A marine radioactivity adaptive detection system and method

Abstract

The present invention discloses an adaptive marine radioactivity detection system and method, comprising a multi-channel scintillator detector array, a multi-channel SiPM array element, a multi-channel SiPM signal readout module, a power control module, a digital multi-channel signal processing system, and a data storage and transmission module. This system addresses the problem of simultaneous detection adaptability in diverse ocean and large river basin radiation scenarios with a wide range of radioactivity intensities. By adaptively adjusting the detection dynamic range, it can simultaneously ensure reliable detection efficiency and accuracy in both background and emergency high-radiation environments.

Description

Technical Field

[0001] The present invention relates to the fields of environmental monitoring technology and nuclear radiation detection technology, and in particular to a marine radioactivity adaptive detection system and method. Background Art

[0002] In recent years, my country has been rapidly developing nuclear submarines and nuclear-powered icebreakers. Simultaneously, the number and operating time of coastal nuclear power plants have continued to increase, significantly increasing the potential for sudden marine nuclear accidents. Therefore, establishing a marine radioactivity detection system for both emergency and routine monitoring of oceans and large river basins is crucial.

[0003] Current marine radioactivity detection solutions often use a single detector or a fixed array of several detectors. Single-detector systems have a limited detection range. To ensure detection of weak underwater signals, detectors often use larger scintillator crystals to improve sensitivity. However, in emergency scenarios involving nuclear accidents, the large amount of radioactive radiation can cause a significant amount of signal accumulation in single-crystal detectors, making effective signal processing difficult. While algorithms exist to address signal accumulation, they cannot completely eliminate this accumulation, resulting in some degree of error in detection results. Therefore, these solutions fail to meet the demanding requirements of marine nuclear accident emergency scenarios. While systems using fixed-number arrays improve detection range to a certain extent and can enhance detection accuracy through specific synthetic spectrum methods, the fixed number of detectors still makes it difficult to flexibly switch between routine weak radioactivity detection and emergency strong radioactivity detection. Adaptive adjustment is impossible, forcing the system to adopt a compromised range, making it difficult to achieve maximum detection efficiency in every scenario.

[0004] At the same time, due to material limitations, detectors have a certain degree of dark count rate properties. During routine underwater detection, due to the extremely low background radiation level, the dark counts spontaneously generated by stray light or noise in the detector crystal can significantly affect the normal counting of background radioactive signals (i.e., dark count coincidence events), thereby affecting the accuracy of the detector's back-end data processing unit in determining valid radiation events. Neither of the above two traditional solutions effectively solves the dark count coincidence problem. Therefore, it is necessary to propose an adaptive detection system and method for detector arrays that can flexibly switch the number of control arrays to change the detection range to adapt to daily and emergency detection scenarios, while also solving the dark count coincidence problem in low-activity detection. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the present invention provides an adaptive marine radioactivity detection system and method that solves the problem that the detection range of existing marine radioactivity detection systems cannot be dynamically adjusted, making it difficult to simultaneously meet the task requirements of nuclear accident emergency response and daily monitoring; at the same time, the existing system does not solve the impact of underwater dark counts on detection results, and cannot meet the flexibility and reliability requirements of marine radioactivity detection.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows: an adaptive marine radioactivity detection system, comprising a multi-channel scintillator detector array, a multi-channel SiPM array element, a multi-channel SiPM signal readout module, a power control module, a digital multi-channel signal processing system, and a data storage and transmission module;

[0007] The multi-channel scintillator detector array is composed of NaI or CeBr3 scintillator detectors for measuring gamma rays. The array is composed of n scintillator detectors, and the geometric arrangement position of each channel of the detector array is simulated by Monte Carlo simulation.

[0008] The multi-channel SiPM array element is composed of n SiPM array elements, each SiPM array element corresponds to receiving the optical signal of one channel in the detector array, and each SiPM array element contains m SiPM units and reads out the signals of m SiPM units at the same time;

[0009] The multi-channel SiPM signal readout module, each channel of which receives the electrical signal output by the SiPM array element of one channel, can read out SiPM multi-unit signals by building a multi-channel charge-sensitive preamplifier circuit or using a dedicated ASIC chip;

[0010] The power control module provides power for the multi-channel SiPM array elements and the multi-channel SiPM signal readout module. It is divided into two parts: high-voltage power supply and analog voltage. It supports digital signal isolation input to control the on and off of the high-voltage power supply and analog power supply of one or more channels;

[0011] The digital multi-channel signal processing system is composed of an analog-to-digital conversion circuit, a dark count coincidence removal module, an intelligent decision-making and signal extraction module, and is capable of achieving dark count removal and intelligently managing the number of channels in the detector array.

[0012] The data storage and transmission system can transmit and store the energy spectrum data of the detector, the system power consumption management data and the detector array management data, and can also manually issue control instructions to perform functional tests on the detection channels.

[0013] Furthermore: the analog-to-digital conversion circuit is designed through an ADC chip and uses a differential input mode to reduce interference caused by environmental noise coupling to the signal to be collected;

[0014] The dark count coincidence removal is specifically as follows: valid counting events are determined by comparing the readout signals of m units in each SiPM array element, thereby achieving the purpose of removing dark counts.

[0015] Furthermore: the intelligent decision-making and signal extraction are realized through the intelligent decision-making control module, trapezoidal forming, energy spectrum acquisition and control interface, which can realize the detection acquisition and energy spectrum output capabilities of the nuclear pulse signals of the multi-channel detector, and can intelligently control and manage the number of detector channels by whether the acquired signals generate accumulation, and can interact with the outside world through the control interface.

[0016] Furthermore: the intelligent decision control module determines whether signal accumulation occurs through the trapezoidal shaping output, and controls the enabling or disabling of the detector channel according to the signal accumulation;

[0017] The trapezoidal shaping, energy spectrum acquisition and control interface is composed of an existing trapezoidal shaping algorithm, an energy spectrum acquisition algorithm and a bus control interface.

[0018] A method for adaptively detecting marine radioactivity, comprising the following steps:

[0019] S1. Place the marine radioactivity adaptive detection system in an open sea area to be tested, so that the detector array is below the water surface for detection;

[0020] S2. The detection system performs parameter initialization, the detection channels start detection work with a low initial number, and the detection data is input into the digital multi-channel signal processing system for acquisition and processing;

[0021] S3. The digital multi-channel signal processing system performs dark count coincidence removal after reading out the signal of each detection channel. After the removal is completed, the effective signal is subjected to trapezoidal shaping and pulse counting.

[0022] S4. After the signal is formed into a trapezoid, a portion of it is input into the intelligent decision control module to determine the degree of signal accumulation. The intelligent decision control module connects to the power control module through a multi-channel control bus based on the accumulation situation to achieve adaptive switching of the number of detection channels used in the control system.

[0023] S5. Repeat steps S2-S4 until the radioactivity adaptability detection of the system is completed.

[0024] Furthermore, the detection work in step S2 is specifically as follows:

[0025] S21, the scintillator detector converts radioactive rays into long-wave photons and inputs them into the SiPM array elements;

[0026] S22, each of the m SiPM units of the SiPM array element converts a portion of the long-wavelength photons into electrical pulse signals and inputs them into the SiPM signal readout circuit;

[0027] S23. After receiving the m SiPM unit signals from a SiPM array element, the SiPM signal readout circuit undergoes signal amplification and signal conditioning, and finally inputs the signals into the analog-to-digital conversion circuit in the digital multi-channel signal processing system for multi-channel acquisition.

[0028] Furthermore, the dark count elimination in step S3 is specifically as follows:

[0029] S31. Setting a counting trigger threshold in the system initialization phase, wherein the counting trigger threshold is set based on prior data obtained from experimental results;

[0030] S32, obtaining signals read out by m SiPM units, and performing a logical AND operation on all signals;

[0031] S33, determining whether the final signal after the operation is greater than the counting trigger threshold, if it is greater than the counting trigger threshold, the signal is determined to be a valid signal, otherwise the signal is determined to be a dark counting invalid signal, and the system will automatically clear the dark counting invalid signal data cache and not count it;

[0032] S34. Repeat steps S32 and S33 to achieve cyclic removal of dark count coincidence events.

[0033] Furthermore, the working process of the intelligent decision control module in step S4 is as follows:

[0034] S41, initializing the count rate threshold and the number of detection channels. The count rate threshold is a priori parameter obtained through experiments, and the number of detection channels selects an intermediate value as the initial working channel;

[0035] S42, after completing the initialization, obtaining the effective counting signal after the dark count is removed, performing a trapezoidal shaping operation on the signal to determine whether the signal is accumulated. If the signal is accumulated, a certain number of detection channels are closed and the process returns to the effective counting signal acquisition step; if the signal is not accumulated, the next step of counting rate determination is performed;

[0036] S43. When there is no accumulation of signals, if the counting rate is less than the counting rate threshold, it indicates that the current signal is weak, and a certain number of detection channels need to be opened to improve the detection sensitivity; if the counting rate is greater than the counting rate threshold, it indicates that the current signal acquisition rate is relatively stable, and the number of detection channels should be maintained;

[0037] S44. Repeat steps S42 and S43 to implement intelligent decision-making control of the number of detection channels.

[0038] The beneficial effects of the present invention are:

[0039] (1) The present invention solves the problem of detection adaptability in different ocean radiation scenarios with a wide range of radioactive intensities (the different scenarios mainly refer to two types: daily monitoring scenarios with only background radiation and emergency monitoring scenarios with strong radiation from nuclear leaks). By adaptively adjusting the detection dynamic range, it is possible to simultaneously ensure reliable detection efficiency and accuracy of detection of radiation activity in both scenarios.

[0040] (2) Existing low-power system solutions mainly focus on low-power design by using low-power chips or solar power supply. The present invention provides another low-power design idea. Since the enabled detector channels are different in different scenarios, the disabled detector channels will save a certain amount of power. That is, by intelligently managing the number of detector channels, not only can the adaptive adjustment of the detection dynamic range described in (1) be achieved, but the detector power consumption can also be used efficiently, thus indirectly achieving the design purpose of low-power management. It provides another effective technical means for the system to conduct long-term detection in open sea areas.

[0041] (3) The present invention solves the problem that the detection accuracy of underwater radioactive background detection is affected by dark count coincidence events during daily detection. The dark count removal method is used to reduce the systematic error of low-activity radiation detection and improve the upper limit of the accuracy of underwater background radiation detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the architecture of an adaptive marine radioactivity detection system;

[0043] Figure 2 Flowchart of the dark count coincidence removal method according to an embodiment of the present invention;

[0044] Figure 3 This is a flow chart of the detection channel intelligent decision-making control method in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0046] like Figure 1As shown, the present invention proposes an adaptive marine radioactivity detection system, which includes: a multi-channel scintillator detector array, a multi-channel SiPM array element, a multi-channel SiPM signal readout module, a power control module, a digital multi-channel signal processing system and a data storage and transmission module.

[0047] A multi-channel scintillator detector array is composed of NaI or CeBr3 scintillator detectors for measuring gamma rays. The array is composed of n scintillator detectors. Monte Carlo simulation is used to simulate the geometric arrangement position of each channel of the detector array to adapt to the system structure.

[0048] A multi-channel SiPM array element is composed of n SiPM array elements. Each SiPM array element corresponds to receiving the light signal of a channel in the detector array, and each SiPM array element contains m SiPM units. Reading out the signals of m SiPM units at the same time is a necessary condition for eliminating dark counts in this channel.

[0049] Multi-channel SiPM signal readout module, each channel corresponds to the electrical signal output by the SiPM array element of one channel, and SiPM multi-unit signal readout can be performed by building a multi-channel charge-sensitive preamplifier circuit or using a dedicated ASIC chip.

[0050] The power control module provides power for the multi-channel SiPM array elements and the multi-channel SiPM signal readout module. It is divided into two parts: high-voltage power supply and analog voltage. It supports digital signal isolation input to control the on and off of the high-voltage power supply and analog power supply of one or more channels.

[0051] The single power supply channel of the high-voltage power supply can be designed by combining a Boost power chip with a charge pump voltage doubling circuit.

[0052] The single power supply channel of the analog power supply can be designed by the dual power output linear voltage regulator chip launched by TI.

[0053] The digital multi-channel signal processing system consists of an analog-to-digital conversion circuit, dark count coincidence removal, intelligent decision-making and signal extraction modules; it can achieve dark count removal and intelligently manage the number of channels in the detector array.

[0054] Digital multi-channel signal processing systems can be designed using FPGA alone, or using FPGA or DSP combined with an MCU coprocessor.

[0055] The analog-to-digital conversion circuit can be designed using the high-precision, high-speed ADC chip launched by ADI, and uses a differential input mode to reduce the interference caused by environmental noise coupling to the collected signal.

[0056] The dark count elimination mechanism is implemented by a program within the system. By comparing the readout signals of m units in each SiPM array element, the valid counting events are determined to achieve the purpose of eliminating dark counts.

[0057] The intelligent decision-making and signal extraction mechanism is composed of an intelligent decision-making control module, trapezoidal forming, energy spectrum acquisition and control interface. It can realize the detection, acquisition and energy spectrum output capabilities of nuclear pulse signals of multi-channel detectors, and can intelligently control and manage the number of detector channels by whether the acquired signals produce accumulation. It can interact with the outside world through the control interface.

[0058] The intelligent decision-making control module is implemented by a program within the system. It determines whether signal accumulation occurs through the trapezoidal output and controls the enablement or disablement of the detector channel according to the signal accumulation situation.

[0059] The trapezoidal shaping, energy spectrum acquisition and control interface are composed of the existing trapezoidal shaping algorithm, energy spectrum acquisition algorithm and bus control interface.

[0060] The data storage and transmission system can transmit and store the detector's energy spectrum data, system power consumption management data, and detector array management data, etc. It can also manually issue control instructions to perform functional tests on the detection channel.

[0061] The data storage and transmission system can use Ethernet, CAN and other field buses to connect to the host computer software in the PC for measurement and control operations.

[0062] In order to overcome the shortcomings of existing systems in marine radioactivity detection and achieve comprehensive, efficient, and adaptive monitoring with adjustable detection dynamic range, the present invention proposes an adaptive marine radioactivity detection method using a multi-channel detector array, which includes the following main steps:

[0063] Step 1: Place the system in an open sea area to be tested, so that the detector array is below the water surface for detection.

[0064] Step 2: The detection system performs parameter initialization, the detection channel starts detection work with a low initial number, and the detection data is input into the digital multi-channel signal processing system for acquisition and processing.

[0065] A detection channel consists of a scintillator detector, a SiPM array element, and a SiPM readout circuit channel. The detailed detection process of a detection channel is as follows:

[0066] Step 21: The scintillator detector converts the radioactive rays into long-wave photons and inputs them into the SiPM array elements.

[0067] Step 22: Each of the m SiPM units of the SiPM array element converts a portion of the long-wave photons into an electrical pulse signal and inputs it into the SiPM signal readout circuit.

[0068] Step 23: After receiving the m SiPM unit signals from a SiPM array element, the SiPM signal readout circuit undergoes signal amplification and signal conditioning, and finally inputs the signals into the analog-to-digital conversion circuit in the digital multi-channel signal processing system for multi-channel acquisition.

[0069] Step 3: After reading out the signal of each detection channel, the digital multi-channel signal processing system performs dark count coincidence removal. After the removal is completed, the effective signal is subjected to trapezoidal shaping and pulse counting.

[0070] like Figure 2 As shown, the dark count coincidence removal method includes the following process:

[0071] Step 31: During the system initialization phase, a counting trigger threshold parameter is set. The parameter is set based on prior data obtained from experimental results.

[0072] Step 32: Obtain the signals read out by m SiPM units and perform a logical AND operation on all the signals.

[0073] Step 33: Determine whether the final signal after the operation is greater than the counting threshold. If it is, it is determined to be a valid signal. Otherwise, it is determined to be a dark count invalid signal. The system will automatically clear the data cache and not count it.

[0074] Step 34: Repeat steps 32 and 33 to achieve cyclic removal of dark count coincidence events.

[0075] Step 4: After the signal is trapezoidally shaped, a portion of it is input to the intelligent decision-making control module to determine the degree of signal accumulation. The intelligent decision-making control module connects to the power control module through a multi-channel control bus based on the accumulation situation to achieve adaptive switching of the number of overall detection channels used in the control system.

[0076] like Figure 3 As shown in Figure 2, the intelligent decision-making control method includes the following processes:

[0077] Step 41: Initialize the count rate threshold and the number of detection channels. The count rate threshold is a priori parameter obtained through experiments, and a moderate number of detection channels is selected as the initial working channels.

[0078] Step 42: After completing the initialization, obtain the effective counting signal after the dark count is removed, and determine whether the signal is accumulated after the signal is subjected to a trapezoidal shaping operation. If the signal is accumulated, close a certain number of detection channels and return to the signal acquisition link; if the signal is not accumulated, proceed to the next step of counting rate judgment.

[0079] Step 43: When there is no accumulation of signals, if the counting rate is less than the threshold, it means that the current signal is extremely weak, and a certain number of detection channels need to be opened to improve the detection sensitivity; if the counting rate is greater than the threshold, it means that the current signal acquisition rate is relatively stable, and the number of detection channels can be maintained.

[0080] Step 44: Repeat steps 42 and 43 to implement intelligent decision-making control of the number of detection channels.

[0081] Step 5: Repeat steps 2 to 4 until the system's radioactive adaptive detection is completed.

Claims

1. An adaptive marine radioactivity detection system, characterized in that: It includes a multi-channel scintillator detector array, a multi-channel SiPM array element, a multi-channel SiPM signal readout module, a power control module, a digital multi-channel signal processing system, and a data storage and transmission module; The multi-channel scintillator detector array is composed of NaI or CeBr3 scintillator detectors for measuring gamma rays. The array is composed of n scintillator detectors, and the geometric arrangement position of each channel of the detector array is simulated by Monte Carlo simulation. The multi-channel SiPM array element is composed of n SiPM array elements, each SiPM array element corresponds to receiving the optical signal of one channel in the detector array, and each SiPM array element contains m SiPM units and reads out the signals of m SiPM units at the same time; The multi-channel SiPM signal readout module, each channel of which receives the electrical signal output by the SiPM array element of one channel, reads the SiPM multi-unit signal by building a multi-channel charge-sensitive preamplifier circuit or using a dedicated ASIC chip; The power control module provides power for the multi-channel SiPM array elements and the multi-channel SiPM signal readout module. It is divided into two parts: high-voltage power supply and analog voltage. It supports digital signal isolation input to control the on and off of the high-voltage power supply and analog power supply of one or more channels; The digital multi-channel signal processing system is composed of an analog-to-digital conversion circuit, a dark count coincidence removal module, an intelligent decision-making and signal extraction module, and is capable of achieving dark count removal and intelligently managing the number of channels in the detector array. The data storage and transmission system can transmit and store the energy spectrum data of the detector, the system power consumption management data and the detector array management data, and can also manually issue control instructions to perform functional tests on the detection channels.

2. The marine radioactivity adaptive detection system according to claim 1, characterized in that: The analog-to-digital conversion circuit is designed through an ADC chip and uses a differential input mode to reduce interference caused by environmental noise coupling to the signal to be collected; The dark count coincidence removal is specifically as follows: valid counting events are determined by comparing the readout signals of m units in each SiPM array element, thereby achieving the purpose of removing dark counts.

3. The marine radioactivity adaptive detection system according to claim 1, characterized in that: The intelligent decision-making and signal extraction are realized through the intelligent decision-making control module, trapezoidal forming, energy spectrum acquisition and control interface, which can realize the detection acquisition and energy spectrum output capabilities of the nuclear pulse signals of the multi-channel detector, as well as the intelligent control and management of the number of detector channels by whether the acquired signals generate accumulation, and interact with the outside world through the control interface.

4. The marine radioactivity adaptive detection system according to claim 3, characterized in that: The intelligent decision control module determines whether signal accumulation occurs based on the trapezoidal output, and controls the enabling or disabling of the detector channel according to the signal accumulation situation; The trapezoidal shaping, energy spectrum acquisition and control interface is composed of an existing trapezoidal shaping algorithm, an energy spectrum acquisition algorithm and a bus control interface.

5. A method for adaptive detection of marine radioactivity, characterized in that: The following steps are involved: S1. Placing the marine radioactivity adaptive detection system according to any one of claims 1 to 4 in an open sea area to be detected, so that the detector array is below the water surface for detection; S2. The detection system performs parameter initialization, the detection channels start detection work with a low initial number, and the detection data is input into the digital multi-channel signal processing system for acquisition and processing; S3. The digital multi-channel signal processing system performs dark count coincidence removal after reading out the signal of each detection channel. After the removal is completed, the effective signal is subjected to trapezoidal shaping and pulse counting. S4. After the signal is formed into a trapezoid, a portion of it is input into the intelligent decision control module to determine the degree of signal accumulation. The intelligent decision control module connects to the power control module through a multi-channel control bus based on the accumulation situation to achieve adaptive switching of the number of detection channels used in the control system. S5. Repeat steps S2-S4 until the radioactivity adaptability detection of the system is completed.

6. The method for adaptive detection of marine radioactivity according to claim 5, characterized in that: The detection work in step S2 is specifically as follows: S21, the scintillator detector converts radioactive rays into long-wave photons and inputs them into the SiPM array elements; S22, each of the m SiPM units of the SiPM array element converts a portion of the long-wavelength photons into electrical pulse signals and inputs them into the SiPM signal readout circuit; S23. After receiving the m SiPM unit signals from a SiPM array element, the SiPM signal readout circuit undergoes signal amplification and signal conditioning, and finally inputs the signals into the analog-to-digital conversion circuit in the digital multi-channel signal processing system for multi-channel acquisition.

7. The method for adaptive detection of marine radioactivity according to claim 5, characterized in that: The dark count elimination in step S3 is specifically as follows: S31. Setting a counting trigger threshold in the system initialization phase, wherein the counting trigger threshold is set based on prior data obtained from experimental results; S32, obtaining signals read out by m SiPM units, and performing a logical AND operation on all signals; S33, determining whether the final signal after the operation is greater than the counting trigger threshold, if it is greater than the counting trigger threshold, the signal is determined to be a valid signal, otherwise the signal is determined to be a dark counting invalid signal, and the system will automatically clear the dark counting invalid signal data cache and not count it; S34. Repeat steps S32 and S33 to achieve cyclic removal of dark count coincidence events.

8. The method for adaptive detection of marine radioactivity according to claim 5, characterized in that: The working process of the intelligent decision control module in step S4 is as follows: S41, initializing the count rate threshold and the number of detection channels. The count rate threshold is a priori parameter obtained through experiments, and the number of detection channels selects an intermediate value as the initial working channel; S42, after completing the initialization, obtaining the valid counting signal after the dark count is removed, performing a trapezoidal shaping operation on the signal to determine whether the signal is accumulated. If the signal is accumulated, a certain number of detection channels are closed, and the process returns to the valid counting signal acquisition step; If the signal does not accumulate, proceed to the next step of counting rate judgment; S43. When there is no accumulation of signals, if the counting rate is less than the counting rate threshold, it indicates that the current signal is weak, and a certain number of detection channels need to be opened to improve the detection sensitivity; if the counting rate is greater than the counting rate threshold, it indicates that the current signal acquisition rate is relatively stable, and the number of detection channels should be maintained; S44. Repeat steps S42 and S43 to implement intelligent decision-making control of the number of detection channels.

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