Neutron measurement system and method based on nano-coating pixel sensor

Abstract

The invention discloses a neutron measurement system and method based on a nano-coating pixel sensor, and relates to the technical field of neutron measurement. The neutron measurement system based on the nano-coating pixel sensor comprises a detector; the detector comprises an active pixel sensor; the light-sensitive surface of the active pixel sensor is not packaged by glass, and the light-sensitive surface of the active pixel sensor is provided with a layered neutron conversion material. The invention discloses a neutron measurement method, which is applied to a neutron measurement system based on a nano-coating pixel sensor. The method comprises the following steps: neutrons and target elements are subjected to nuclear reaction, and generated alpha rays are incident to a light sensing surface of the active pixel sensor, so that the active pixel sensor generates radiation response signals; and the indirect measurement of the neutrons is realized by counting the radiation response signal. The active pixel sensor has the advantages that the specific neutron conversion material is combined with the active pixel sensor, neutron detection is converted into alpha particle detection which the active pixel sensor is good at, and the detection efficiency of neutrons (especially thermal neutrons) is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of neutron measurement, and in particular to a neutron measurement system and method based on a nano-coating pixel sensor. Background Art

[0002] Neutrons are uncharged elementary particles. Due to their magnetic moment and strong penetrability, there is a demand for neutron measurement in many fields, including nuclear energy (monitoring the neutron radiation dose received by personnel during the operation and maintenance of nuclear power plants to ensure personnel safety), medicine (in radiotherapy, accurately measuring the neutron dose around the treatment area to ensure patient safety), and materials (using neutron diffraction technology to non-destructively obtain information such as the internal crystal phase, grain orientation and size, and residual stress of the material, which is used for mechanism research, processing optimization, and failure assessment of new materials and new components).

[0003] In the field of neutron measurement, neutron detectors based on helium-3 as the working medium are widely used. Helium-3 neutron detectors have high sensitivity and efficiency. However, with the rapid development of neutron measurement technology, the supply of helium-3 resources has become increasingly tight, causing the cost of helium-3 neutron detectors to gradually increase. Therefore, it is urgent to develop neutron detectors based on new neutron measurement materials.

[0004] As an alternative to helium-3 neutron detectors, neutron detectors based on new scintillator materials and semiconductor materials have been developed one after another. However, these neutron detectors often have problems such as large size, high cost, or inability to simultaneously take into account high sensitivity and spatial resolution (i.e., distinguishing the direction of the neutron source). Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a neutron measurement system and method based on a nano-coated pixel sensor, which solves the problems of existing neutron detectors based on new scintillator materials and semiconductor materials being large in size, high in cost, or unable to take into account both high sensitivity and spatial resolution.

[0006] The technical solution of the present invention is: a neutron measurement system based on a nano-coated pixel sensor, comprising a detector; the detector comprises an active pixel sensor; the photosensitive surface of the active pixel sensor has no glass packaging, and a layered neutron conversion material is attached to or placed on the photosensitive surface of the active pixel sensor or arranged opposite to it in the air, and the neutron conversion material is used to undergo a nuclear reaction with neutrons and generate alpha rays.

[0007] A further technical solution of the present invention is: the neutron conversion material is placed on or arranged in space on the photosensitive surface of the active pixel sensor, the neutron conversion material is a two-dimensional hexagonal boron nitride film with a thickness between 200nm and 2um, the two-dimensional hexagonal boron nitride film is attached to the surface of the copper foil, and the boron element in the two-dimensional hexagonal boron nitride is 10 B.

[0008] A further technical solution of the present invention is: the processing process of the active pixel sensor is as follows: prepare a copper foil sheet with the same size and shape as the photosensitive surface of the active pixel sensor for use; first use chemical vapor deposition to deposit a layer of two-dimensional hexagonal boron nitride film with a thickness of between 200nm and 2um on the surface of the copper foil, that is, to obtain the neutron conversion material; then, the two-dimensional hexagonal boron nitride film in the neutron conversion material is bonded to the photosensitive surface of the active pixel sensor from which the glass package has been stripped or arranged in space.

[0009] A further technical solution of the present invention is that a layer of moderating material for slowing down fast neutrons into slow neutrons is attached to the surface of the copper foil that is not in contact with the two-dimensional hexagonal boron nitride, and the moderating material is paraffin.

[0010] A further technical solution of the present invention is: the neutron conversion material is attached to the photosensitive surface of the active pixel sensor, the neutron conversion material is a lithium fluoride film with a thickness between 200nm and 2um, and the lithium element in the lithium fluoride is 6 Li.

[0011] A further technical solution of the present invention is: the processing process of the active pixel sensor is as follows: a layer of lithium fluoride film with a thickness of 200nm to 2um is evaporated on the photosensitive surface of the active pixel sensor from which the glass package has been removed by vacuum thermal evaporation coating technology.

[0012] 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 lithium fluoride film, and the moderating material is paraffin.

[0013] A further technical solution of the present invention is: the neutron conversion material is placed on or arranged in space on the photosensitive surface of the active pixel sensor, the neutron conversion material is a boron carbide film with a thickness between 200nm and 2um, the boron carbide film is attached to the surface of the copper foil, and the boron element in the boron carbide is 10 B.

[0014] A further technical solution of the present invention is: the processing process of the active pixel sensor is as follows: prepare a copper foil sheet with the same size and shape as the photosensitive surface of the active pixel sensor for use; first use a magnetron sputtering method to deposit a layer of boron carbide film with a thickness of 200nm~2um on the surface of the copper foil, that is, to obtain the neutron conversion material; then, the boron carbide film in the neutron conversion material is placed on the photosensitive surface of the active pixel sensor from which the glass package has been stripped, or arranged in space to face each other.

[0015] A further technical solution of the present invention is that a layer of moderation material for slowing down fast neutrons into slow neutrons is attached to the surface of the copper foil that is not in contact with the boron carbide, and the moderation material is paraffin.

[0016] The technical solution of the present invention is: a neutron measurement method, applied to the above-mentioned neutron measurement system based on nano-coating pixel sensor; The detector further includes a circuit board and a chip board; the active pixel sensor is mounted on the circuit board, the circuit board is communicatively connected to the chip board, 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; the neutron detection system based on the nano-coated pixel sensor also includes a PC; the PC is communicatively connected to the chip board, and the PC is used to adjust the parameters of the active pixel sensor, and store and display the frame image containing the radiation response signal; The method is as follows: when neutrons pass through the neutron conversion material, a nuclear reaction occurs with the target element, and the generated alpha rays are incident on the photosensitive surface of the active pixel sensor, causing the active pixel sensor to generate a radiation response signal; the chip board receives the output data of the active pixel sensor through the SoC chip, and processes it into continuous frame images and transmits it to the PC, and the indirect measurement of neutrons is achieved by counting the radiation response signals.

[0017] Compared with the prior art, the present invention has the following advantages: 1. It combines specific neutron conversion materials with active pixel sensors to convert neutron detection into alpha particle detection, which is what active pixel sensors are good at, significantly improving the detection efficiency of neutrons (especially thermal neutrons).

[0018] 2. Compared with existing neutron detectors based on new scintillator materials and semiconductor materials, it has the advantages of small size, low manufacturing and use costs, and high sensitivity and spatial resolution (combining the orientation of the active pixel sensor and the concentrated area of ​​the radiation response signal in the frame image, the direction of the neutron source can be distinguished).

[0019] 3. Flexible configuration of functions: According to actual application requirements, the visible light detection capability of the active pixel sensor can be selectively retained (using lithium fluoride (LiF) coating, but the neutron detection capability is relatively weak) or focused on stronger neutron detection capability (using two-dimensional hexagonal boron nitride (2D h-BN) or boron carbide (B4C) or 10 B single-element coating, but can no longer be used to detect visible light), achieving flexible configuration of functions.

[0020] 4. High system integration: The entire system is built on CMOS APS, which is easy to integrate with other electronic systems, making it easy to realize miniaturized and portable neutron detection equipment.

[0021] The present invention is further described below in conjunction with the figures and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1is a schematic diagram of the structure of the detector in Example 1; Figure 2 The schematic diagram of the structure of the detector in Example 2 Figure 3 is a schematic diagram of the structure of the detector in Example 3; Figure 4 This is a schematic diagram of the structure of the detector in Example 4.

[0023] Legend: active pixel sensor 1; boron nitride 21; lithium fluoride 22; boron carbide 23; 10 B element 24; copper foil 25.

[0024] Note: Example 3 defines two ways of placement: close-fitting placement and spaced-apart placement. Figure 2 Only the spaced-apart arrangement is shown. DETAILED DESCRIPTION Example 1

[0025] like Figure 1 As shown, a neutron measurement system based on a nano-coated pixel sensor includes a detector. The detector includes an active pixel sensor 1. The photosensitive surface of the active pixel sensor 1 is not glass-encapsulated, and a layered neutron conversion material is attached to the photosensitive surface of the active pixel sensor 1. The neutron conversion material is used to undergo a nuclear reaction with neutrons and generate alpha rays.

[0026] The neutron conversion material is placed on or arranged in space on the photosensitive surface of the active pixel sensor 1. The neutron conversion material is a two-dimensional hexagonal boron nitride 21 film with a thickness between 200nm and 2um. The two-dimensional hexagonal boron nitride 21 film is attached to the surface of the copper foil 25. The boron element in the two-dimensional hexagonal boron nitride 21 is 10 B.

[0027] The processing process of the active pixel sensor is as follows: prepare a copper foil 25 with the same size and shape as the photosensitive surface of the active pixel sensor 1 for use; first, use chemical vapor deposition to deposit a two-dimensional hexagonal boron nitride 21 film with a thickness of 200nm to 2um on the surface of the copper foil 25 (the boron element in the two-dimensional hexagonal boron nitride 21 is 10 B), that is, obtaining the neutron conversion material; and then attaching the two-dimensional hexagonal boron nitride 21 film in the neutron conversion material to the photosensitive surface of the active pixel sensor 1 from which the glass package has been removed or arranging them opposite to each other in the air.

[0028] When the spaced-apart arrangement is adopted, the distance between the surface of the two-dimensional hexagonal boron nitride connected to the copper foil and the photosensitive surface of the active pixel sensor should be less than 2 mm. Regardless of whether the placement or spaced-apart arrangement is adopted, an external fixing structure (support structure) is required to keep the active pixel sensor and the neutron conversion material relatively fixed.

[0029] Preferably, a layer of moderation material for slowing down fast neutrons into slow neutrons is attached to the surface of the copper foil 25 that is not in contact with the two-dimensional hexagonal boron nitride 21, so as to improve the measurement efficiency. The moderation material is paraffin, and the thickness of the moderation material is selected according to the maximum energy of the incident fast neutrons. Example 2

[0030] like Figure 2 As shown, the difference between this embodiment and embodiment 1 is that the neutron conversion material is attached to the photosensitive surface of the active pixel sensor 1, the neutron conversion material is a lithium fluoride 22 film with a thickness between 200nm and 2um, and the lithium element in the lithium fluoride 22 is 6 Li.

[0031] The processing process of the active pixel sensor is as follows: a layer of lithium fluoride 22 thin film with a thickness of 200nm to 2um is evaporated on the photosensitive surface of the active pixel sensor 1 from which the glass package has been removed (the lithium element in lithium fluoride is 6 Li).

[0032] Preferably, a layer of moderation material for slowing down fast neutrons into slow neutrons is attached to the surface of the lithium fluoride 22 film to improve the measurement efficiency. The moderation material is paraffin, and the thickness of the moderation material is selected according to the maximum energy of the incident fast neutrons. Example 3

[0033] like Figure 3 As shown, the difference between this embodiment and embodiment 1 is that the neutron conversion material is placed on or arranged in space on the photosensitive surface of the active pixel sensor 1, the neutron conversion material is a boron carbide 23 film with a thickness between 200nm and 2um, the boron carbide 23 film is attached to the surface of the copper foil 25, and the boron element in the boron carbide 23 is 10 B.

[0034] The processing process of the active pixel sensor is as follows: prepare a copper foil 25 with the same size and shape as the photosensitive surface of the active pixel sensor for use; first, use a magnetron sputtering method to deposit a boron carbide 23 film with a thickness of 200nm to 2um on the surface of the copper foil 25 (the boron element in the boron carbide 23 is 10 B), that is, the neutron conversion material is obtained; and then the boron carbide 23 film in the neutron conversion material is placed on the photosensitive surface of the active pixel sensor 1 from which the glass package has been removed or arranged in space to face each other.

[0035] When the spaced-apart arrangement is adopted, the distance between the surface of the side where the boron carbide is connected to the copper foil and the photosensitive surface of the active pixel sensor should be less than 2 mm. Regardless of whether the placement or spaced-apart arrangement is adopted, an external fixing structure (support structure) is required to keep the active pixel sensor and the neutron conversion material relatively fixed.

[0036] Preferably, a layer of a moderating material for moderating fast neutrons into slow neutrons is attached to the surface of the copper foil 25 that is not in contact with the boron carbide 23, and the moderating material is paraffin. Example 4

[0037] like Figure 4 As shown, the difference between this embodiment and embodiment 1 is that the neutron conversion material is placed on or arranged directly opposite to the photosensitive surface of the active pixel sensor 1, and the neutron conversion material has a thickness of 200nm to 2um. 10 B single substance 24 film, 10 The thin film of B element 24 is attached to the surface of copper foil 25 .

[0038] The processing process of the active pixel sensor is as follows: prepare a copper foil sheet 25 having the same size and shape as the photosensitive surface of the active pixel sensor 1 for use; first, use chemical vapor deposition to deposit a layer of copper foil 25 with a thickness of 200nm to 2um; 10 B single substance 24 thin film, thus obtaining the neutron conversion material; then 10 The B single substance 24 film is attached to the photosensitive surface of the active pixel sensor 1 from which the glass package has been removed, or is arranged opposite to it in the air.

[0039] When the spaced-to-space arrangement is adopted, 10 The distance between the surface of the side where the B element is connected to the copper foil and the photosensitive surface of the active pixel sensor should be less than 2 mm. Regardless of whether the placement is pasted or arranged in space, the active pixel sensor and the neutron conversion material need to be relatively fixed by an external fixing structure (support structure).

[0040] A neutron measurement method is applied to the above-mentioned neutron measurement system based on nano-coating pixel sensor. The detector also includes a circuit board and a chip board; the active pixel sensor is mounted on the circuit board, the circuit board is connected to the 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; the neutron detection system based on the nano-coating pixel sensor also includes a PC; the PC is connected to the chip board for communication, and the PC is used to adjust the parameters of the active pixel sensor, and store and display the frame image containing the radiation response signal.

[0041] The method is as follows: when neutrons pass through the neutron conversion material, nuclear reactions occur with the target element, generating alpha rays that are very sensitive to the active pixel sensor. The alpha rays are incident on the photosensitive surface of the active pixel sensor, causing the active pixel sensor to generate a radiation response signal; the chip board receives the output data of the active pixel sensor through the SoC chip, processes it and converts it into continuous frame images and transmits it to the PC, and indirectly measures the neutrons by counting the radiation response signals.

[0042] Corresponding to the situation in Example 1: when the neutron conversion material is the two-dimensional hexagonal boron nitride (2D h-BN), the target element is 10 B; At this time, the neutron and 10 B nuclear reaction is as follows: n+ 10 B → α+ 7 Li+2.792MeV.

[0043] Corresponding to the situation of Example 2: when the neutron conversion material is lithium fluoride (LiF), the target element is 6 Li, at this time, the neutron and 6 The nuclear reaction of Li is as follows: n+ 6 Li→α+ 3 T+4.786MeV.

[0044] Corresponding to the situation of Example 3: when the neutron conversion material is the boron carbide (B4C), the target element is 10 B; At this time, the neutron and 10 B nuclear reaction is as follows: n+ 10 B → α+ 7 Li+2.792MeV.

[0045] Corresponding to the situation of Example 4: when the neutron conversion material is 10 When B is a single substance, neutrons and 10 B nuclear reaction is as follows: n+ 10 B → α+ 7 Li+2.792MeV.

Claims

1. Neutron measurement system based on nano-coated pixel sensor, characterized by: It includes a detector; the detector includes an active pixel sensor; the photosensitive surface of the active pixel sensor has no glass packaging, and a layered neutron conversion material is attached to, placed on, or arranged opposite to the photosensitive surface of the active pixel sensor in the air, and the neutron conversion material is used to undergo a nuclear reaction with neutrons and generate alpha rays.

2. The neutron measurement system based on nano-coating pixel sensor according to claim 1, characterized in that: The neutron conversion material is placed on or opposite to the photosensitive surface of the active pixel sensor. The neutron conversion material is a two-dimensional hexagonal boron nitride film with a thickness between 200nm and 2um. The two-dimensional hexagonal boron nitride film is attached to the surface of the copper foil. The boron element in the two-dimensional hexagonal boron nitride is 10 B.

3. The neutron measurement system based on nano-coating pixel sensor according to claim 2, characterized in that: The processing process of the active pixel sensor is as follows: prepare a copper foil sheet with the same size and shape as the photosensitive surface of the active pixel sensor for use; first use chemical vapor deposition to deposit a layer of two-dimensional hexagonal boron nitride film with a thickness of between 200nm and 2um on the surface of the copper foil, that is, obtain the neutron conversion material; then, the two-dimensional hexagonal boron nitride film in the neutron conversion material is bonded to the photosensitive surface of the active pixel sensor from which the glass package has been removed, or arranged in space to face each other.

4. The neutron measurement system based on nano-coating pixel sensor according to claim 3, characterized in that: A layer of moderation material for slowing down fast neutrons into slow neutrons is attached to the surface of the copper foil that is not in contact with the two-dimensional hexagonal boron nitride. The moderation material is paraffin.

5. The neutron measurement system based on nano-coating pixel sensor according to claim 1, characterized in that: The neutron conversion material is attached to the photosensitive surface of the active pixel sensor. The neutron conversion material is a lithium fluoride film with a thickness between 200nm and 2um. The lithium element in the lithium fluoride is 6 Li.

6. The neutron measurement system based on nano-coating pixel sensor according to claim 5, characterized in that: The processing process of the active pixel sensor is as follows: a lithium fluoride film with a thickness of 200nm to 2um is deposited on the photosensitive surface of the active pixel sensor from which the glass package has been removed by using vacuum thermal evaporation coating technology.

7. The neutron measurement system based on nano-coating pixel sensor according to claim 6, characterized in that: A layer of moderating material for moderating fast neutrons into slow neutrons is attached to the surface of the lithium fluoride film, and the moderating material is paraffin.

8. The neutron measurement system based on nano-coating pixel sensor according to claim 1, characterized in that: The neutron conversion material is placed on or arranged in space on the photosensitive surface of the active pixel sensor. The neutron conversion material is a boron carbide film with a thickness of 200nm to 2um. The boron carbide film is attached to the surface of the copper foil. The boron element in the boron carbide is 10 B.

9. The neutron measurement system based on nano-coating pixel sensor according to claim 8, characterized in that: The processing process of the active pixel sensor is as follows: prepare a copper foil sheet with the same size and shape as the photosensitive surface of the active pixel sensor for use; first use a magnetron sputtering method to deposit a boron carbide film with a thickness of between 200nm and 2um on the surface of the copper foil, that is, obtain the neutron conversion material; then place the boron carbide film in the neutron conversion material on the photosensitive surface of the active pixel sensor from which the glass package has been stripped, or arrange them opposite to each other in the air.

10. The neutron measurement system based on nano-coating pixel sensor according to claim 9, characterized in that: A layer of moderation layer material for slowing down fast neutrons into slow neutrons is attached to the surface of the copper foil that is not in contact with the boron carbide. The moderation material is paraffin.

11. A neutron measurement method, applied to the neutron measurement system based on the nano-coating pixel sensor according to any one of claims 1 to 7; Its characteristics are: The detector further includes a circuit board and a chip board; the active pixel sensor is mounted on the circuit board, the circuit board is communicatively connected to the chip board, 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; the neutron detection system based on the nano-coated pixel sensor also includes a PC; the PC is communicatively connected to the chip board, and the PC is used to adjust the parameters of the active pixel sensor, and store and display the frame image containing the radiation response signal; The method is as follows: when neutrons pass through the neutron conversion material, nuclear reactions occur with the target element, and the generated alpha rays are incident on the photosensitive surface of the active pixel sensor, so that the active pixel sensor generates a radiation response signal; The chip board receives the output data of the active pixel sensor through the SoC chip, processes it into continuous frame images and transmits them to the PC, and realizes indirect measurement of neutrons by counting the radiation response signals.

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