A system for rapid identification of artificial radiation

Abstract

The application discloses a system for rapidly identifying artificial radiation, and relates to the technical field of nuclear radiation protection. The system comprises an organic scintillator, a photomultiplier, a threshold comparison circuit and a processing module. The organic scintillator is used for absorbing gamma rays of a current environment and emitting photons when excited atoms and molecules are de-excited. The photomultiplier is used for converting the emitted photons into electric pulse signals. The threshold comparison circuit is used for comparing the amplified electric pulse signals with four voltage thresholds respectively through four comparators to obtain four count rates. The processing module is used for obtaining count rates between different voltage thresholds according to the four count rates, and obtaining corresponding weights according to the count rates between the different voltage thresholds. The absolute values of the differences between the multiple weights and a pulse radiation distribution characteristic factor in a natural background radiation environment are summed to obtain a summation result. Whether artificial radiation exists is determined according to the summation result. Through the multi-threshold pulse counting and weight distribution analysis method, whether an artificial radiation source exists can be rapidly judged within 100 ms.

Description

Technical Field

[0001] This invention relates to the field of nuclear radiation protection technology, and in particular to a system for rapidly identifying artificial radiation. Background Technology

[0002] In nuclear power plants, nuclear facilities, isotope applications, and many nuclear emergency response sites, it is required to quickly distinguish between natural and artificial radioactivity in environmental radioactivity monitoring to prevent the illegal outflow of radionuclides and the resulting radiation pollution and other problems.

[0003] Portable gamma dose rate meters or portable nuclide identifiers are generally used for monitoring radioactive gamma nuclides at the radiation monitoring site. Although commonly used portable gamma dose rate meters have the characteristics of fast response and simple use, they cannot distinguish between natural and artificial radioactivity. Portable nuclide identifiers rely on the detection and location of full-energy peaks in the energy spectrum and determine the type of nuclide by matching the energy corresponding to the peak position of the full-energy peak. However, it takes a long time to obtain the energy spectrum and has poor identification ability in complex environments. Summary of the Invention

[0004] Based on the shortcomings of the existing technology, the present invention provides a system for rapidly identifying artificial radiation, which solves the problems that existing portable gamma dose rate meters cannot distinguish between natural and artificial radioactivity and that existing portable nuclide identifiers have low identification efficiency.

[0005] The present invention adopts the following technical solution: In a first aspect, the present invention provides a system for rapidly identifying artificial radiation, comprising: Organic scintillators are used to absorb gamma rays from the current environment. The gamma rays ionize or excite the atoms and molecules of the organic scintillator. When the excited atoms and molecules de-excite, they emit photons. A photomultiplier tube is used to convert emitted photons into electrical pulse signals; A signal amplifier circuit is used to amplify electrical pulse signals; The threshold comparison circuit is used to compare the amplified electrical pulse signal with four voltage thresholds through four comparators, and obtain the four counting rates based on the comparison results. The processing module is used to obtain the count rate between different voltage thresholds based on the four count rates, and to obtain the corresponding weights based on the count rate between different voltage thresholds; to sum the absolute values ​​of the differences between multiple weights and the pulse radiation distribution characteristic factors in the natural background radiation environment, and to obtain the summation result; if the summation result exceeds the preset threshold, it is determined that artificial radiation exists.

[0006] Preferably, the step of comparing the amplified electrical pulse signal with four voltage thresholds using four comparators, and obtaining the four counting rates based on the comparison results, specifically includes: When the amplified electrical pulse signal exceeds the voltage threshold of one channel, that channel generates a digital pulse signal; The digital pulse signal is counted to obtain the corresponding count rate.

[0007] Preferably, the four voltage thresholds are set from smallest to largest, namely the first threshold, the second threshold, the third threshold, and the fourth threshold. The specific count rates for different voltage thresholds are as follows: R 01 =R0-R1; R 12 =R1-R2; R 23 =R2-R3; R 34 =R3; In the formula, R 01 R is the count rate between the first threshold and the second threshold. 12 R is the count rate between the second and third thresholds. 23 R is the count rate between the third and fourth thresholds. 34 R0 is the count rate of the first threshold, R1 is the count rate of the second threshold, R2 is the count rate of the third threshold, and R3 is the count rate of the fourth threshold.

[0008] The preferred weights are as follows: V 01 =R 01 / R0; V 12 =R 12 / R0; V 23 =R 23 / R0; V 34 =R 34 / R0; In the formula, V 01 V represents the weight between the first and second thresholds. 12 V represents the weights between the second and third thresholds. 23 V represents the weights between the third and fourth thresholds. 34 The weights are greater than the fourth threshold.

[0009] Preferably, the summation result is as follows: Q=|V 01 -Q0|+|V 12 -Q1|+|V 23 -Q2|+|V 33 -Q3|; In the formula, Q is the summation result, and Q0, Q1, Q2 and Q3 are the pulse radiation distribution characteristic factors in the background radiation environment, respectively.

[0010] Preferably, the processing module is controlled by an MCU, and the four voltage thresholds are generated by a digital-to-analog converter controlled by the MCU.

[0011] Preferably, it also includes a high-voltage power supply for providing operating voltage to the photomultiplier tube.

[0012] Compared with the prior art, the above-mentioned at least one technical solution adopted by the present invention can achieve the following beneficial effects: This invention uses an organic scintillator as a detector to detect gamma rays in the current environment, obtaining electrical pulse signals. Four comparators are used to compare the amplified electrical pulse signals with four voltage thresholds to obtain four count rates. Weights are assigned based on the count rates between different voltage thresholds. The absolute values ​​of the differences between multiple weights and the pulse radiation distribution characteristic factors in the natural background radiation environment are summed to obtain a summation result. The presence of artificial radiation is determined based on the summation result. This invention, through a multi-threshold pulse counting and weight distribution analysis method, can quickly determine the presence of artificial radiation sources within 100ms, improving the identification response speed by tens of times compared to the several minutes required for full-spectrum acquisition and energy peak matching of traditional nuclide identifiers. This invention establishes a pulse amplitude distribution characteristic factor of natural background radiation and calculates the difference between the current weights and the characteristic factor in real time, thereby reliably identifying artificial radiation components in complex and variable natural background environments. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a system for rapidly identifying artificial radiation according to the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1 The system principle block diagram of the present invention is as follows: Figure 1 As shown, it mainly consists of six parts: an organic scintillator, a photomultiplier tube (PMT), a high-voltage power supply, a signal amplification circuit, a threshold comparison circuit, and an MCU for processing. The high-voltage power supply provides the operating voltage to the photomultiplier tube. The threshold comparison circuit uses a low-power four-channel comparator.

[0017] Its working principle is as follows: When gamma rays irradiate an organic scintillator, the atoms and molecules of the scintillator are ionized or excited. When the excited atoms and molecules de-excite, they emit photons. De-excitation refers to the physical process by which excited atomic nuclei release energy through gamma rays or internal conversion electrons, transitioning to a lower energy level or the ground state. These photons are then collected on the photocathode of the photomultiplier tube, and through the photoelectric effect and multiple multiplication stages, an electrical pulse signal is ultimately generated. This electrical pulse signal is a voltage signal. As a traditional optoelectronic device, the photomultiplier tube has advantages including good sensitivity, a wide dynamic range, and a broad spectral response. Because the photomultiplier tube has extremely low dark current, it possesses an excellent signal-to-noise ratio.

[0018] The signal amplification circuit amplifies the electrical pulse signal emitted by the photomultiplier tube and inputs it to the threshold comparison circuit. The threshold comparison circuit uses four voltage threshold comparison channels, with the four voltage thresholds set from smallest to largest: the first threshold, the second threshold, the third threshold, and the fourth threshold. The voltage comparison thresholds are generated by a digital-to-analog converter (DAC) controlled by an MCU. The input signal is compared with each of the four voltage thresholds. When the input signal voltage exceeds a certain threshold, that channel generates a digital pulse signal. By counting the pulses generated by the four comparators, pulse distribution spectra of different energies can be obtained. Since the pulse radiation distribution is almost constant in a natural background radiation environment, a characteristic reference pulse amplitude distribution can be obtained, thus forming a reference parameter for determining the presence of an artificial radiation source. During measurement, if this reference parameter deviates significantly from the reference pulse amplitude distribution value, it can be determined that an artificial gamma radiation source exists.

[0019] The data processing procedure is as follows: 7) The MCU data processing unit collects the count rate of the four-channel comparator and sets them as R0, R1, R2 and R3 respectively.

[0020] 8) Calculate the count rates for different voltage thresholds, as follows: R 01 =R0-R1; R 12 =R1-R2; R 23 =R2-R3; R 34 =R3; 9) Calculate the weights for different voltage threshold count rates: V 01 =R 01 / R0; V 12 =R 12 / R0; V 23 =R 23 / R0; V 34 =R 34 / R0; 10) Compare the weights of different threshold count rates with the characteristic factors of pulsed radiation distribution in the natural background radiation environment. The characteristic factors of the background environment are manually measured and written in, and are respectively set as Q0, Q1, Q2, and Q3. Calculate the sum of the absolute values ​​of the comparison values ​​for each energy segment, Q; Q=|V 01 -Q0|+|V 12 -Q1|+|V 23 -Q2|+|V 33 -Q3|; 11) The closer the Q value is to 0, the closer the current radiation pulse distribution is to the pulse radiation distribution in the natural background radiation environment. The larger the value, the more likely artificial radiation exists in the current environment. Generally, when this value exceeds 0.2, it is considered that an artificial radiation source exists.

[0021] This invention uses the organic scintillator detector of a common gamma dose rate meter, which is lower in cost, faster in response, and more robust and durable than the NaI scintillator used in nuclide identification meters.

[0022] Organic scintillators have poor energy resolution and are not sensitive to distinguishing details of the energy spectrum, but they meet the requirements for coarse distribution calculation. Compared with nuclide identifiers, this scheme can only identify the presence of artificial radiation and cannot accurately identify the type of nuclide. However, nuclide identifiers usually require several minutes of full-spectrum measurement before identification. This scheme can identify nuclides with an identification speed of up to 100ms, which greatly improves the rapid identification response of artificial nuclides. Common gamma dose rate meters can only detect changes in gamma dose rate and cannot distinguish whether they are caused by natural or artificial radiation. This invention can quickly identify artificial nuclides and facilitate rapid on-site investigation of artificial nuclides.

[0023] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0024] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A system for rapidly identifying artificial radiation, characterized in that, include: Organic scintillators are used to absorb gamma rays from the current environment. The gamma rays ionize or excite the atoms and molecules of the organic scintillator. When the excited atoms and molecules de-excite, they emit photons. A photomultiplier tube is used to convert emitted photons into electrical pulse signals; A signal amplifier circuit is used to amplify electrical pulse signals; The threshold comparison circuit is used to compare the amplified electrical pulse signal with four voltage thresholds through four comparators, and obtain the four counting rates based on the comparison results. The processing module is used to obtain the count rate between different voltage thresholds based on the four count rates, and to obtain the corresponding weights based on the count rate between different voltage thresholds; The summation result is obtained by summing the absolute values ​​of the differences between multiple weights and the characteristic factors of pulse radiation distribution in the natural background radiation environment; If the summation result exceeds a preset threshold, it is determined that artificial radiation exists.

2. The system for rapidly identifying artificial radiation as described in claim 1, characterized in that, The process involves comparing the amplified electrical pulse signal with four voltage thresholds using four comparators, and obtaining the four count rates based on the comparison results. Specifically, this includes: When the amplified electrical pulse signal exceeds the voltage threshold of one channel, that channel generates a digital pulse signal; The digital pulse signal is counted to obtain the corresponding count rate.

3. The system for rapidly identifying artificial radiation as described in claim 1, characterized in that, The four voltage thresholds are set from smallest to largest, namely the first threshold, the second threshold, the third threshold, and the fourth threshold. The count rates for different voltage thresholds are shown below: R 01 =R0-R1; R 12 =R1-R2; R 23 =R2-R3; R 34 =R3; In the formula, R 01 R is the count rate between the first threshold and the second threshold. 12 R is the count rate between the second and third thresholds. 23 R is the count rate between the third and fourth thresholds. 34 R0 is the count rate of the first threshold, R1 is the count rate of the second threshold, R2 is the count rate of the third threshold, and R3 is the count rate of the fourth threshold.

4. The system for rapidly identifying artificial radiation as described in claim 3, characterized in that, The corresponding weights are as follows: V 01 =R 01 / R0; V 12 =R 12 / R0; V 23 =R 23 / R0; V 34 =R 34 / R0; In the formula, V 01 V represents the weight between the first and second thresholds. 12 V represents the weights between the second and third thresholds. 23 V represents the weights between the third and fourth thresholds. 34 The weights are greater than the fourth threshold.

5. A system for rapidly identifying artificial radiation as described in claim 4, characterized in that, The summation result is shown below: Q=|V 01 -Q0|+|V 12 -Q1|+|V 23 -Q2|+|V 33 -Q3|; In the formula, Q is the summation result, and Q0, Q1, Q2 and Q3 are the pulse radiation distribution characteristic factors in the background radiation environment, respectively.

6. The system for rapidly identifying artificial radiation as described in claim 1, characterized in that, The processing module is controlled by an MCU, and the four voltage thresholds are generated by a digital-to-analog converter controlled by the MCU.

7. A system for rapidly identifying artificial radiation as described in claim 1, characterized in that, It also includes a high-voltage power supply to provide the operating voltage for the photomultiplier tube.

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