electronic board daughterboard, an HMI display screen, an uninterruptible power supply UPS, an industrial computer containing a host computer software, and the main electronic board motherboard includes a ZYNQ chip, a Gigabit Ethernet communication interface module, an HDMI interface module and a power module.

[0119] The ZYNQ chip is used to identify and process electrical signals and provide data and control interfaces for other modules. The PL end of the ZYNQ chip is used to implement data acquisition, filtering, smoothing, PSD algorithm, etc., which is called the lower computer. The upper computer is at the PS end or remote control end of the ZYNQ chip. The ZYNQ PS end is embedded in the LINUX system, and the upper computer is developed in the system, or the upper computer software is developed at the remote control end to control the ZYNQ PL end. Specifically, the functional modules of the ZYNQ chip mainly include: ADC and clock chip configuration module, clock and reset module, ADC data acquisition module, FIFO data cache module, neutron, gamma discrimination algorithm, Gigabit Ethernet communication, DMA control module. The ADC data acquisition module and the clock configuration module mainly complete the configuration of the ADC and clock chip; the clock and reset module contains 4 clock domains, using low-level reset, and the reset signal is provided by the PS end of ZYNQ and the host computer software; the function of the digital pulse processing and identification module is to avoid the interference of background noise and detector background through the threshold method, collect valid pulses and perform pulse shape recognition; the ZYQN chip uploads data through the Gigabit Ethernet bus; the DMA control module is mainly used for high-speed data transmission between PL and PS. The Gigabit Ethernet communication interface module is used for data interaction between the host computer and the slave computer; the power supply module uses a voltage regulator to reduce the voltage of the external power supply to power the circuit board.

[0120] Furthermore, the ZYNQ chip integrates a K7 series high-performance FPGA and an A9 series high-performance ARM. Compared with a single onboard FPGA, the ZYNQ chip integrates a dual-core ARM, which can perform embedded programming and high-precision floating-point operations; compared with a single onboard ARM, the ZYNQ chip integrates a K7 series FPGA, which can perform high-speed operations; compared with both onboard FPGA and ARM, ZYNQ has a higher degree of integration.

[0121] The main electronics board sub-board mainly includes analog signal conditioning module, ADC sampling module, clock chip module and power supply module. The analog conditioning module conditions the signal from the preamplifier and converts the electrical signal into a differential signal; the ADC sampling module obtains enough sampling points for each pulse signal for algorithm analysis; the clock chip module is used to ensure the stability of the timing and acquisition system of ZYNQ. The main electronics board motherboard and the main electronics board sub-board are connected through the FMC connector.

[0122] The host computer 5 is connected to the mixed radiation field radiation monitoring prototype 4 and is used to display and calculate the electrical signal after screening and processing to realize radiation monitoring.

[0123] The overall process of the radiation monitoring device performing the radiation monitoring method is as follows:

[0124] 1) Using a CLYC detector to detect and receive the neutron gamma radiation signal of the mixed radiation field, and converting the signal into an electrical signal via a photomultiplier tube.

[0125] 2) The electrical signal enters the preamplifier, and the first-stage circuit of the preamplifier converts the input current signal into a voltage signal, and then the signal is output through the second-stage shaping circuit containing baseline adjustment.

[0126] 3) The output signal of the preamplifier is transmitted to the main electronics board through the SMA interface and enters the analog signal conditioning module, which conditions the analog signal input from the front end and converts the electrical signal from the preamplifier into a differential signal.

[0127] 4) The differential signal output by the conditioning circuit enters the ADC sampling module for sampling, quantization, encoding and conversion into a digital signal.

[0128] 5) The digital signal output by the ADC sampling module is sent to the ZYNQ chip for neutron and gamma signal identification and processing.

[0129] 6) Finally, data interaction with the host computer is achieved through Gigabit Ethernet. The host computer PSD software displays and calculates the signals processed by the ZYNQ chip to achieve radiation monitoring.

[0130] In a specific embodiment of the present invention, a gamma energy resolution experiment is carried out on a mixed radiation field radiation monitoring prototype and a standard instrument CANE using a Cs137 radiation source. The experimental results corresponding to the mixed radiation field radiation monitoring prototype are as follows: Figure 8 As shown. Figure 8It can be seen below that the energy resolution of the hybrid radiation field radiation monitoring prototype is 4.95%; the energy resolution corresponding to the standard instrument CANE analysis is 4.902%, both of which are less than the standard indicator (Cs137 energy resolution <5%). This result shows that the hybrid radiation field radiation monitoring prototype of the present invention has good energy resolution and can more accurately identify and distinguish radiation sources of different energies.

[0131] It should be understood that a radiation monitoring device for a mixed radiation field is consistent with the description of a corresponding embodiment of a radiation monitoring method for a mixed radiation field, so it will not be described in detail in this embodiment.

[0132] In summary, it can be seen from the above description that the radiation monitoring device of a mixed radiation field of the present invention can achieve the following technical effects:

[0133] 1. The hybrid radiation field monitoring device of the present invention includes a CLYC detector, a photomultiplier tube, a preamplifier, a hybrid radiation field radiation monitoring prototype and a host computer. By embedding a ZYNQ chip as a core processing chip on the main electronic board motherboard of the hybrid radiation field radiation monitoring prototype, the PSD discrimination algorithm in the ZYNQ chip can more accurately and quickly distinguish and extract neutron gamma ray signals. The signal processing method implemented by the ZYNQ chip is highly flexible, and can realize precise energy measurement and dose calculation as well as real-time monitoring of environmental radiation, which is more suitable for industrial applications.

[0134] 2. The hybrid radiation field monitoring device of the present invention adopts a CLYC detector for signal detection. The detector has the advantages of high energy resolution, efficient detection and strong radiation resistance, so that the present invention can better detect low-intensity radiation signals and also has good detection performance in high-radiation environments.

[0135] 3. The present invention embeds the Linux system inside the ZYNQ chip to realize local detection of neutron gamma discrimination data, and realizes remote data monitoring function through reserved network port communication, which can overcome the shortcomings of the traditional waveform discrimination device with large size, realize low power consumption and small size design, and make the mixed radiation field monitoring device more portable and stable.

[0136] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0137] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0138] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, which can be embodied in any computer-readable medium for use by an instruction execution system, apparatus or device (such as a computer-based system, a system including a processor or other system that can fetch instructions from an instruction execution system, apparatus or device and execute instructions), or used in combination with these instruction execution systems, apparatuses or devices.

[0139] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0140] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

Claims

1. A radiation monitoring method for a mixed radiation field, characterized in that: include: Detect and receive neutron gamma radiation signals from the mixed radiation field; Preprocessing the neutron gamma radiation signal to convert the neutron gamma radiation signal into a corresponding digital signal; Performing signal identification processing on the digital signal by using PSD technology; The digital signal after screening and processing is displayed and calculated to achieve radiation monitoring.

2. The method according to claim 1, characterized in that Preprocessing the neutron gamma radiation signal to convert the neutron gamma radiation signal into a corresponding digital signal includes: amplifying the neutron gamma radiation signal; converting the amplified neutron gamma radiation signal into a differential signal; The differential signal is sampled, quantized, and encoded to be converted into a digital signal.

3. The method according to claim 1, characterized in that The digital signal is processed by using the PSD technology, including: Performing SK filtering on the digital signal; Smoothing the digital signal after SK filtering; According to the smoothed digital signal, a corresponding baseline threshold is determined by a peak finding algorithm, and a baseline zeroing operation is performed on the digital signal; According to the digital signal after the baseline zeroing operation, respectively calculating the corresponding long gate integral and short gate integral; Performing secondary smoothing processing on the digital signal after the SK filtering processing, and performing peak search and nuclear pulse signal counting based on the result after the secondary smoothing processing; The digital signal is identified based on the long gate integration, the short gate integration, the peak search condition and the nuclear pulse signal count.

4. The method according to claim 1, characterized in that: Perform display calculations on the digital signal after screening, including: The quality factor is determined by using formula 1, and the discrimination effect of the digital signal is quantified by the quality factor. The formula 1 is: Among them, FOM is the quality factor, S represents the distance between the highest peaks of the gamma peak and the neutron peak, FWHM γ Indicates the half-width of the gamma peak, FWHM n represents the half-width at half-maximum of the neutron peak.

5. The method according to claim 3, characterized in that: Performing SK filtering on the digital signal includes: The digital signal is subjected to SK filtering processing according to Formula 2, wherein: Among them, y i Represents the digital signal after SK filtering. Δt is the sampling period of ADC, RC is the product of the resistance and capacitance of the first-order RC low-pass filter circuit, D represents the gain of SK filter, x i Indicates the sample value of ADC.

6. The method according to claim 3, characterized in that Smoothing the digital signal after SK filtering, including: According to formula 3, the digital signal after SK filtering is smoothed. In formula 3, B (i) =B (i-1) +m*[x i -B (i-1) ], where B (i) is the output value of the i-th sample value after first-order RC filtering, B (i-1) is the output value of the i-1th sample value after first-order RC filtering, x i is the sampling value of ADC.

7. The method according to claim 3, characterized in that According to the digital signal after the baseline zeroing operation, the corresponding long gate integral and short gate integral are calculated respectively, including: Based on the digital signal after the baseline zeroing operation, the corresponding long gate integral and short gate integral are calculated respectively by formula 4, wherein: Among them, Z b is the long gate integral or short gate integral, i represents the i-th signal sampling point counted from the time when the nuclear pulse signal is detected, b is the long gate value or short gate value, x i is the amplitude of the signal sampled.

8. The method according to claim 3, characterized in that Based on the long gate integration, the short gate integration, the peak search condition and the nuclear pulse signal count, the digital signal is identified, including: Based on the long gate integral and the short gate integral, the functional spectral density value corresponding to the digital signal is determined by formula 5, wherein: Among them, Q long represents the Nagato integral, Q short is the short gate integration, PSD is the functional spectral density value of the neutron pulse signal or the gamma pulse signal; Generate a PSD depth map according to the functional spectral density value, the peak search condition and the nuclear pulse signal count; The digital signal is identified by using the PSD depth map.

9. The method according to claim 3, characterized in that: The digital signal after the SK filtering process is subjected to Gaussian quadratic smoothing. The calculation formula of the Gaussian quadratic smoothing process is Formula 6. Formula 6: Where w[i] is the impulse response function, n represents the position of the sampling point from left to right in the window, N is the window size, x[ni] is the sampling value of the ADC, and y[n] is the signal output value after Gaussian quadratic smoothing.

10. A radiation monitoring device for a mixed radiation field, characterized in that: The radiation monitoring device is used to perform the radiation monitoring method according to any one of claims 1 to 9, and the radiation monitoring device comprises: A CLYC detector, used to detect and receive the neutron gamma radiation signal of the mixed radiation field; a photomultiplier tube, the photomultiplier tube is connected to the CLYC detector, and is used to convert the neutron gamma radiation signal into a corresponding electrical signal; A preamplifier is used to receive the electrical signal and amplify the electrical signal; a mixed radiation field radiation monitoring prototype is used to identify the amplified electrical signal; A host computer is connected to the mixed radiation field radiation monitoring prototype and is used to display and calculate the electrical signal after screening and processing to achieve radiation monitoring.

11. The device according to claim 10, characterized in that The hybrid radiation field radiation monitoring prototype includes a main electronic board daughter board, a main electronic board mother board, an HMI display screen, an uninterruptible power supply UPS and an industrial computer containing host computer software. The main electronic board daughter board is connected to the main electronic board mother board through an FMC connector.

12. The device according to claim 11, characterized in that The main electronics board sub-board includes: an analog signal conditioning module and an ADC sampling module. The analog signal conditioning module is used to condition the electrical signal processed by the preamplifier and convert the electrical signal into a differential signal; the ADC sampling module is used to sample, quantize and encode the differential signal and convert the differential signal into a digital signal.

13. The device according to claim 12, characterized in that The main electronic board motherboard includes a ZYNQ chip, and the ZYNQ chip is used to identify and process the digital signal.

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