Neutron-gamma mixed radiation screening method based on radiation response signal

Abstract

The invention discloses a neutron-gamma mixed radiation screening method based on a radiation response signal. The neutron-gamma mixed radiation screening method depends on a nano-coating CMOS sensor neutron measurement system. The neutron measurement system of the nano-coating CMOS sensor comprises a detector, the detector comprises a CMOS sensor; a LiF thin film is attached to the light-sensitive surface of the CMOS sensor; the method comprises the following steps that a part of neutrons enable the CMOS sensor to generate a radiation response signal A; the other part of neutrons and 6Li are subjected to nuclear reaction to generate alpha rays and 3T ions, so that the CMOS sensor respectively generates a radiation response signal B and a radiation response signal C; the gamma ray enables the CMOS sensor to generate a radiation response signal D; and according to the difference of the four radiation response signals in morphology and / or gray values, discriminating the neutron-gamma mixed radiation field. The detector formed by combining the LiF film and the CMOS sensor is used for discriminating a neutron-gamma mixed radiation field and can be used for monitoring nuclear leakage of a reactor.

Description

Technical Field

[0001] The invention relates to the field of nuclear science and technology, in particular to a neutron-gamma mixed radiation identification method based on radiation response signals. Background Art

[0002] Neutron-gamma ray mixed radiation discrimination is an important research direction in nuclear science, and its main purpose is to accurately distinguish neutrons and gamma rays in complex radioactive environments. Due to the interaction between neutrons and the surrounding environment, such as non-ejective scattering and radiation capture by slow neutrons, gamma rays often coexist with neutrons, making the discrimination of neutrons and gamma rays a challenge.

[0003] The current neutron-gamma mixed radiation field identification methods have experienced a development process from "mixed radiation time domain identification method" to "intelligent identification technology based on machine learning". However, these methods still have some shortcomings in practical applications, such as: 1. Poor identification effect at low energy thresholds; 2. Sensitive to noise in electronic systems, resulting in distortion and inaccuracy of identification results; 3. Identification accuracy depends on high-quality training sets, which are difficult and costly to obtain. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a neutron-gamma mixed radiation discrimination method based on radiation response signals, which solves the problems of poor discrimination effect of the existing neutron-gamma ray mixed radiation discrimination technology at low energy thresholds, sensitivity to noise in electronic systems, and dependence of discrimination accuracy on high-quality training sets.

[0005] The technical solution of the present invention is: a neutron-gamma mixed radiation discrimination method based on radiation response signals, relying on a nano-coated CMOS sensor neutron measurement system; The nano-coated CMOS sensor neutron measurement system includes a detector, a circuit board, a chip board and a PC; the detector includes a CMOS sensor; the photosensitive surface of the CMOS sensor has no glass packaging, and a LiF film with a thickness of 200nm to 2um is attached to the photosensitive surface of the CMOS sensor. The lithium element in LiF is 6 Li; The CMOS sensor is mounted on a circuit board, the circuit board is connected to a chip board for communication, a SoC chip is mounted on the chip board, and the chip board is used to output a frame image containing a radiation response signal; a PC is connected to the chip board for communication, and the PC is used to identify the radiation response signal in the frame image; The method is as follows: the neutrons incident on the LiF film are divided into two parts, one part of the neutrons directly passes through the LiF film without 6Li undergoes a nuclear reaction and is incident on the photosensitive surface of the CMOS sensor, causing the CMOS sensor to generate a radiation response signal A; another part of the neutrons passes through the LiF film and reacts with 6 Li undergoes nuclear reaction, producing α rays and 3 The T ions are incident on the CMOS sensor, causing the CMOS sensor to generate radiation response signals B and C respectively; the γ rays incident on the LiF film directly pass through the LiF film without reacting with the 6 Li undergoes a nuclear reaction and is incident on the photosensitive surface of the CMOS sensor, causing the CMOS sensor to generate a radiation response signal D; based on the differences in morphology and / or grayscale values ​​of the above four radiation response signals, neutrons, α rays, 3 T ions and gamma rays, thereby realizing the identification of neutron-gamma mixed radiation fields.

[0006] A further technical solution of the present invention is: the radiation response signal D excited by gamma rays is in the shape of one or more rectangles with an aspect ratio greater than 2:1, and the grayscale values ​​of more than 80% of the pixels in the radiation response signal D are greater than 230; the radiation response signal A excited by neutrons is in the shape of a circle, an ellipse or a square, and the grayscale values ​​of only less than 20% of the pixels in the central area of ​​the radiation response signal A are between 50 and 60, and the average grayscale values ​​of the pixels in the remaining areas are between 10 and 30; the radiation response signal B excited by alpha rays is in the shape of a circle, an ellipse or a square, and the grayscale values ​​of more than 70% of the pixels in the radiation response signal B are greater than 230; 3 The radiation response signal C excited by T ions is circular, elliptical or square in shape. The grayscale value of the radiation response signal C reaches above 230 only in the central area where no more than 10% of the pixels have a grayscale value above 230, and the average grayscale value of the pixels in the remaining area is between 50-120.

[0007] A further technical solution of the present invention is: when one or more of radiation response signal A, radiation response signal B, radiation response signal C, and radiation response signal D exist in the frame image at the same time, it means that the neutron-gamma mixed radiation field is identified.

[0008] A further technical solution of the present invention is: the processing process of the CMOS sensor is as follows: a LiF film with a thickness of 200nm to 2um is evaporated on the photosensitive surface of the CMOS sensor from which the glass package has been removed by using vacuum thermal evaporation coating technology.

[0009] A further technical solution of the present invention is that a layer of moderating material for moderating fast neutrons into slow neutrons is attached to the surface of the LiF film, and the moderating material is paraffin.

[0010] Compared with the prior art, the present invention has the following advantages: 1. The detector formed by combining LiF film with CMOS sensor is used for the identification of neutron-gamma mixed radiation field, which solves the problems of poor identification effect at low energy threshold, sensitivity to noise in electronic system and dependence of identification accuracy on high-quality training set in existing neutron-gamma mixed radiation identification technology, and can be used to monitor nuclear leakage in reactors. Neutrons in the mixed radiation field are converted by LiF film to generate alpha rays and 3 T ions are incident on the photosensitive surface of the CMOS sensor, and the gamma rays and part of the neutrons in the mixed radiation field do not react with the LiF film and are incident on the photosensitive surface of the CMOS sensor. The radiation response signals generated by the CMOS sensor excited by the above four rays and particles have great differences in morphology and / or grayscale values ​​(this is due to the different response capabilities of the CMOS sensor to the above four rays or particles). Therefore, they can be accurately distinguished, thereby achieving the purpose of identifying the neutron-gamma mixed radiation field.

[0011] 2. Achieve efficient neutron detection and identification: Based on the efficient conversion capability of LiF coating for neutrons, neutrons that are insensitive to CMOS sensors are converted into α rays that are sensitive to CMOS sensors, significantly improving the detection efficiency of neutrons (especially low-energy neutrons), thereby providing a prerequisite for the identification of neutron-gamma mixed radiation fields.

[0012] 3. Retain the visible light imaging function of the CMOS sensor: LiF is a transparent material. When attached to the photosensitive surface of the CMOS sensor, it does not affect the CMOS sensor's detection of visible light, thus retaining the imaging capability of the CMOS sensor.

[0013] 4. Achieve low cost and portability: Based on the miniaturization and integrated design of CMOS sensors, combined with the economical and efficient LiF coating evaporation technology, the system cost is effectively reduced and the portability is improved.

[0014] 5. Flexibility and expandability: The configuration of the coating material and CMOS sensor can be adjusted according to specific detection requirements to adapt to different neutron detection scenarios.

[0015] 6. Real-time image feedback and processing: Combined with the existing image noise suppression algorithm, the radiation response signal in the frame image is extracted and suppressed, thereby providing clear imaging pictures and real-time radiation monitoring feedback.

[0016] The present invention is further described below in conjunction with the figures and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the connection diagram of the nano-coated CMOS sensor neutron measurement system; Figure 2is a schematic diagram of the structure of the detector; Figure 3 is a histogram of pixel values ​​of the radiation response signal D excited by γ-rays; Figure 4 is a histogram of pixel values ​​of a radiation response signal A stimulated by a neutron; Figure 5 is a histogram of pixel values ​​of the radiation response signal B excited by α rays; Figure 6 for 3 Pixel value histogram of the radiation response signal C excited by T ions.

[0018] Legend: detector 1; CMOS sensor 11; LiF film 12; circuit board 2; chip board 3; PC 4. DETAILED DESCRIPTION Example 1

[0019] like Figure 1-2 As shown, the nano-coated CMOS sensor neutron measurement system includes a detector 1, a circuit board 2, a chip board 3 and a PC 4. The detector 1 includes a CMOS sensor 11, the photosensitive surface of the CMOS sensor 11 is not glass-encapsulated, and the photosensitive surface of the CMOS sensor 11 is attached with a LiF film 12 with a thickness of 200nm to 2um. The lithium element in LiF is 6 Li. The CMOS sensor 11 is mounted on the circuit board 2, the circuit board 2 is connected to the chip board 3 for communication, the chip board 3 is equipped with a SoC chip, and the chip board 3 is used to output a frame image containing a radiation response signal. The PC 4 is connected to the chip board 3 for communication, and the PC 4 is used to identify the radiation response signal in the frame image.

[0020] Preferably, the processing process of the CMOS sensor is as follows: a LiF thin film with a thickness of 200nm to 2um is deposited on the photosensitive surface of the CMOS sensor from which the glass package has been removed by using vacuum thermal evaporation coating technology.

[0021] Preferably, a layer of moderating material for moderating fast neutrons into slow neutrons is attached to the surface of the LiF film, and the moderating material is paraffin.

[0022] The neutron-gamma mixed radiation discrimination method based on the radiation response signal is based on the above-mentioned nano-coated CMOS sensor neutron measurement system. The method is as follows: The neutrons incident on the LiF film are divided into two parts. One part of the neutrons directly passes through the LiF film without interacting with the LiF film. 6 Li undergoes a nuclear reaction and is incident on the photosensitive surface of the CMOS sensor, causing the CMOS sensor to generate a radiation response signal A; another part of the neutrons passes through the LiF film and reacts with 6Li undergoes nuclear reaction (n+ 6 Li→α+ 3 T+4.786MeV), producing α rays and 3 The T ions are incident on the CMOS sensor, causing the CMOS sensor to generate radiation response signals B and C. The gamma rays incident on the LiF film pass directly through the LiF film without 6 Li undergoes a nuclear reaction and is incident on the photosensitive surface of the CMOS sensor, causing the CMOS sensor to generate a radiation response signal D.

[0023] According to the differences in morphology and / or grayscale values ​​of the above four radiation response signals, neutrons, α rays, 3 T ions and gamma rays, thereby realizing the identification of neutron-gamma mixed radiation fields.

[0024] See also Figure 3 The radiation response signal D excited by the gamma ray is in the shape of one or more rectangles with an aspect ratio greater than 2:1, and the grayscale values ​​of more than 80% of the pixels in the radiation response signal D reach more than 230.

[0025] See also Figure 4 The radiation response signal A excited by neutrons is circular, elliptical or square in shape. The grayscale value of the radiation response signal A reaches between 50 and 60 only in less than 20% of the pixels in the central area, and the average grayscale value of the pixels in the remaining area is between 10 and 30.

[0026] See also Figure 5 The radiation response signal B excited by α rays is circular, elliptical or square in shape, and the grayscale values ​​of more than 70% of the pixels in the radiation response signal B are above 230.

[0027] See also Figure 6 , 3 The radiation response signal C excited by T ions is circular, elliptical or square in shape. The grayscale value of the radiation response signal C reaches above 230 only in the central area where no more than 10% of the pixels have a grayscale value above 230, and the average grayscale value of the pixels in the remaining area is between 50-120.

[0028] When one or more of the radiation response signal A, the radiation response signal B, the radiation response signal C, and the radiation response signal D exist simultaneously in the frame image, it means that the neutron-gamma mixed radiation field has been identified.

Claims

1. A neutron-gamma mixed radiation identification method based on radiation response signals, characterized in that: Neutron measurement system based on nano-coated CMOS sensor; The nano-coated CMOS sensor neutron measurement system includes a detector, a circuit board, a chip board and a PC; the detector includes a CMOS sensor; the photosensitive surface of the CMOS sensor has no glass packaging, and a LiF film with a thickness of 200nm to 2um is attached to the photosensitive surface of the CMOS sensor. The lithium element in LiF is 6 Li; The CMOS sensor is mounted on a circuit board, the circuit board is connected to a chip board for communication, a SoC chip is mounted on the chip board, and the chip board is used to output a frame image containing a radiation response signal; a PC is connected to the chip board for communication, and the PC is used to identify the radiation response signal in the frame image; The method is as follows: the neutrons incident on the LiF film are divided into two parts, one part of the neutrons directly passes through the LiF film without 6 Li undergoes a nuclear reaction and is incident on the photosensitive surface of the CMOS sensor, causing the CMOS sensor to generate a radiation response signal A; another part of the neutrons passes through the LiF film and reacts with 6 Li undergoes nuclear reaction, producing α rays and 3 The T ions are incident on the CMOS sensor, causing the CMOS sensor to generate radiation response signals B and C respectively; the γ rays incident on the LiF film directly pass through the LiF film without reacting with the 6 Li undergoes a nuclear reaction and is incident on the photosensitive surface of the CMOS sensor, causing the CMOS sensor to generate a radiation response signal D; based on the differences in morphology and / or grayscale values ​​of the above four radiation response signals, neutrons, α rays, 3 T ions and gamma rays, thereby realizing the identification of neutron-gamma mixed radiation fields.

2. The neutron-gamma mixed radiation identification method based on radiation response signal according to claim 1, characterized in that: The radiation response signal D excited by gamma rays is in the shape of one or more rectangles with an aspect ratio greater than 2:1, and the grayscale values ​​of more than 80% of the pixels in the radiation response signal D are greater than 230; the radiation response signal A excited by neutrons is in the shape of a circle, an ellipse or a square, and the grayscale values ​​of only less than 20% of the pixels in the central area of ​​the radiation response signal A are between 50 and 60, and the average grayscale value of the pixels in the remaining areas is between 10 and 30; the radiation response signal B excited by alpha rays is in the shape of a circle, an ellipse or a square, and the grayscale values ​​of more than 70% of the pixels in the radiation response signal B are greater than 230; 3 The radiation response signal C excited by T ions is circular, elliptical or square in shape. The grayscale value of the radiation response signal C reaches above 230 only in the central area where no more than 10% of the pixels have a grayscale value above 230, and the average grayscale value of the pixels in the remaining area is between 50-120.

3. The neutron-gamma mixed radiation identification method based on radiation response signal according to claim 2 is characterized in that: When one or more of the radiation response signal A, the radiation response signal B, the radiation response signal C, and the radiation response signal D exist simultaneously in the frame image, it means that the neutron-gamma mixed radiation field has been identified.

4. The neutron-gamma mixed radiation identification method based on radiation response signal according to claim 3 is characterized in that: The processing process of the CMOS sensor is as follows: a LiF film with a thickness of 200nm to 2um is deposited on the photosensitive surface of the CMOS sensor from which the glass package has been removed by using vacuum thermal evaporation coating technology.

5. The neutron-gamma mixed radiation identification method based on radiation response signal according to claim 4 is characterized in that: A layer of moderating material for slowing down fast neutrons into slow neutrons is attached to the surface of the LiF film, and the moderating material is paraffin.

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