A neutron sensitive microchannel plate, a neutron detector and a method of manufacturing the same

Abstract

The application discloses a neutron-sensitive micro-channel plate, a neutron detector and a manufacturing method thereof, and belongs to the technical field of neutron detectors. The neutron-sensitive micro-channel plate comprises a glass substrate, a plurality of micro-channels penetrating through the thickness direction of the glass substrate are formed on the glass substrate, the micro-channels are in a conical hole structure, the aperture of the inlet end of the micro-channels is smaller than the aperture of the outlet end, and the opening rate of the inlet end is lower than the opening rate of the outlet end; a secondary electron multiplication functional layer is formed in the inner wall of the micro-channels; the secondary electron multiplication functional layer comprises a resistance layer and 10 a B2O3 secondary electron emission layer, the resistance layer is in contact with the inner wall of the micro-channels, 10 the B2O3 secondary electron emission layer is covered above the resistance layer, 10 the B2O3 secondary electron emission layer has the dual effects of secondary electron emission and electron multiplication; and electrode layers are formed on the upper and lower surfaces of the glass substrate, so that the neutron-sensitive micro-channel plate breaks through the contradiction between the opening rate and the detection efficiency of a conventional micro-channel plate and improves the detection efficiency.

Description

Technical Field

[0001] This invention belongs to the field of neutron detector technology, specifically relating to a neutron-sensitive microchannel plate, a neutron detector, and a method for manufacturing the same. Background Technology

[0002] Neutron imaging is an effective means of determining the microstructure and motion of materials, and revealing the internal structure of various engineering materials and components. In neutron imaging technology, microchannel plates (MCPs) are widely regarded as an alternative to traditional methods due to their high image resolution and detection efficiency. 3 He gas detector tubes are an ideal choice. Traditional MCPs used for photomultiplication typically employ a through-hole microchannel structure with a uniform aperture of less than 10µm and an aspect ratio greater than 40:1, achieving an electron multiplication factor ≥10. 4 The channel walls primarily serve a structural support function and are unrelated to the electron multiplication characteristics within the channel; furthermore, the aperture ratios at the inlet and outlet ends are identical. The aperture ratio of the MCP is given by the aperture ratio formula. It is confirmed that, among them, denoted by d, we represent the aperture ratio of the MCP; d represents the pore size of the microchannels in the MCP; and D represents the center-to-center distance between adjacent pores in the MCP. The aperture ratio of conventionally designed MCPs is approximately 60%, and a larger aperture ratio is generally considered more beneficial for electron transport and signal output. Furthermore, when isotopes... 10 When B is introduced into a traditional MCP glass substrate, it can be endowed with the ability to respond to thermal neutrons, thereby realizing neutron radiography. The principle is as follows: [The text abruptly shifts to a different topic] ...in the glass substrate... 10 After B captures a thermal neutron, it will undergo... 10 B(n,α) 7 Li nuclear reactions, the conditions that the nuclear reactions must satisfy are:

[0003] The high-energy charged particles produced by the nuclear reaction will directly release secondary electrons into the MCP channel, making full use of the electron multiplication function of the MCP microchannel, forming a large electron cloud that is output, which facilitates the decoding of the signal at the anode.

[0004] Existing research has shown that using 10 Using B2O3 instead of ordinary B2O3 in the preparation of microchannel plate glass substrates, 10 When the B2O3 doping concentration is 10 mol%, the thickness is 0.6 mm, the pore size is 6 µm, the wall thickness is 2 µm, and the deflection angle is 3° or 6°, neutron radiography can be achieved, according to theoretical simulations. 10 The higher the doping concentration of boron, the greater the detection efficiency that can be obtained, but doping is only performed in the glass substrate. 10 The measured maximum thermal neutron detection efficiency of B2O3 is only 24%. The thermal neutron detection efficiency of neutron-sensitive microchannel plates (MCPs) is...10 The concentration of boron doping is directly proportional to the concentration of boron doping, and inversely proportional to the aperture ratio of the MCP. Because 10 Boron is doped within the glass substrate of the MCP, and the proportion of the substrate in the effective detection area directly determines the accessible proportion of the neutron beam. When doped... 10 When the aperture ratio of a neutron-sensitive MCP of type B is 60%, the glass substrate accounts for no more than 40% of the effective area, resulting in a theoretical maximum thermal neutron detection efficiency of approximately 40%. To improve the neutron capture probability, existing technologies often employ a design scheme that introduces a 3°~6° deflection angle into the microchannel. This increases the contact opportunity between the neutron beam and the glass substrate, thus improving detection efficiency. However, this scheme has a significant drawback: neutrons incident at the same location may be captured by neutrons from different aperture walls. 10 B-type neutron capture causes the center of the emitted electron cloud to deviate from the original incident position by several aperture spacings, severely affecting the positioning accuracy of the incident neutrons. To address this bottleneck, related technologies have proposed different structural optimization paths. For example, Chinese invention patent application CN120183982A discloses a gradient diameter microchannel plate structure. This structure uses a femtosecond laser to process the microchannel into a conical structure with an inlet aperture larger than the outlet aperture. The ratio of aperture depth to outlet diameter is controlled between 30 and 200, and the cone angle is between 1° and 5°. The inner wall is coated with a Cs-containing Al₂O₃-SiO₂-B₂O₃ sol, and the microchannel blank is obtained through a hydrogen reduction process. This scheme aims to increase the aperture ratio, improve electron focusing characteristics, and increase the probability of electrons entering the MCP. However, when this structure is used for neutron capture, it actually reduces the probability of neutron capture.

[0005] In summary, the inlet aperture ratio of a neutron-sensitive MCP is inversely proportional to the neutron capture probability. Traditional neutron-sensitive MCPs use glass substrates for doping. 10 Scheme B has the same inlet and outlet opening ratios, but is affected by... 10 The limited escape range of B-nuclear reaction products and the requirement for a channel wall thickness of ≤2μm prevent further reduction in aperture ratio, hindering the improvement of neutron capture probability. Therefore, overcoming the inherent contradiction between aperture ratio and high neutron capture probability, and significantly increasing the interaction probability between neutrons and sensitive materials while maintaining the MCP electron multiplication function, has become a core challenge restricting the development of neutron imaging detectors. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide a neutron-sensitive microchannel plate, a neutron detector, and a method for manufacturing the same, by constructing an asymmetric conical microchannel structure with an inlet aperture much smaller than the outlet aperture and by fabricating [the following] on the inner wall of the microchannel. 10 The B2O3 secondary electron emission layer method allows for the inclusion of electrons along the neutron incident path. 10The increased effective working area of ​​the boron-doped glass substrate effectively overcomes the contradiction between the aperture ratio and detection efficiency of conventional MCPs, thus significantly improving neutron detection efficiency.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention provides a neutron-sensitive microchannel plate, comprising a glass substrate, on which a plurality of microchannels penetrating the thickness direction of the glass substrate are formed. Each microchannel has a tapered through-hole structure, with the inlet diameter smaller than the outlet diameter and the inlet aperture ratio lower than the outlet aperture ratio. A secondary electron multiplication functional layer is formed in the inner wall of the microchannel. The secondary electron multiplication functional layer includes a resistive layer and... 10 The B2O3 secondary electron emission layer, the resistive layer is in contact with the inner wall of the microchannel, the... 10 A B2O3 secondary electron emission layer covers the resistive layer. 10 The B2O3 secondary electron emission layer has the dual function of secondary electron emission and electron multiplication; electrode layers are formed on the upper and lower surfaces of the glass substrate.

[0009] In one embodiment, the aperture of the inlet end is greater than or equal to 1µm; the aperture of the outlet end is 5µm to 20µm; and the center distance between adjacent microchannels is 6µm to 20µm.

[0010] In one embodiment, the aperture of the outlet end is 5 to 10 times the aperture of the inlet end.

[0011] In one embodiment, the thickness of the secondary electron multiplication functional layer is 50 nm to 230 nm, and the thickness of the resistive layer is 10 nm to 80 nm. 10 The thickness of the secondary electron emission layer of B2O3 is 40nm~150nm.

[0012] In one embodiment, the resistive layer is a composite layer composed of alternating W layers and Al2O3 layers, wherein the thickness of each W layer is 0.2 nm and the thickness of each Al2O3 layer is 0.4 nm.

[0013] In one embodiment, the 10 An Al2O3 layer is formed on the upper layer of the B2O3 secondary electron emission layer, and the thickness of the Al2O3 layer is less than 2 nm; the electrode layer is a nickel-chromium alloy layer, and the thickness of the electrode layer is 0.5 µm to 1 µm.

[0014] In one embodiment, the glass substrate is doped with isotopes. 10 B2O3, an isotope in the raw materials for preparing the glass substrate. 10The molar content of B2O3 is 10 mol% to 50 mol%.

[0015] Furthermore, in molar percentage, the glass substrate comprises 30%~70% SiO2 and 10%~50% isotopes. 10 It is made of B2O3, 1%~5% Al2O3, 3%~5% TiO2, 1%~3% Bi2O3 and 3%~8% PbO.

[0016] Furthermore, in molar percentage, the glass substrate comprises 30%~70% SiO2 and 15%~50% isotopes. 10 It is made of B2O3, 1%~5% Al2O3, 3%~5% TiO2, 1%~3% Bi2O3 and 3%~8% PbO.

[0017] The present invention also provides a method for manufacturing a neutron-sensitive microchannel plate, which includes the following steps:

[0018] Provide glass substrates;

[0019] The glass substrate is modified locally by oblique laser incidence, forming a laser modification region with a tapered path;

[0020] Alternating acid and alkali etching removes the laser-modified area, forming a microchannel with a tapered through-hole structure; the inlet diameter of the microchannel is smaller than the outlet diameter, and the opening ratio of the inlet is lower than the opening ratio of the outlet.

[0021] A resistive layer and an atomic layer deposition technique were used to sequentially deposit resistive layers on the inner wall of the microchannel. 10 The B2O3 secondary electron emission layer forms a secondary electron multiplication functional layer;

[0022] Electrode layers are formed by magnetron sputtering on the upper and lower surfaces of the glass substrate.

[0023] In one embodiment, the incident angle of the oblique laser incidence is inversely proportional to the thickness of the glass substrate, and the incident angle of the oblique laser incidence is 1° to 8°.

[0024] The present invention also provides a neutron detector, comprising a neutron-sensitive microchannel plate, a signal readout anode, and a high-voltage power supply; the neutron-sensitive microchannel plate and the signal readout anode are disposed opposite to each other, and the high-voltage power supply is applied to both ends of the electrode layer of the neutron-sensitive microchannel plate.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention provides a neutron-sensitive microchannel plate (MCP), a single microchannel plate that combines neutron trapping and electron multiplication functions. The MCP's glass substrate and the inner wall of the microchannel... 10 The B2O3 secondary electron emission layer jointly undertakes the task of neutron capture; while the microchannel structure itself provides the physical space and electric field environment for electron multiplication, realizing signal amplification. The entire detection process follows a clear physical chain: "neutron → charged particle → electron → signal amplification". The first step: neutron capture and charged particle generation. Incident thermal neutrons and sensitive nuclides... 10 B occurred 10 B(n,α) 7 Li nuclear reaction, generating high-energy alpha particles and 7 Charged particles such as Li ions. This process mainly occurs on the inner wall. 10 In the secondary electron emission layer of B2O3. Step Two: Electron Multiplication and Signal Amplification. The charged particles produced by the nuclear reaction have limited energy, only able to excite a small number of primary electrons; these electrons are accelerated and collide with the inner wall under the strong electric field of the microchannel, passing through... 10 The B2O3 secondary electron emission layer enables efficient secondary electron emission and cascaded electron multiplication. Ultimately, the multiplied electron cloud is emitted from the outlet and collected by the anode under the high voltage applied to the upper and lower electrodes, converting it into a detectable current or voltage pulse signal. The inherent contradiction of traditional MCPs lies in the fact that while the presence of microchannels ensures electron multiplication, it leads to an increased aperture ratio and a decreased proportion of solid glass, thereby reducing... 10 The total amount of nitrogen (B) weakens the neutron capture efficiency; conversely, reducing the aperture ratio to improve capture efficiency limits electron multiplication performance and affects signal detection. Therefore, this invention, by reducing the aperture ratio at the inlet and maintaining the aperture ratio at the outlet, ensures that neutrons act on the nitrogen-rich electrons with a high probability in the early stages of incidence. 10 The B-glass region ensures sufficient electron transmission and multiplication space on the exit side, thereby effectively overcoming the fundamental contradiction between aperture ratio and detection efficiency and significantly improving the overall neutron detection efficiency.

[0027] This invention provides a method for manufacturing a neutron-sensitive microchannel plate. First, a tapered microchannel is formed by laser-modified glass substrate combined with an alternating acid-base etching process, replacing traditional deflection angle etching and avoiding channel misalignment and uneven wall thickness. Second, atomic layer deposition technology is used to prepare... 10 The B2O3 film acts as a secondary electron emission layer. 10 The B2O3 thin film improves the neutron radiographic detection efficiency of MCP, making the thermal neutron detection efficiency ≥60%; finally, the magnetron sputtering electrode layer ensures reliable voltage loading at both ends. Attached Figure Description

[0028] Figure 1 A schematic cross-sectional view of a neutron-sensitive microchannel plate provided by the present invention;

[0029] Figure 2 A flowchart illustrating a method for manufacturing a neutron-sensitive microchannel plate provided by the present invention;

[0030] Figure 3 A three-dimensional cross-sectional view of a neutron-sensitive microchannel plate provided by the present invention;

[0031] Figure 4 For the present invention 10 The curve of the secondary electron emission coefficient of the B2O3 secondary electron emission layer as a function of voltage.

[0032] Wherein: 1-glass substrate; 2-entry end; 3-exit end; 4-microchannel. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0034] The present invention will now be described in further detail with reference to the accompanying drawings:

[0035] This invention proposes a doping method capable of achieving high thermal neutron detection efficiency. 10 B describes a neutron-sensitive microchannel plate, a neutron detector, and a method for manufacturing the same. The structure of the neutron-sensitive microchannel plate is as follows: Figure 1 and Figure 3 As shown.

[0036] like Figure 1 and Figure 3 As shown, a neutron-sensitive microchannel plate includes a glass substrate 1. Multiple microchannels 4 penetrating the thickness direction of the glass substrate 1 are formed on the glass substrate 1. Each microchannel 4 has a tapered through-hole structure. The aperture of the inlet end 2 of the microchannel 4 is smaller than the aperture of the outlet end 3, and the aperture ratio of the inlet end 2 is lower than that of the outlet end 3. A secondary electron multiplication functional layer is formed in the inner wall of the microchannel 4. The secondary electron multiplication functional layer includes a resistive layer and... 10 The B2O3 secondary electron emission layer and the resistive layer are in contact with the inner wall of microchannel 4. 10 A B2O3 secondary electron emission layer covers the resistive layer. 10 The B2O3 secondary electron emission layer has the dual function of secondary electron emission and electron multiplication; electrode layers are formed on the upper and lower surfaces of the glass substrate 1.

[0037] The inventive point of this invention lies in two aspects: firstly, by reducing the aperture ratio of the inlet end 2 to increase the neutron capture probability, while maintaining the aperture ratio of the outlet end 3 to ensure electron multiplication performance; secondly, by forming a structure on the inner wall of the microchannel 4 that combines secondary electron emission and electron multiplication. 10 The B2O3 secondary electron emission layer improves detection efficiency. This effectively overcomes the constraint between aperture ratio and detection efficiency in conventional MCPs, significantly enhancing thermal neutron detection efficiency.

[0038] Furthermore, the aperture of the inlet end 2 is greater than or equal to 1µm; the aperture of the outlet end 3 is 5µm to 20µm; and the center-to-center distance between adjacent microchannels 4 is 6µm to 20µm. See also... Figure 1 , Figure 1 In this diagram, 'a' represents the aperture of the inlet end 2 of the microchannel 4 of the neutron-sensitive MCP, with a value ranging from a ≥ 1µm; 'b' represents the aperture of the outlet end 3 of the microchannel 4 of the neutron-sensitive MCP, with a value ranging from 5µm ≤ b ≤ 20µm; and 'c' represents the center-to-center distance between adjacent microchannels 4, with a value ranging from 6µm ≤ c ≤ 20µm. The aperture of the inlet end 2 of the microchannel 4 is smaller than the aperture of the outlet end 3.

[0039] Furthermore, the diameter of the outlet end 3 is 5 to 10 times the diameter of the inlet end 2.

[0040] For example, when a=1µm, b=8µm, and c=10µm, the aperture ratio of the inlet end 2 of the neutron-sensitive MCP is 0.9%, and the aperture ratio of the outlet end 3 is 58%. When the inlet end 2 is directly facing the neutron beam injection, the probability of neutrons being captured by the neutron-sensitive microchannel plate provided by this invention is 57% higher than that of a conventional through-hole microchannel plate with an aperture of 8µm and a wall thickness of 2µm.

[0041] Furthermore, the thickness of the secondary electron multiplication functional layer is 50nm~230nm, and the thickness of the resistive layer is 10nm~80nm. 10 The thickness of the secondary electron emission layer of B2O3 is 40nm~150nm.

[0042] Furthermore, the resistive layer is a composite layer composed of alternating W layers and Al2O3 layers. The thickness of each W layer in the resistive layer is 0.2 nm, and the thickness of each Al2O3 layer is 0.4 nm. The W layers provide conductive pathways, while the Al2O3 layers act as insulating spacers to regulate electron tunneling probability and thermal stability. The ultrathin periodic stacking can construct a uniform and stable resistive network at the nanoscale, which not only meets the surface resistance required for MCP operation but also avoids the problems of large resistance dispersion and uneven multiplication caused by thickness fluctuations in traditional single resistive films, ensuring the consistency and long-term stability of the electron multiplication response across the entire plate.

[0043] Furthermore, the aforementioned10 An Al2O3 layer is formed on top of the B2O3 secondary electron emission layer, and the thickness of the Al2O3 layer is less than 2 nm. 10 B2O3 materials are prone to moisture absorption and deliquescence in air, leading to a rapid decline in secondary electron emission performance. This Al2O3 layer can effectively prevent this. 10 The B2O3 layer absorbs moisture and deteriorates, significantly improving the environmental durability of the secondary electron emission layer and meeting long-term operation requirements.

[0044] Furthermore, the electrode layer is a nickel-chromium alloy layer with a thickness of 0.5µm to 1µm. Nickel-chromium alloy has a suitable resistivity, and a thickness of 0.5µm to 1µm can meet the requirement of uniform electric field distribution when high voltage (typically on the order of kV) is applied across the MCP, avoiding localized Joule heating or electric field distortion.

[0045] Furthermore, the glass substrate 1 of the neutron-sensitive microchannel plate is... 10 B-doped glass substrate 1, the 10 The beta-doped glass substrate 1 is doped with isotopes. 10 B2O3, 10 Isotopes in the raw materials for preparing boron-doped glass substrate 1 10 The molar content of B2O3 is 10 mol% to 50 mol%.

[0046] In mole percentage, the 10 The boron-doped glass substrate 1 consists of 30%–70% SiO2 and 10%–50% isotopes. 10 It is made of B2O3, 1%~5% Al2O3, 3%~5% TiO2, 1%~3% Bi2O3 and 3%~8% PbO.

[0047] This multi-element glass system further improves the efficiency per unit volume. 10 The increased boron atom density enhances the probability of thermal neutron nuclear reactions, providing a more reliable material basis for improving detection efficiency.

[0048] like Figure 2 As shown, the present invention also provides a method for manufacturing a neutron-sensitive microchannel plate, comprising the following steps:

[0049] S1: Provides glass substrate 1;

[0050] S2: The glass substrate 1 is modified locally by oblique laser incidence to form a laser modification area with a tapered path;

[0051] S3: Alternating acid and alkali etching removes the laser-modified area, forming a microchannel 4 with a tapered through-hole structure; the aperture of the inlet end 2 of the microchannel 4 is smaller than the aperture of the outlet end 3, and the opening ratio of the inlet end 2 is lower than the opening ratio of the outlet end 3.

[0052] S4: A resistive layer and an atomic layer deposition technique are used to sequentially deposit on the inner wall of the microchannel 4. 10 The B2O3 secondary electron emission layer forms a secondary electron multiplication functional layer;

[0053] S5: Electrode layers are formed by magnetron sputtering on the upper and lower surfaces of the glass substrate 1.

[0054] Furthermore, the incident angle of the oblique laser incidence is inversely proportional to the thickness of the glass substrate 1, and the incident angle of the oblique laser incidence is 1°~8°.

[0055] In one specific embodiment of the present invention, a method for manufacturing a neutron-sensitive microchannel plate is provided, comprising the following steps:

[0056] S1: Provide 10 B-doped glass substrate 1:

[0057] 10 The raw materials for preparing the boron-doped glass substrate 1 include SiO2. 10 B₂O₃, Al₂O₃, TiO₂, Bi₂O₃, PbO, of which SiO₂ 10 B2O3 accounts for a large proportion, while other elements account for a small proportion. 10 Isotopes in B-doped glass substrate 1 10 The molar percentage of B2O3 ranges from 10% to 50%. The purity of each raw material is ≥99.99% (total metal-based impurities <10 ppm). The specific preparation process involves... 10 The raw materials for preparing the boron-doped glass substrate 1 were mixed by weighing according to the following molar percentages: 30%~70% SiO2 and 10%~50% isotope. 10 B2O3, 1%~5% Al2O3, 3%~5% TiO2, 1%~3% Bi2O3, and 3%~8% PbO were placed in a platinum crucible and melted at 1100℃~1300℃ for 2 hours under high-purity nitrogen protection. After stirring evenly, the mixture was poured into a mold preheated to 500℃ and held for 30 minutes. The mixture was then annealed at 500℃ for 2 hours to eliminate internal stress, resulting in a transparent and homogeneous glass preform free of crystallization and bubbles. 10 B-doped glass substrate 1.

[0058] S2: Modify the channel area with laser, using oblique laser incidence. 10 Localized modification of the boron-doped glass substrate 1 is performed to form a laser-modified region with a tapered path:

[0059] S21: Laser modification 10 When using a boron-doped glass substrate 1, laser treatment is applied to the conical region for modification, such as... Figure 3The inner wall region of the microchannel 4 shown will 10 A boron-doped glass substrate 1 is placed on a three-dimensional precision motion platform and irradiated with a femtosecond pulsed laser (center wavelength 800nm, pulse width ≤500fs, repetition rate 1kHz, single pulse energy ≤10µJ) or a picosecond ultrafast pulsed laser; the laser is incident at an inclined angle on... 10 The surface of the be-doped glass substrate 1, the incident angle according to 10 The thickness of the boron-doped glass substrate 1 is set to vary from 1° to 8°; the laser focus scans along the depth direction with an inverted conical path, the scanning speed is 200 µm / s, the single-point dwell time is 100 ns, and the energy density at the focal point is controlled between 0.1 and 0.5 J / cm². 2 ;

[0060] S22: After modification, ultrasonically clean with acetone for 10 minutes, then rinse with anhydrous ethanol and dry with nitrogen.

[0061] The principle is that the laser beam rotates at a constant speed around the central axis of each preset hole position to ensure that the modified area is symmetrical in a ring. The structure and acid and alkali corrosion resistance of the material in the area irradiated by the laser are changed, and the modified glass is easily corroded. The laser photons break the atomic bonds and distort the lattice in the local area of ​​the glass through multiphoton absorption or tunnel ionization, forming the "modified area".

[0062] S3: Alternating acid and alkali etching removes the laser-modified areas, forming a microchannel with a tapered through-hole structure. 4:

[0063] The laser-modified glass substrate 1 was sequentially immersed in the etching solution: first, it was placed in a 5wt% hydrofluoric acid (HF) aqueous solution and etched at room temperature for 30 minutes; after removal, it was ultrasonically cleaned with deionized water for 5 minutes; then, it was immersed in a 1mol / L sodium hydroxide (NaOH) aqueous solution and etched at room temperature for 15 minutes; it was cleaned again with deionized water; this HF-NaOH cycle was repeated 4 times; after each etching, it was thoroughly rinsed and dried; finally, the laser-modified area was completely removed, forming a tapered through-hole array that penetrated the thickness.

[0064] The chemical etching rate of the modified region is at least 50 times higher than that of the unmodified region. By performing a wet etching process that alternates between acid etching and alkaline etching multiple times, all laser-modified regions can be selectively removed, thereby forming microchannels 4 that extend through the thickness direction in the glass substrate 1.

[0065] S4: A secondary electron multiplication functional layer was prepared on the inner wall of microchannel 4 using atomic layer deposition (ALD) technology.

[0066] S41: The etched glass substrate 1 is placed into the atomic layer deposition (ALD) equipment chamber and evacuated to ≤10Pa;

[0067] S42: Resistance layer deposition: W layer is deposited using W(CO)6 and H2O as precursors, and Al2O3 layer is deposited using TMA (trimethylaluminum) and H2O as precursors. The two are carried out alternately in a cycle unit of "W layer deposition, high-purity nitrogen purging (20s), Al2O3 layer deposition, high-purity nitrogen purging (15s)".

[0068] The W(CO)6 pulse duration is 3s, and the TMA pulse duration is 1.5s. The W layer deposition thickness is 0.2nm per round, and the Al2O3 layer deposition thickness is 0.4nm per round. The total number of cycles is determined according to the target thickness, so that the total thickness of the resistive layer is controlled within the range of 10nm~80nm. The entire deposition process is carried out at a constant temperature of 150℃, with temperature fluctuations ≤±1℃. The chamber pressure is stably maintained at 5Pa by the vacuum pump group and the mass flow controller.

[0069] S43: 10 B2O3 secondary electron emission layer deposition: switching the precursor to 10 B(OCH3)3 / H2O, 10 B(OCH3)3 is stored in an inert atmosphere glove box, with the delivery pipeline heated to 40°C and protected by high-purity nitrogen (≥99.999%) throughout; the pulse duration is 2s, the H2O pulse duration is 2s, and the purging time is 15s; the number of deposition cycles is controlled to perform atomic layer deposition on the resistive layer surface, forming... 10 A B2O3 film was applied, with the thickness of the emission layer ranging from 40 nm to 150 nm. The deposition temperature was 150 °C, and the chamber pressure was maintained at 5 Pa.

[0070] S5: Desiccant-resistant protective layer deposition: In 10 TMA / H2O is continuously introduced above the B2O3 secondary electron emission layer for 5 to 10 ALD cycles to grow a dense Al2O3 passivation layer with a thickness of 1.5 nm to 2.0 nm. After the entire ALD process is completed, the layer is annealed at 200 °C for 30 minutes in a nitrogen atmosphere to improve the film density and interface stability.

[0071] Using atomic layer deposition technology 10 An electron multiplication functional layer is fabricated in microchannel 4 of a boron-doped glass substrate 1. The secondary electron multiplication functional layer includes a resistive layer and... 10 The B2O3 secondary electron emission layer contains a resistive layer composed of W / Al2O3. 10 The composition of the secondary electron emission layer of B2O3 is as follows: 10 B2O3 has been obtained through multiple experimental tests. 10 The secondary electron emission characteristics of the B2O3 secondary electron emission layer under different voltages, such as Figure 4As shown, it is confirmed that the voltage corresponding to the maximum secondary electron emission coefficient of 2.18 is 251V, which is applicable to electron multiplication.

[0072] S6: In 10 Electrode layers were fabricated on the upper and lower surfaces of the boron-doped glass substrate 1 using magnetron sputtering technology.

[0073] The glass substrate 1, after the deposition of the secondary electron multiplication functional layer, is transferred to a magnetron sputtering apparatus to prepare metal layers as electrode layers on the upper and lower end faces of the MCP; the background vacuum is better than 5×10⁻⁶. -3 Pa; using a NiCr alloy target (Ni:Cr=80:20), a nickel-chromium alloy thin film was simultaneously sputtered and deposited on the upper and lower surfaces of the glass substrate 1; the sputtering power was 200W, the atmosphere was argon, the pressure was 0.5Pa, and the deposition time was controlled at 10~20 minutes, resulting in an electrode layer thickness of 0.5µm~1.0µm; after deposition, the material was naturally cooled to room temperature to obtain a neutron-sensitive microchannel plate with complete device function.

[0074] The present invention also provides a neutron detector, comprising a neutron-sensitive microchannel plate, a signal readout anode, and a high-voltage power supply; the neutron-sensitive microchannel plate and the signal readout anode are disposed opposite to each other, and the high-voltage power supply is applied to both ends of the electrode layer of the neutron-sensitive microchannel plate.

[0075] In summary, this invention significantly improves the detection performance of neutron-sensitive microchannel plates. Firstly, regarding the material system, isotopes are employed... 10 B2O3 replaces B2O3 in traditional glass, and isotopes are used. 10 Increasing the molar percentage of B2O3 to 10%~50% increases the thermal neutron detection efficiency of neutron-sensitive MCPs by more than 300 times. Secondly, traditional MCPs are fabricated using a large number of hollow capillaries (microchannels) arranged in a two-dimensional pattern, sliced ​​to form a sheet-like structure. The inlet and outlet apertures of traditional MCPs are the same. This invention, in its structural design, abandons the symmetrical structure of traditional MCPs where the inlet and outlet apertures are the same, such as... Figure 1 and Figure 3 As shown, a conical microchannel 4 with an inlet end 2 aperture much smaller than the outlet end 3 was fabricated using laser-modified glass technology. This allows the incident neutron beam to preferentially impact the solid glass region, effectively improving the interaction between neutrons and the glass containing... 10 The interaction probability of material B. Compared with the prior art where the opening ratios of the inlet end 2 and the outlet end 3 of the glass substrate 1 are the same, the opening ratio of the inlet end 2 of the glass substrate 1 in this invention is much smaller than the opening ratio of the outlet end 3. The advantage is that it increases the solid proportion of the inlet end 2, which is equivalent to increasing the solid proportion of the glass substrate 1. 10The probability of neutron capture by B greatly increases the neutron detection efficiency. Because the aperture ratio of inlet 2 is significantly reduced (as low as 0.9%), the proportion of the glass substrate 1 in the effective area is greatly increased, thus breaking through the bottleneck of detection efficiency limit (≤40%) caused by high aperture ratio in traditional devices. The measured thermal neutron detection efficiency can reach over 60%. Finally, in the functional layer fabrication process, atomic layer deposition technology is used to replace the traditional hydrogen reduction process to prepare the secondary electron multiplication functional layer. A W / Al2O3 resistive layer and a... are constructed on the inner wall of microchannel 4. 10 The multilayer functional structure composed of B2O3 secondary electron emission layers not only achieves uniform conformal deposition within complex conical channels but also overcomes the technical limitation of traditional processes relying on lead-containing glass substrates, allowing for greater flexibility in substrate selection. Simultaneously, by covering the emission layer surface with an Al2O3 moisture-proof layer less than 2 nm thick, the environmental stability and lifespan of the device are further enhanced. The synergistic effect of these technologies achieves a balance between high detection efficiency, high spatial resolution, and high reliability, providing key core component support for high-performance neutron imaging systems.

[0076] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A neutron sensitive microchannel plate, characterized by, The application relates to a glass substrate (1) provided with a plurality of micro-channels (4) penetrating through the thickness direction of the glass substrate (1), the micro-channels (4) are in a tapered hole structure, the aperture of the inlet end (2) of the micro-channels (4) is smaller than the aperture of the outlet end (3), and the opening rate of the inlet end (2) is lower than the opening rate of the outlet end (3); a secondary electron multiplication functional layer is formed in the inner wall of the micro-channels (4); the secondary electron multiplication functional layer comprises a resistance layer and a B2O3 secondary electron emission layer. 10 The resistance layer is in contact with the inner wall of the micro-channels (4), the B2O3 secondary electron emission layer is arranged above the resistance layer, the B2O3 secondary electron emission layer has the dual functions of secondary electron emission and electron multiplication, and electrode layers are formed on the upper and lower surfaces of the glass substrate (1). 10 The resistance layer is in contact with the inner wall of the micro-channels (4), the B2O3 secondary electron emission layer is arranged above the resistance layer, the B2O3 secondary electron emission layer has the dual functions of secondary electron emission and electron multiplication, and electrode layers are formed on the upper and lower surfaces of the glass substrate (1). 10 The resistance layer is in contact with the inner wall of the micro-channels (4), the B2O3 secondary electron emission layer is arranged above the resistance layer, the B2O3 secondary electron emission layer has the dual functions of secondary electron emission and electron multiplication, and electrode layers are formed on the upper and lower surfaces of the glass substrate (1).

2. A neutron sensitive microchannel plate according to claim 1, wherein The aperture of the inlet end (2) is greater than or equal to 1 µm; the aperture of the outlet end (3) is 5 µm to 20 µm; the center distance between adjacent microchannels (4) is 6 µm to 20 µm.

3. A neutron sensitive microchannel plate according to claim 1, wherein The aperture of the outlet end (3) is 5 to 10 times the aperture of the inlet end (2).

4. A neutron sensitive microchannel plate according to claim 1, wherein The thickness of the secondary electron multiplication functional layer is 50 nm to 230 nm, the thickness of the resistance layer is 10 nm to 80 nm, and the thickness of the 10 The thickness of the B2O3 secondary electron emission layer is 40 nm to 150 nm.

5. A neutron sensitive microchannel plate according to claim 1 wherein, The resistance layer is a composite layer composed of W layers and Al2O3 layers.

6. A neutron sensitive microchannel plate according to claim 1, wherein The 10 An Al2O3 layer is formed on the upper layer of the B2O3 secondary electron emission layer, the thickness of the Al2O3 layer is less than 2nm; the electrode layer is a nickel-chromium alloy layer, the thickness of the electrode layer is 0.5-1µm.

7. A neutron sensitive microchannel plate according to claim 1 wherein, The glass substrate (1) is doped with an isotope 10 B2O3, the glass substrate (1) is doped with an isotope 10 The molar content of B2O3 is 10 mol% to 50 mol%.

8. A method for manufacturing a neutron sensitive microchannel plate, for manufacturing a neutron sensitive microchannel plate according to any one of claims 1 to 7, characterized in that The method comprises the following steps: Providing a glass substrate (1); Performing local area modification on the glass substrate (1) by laser oblique incidence to form a laser modified area of a tapered path; Performing acid-base alternate etching to remove the laser modified area to form a microchannel (4) of a tapered via structure; the aperture of the inlet end (2) of the microchannel (4) is smaller than the aperture of the outlet end (3), and the opening rate of the inlet end (2) is lower than the opening rate of the outlet end (3); The inner wall of the microchannel (4) is sequentially coated with a resistance layer and a B2O3 secondary electron emission layer by atomic layer deposition technology 10 B2O3 secondary electron emission layer, forming a secondary electron multiplication function layer Forming an electrode layer on the upper and lower surfaces of the glass substrate (1) by magnetron sputtering.

9. The method of claim 8, wherein the method further comprises: The incidence angle of the laser oblique incidence is inversely proportional to the thickness of the glass substrate (1), and the incidence angle of the laser oblique incidence is 1° to 8°.

10. A neutron detector, characterized by The neutron sensitive microchannel plate, the signal readout anode and the high voltage power supply are provided according to any one of claims 1 to 7; the neutron sensitive microchannel plate and the signal readout anode are oppositely arranged, and the high voltage power supply is applied to both ends of the electrode layer of the neutron sensitive microchannel plate.

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