A type based on 6 Absolute measurement device of single-energy neutron fluence of LiF telescope system

Abstract

This invention discloses a method based on 6 The monoenergetic neutron fluence absolute measurement device for the LiF telescope system, belonging to the field of neutron detection technology, includes a cylindrical body. A collimating aperture is installed inside the cylinder, comprising a first central aperture and a second central aperture. The first and second central apertures are coaxially aligned and have the same diameter. A composite layered neutron converter is installed at the first central aperture. The composite layered neutron converter includes an aluminum substrate, and the upper surface of the aluminum substrate is coated with a... 6 A passivated ion-implanted planar silicon detector is positioned behind the second central hole of the LiF active layer. This detector is equipped with an SMA connector. A rear cover is located at the other end of the casing, with a BNC female connector at its center leading out signal lines. Based on this structural design, absolute measurement of monoenergetic neutron fluence in the energy range of 1 keV to 100 keV can be achieved. This contributes to establishing a benchmark study of monoenergetic neutron fluence in the 1 keV to 100 keV energy range, ensuring the traceability and accuracy of monoenergetic neutron fluence measurement results.

Description

Technical Field

[0001] This invention belongs to the field of neutron detection technology, specifically relating to a method based on 6 The monoenergetic neutron fluence absolute measurement device of the LiF telescope system. Background Technology

[0002] Neutrons, as ideal probes and advanced tools in numerous fields, are widely used in fundamental nuclear physics, national security, medical health, and aerospace. Monoenergetic neutron fluence is a crucial physical quantity in neutron science research and applications; its accuracy directly affects the accuracy of other neutron parameters. Providing accurate values ​​for monoenergetic neutron fluence is a vital task in neutron metrology. Especially in the 1keV to 100keV medium-energy neutron region, the absolute measurement of monoenergetic neutron fluence has become a major technical challenge for multidisciplinary development. In the nuclear energy field, the medium-energy neutron region is the core distribution zone of nuclide absorption resonance peaks, directly affecting reactor fuel breeding efficiency and safety verification. Precise data on its fission and capture cross-sections are crucial for nuclear waste transmutation and reactor simulation. In the field of radiotherapy, the specific targeted killing effect of boron neutron capture therapy on cancer cells is closely related to the response of neutron detection equipment, requiring precise calibration using monoenergetic neutron radiation. In astrophysics, neutron capture cross-section data for stellar S- and R-processes rely on precise measurements in the intermediate-energy neutron region, providing crucial parameters for understanding the synthesis mechanisms of heavy elements in the universe. In radiation protection, performance evaluation of neutron shielding materials and calibration of neutron dosimeters require high-accuracy data from this energy region. Currently, three of the 13 monoenergetic neutron energy points recommended by the International Organization for Standardization (ISO) (2keV, 8keV, and 24keV) are located in this energy region, primarily used for neutron nucleus data measurement, calibration of neutron detectors and measuring instruments, and neutron metrological comparisons.

[0003] The monoenergetic neutron fluence rate standard is one of the sources for the transfer of monoenergetic neutron fluence rate values. Currently, the reference devices used for absolute measurement of monoenergetic neutron fluence include recoil proton proportional counters and recoil proton telescopes, which are important components of the neutron metrology system. Both recoil proton proportional counters and recoil proton telescopes are based on the standard cross section method (neutron-proton scattering cross section), measuring fast neutron fluence by detecting recoil protons generated by the elastic scattering of neutrons with hydrogen atoms. The applicable energy range of recoil proton telescopes is 2 MeV to 20 MeV, while the theoretical detection energy range of recoil proton proportional counters is 10 keV to 2 MeV, covering only a portion of the 1 keV to 100 keV medium-energy neutron region. In actual measurements, for fast neutrons with energies below 100 keV, the measurement results are unsatisfactory due to the influence of gamma rays in the radiation field. The pulse height spectra generated by neutron counting and gamma counting overlap, making it impossible to effectively measure fast neutron fluence rates below 100 keV, thus limiting the applicable energy range of recoil proton proportional counters. Therefore, the current transfer of neutron fluence values ​​in the 1 keV to 100 keV range mainly relies on indirect calibration via a standard neutron radiation field using relative measuring devices (such as long neutron counters). The lack of an absolute reference device for measuring monoenergetic neutron fluence rates in the mid-energy range leads to a break in the traceability chain, making it impossible to guarantee the reliability of the energy response calibration of neutron detectors and neutron dosimeters. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by inventing a method based on 6 The monoenergetic neutron flux absolute measurement device of the LiF telescope system is used for the absolute measurement of neutron flux in the 1 keV to 100 keV medium-energy neutron region. It helps to carry out benchmark research on neutron flux in the 1 keV to 100 keV energy region and ensures the traceability and accuracy of neutron flux measurement results.

[0005] The technical solution adopted in this invention is as follows:

[0006] A type based on 6 The monoenergetic neutron fluence absolute measurement device of the LiF telescope system includes a cylindrical body. A collimation stop is disposed within the cylindrical body. The collimation stop includes a first plate disposed at one end of the cylindrical body and a second plate disposed inside the cylindrical body. The first and second plates have a first central hole and a second central hole respectively, which are coaxially aligned and have the same diameter. A composite layered neutron converter is mounted on the outer side of the first plate at the first central hole. The composite layered neutron converter includes an aluminum substrate, and the upper surface of the aluminum substrate is coated with a... 6 The LiF active layer, 6The LiF active layer faces the first central hole. A passivated ion implantation planar silicon detector is located behind the second central hole inside the cylinder. The passivated ion implantation planar silicon detector is covered with a γ-ray shielding layer. An SMA connector is located on the side of the passivated ion implantation planar silicon detector away from the second central hole. A rear cover is located at the end of the cylinder away from the first plate. A BNC female connector base leads out signal lines at the center of the rear cover. The SMA connector is signal-connected to the BNC female connector base leads out signal lines. A charge-sensitive preamplifier, a shaping main amplifier, a high-speed analog-to-digital converter, and a computer are also provided, which are connected in sequence by electrical signals. The BNC female connector base leads out signal lines are electrically connected to the charge-sensitive preamplifier.

[0007] Furthermore, the distance between the first central hole and the second central hole is 10mm.

[0008] Furthermore, the diameters of the first central hole and the second central hole are 15 mm.

[0009] Furthermore, the distance between the passivated ion-implanted planar silicon detector and the back cover is 80 mm.

[0010] Furthermore, the cylinder, the first plate, the second plate, and the rear cover are made of stainless steel.

[0011] Furthermore, the second central hole is chamfered.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0013] 1. In this invention, based on 6 The absolute measurement device for monoenergetic neutron fluence of the LiF telescope system includes a composite layered neutron converter, a stainless steel collimating aperture, a passivated ion-implanted planar silicon detector, and a signal processing system (charge-sensitive preamplifier, shaping main amplifier, high-speed analog-to-digital converter, and computer), enabling absolute measurement of monoenergetic neutron fluence in the energy range of 1 keV to 100 keV. Based on the standard nuclear reaction cross section (… 6 Li (n, α) 3 With H-section uncertainty <1%, a linear relationship was established between monoenergetic neutron fluence and nuclear reaction product count. Using... 6 The α (2.05 MeV) and tritium nuclei (2.73 MeV) produced by the Li(n, α) reaction can be effectively distinguished from the γ background signal in the radiation field by setting a threshold. This can help establish a benchmark study of monoenergetic neutron fluence in the energy range of 1 keV to 100 keV, ensuring the traceability and accuracy of monoenergetic neutron fluence measurement results. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0015] Figure 1 This is a schematic diagram of the structure of the present invention.

[0016] Markings in the diagram: 1-Cylinder body, 2-First plate, 3-Second plate, 4-First center hole, 5-Second center hole, 6-Aluminum base, 7- 6 8-LiF active layer, 9-Passivated ion implantation planar silicon detector, 10-SMA connector, 11-Back cover, 12-BNC female connector base for signal lead-out, 13-Charge sensitive preamplifier, 14-Shaped main amplifier, 15-High-speed analog-to-digital converter, 16-Computer, 17-Chamfer. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0019] It should be noted that the labels and letters in the following figures represent similar items, therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only used for the purpose of simplifying the description of this invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0021] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Refer to the instruction manual. Figure 1 ,

[0024] A type based on 6 The monoenergetic neutron fluence absolute measurement device of the LiF telescope system includes a cylindrical body. A collimation stop is disposed within the cylindrical body. The collimation stop includes a first plate disposed at one end of the cylindrical body and a second plate disposed inside the cylindrical body. The first and second plates have a first central hole and a second central hole respectively, which are coaxially aligned and have the same diameter. A composite layered neutron converter is mounted on the outer side of the first plate at the first central hole. The composite layered neutron converter includes an aluminum substrate, and the upper surface of the aluminum substrate is coated with a... 6 The LiF active layer, 6The LiF active layer faces the first central hole. A passivated ion implantation planar silicon detector is located behind the second central hole inside the cylinder. The passivated ion implantation planar silicon detector is covered with a γ-ray shielding layer. An SMA connector is located on the side of the passivated ion implantation planar silicon detector away from the second central hole. A rear cover is located at the end of the cylinder away from the first plate. A BNC female connector base leads out signal lines at the center of the rear cover. The SMA connector is signal-connected to the BNC female connector base leads out signal lines. A charge-sensitive preamplifier, a shaping main amplifier, a high-speed analog-to-digital converter, and a computer are also provided, which are connected in sequence by electrical signals. The BNC female connector base leads out signal lines are electrically connected to the charge-sensitive preamplifier.

[0025] Specifically, the distance between the first central hole and the second central hole is 10mm.

[0026] Specifically, the diameters of the first central hole and the second central hole are 15 mm.

[0027] Specifically, the distance between the passivated ion-implanted planar silicon detector and the back cover is 80 mm.

[0028] Specifically, the cylinder, the first plate, the second plate, and the rear cover are made of stainless steel.

[0029] Specifically, the second center hole is chamfered.

[0030] In the implementation of this invention, the standard section method is used ( 6 Li (n, α) 3 With H-section uncertainty <1%, a linear relationship was established between monoenergetic neutron flux rate and nuclear reaction product count. Direct source tracing of monoenergetic neutron flux rate in the energy range of 1 keV to 100 keV was achieved through a telescope structure and a passivated ion-implanted planar silicon detector.

[0031] The device consists of a cylindrical body, a rear cover, a composite layered neutron converter, a collimating aperture, a passivated ion implantation planar silicon detector, and a signal processing system (charge-sensitive preamplifier, shaping main amplifier, high-speed analog-to-digital converter, and computer), as detailed below:

[0032] A composite layered neutron converter comprises a 20 μm thick aluminum substrate and a 500 mg / cm² enriched 6LiF active layer deposited on its surface. The aluminum substrate provides mechanical support. 6 The LiF active layer acts as a neutron converter. During measurement, neutrons pass through... 6 LiF active layer formation 6The Li(n, α) nuclear reaction, with a reaction energy of 4.78 MeV, produces α nuclei of 2.05 MeV and tritium nuclei of 2.73 MeV. The high-energy nuclear reaction products can be effectively distinguished from the monoenergetic neutron signal and the background gamma signal by setting a threshold. The tritium nuclei pass through a two-stage collimation aperture to a passivated ion-implanted planar silicon detector. The collimation aperture is made of stainless steel, and the first and second central holes on the first and second plates are both 15 mm in diameter and 10 mm apart. The second central hole is chamfered to reduce neutron scattering. The passivated ion-implanted planar silicon detector is surrounded by a gamma-ray shielding material to achieve active shielding of the background gamma rays. At an operating bias of 10V, the depletion layer thickness is approximately 60 μm, the resolution for 5.486 MeV α particles is 25 keV, and the background noise level is 19 keV. The signal processing system uses a charge-sensitive preamplifier cascaded with a shaping main amplifier, and a high-speed analog-to-digital converter for digital acquisition and data analysis. By limiting the solid angle of the neutron converter to the PIPS detector unit using a collimating aperture, a pulse height spectrum with distinct tritium nucleus characteristic peaks can theoretically be obtained. Based on pulse height spectrum analysis and pulse amplitude discrimination techniques, the absolute efficiency of the detector for a unit fluence of incident fast neutrons is finally given, achieving absolute measurement of the monoenergetic neutron fluence rate.

[0033] The above description constitutes an embodiment of the present invention. The foregoing descriptions are preferred embodiments of the present invention. Unless there is a clear contradiction or a prerequisite for a particular preferred embodiment, the preferred embodiments can be arbitrarily combined and used. The embodiments and specific parameters described are merely for clearly illustrating the verification process of the invention and are not intended to limit the scope of patent protection of the present invention. The scope of patent protection of the present invention is still determined by its claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention should also be included within the scope of protection of the present invention.

Claims

1. A method based on 6 The absolute measurement device for the monoenergetic neutron fluence rate of the LiF telescope system is characterized in that... The device includes a cylindrical body (1), inside which a collimating aperture is provided. The collimating aperture includes a first plate (2) disposed at one end of the cylindrical body (1) and a second plate (3) disposed inside the cylindrical body (1). The first plate (2) and the second plate (3) are respectively provided with a first central hole (4) and a second central hole (5). The first central hole (4) and the second central hole (5) are coaxially arranged and have the same diameter. A composite layered neutron converter is installed on the outside of the first plate (2) at the first central hole (4). The composite layered neutron converter includes an aluminum substrate (6). The upper surface of the aluminum substrate (6) is coated with a... 6 The LiF active layer (7) 6 The LiF active layer (7) faces the first central hole (4). A passivated ion implantation planar silicon detector (8) is provided inside the cylinder (1) behind the second central hole (5). The passivated ion implantation planar silicon detector (8) is covered with a γ-ray shielding layer. An SMA connector (9) is provided on the side of the passivated ion implantation planar silicon detector (8) away from the second central hole (5). A rear cover (10) is provided at the end of the cylinder (1) away from the first plate (2). A BNC female base lead-out signal line (11) is provided at the center of the rear cover (10). The SMA connector (9) is connected to the BNC female base lead-out signal line (11). A charge-sensitive preamplifier (12), a shaping main amplifier (13), a high-speed analog-to-digital converter (14), and a computer (15) are also provided in sequence and connected by electrical signals. The BNC female base lead-out signal line (11) is connected to the charge-sensitive preamplifier (12) by electrical signals.

2. A method based on claim 1 6 The absolute measurement device for the monoenergetic neutron fluence rate of the LiF telescope system is characterized in that... The distance between the first central hole (4) and the second central hole (5) is 10 mm.

3. A method based on claim 1 6 The absolute measurement device for the monoenergetic neutron fluence rate of the LiF telescope system is characterized in that... The diameters of the first central hole (4) and the second central hole (5) are 15 mm.

4. A method based on claim 1 6 The absolute measurement device for the monoenergetic neutron fluence rate of the LiF telescope system is characterized in that... The distance between the passivated ion-implanted planar silicon detector (8) and the back cover (10) is 80 mm.

5. A method based on claim 1 6 The absolute measurement device for the monoenergetic neutron fluence rate of the LiF telescope system is characterized in that... The cylinder (1), the first plate (2), the second plate (3), and the rear cover (10) are made of stainless steel.

6. A method based on claim 1 6 The absolute measurement device for the monoenergetic neutron fluence rate of the LiF telescope system is characterized in that... The second center hole (5) is provided with a chamfer (16).

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