GM counter tube suitable for alpha / beta / gamma ray and neutron measurement and manufacturing method thereof

Abstract

The application provides a GM counting tube suitable for alpha / beta / gamma ray and neutron measurement and a manufacturing method thereof. The GM counting tube comprises a cathode shell, a first detection window and a second detection window, a boron neutron sensitive layer coated on a part of the outer surface of the first detection window and / or a part of the outer surface of the second detection window, an insulating seat, a first anode wire and a second anode wire with a hole in the middle, wherein the first end of the second anode wire is communicated with the middle part of the first anode wire, and the second end of the second anode wire penetrates through the insulating seat and is led out to the outside of the cathode shell. The GM counting tube realizes the function of simultaneously detecting alpha, beta, gamma ray and neutron, and the boron neutron sensitive layer is on the outer surface of the detection window, so that daily maintenance and repair are facilitated.

Description

Technical Field

[0001] This invention relates to the field of nuclear radiation detection technology, and in particular to a GM counter tube suitable for measuring α / β / γ rays and neutrons, and its manufacturing method. Background Technology

[0002] Geiger-Miller counters (hereinafter referred to as "GM counters") are commonly used gaseous nuclear radiation detection devices in the field of nuclear radiation detection. They are used to record the occurrence of nuclear radiation events. Although they cannot distinguish the type and energy of radioactive particles, they have advantages such as high sensitivity, large pulse amplitude, and high stability. Furthermore, they are simple in structure and low in cost, giving them irreplaceable application advantages. Traditional GM counters are mainly suitable for gamma-ray measurement. By increasing the detection window, they can be widely used for measuring alpha, beta, and low-energy gamma rays, making them one of the most widely applicable nuclear radiation detection devices. Neutron radiation, as a highly penetrating particle stream, mainly originates from nuclear reaction processes and is commonly found in nuclear reactors, particle accelerators, radioactive isotopes, and cosmic rays. It is also an important source of nuclear radiation, but no reports have been found regarding GM counters suitable for neutron detection.

[0003] Currently, the most common neutron detectors include boron-coated proportional counters and He-3 proportional counters. These detectors are specifically designed for neutron detection and are not suitable for measuring alpha, beta, or low-energy gamma rays. He-3 proportional counters, in particular, are subject to supply constraints of the raw material He-3, resulting in higher production costs. Boron-coated proportional counters, with their high detection efficiency and strong anti-interference capabilities, have become a focus of neutron detector research in recent years. Tsinghua University has studied the effect of boron coating thickness on the detection efficiency of boron-coated proportional counters, proposing that the overall ion emission rate at the boron layer interface under unit nuclear reaction rate is approximately positively linearly correlated with the boron layer thickness when the coating thickness is less than 1.5 μm, and decreases when the coating thickness is greater than 1.5 μm. The rate of increase slows down with increasing boron coating thickness after μm (Zhu Chaoyang, Li Litao, Wang Zhentao. Study on the effect of boron coating thickness on detection efficiency of boron-coated proportional counter tube [J]. Nuclear Power Engineering, 2023, 44(01):148-153.); Nanjing University of Aeronautics and Astronautics, China Shipbuilding Industry Corporation, etc. proposed a new type of boron-coated proportional counter. In addition to the boron coating process on the inner wall of the tube, 14 double-sided boron-coated epoxy sheets were added inside the tube to further improve the neutron sensitivity of the boron-coated proportional counter (Zhang Zixia, Wei Zhiyong, Zhu Li, et al. Development of a new type of boron-coated proportional counter and its experimental testing and simulation calculation [J]. Atomic Energy Science and Technology, 2015, 49(03):545-551.); Southwestern Institute of Physics of Nuclear Industry and China Nuclear Power Research and Design Institute proposed a method for preparing a neutron sensitive layer on the tube wall, which improved the purity of the boron neutron sensitive layer and its interfacial bonding force with the inner wall of the counting tube (CN202110098750.7). It is known that the thickness of the boron neutron-sensitive layer is typically on the order of μm. The neutron counting lifetime of a boron-coated proportional counter tube depends primarily on the rate of consumption of the boron neutron-sensitive layer. As the boron neutron-sensitive layer is depleted due to nuclear reactions caused by neutron irradiation, its neutron detection efficiency will significantly decrease. Theoretically, the lifetime of a boron-coated proportional counter tube operating under a moderate-intensity radiation field (neutron fluence ≤ 10 n·cm⁻²·s⁻¹) is less than 3 years. Furthermore, due to the working principle of the boron-coated proportional counter tube, the boron neutron-sensitive layer can only be applied to the inner wall of the tube, which is not conducive to repair and routine maintenance. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, the purpose of this invention is to propose a GM counter tube suitable for α / β / γ ray and neutron measurement and its manufacturing method, so that the GM counter tube is suitable for both α / β / γ ray and neutron measurement, and solves the shortcomings of the current boron neutron sensitive layer coating technology that is not conducive to repair and daily maintenance, thereby further improving the applicability and maintainability of the GM counter tube.

[0006] To achieve the above objectives, the first aspect of the present invention provides a GM counter tube suitable for α / β / γ ray and neutron measurement, comprising: Cathode housing; The first detection window and the second detection window are respectively sealed and connected to the left and right ends of the cathode housing; A boron neutron-sensitive layer is coated on a portion of the outer surface of the first detection window and / or a portion of the outer surface of the second detection window; An insulating base is sealed to the side wall of the cathode housing; The first anode wire is disposed inside the cathode housing; The second anode wire has a hole in the middle. The first end of the second anode wire is connected to the middle of the first anode wire, and its second end passes through the insulating base and extends to the outside of the cathode housing.

[0007] According to one embodiment of the present invention, the cathode housing is made of stainless steel and has a cylindrical structure.

[0008] According to one embodiment of the present invention, the boron neutron sensitive layer includes a first boron neutron sensitive layer and a second boron neutron sensitive layer, both of which are annular and are coated on the outer surfaces of the first detection window and the second detection window, respectively.

[0009] A second aspect of this invention provides a method for fabricating a GM counter tube suitable for α / β / γ ray and neutron measurement as described in the first aspect, comprising: An insulating base is installed on the cathode housing; Install the first anode wire and the second anode wire; Connect the first and second detection windows to the cathode housing; Preparation of coating solution; A first boron neutron sensitive layer and a second boron neutron sensitive layer are formed by spraying a coating solution onto the first and second detection windows; Vacuuming and inflation.

[0010] According to one embodiment of the present invention, the coating solution comprises the following components in parts by weight: 10-12 parts of amorphous nano-boron powder, 1.5-2.0 parts of polyvinylpyrrolidone, 45-50 parts of N,N-dimethylformamide, 38-43 parts of ethanol, and 0.3-0.5 parts of dispersant.

[0011] According to one embodiment of the present invention, the preparation of the coating solution includes: Take N,N-dimethylformamide and anhydrous ethanol, pour them into a beaker, stir and mix them evenly to obtain a mixed solvent; Slowly add the weighed polyvinylpyrrolidone powder to the mixed solvent and stir continuously for ≥2 h until the polyvinylpyrrolidone is completely dissolved and a uniform viscous solution is formed. Add the dispersant and continue stirring for ≥30 min. While stirring, slowly add the weighed amorphous nano boron powder in small batches and stir for ≥2 h to achieve preliminary dispersion. Place the beaker in an ice-water bath with a water temperature of <25°C, immerse the ultrasonic disperser probe below the liquid surface for intermittent dispersion, and maintain the total ultrasonic dispersion time for ≥15 min to obtain a monodisperse nano boron powder suspension. The prepared coating solution is allowed to stand, stirred, and then set aside to achieve degassing.

[0012] According to one embodiment of the present invention, the process of forming a first boron neutron sensitive layer and a second boron neutron sensitive layer by spraying a coating solution onto the first and second detection windows includes: Masks are placed on the first and second detection windows respectively, and an ultrasonic nozzle is used to spray the coating solution onto the outer surfaces of the first and second detection windows to form annular first and second boron neutron sensitive layers.

[0013] According to one embodiment of the present invention, before placing the mask on the first detection window and the second detection window respectively, and spraying the coating solution onto the outer surfaces of the first detection window and the second detection window respectively using an ultrasonic nozzle to form annular first boron neutron sensitive layers and second boron neutron sensitive layers, the following steps are included: Nitrogen gas is used to purge the outer surfaces of the first and second detection windows to be coated. The first and second detection windows are ultrasonically cleaned. The uncoated GM counter tubes were placed in a cleanroom oven, baked, and then stored. A base is set on the substrate, and the GM counter tube is mounted on the base. The substrate temperature is set to 80-90°C, and heat is conducted to the GM counter tube through the base.

[0014] According to one embodiment of the present invention, it further includes: Place the coated GM counter tube in a drying oven and maintain it at 170-190°C for 20-40 minutes to remove residual solvent from the coating solution and allow the polyvinylpyrrolidone polymer to undergo slight crosslinking.

[0015] According to one embodiment of the present invention, it further includes: When the boron neutron sensitive layer of the coated GM counter tube is worn, consumed, or its condition changes, the boron neutron sensitive layer is removed using a cleaning solution, and the boron neutron sensitive layer is recoated onto the detection window. The cleaning solution includes the following components by weight: 8-9 parts N,N-dimethylformamide, 1 part deionized water, 0.3-0.5 parts benzotriazole, and 0.5-1 part ultrasonic cleaner.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The GM counter tube for measuring α / β / γ rays and neutrons according to the present invention, by coating a portion of the outer surface of the detection window with a boron neutron-sensitive layer, ensures that the nuclear reaction process of boron and neutrons inevitably produces α particles and... 7 Li ions, after entering the sensitive area of ​​the counter tube, will drift, ionize, and avalanche with the working gas under the action of an electric field. Along a very short path, they will collide with air molecules through Coulomb forces, rapidly decelerating and generating a large number of ion pairs, which will eventually be recorded as electrical signals. This enables the simultaneous detection of α, β, γ rays and neutrons. Furthermore, the boron neutron sensitive layer is on the outer surface of the detection window, which is convenient for daily maintenance and repair.

[0017] 2. The method for manufacturing a GM counter tube suitable for α / β / γ-ray and neutron measurement according to the present invention enables the GM counter tube to be used for both α / β / γ-ray and neutron measurement, and overcomes the shortcomings of the existing boron neutron sensitive layer coating technology, which is not conducive to repair and daily maintenance, thus further improving the applicability and maintainability of the GM counter tube. The GM counter tube manufactured by the method of the present invention can provide reliable early warning functions in radioactive contaminated sites, single radiation fields, or mixed radiation fields. When used in conjunction with a traditional GM counter tube, it can achieve neutron field discrimination and source direction estimation.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. Wherein: Figure 1 This is a cross-sectional view of a GM counter tube for measuring α / β / γ rays and neutrons, proposed in an embodiment of the present invention.

[0020] Figure 2 This is a diagram showing the connection structure of the first anode wire and the second anode wire in one embodiment of the present invention.

[0021] Figure 3 This is a cross-sectional schematic diagram of the second anode wire in one embodiment of the present invention.

[0022] Figure 4This is a left view of a GM counter tube suitable for measuring α / β / γ rays and neutrons in one embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of a boron neutron-sensitive layer sprayed in one embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of a mask blocking the ultrasonic nozzle spraying path in one embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures: 1-Cathode shell, 2-First anode wire, 3-Second anode wire, 4-Insulating base, 5-First detection window, 6-Second detection window, 7-First boron neutron sensitive layer, 8-Second boron neutron sensitive layer, 21-Ultrasonic nozzle, 22-Base, 23-Mask, 24-Substrate, 31-Hole. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Rather, embodiments of the invention include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0027] The following is combined with Figures 1 to 4 This describes a GM counter tube suitable for α / β / γ ray and neutron measurement according to an embodiment of the present invention.

[0028] According to an embodiment of the present invention, a GM counter tube suitable for measuring α / β / γ rays and neutrons includes a cathode housing 1, a first anode wire 2, a second anode wire 3, an insulating base 4, a first detection window 5, a second detection window 6, and a boron neutron sensitive layer.

[0029] The cathode housing 1 is the negative electrode of the GM counter tube and is made of conductive metal. The specific type of the cathode housing 1 is determined according to actual needs and is not limited thereto. For example, the cathode housing 1 can be a cuboid, cylinder, or other shapes. The first detection window 5 and the second detection window 6 are respectively sealed and connected to the left and right ends of the cathode housing 1. The first detection window 5 and the second detection window 6 can be made of materials such as mica, titanium, or beryllium, and are used to allow α / β / γ rays and neutrons to penetrate into the cathode housing 1. A boron neutron-sensitive layer is coated on a portion of the outer surface of the first detection window 5 and / or a portion of the outer surface of the second detection window 6. The boron neutron-sensitive layer can be coated on the outer surface of the first detection window 5 or the second detection window 6, or both, depending on actual needs. The area ratio of the boron neutron-sensitive layer to the detection window is determined according to actual needs and is not limited thereto. The shape of the boron neutron-sensitive layer is determined according to actual needs and is not limited thereto. For example, the boron neutron-sensitive layer can be annular, circular, rectangular, or other irregular shapes. The thickness of the boron neutron sensitive layer is 1-3 μm. The insulating base 4 is sealed to the side wall of the cathode housing 1. The function of the insulating base 4 is to electrically isolate the cathode housing from the anode wire and to seal it to the cathode housing 1. The material of the insulating base 4 is selected according to actual needs and is not limited thereto. For example, the insulating base 4 is made of ceramic. The first anode wire 2 is disposed inside the cathode housing 1. The second anode wire 3 has a hole 31 in the middle. The first end of the second anode wire 3 communicates with the middle of the first anode wire 2, and its second end passes through the insulating base 4 and extends to the outside of the cathode housing 1. The first anode wire 2 and the second anode wire 3 can be connected by welding. The welding method is selected according to actual needs, such as laser welding. The GM counter tube of this embodiment adopts a double-ended detection window design. Due to the presence of the double-ended detection window, the structure of the anode leading out from the bottom of the traditional cylindrical GM counter tube cannot be used.

[0030] The GM counter tube of this invention does not require a dedicated charging and venting pipeline. It adopts an innovative integrated design of the anode wire and the charging and venting pipeline. A hole 31 is set in the center of the second anode wire 3. Without affecting the original electrode function of the anode wire, the GM counter tube is vacuum sealed using the hole 31. The working gas can be injected into the cathode housing 1 through the hole 31. After the GM counter tube working gas sealing process is completed, the end through hole of the second anode wire 3 is sealed. At this time, the detection window, cathode housing 1, insulating base 4 and second anode wire 3 form a completely sealed space. This sealed space is the sensitive area of ​​the GM counter tube.

[0031] like Figure 1As shown, in some embodiments, the cathode housing 1, the first anode wire 2, and the second anode wire 3 are made of stainless steel, and the cathode housing 1 has a cylindrical structure. The cathode housing 1 has a diameter of 20 mm, a length of 120 mm, and a thickness of 0.5 mm. The first anode wire 2 has a diameter of 1 mm and a length of 110 mm. The second anode wire 3 has a diameter of 1 mm and a length of 20 mm. The first detection window 5 and the second detection window 6 are made of mica, with a diameter of 20 mm and a thickness of 3 μm. The insulating ceramic is made of magnesium ceramic. The working gas inside the GM counter tube is a Ne / Br2 mixture with a volume ratio of 95:5. Of course, the working gas is not limited to Ne / Br2; it can be two or more combinations of gases such as neon, argon, helium, bromine, chlorine, ethanol, and diethyl ether.

[0032] The boron (B)-neutron (n) nuclear reaction formula is: (Equation 1) Ground state branch (94% probability) 10 B+n→ 4 He(α) (1.78 MeV)+ 7 Li (1.02 MeV) (Equation 2) Excited state branch (6% probability) 10 B+n→ 4 He(α) (1.47 MeV)+ 7 Li (0.84 MeV) + γ (478 KeV) Because the nuclear reaction between boron and neutrons inevitably produces alpha particles and... 7 Li ions, therefore, the principle of GM counter tube detection of neutrons is to set up a boron neutron sensitive layer to record the alpha particles produced in the boron-neutron nuclear reaction process. 7 Li ions, alpha particles and 7 When Li ions are incident into the sensitive volume of the GM counter tube, they undergo drift, ionization, and avalanche effects with the working gas under the influence of an electric field. Along an extremely short path, they collide with air molecules via Coulomb forces, rapidly decelerating and generating a large number of ion pairs, which are ultimately recorded as electrical signals. Generating one ion pair in air requires an average of about 34 eV of energy. For example, a 1.78 MeV alpha particle can generate approximately 52,000 ion pairs. This enormous initial ionization makes the signal easily amplified and detected, forming the basis for the high-sensitivity neutron detection technology in boron neutron detection. However, at the same time, due to their large mass and high charge, alpha particles and Li ions exhibit very high linear energy transfer along their paths, meaning that the energy deposited per unit distance is extremely large, resulting in a very short range.

[0033] Taking a 1.78 MeV alpha particle as an example, its CSD (continuous moderation approximation) range in dry air is approximately 1.133E-03 g / cm³. 2 At 0°C and 1 standard atmosphere, the average range of an alpha particle with an energy of 1.78 MeV in air is approximately 0.87 cm. Similarly, in both the ground-state and excited-state branches of the boron-neutron nuclear reaction, the alpha particles and Li ions produced have relatively low energies and very short ranges in air, ranging from mm to cm.

[0034] In existing technologies, boron neutron detection technology employs a method involving an embedded boron neutron sensitive layer, such as a boron-coated proportional counter tube. The boron neutron sensitive layer is located on the inner side of the tube wall. When a boron-neutron nucleus reaction occurs in the boron neutron sensitive layer, releasing alpha particles... 7 After Li ions, α particles and 7 Li ions must be able to directly contact and ionize the working gas inside the counting tube to ensure that all their energy is deposited in the gas, thus generating a complete electrical signal that can be recorded. If coated on the outside of the counting tube, alpha particles... 7 Li ions cannot penetrate the tube wall to enter the sensitive region of the counter tube, thus failing to generate a detection signal. Therefore, whether the GM counter tube can detect neutrons depends on the alpha particles produced by the boron-neutron nuclear reaction. 7 Whether Li ions can enter the sensitive region of the GM counter tube.

[0035] The proposed embodiment of this invention utilizes a GM counter tube suitable for measuring α / β / γ rays and neutrons. It employs a dual-detection-window structure to extend the angular response of the GM counter tube to neutrons, low-energy γ rays, and low-energy β rays. In one example, such as... Figure 4 As shown, the boron neutron sensitive layer includes a first boron neutron sensitive layer 7 and a second boron neutron sensitive layer 8. Both the first boron neutron sensitive layer 7 and the second boron neutron sensitive layer 8 are annular and are coated on the outer surfaces of the first detection window 5 and the second detection window 6, respectively, forming a composite detection window structure. A well-designed composite detection window structure can not only ensure the safe exchange of alpha particles, the product of the boron-neutron nuclear reaction, with the neutron nuclei... 7 Li ions can pass through the detection window into the sensitive area of ​​the GM counter tube, while also ensuring that the boron neutron sensitive layer does not seriously affect the original detection efficiency of the detection window for alpha particles.

[0036] The following is a theoretical analysis and calculation process for the structural design of the composite detection window: The detection window should be made of materials such as mica, titanium, and beryllium. Among them, mica film is currently a commonly used detection window material. Due to its material and density properties, natural muscovite has good permeability to alpha particles, low-energy gamma rays, and low-energy beta rays, while also having good airtightness and structural strength. The thickness of natural mica films that have been put into engineering applications is usually in the μm range (1.5-3 mg / cm²). 2(Mass production is possible, but thinner films require screening). If artificially synthesized mica films are used, the thickness can be further reduced. For Am-241, the typical energy of the emitted alpha particles after decay is 5.486 MeV, with a range of approximately 3.5 cm in air. For mica with a thickness of 5 μm, the transmittance is theoretically close to 100%. However, the alpha particles and 7Li ions released by the boron-neutron nuclear reaction have even lower energies. Therefore, a composite structure of the boron neutron sensitive layer and the detection window needs to be considered in conjunction to achieve ideal performance.

[0037] like Figure 4 As shown, the composite detection window adopts a structure with a mica thin film surrounded by an annular boron neutron sensitive layer. In a certain implementation example, the diameter of the mica thin film, i.e., the detection window and the second detection window 6, is Φ20 mm, and the thickness is 3 μm. The outer side of the mica thin film is covered by an annular boron neutron sensitive layer, i.e., the first boron neutron sensitive layer 7 and the second boron neutron sensitive layer 8, with an inner diameter of Φ12.0 mm, an outer diameter of Φ20.0 mm, an annular width of 4.0 mm, and an area of ​​approximately 201 mm². 2 It occupies 64% of the entire detection window area, the boron neutron sensitive layer is 1.5 μm thick, and the central mica bare window has a diameter of Φ12.0 mm and an area of ​​approximately 113 mm². 2 It accounts for 36% of the total detection window area.

[0038] The fabrication of the GM counter tube requires evaluation of the neutron response capability of the composite detection window. This involves joint analysis to calculate the neutron capture probability of the boron neutron-sensitive layer, the escape probability of α-particles / Li ions, and the charge collection efficiency within the sensitive region, while also considering the anisotropy of the neutron emission direction. The neutron capture probability of the composite detection window first requires consideration of the incident neutron type. Since the neutron capture cross-section is generally inversely proportional to the neutron velocity, the B-10 isotope has the largest capture cross-section for thermal neutrons, reaching 3837±9 barn. Thermal neutrons belong to the subclass of slow neutrons (<1 keV), referring to neutrons in thermal equilibrium with the surrounding medium. Their energy distribution follows the Maxwell-Boltzmann distribution, and at standard temperatures (293 K or 20°C), their most probable energy is: In the above formula, K is the Boltzmann constant, and T is the absolute temperature. The B-10 counter has a certain response to hyperthermal neutrons with energies ranging from 1 to 100 eV, but its response to slow neutrons (100 eV to 1 keV) is poor, and it has almost no response to fast neutrons (energy > 1 keV), resulting in extremely low detection efficiency. Therefore, the GM counter tube proposed in this embodiment is mainly suitable for measuring thermal neutrons with energies of 0.025 eV. However, by combining it with moderator materials such as polyethylene and paraffin, the energy of fast neutrons can be rapidly lost, eventually transforming into thermal neutrons which are then recorded by the GM counter tube. If a neutron moderator is placed outside one end of the detection window, the detection capability of the current detection window for fast neutrons can be guaranteed, while the other end of the detection window can still effectively detect alpha particles and low-energy gamma and beta rays.

[0039] For a single composite detector window, in one implementation, the first and second boron neutron-sensitive layers (7, 8) are prepared using pure boron with a pure boron density ρ B Approximately 2.34 g / cm³ 3 Given a boron layer thickness d of 1.5 μm, purity ≥ 99.9%, and B-10 abundance C ≥ 95%, the effective molar mass M of the boron neutron-sensitive layer is... eff Approximately 10 g / mol, the total number of B-10 atoms per unit volume is expressed as: In the above formula, N A Using Avogadro's constant, the final calculated density of B-10 atoms in the boron layer, n, is approximately 1.3 × 10⁻⁶. 23 cm -3 When a neutron interacts with matter, its energy decays exponentially. Therefore, the capture probability P of a thermal neutron in a boron neutron-sensitive layer is... n Represented as: In the above formula, σ represents the thermal neutron capture cross section of the boron neutron sensitive layer, which is approximately 3837 × 10⁻⁶. −24 cm 2 Calculations show that the capture probability of thermal neutrons by a pure boron neutron-sensitive layer is approximately 52.7%, meaning that the boron neutron-sensitive layer receives neutrons and produces alpha particles. 7 The probability of Li ions.

[0040] Whether the GM counter can detect neutrons also depends on the boron-neutron nuclear reaction product, the alpha particle. 7 Whether Li ions can enter the sensitive region of the GM counter tube requires calculation of the interaction between alpha particles and... 7 The escape probability of Li ions. In the boron-neutron nucleus reaction, alpha particles and... 7 Li ions strictly obey momentum conservation; in ground-state reactions (occurring with a 94% probability), α particles and... 7Li ions emit back-to-back at an angle of 180°, in an excited-state reaction (6% probability). The alpha particle and... 7 The angle between the back of the Li ion and the emission path is 160°, which is verified by Monte Carlo numerical simulation. In 1 million events of boron-neutron nuclear reactions, the alpha particle and... 7 In over 99.98% of Li ion events, the emission occurred back-to-back, and the emission direction was randomly distributed in space. Therefore, the alpha particle and... 7 The average escape probability of Li ions in all directions is about 50%, meaning that when boron-neutron nuclear reactions form alpha particles and... 7 After Li ions, when α particles enter the sensitive region of the GM counter tube... 7 The Li ion emission path will be far from the sensitive region. 7 (Li ion escape), and 7 When Li ions are injected into the sensitive region of the GM counter, the emission path of alpha particles will be far from the sensitive region (alpha particle escape). Ideally, in each boron-neutron nuclear reaction event, almost one particle's emission path will be directed towards the sensitive region of the GM counter. In principle, the GM counter will receive any boron-neutron nuclear reaction product alpha particle and... 7 Neutrons can be detected in all Li ions.

[0041] Furthermore, a numerical model of the mica detector window and the boron neutron sensitive layer was established through Monte Carlo numerical simulation. The mica detector window was made of KAl2Si3O4. 10 (OH)₂, density approximately 2.8 g / cm³ 3 It can be seen that 1.01 MeV 7 The range of Li ions in mica is approximately 1 μm, which is almost insufficient to penetrate a 3 μm thick mica detection window; therefore, penetration through this window is not considered. 7 Li ions recognize neutron capture signals, but it's also crucial to ensure at least one particle enters the sensitive region of the GM counter. For 1.78 MeV alpha particles, their range in pure boron far exceeds the 1.5 μm thickness of the boron neutron-sensitive layer. Furthermore, after the boron-neutron nuclear reaction, the alpha particle may be released at any location within the boron neutron-sensitive layer. The escape path of the alpha particle is: reaction point – through the remaining boron layer – through mica – into the sensitive region of the GM counter. Based on the uniform distribution assumption, the average remaining penetration thickness of the alpha particle is 0.75 μm. Simulation calculations show that in 5 million events, the number of times a 1.78 MeV alpha particle simultaneously penetrates both the 0.75 μm boron neutron-sensitive layer and the 3 μm mica detection window is 4.91 million (covering 98% of the events). Therefore, the final escape probability η of the alpha particle is... α Approximately 49%. Therefore, the neutron intrinsic detection efficiency of a single detection window of the GM counter is: Neutrons incident on the boron neutron-sensitive layer have a 26% probability of generating a detectable electrical signal. Since the boron neutron-sensitive layer does not cover the entire detection window, the effective neutron detection efficiency of a single detection window is approximately 16.64% when the boron coating coverage is 64%. Because the GM counter has identical detection windows at both ends, placing it in an isotropic neutron field expands the effective solid angle of the GM counter and improves its angular response to neutrons, gamma rays, and beta rays. Ideally, the total efficiency is the sum of the efficiencies of the two detection windows. However, considering the obstruction from the GM counter itself, the total efficiency of the dual detection windows is approximately 1.8-1.9 times that of a single window. In a uniform neutron field, the total thermal neutron detection efficiency of the GM counter can be increased to approximately 30%. When the thermal neutron fluence is 10... 4 n·cm -2 ·s -1 At typical reference values, the dual-ended detection window GM counter is expected to produce a count rate of approximately 9420 CPS, demonstrating effective design. This general-purpose GM counter, designed to simultaneously detect alpha, beta, and gamma rays and neutrons, is sufficient to provide reliable warning functionality in strong neutron fields. The dual-ended detection window design further enhances the GM counter's ability to simultaneously detect alpha particles incident from two directions in certain applications such as slits and pipes.

[0042] Regarding the impact of adding a boron neutron sensitive layer outside the detection window on the detection efficiency of the original α, β, and γ rays in the GM counter tube, taking the α particle with the shortest range as an example, some α particles need to penetrate the annular boron neutron sensitive layer before penetrating the mica detection window. Due to the low atomic number and density of boron, the thickness at the μm level has a very limited impact on α particles. Taking the 5.486 MeV alpha particle emitted by Am-241 as an example, after penetrating a 1.5 μm boron neutron sensitive layer, only about 0.1 MeV of energy is lost, which is still sufficient to penetrate the mica detection window and reach the sensitive region of the GM counter. However, considering that the presence of the boron neutron sensitive layer may introduce additional geometric obstruction or scattering, Monte Carlo numerical simulation shows that with the current structure and materials, the 1.5 μm boron neutron sensitive layer will cause an absolute decrease in the alpha particle detection efficiency of about 3.4%. Sacrificing some alpha detection efficiency ensures the GM counter's ability to detect neutrons. In practical applications, the detection window structure can be designed collaboratively according to the application objectives, and the thickness, area, and distribution mode (ring, circle, gradient, dispersion) of the boron neutron sensitive layer can be adjusted to achieve the optimal particle detection state.

[0043] Since the boron neutron sensitive layer in this embodiment of the invention is placed outside the detection window, the boron neutron sensitive layer can be repaired and maintained, further extending its service life.

[0044] Combination Figures 1 to 4 As shown in the figure, this invention also proposes a method for fabricating a GM counter tube suitable for α / β / γ ray and neutron measurement. The implementation process of this method is as follows: Step S102: Install the insulating base 4 on the cathode housing 1.

[0045] Step S104: Install the first anode wire 2 and the second anode wire 3.

[0046] Step S106: Connect the first detection window 5 and the second detection window 6 to the cathode housing 1.

[0047] Step S108: Prepare the coating solution.

[0048] In step S110, a first boron neutron sensitive layer 7 and a second boron neutron sensitive layer 8 are formed by spraying a coating solution onto the first detection window 5 and the second detection window 6.

[0049] In this embodiment, the boron neutron-sensitive layer is prepared using pure boron with a purity ≥99.9% and a B-10 abundance ≥95%. Pure boron is a black or dark brown powder at room temperature. Amorphous boron has high reactivity and can be prepared into nano- to micron-sized powders through high-energy ball milling or liquid-phase ultrasonic crushing. Ball milling was used for dispersion in a planetary ball mill within a glove box under an inert Ar atmosphere (O2, H2O <1 ppm), with zirconium oxide as the milling medium at a ball-to-particle ratio of 20:1. Anhydrous ethanol with a purity of ≥99% was added, and the milling was performed for 20-30 hours. The milling balls and boron powder were then separated using a sieve to obtain amorphous nano-boron powder with a particle size D50 ≤500 nm. This embodiment utilizes amorphous nano-boron powder to prepare a coating solution with a soluble polymer as a binder. A boron neutron sensitive layer is formed on the surface of the mica detection window using ultrasonic spraying technology. Subsequently, by utilizing the dissolution property of this coating in a specific solvent, the entire boron neutron sensitive layer is completely peeled off by a demolding process without damaging key components such as the GM counter tube mica detection window and cathode housing 1, thereby achieving lifetime maintainability of the boron neutron sensitive layer.

[0050] Step S112: Vacuuming and inflation.

[0051] The method for fabricating a GM counter tube suitable for α / β / γ-ray and neutron measurement according to embodiments of the present invention enables the GM counter tube to be used for both α / β / γ-ray and neutron measurement. It also overcomes the shortcomings of existing boron neutron sensitive layer coating techniques, which are difficult to repair and maintain, further improving the applicability and maintainability of the GM counter tube. The GM counter tube fabricated by the method of the present invention can provide reliable early warning functions in radioactive contaminated sites, single radiation fields, or mixed radiation fields. When used in conjunction with traditional GM counter tubes, it can achieve neutron field discrimination and source direction estimation.

[0052] In some embodiments, the coating solution comprises the following components in parts by weight: 10-12 parts of amorphous nano-boron powder, 1.5-2.0 parts of polyvinylpyrrolidone, 45-50 parts of N,N-dimethylformamide, 38-43 parts of ethanol, and 0.3-0.5 parts of dispersant.

[0053] Amorphous boron nanopowder is the core functional material of the boron neutron-sensitive layer. Polyvinylpyrrolidone (PVP) acts as a binder, providing excellent film-forming properties and adhesion, and is readily and completely soluble in polar organic solvents. N,N-dimethylformamide (NDM) is the main solvent, exhibiting good dispersibility and solubility for both PPVP and amorphous boron nanopowder, facilitating the leveling of atomized droplets during ultrasonic spraying and forming a uniform boron neutron-sensitive layer. Anhydrous ethanol serves as a co-solvent, reducing the surface tension of NDM, improving atomization, accelerating coating surface drying, and preventing sagging. A high-efficiency polymeric dispersant prevents the agglomeration of boron nanopowder, ensuring long-term stability of the coating solution (>24 hours without stratification), resulting in a smooth and uniform coating. BYK-190 (Germany) can be used as the dispersant; other raw material types and manufacturers are not specifically specified and can be prepared in-house or purchased commercially.

[0054] In one example, polyvinylpyrrolidone can be replaced by hydroxypropyl methylcellulose, N,N-dimethylformamide can be replaced by dimethylacetamide, and ethanol can be replaced by isopropanol.

[0055] In some embodiments, step S108, preparing the coating solution includes: Step S1081: Take N,N-dimethylformamide and anhydrous ethanol, pour them into a beaker, stir and mix evenly to obtain a mixed solvent.

[0056] In this embodiment, the beaker is placed on a magnetic stirrer and stirred at 500 rpm for 5 minutes.

[0057] Step S1082: Slowly add the weighed polyvinylpyrrolidone powder to the mixed solvent and stir continuously for ≥2 h until the polyvinylpyrrolidone is completely dissolved and a uniform viscous solution is formed. Add the dispersant and continue stirring for ≥30 min. While stirring, slowly add the weighed amorphous nano boron powder in small batches and stir for ≥2 h to achieve preliminary dispersion.

[0058] Step S1083: Place the beaker in an ice-water bath with a water temperature of <25°C, immerse the ultrasonic disperser probe below the liquid surface for intermittent dispersion, and maintain the total ultrasonic dispersion time for ≥15 min to obtain a monodisperse nano boron powder suspension.

[0059] In this embodiment, the ultrasonic disperser probe is immersed 1-2 cm below the liquid surface, the ultrasonic power is set to 400W, and the dispersion is performed intermittently.

[0060] Step S1084: Let the prepared coating solution stand, stir, and set aside to achieve degassing.

[0061] In this embodiment, the coating solution is allowed to stand for 4 hours, and then stirred at a low speed of ≤200 rpm to remove bubbles. The coating solution that has been left to stand for a long time needs to be ultrasonically dispersed again before use.

[0062] Combination Figure 5 and Figure 6 As shown, in some embodiments, step S110, which involves spraying a coating solution onto the first detection window 5 and the second detection window 6 to form a first boron neutron sensitive layer 7 and a second boron neutron sensitive layer 8, includes: In step S1106, the mask 23 is placed on the first detection window 5 and the second detection window 6 respectively, and the coating solution is sprayed onto the outer surfaces of the first detection window 5 and the second detection window 6 using the ultrasonic nozzle 21 to form annular first boron neutron sensitive layer 7 and second boron neutron sensitive layer 8 respectively.

[0063] In this embodiment, the mask 23 is made of stainless steel foil. The mask 23 blocks the ultrasonic spraying path to achieve the fabrication of the annular boron neutron-sensitive layer. The shape and size of the mask 23 have a complementary effect on the film morphology of the annular boron neutron-sensitive layer.

[0064] The ultrasonic nozzle 21 is a 60 kHz focusing ultrasonic nozzle. The coating solution supply rate is 0.15–0.30 mL / min. The low-speed supply ensures uniform atomization. The moving speed of the ultrasonic nozzle 21 is 5–10 mm / s, and the spraying distance is 10–15 cm. The optimal distance is selected according to the spraying state to ensure that the solvent partially evaporates before the atomized droplets reach the surface, forming a semi-dry deposition and preventing film flow. The film thickness is controlled at 0.15–0.2 μm for each spray, covering 8–10 layers. The film layer spraying interval is ≥20 seconds to avoid film cracking, ultimately forming a boron neutron-sensitive layer with a thickness of 1.5 μm.

[0065] In some embodiments, step S1110, before placing the mask 23 on the first detection window 5 and the second detection window 6 respectively, and spraying the coating solution onto the outer surfaces of the first detection window 5 and the second detection window 6 with the ultrasonic nozzle 21 to form the annular first boron neutron sensitive layer 7 and the second boron neutron sensitive layer 8, includes: Step S1101: Use nitrogen gas flow to blow away the outer surfaces of the first detection window 5 and the second detection window 6 to be sprayed.

[0066] In this embodiment, a nitrogen gas flow is used to remove large particles.

[0067] Step S1102: Perform ultrasonic cleaning on the first detection window 5 and the second detection window 6.

[0068] In this embodiment, the GM counter tube is placed in an ultrasonic cleaning apparatus, with the mica detection window to be coated immersed 3-5 cm below the surface of the ultrasonic cleaning liquid. The cleaning liquid is acetone or anhydrous ethanol. The ultrasonic cleaning frequency is set to 120 kHz, the cleaning temperature to 60±5 °C, and the ultrasonic power <100 W to prevent damage to the mica detection window. The cleaning time is ≤5 min, and the process is repeated 2-3 times. Then, dry, mild nitrogen gas is used to blow away any residual ethanol from the mica detection window and the surface of the GM counter tube wall.

[0069] Step S1103: Place the uncoated GM counter tube in a cleanroom oven, bake it, and then store it.

[0070] In this embodiment, the temperature of the dust-free oven is set to 80°C, and the food is stored after baking for 10 minutes.

[0071] Step S1104: A base 22 is provided on the substrate 24, and the GM counter tube is mounted on the base 22. The substrate temperature is set to 80-90°C, and heat is conducted to the GM counter tube through the base 22.

[0072] In this embodiment, the heat from the substrate 24 can be conducted to the GM counter tube through the base 22, ensuring that the surface temperature of the mica detection window is high enough to quickly evaporate the solvent, allowing the coating to solidify rapidly and preventing boron powder from agglomerating due to solvent flow, thereby forming a uniform boron film. The base 22 can be made of stainless steel.

[0073] In some embodiments, the method for fabricating a GM counter tube suitable for α / β / γ ray and neutron measurement further includes: Step 1107: Place the coated GM counter tube in a drying oven and maintain it at 170-190°C for 20-40 minutes to remove residual solvent from the coating solution and allow the polyvinylpyrrolidone polymer to undergo slight crosslinking.

[0074] In this embodiment, by lightly crosslinking the polyvinylpyrrolidone polymer, the mechanical stability and wear resistance of the coating during use are improved. The crosslinking process of the polyvinylpyrrolidone polymer is reversible, which facilitates subsequent dissolution and removal. After film formation, the boron purity of the boron neutron-sensitive layer is ≥92%, with the main impurities coming from elements such as C, O, and N in the polyvinylpyrrolidone polymer. The boron purity is mainly determined by the purity of the raw boron powder and the addition ratio of polyvinylpyrrolidone, and the ratio can be adjusted according to actual requirements.

[0075] In some embodiments, the method for fabricating a GM counter tube suitable for measuring α / β / γ rays and neutrons further includes: Step S112: When the boron neutron sensitive layer of the coated GM counter tube is worn, consumed, or its state changes, the boron neutron sensitive layer is removed using a cleaning solution, and the boron neutron sensitive layer is recoated onto the detection window. The cleaning solution includes the following components by weight: 8-9 parts N,N-dimethylformamide, 1 part deionized water, 0.3-0.5 parts benzotriazole, and 0.5-1 part ultrasonic cleaner.

[0076] When preparing the cleaning solution, first add benzotriazole and ultrasonic cleaning agent to N,N-dimethylformamide, stir magnetically until completely dissolved, and finally add deionized water and mix well.

[0077] In this embodiment, N,N-dimethylformamide solvent is used to completely dissolve the polyvinylpyrrolidone polymer, which serves as the coating framework, thereby causing the entire boron neutron-sensitive layer to detach from the substrate in fragments or as a peel. This not only efficiently removes the boron neutron-sensitive layer, but also removes reaction products such as Li compounds and He bubbles generated by neutron irradiation within the coating along with the coating. The cleaning solution formulation includes N,N-dimethylformamide, deionized water, benzotriazole, and an ultrasonic cleaner. N,N-dimethylformamide is the main solvent, which can efficiently dissolve the polyvinylpyrrolidone polymer. Both uncrosslinked and lightly crosslinked polyvinylpyrrolidone can rapidly swell and dissolve under the action of N,N-dimethylformamide. A small amount of deionized water acts as a co-solvent, accelerating the swelling process of polyvinylpyrrolidone. Benzotriazole, as a corrosion inhibitor specifically for stainless steel, can form a dense passivation protective film on the stainless steel surface, effectively preventing any form of corrosion from the solution. Ultrasonic cleaning agents use neutral or weakly alkaline nonionic surfactants, regardless of type, which can further reduce the surface tension of the cleaning solution and accelerate the peeling process by allowing the solution to penetrate into the micro-cracks of the coating.

[0078] When the boron neutron sensitive layer of the GM counter tube is worn, consumed, or its state changes, the boron neutron sensitive layer is removed and a new boron neutron sensitive layer is prepared by re-coating. The process does not affect the working performance of the GM counter tube. During the film cleaning process, the boron neutron sensitive layer is completely immersed 3-5 cm below the cleaning liquid surface. The cleaning liquid is heated to 60±5 °C to accelerate the dissolution process. If necessary, ultrasonic cleaning technology is used for assistance. The ultrasonic cleaning frequency is set to 120 kHz, the power is <100 W, and the cleaning time is ≤5 min. After visually observing that the boron neutron sensitive layer has been completely curled and peeled off, the GM counter tube is removed and immediately rinsed with a large amount of anhydrous ethanol. The residual ethanol on the mica detection window and the surface of the GM counter tube wall is dried from the side with dry, mild nitrogen gas. After the boron neutron sensitive layer of the double-ended detection window is removed, the GM counter tube is placed in a cleanroom oven at 80°C and baked for 10 minutes before storage. Before re-implementing the coating process, the mica detection window needs to be inspected under an optical microscope or white light interferometer to confirm that there is no coating residue or damage.

[0079] The entire cleaning process is a physical dissolution and peeling process, without the involvement of strong acids or alkalis. It will not etch the silicon-oxygen structure of the mica probe window and will not cause mica delamination or changes in its physicochemical properties. The cleaning solution has extremely low corrosiveness to stainless steel. Benzotriazole is specifically added to the formula to ensure the integrity of the passivation film on the stainless steel components of the GM counter tube that come into contact with the cleaning solution, preventing defects such as pitting or intergranular corrosion on the outer wall of the GM counter tube stainless steel.

[0080] The ultrasonic spraying process for boron neutron sensitive layers is stable, and the cleaning method is simple and efficient, making it suitable for laboratory and mass production maintenance. The main cost of boron neutron sensitive layers comes from the enrichment of B-10 powder. Although expensive, the ultrasonic spraying technology achieves a film-forming state at the μm level with minimal loss. Even with a 70% process loss rate, the consumption of enriched B-10 powder for a single-sided detection window is only 2-3 mg, making the cost controllable.

[0081] This invention relates to a method for fabricating a GM counter tube for measuring α / β / γ rays and neutrons. It employs a dual-end detection window design and an external stepped boron neutron-sensitive layer coating, making it suitable for both α / β / γ ray and neutron measurements. Furthermore, it overcomes the shortcomings of current boron neutron-sensitive layer coating technology, which hinders repair and routine maintenance, further improving the applicability and maintainability of the GM counter tube. It can be widely applied in scenarios such as nuclear facility inspection, personnel radiation early warning, site monitoring, and surface contamination monitoring. Combined with energy compensation and moderator processes, it enables traditional environmental radiation detectors to simultaneously measure α, β, γ rays and neutrons (thermal neutrons, fast neutrons, etc.), providing reliable early warning functions in radioactively contaminated sites, single radiation fields, or mixed radiation fields. When used in conjunction with a traditional GM counter tube, it can achieve neutron field discrimination and source direction estimation capabilities.

[0082] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0083] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0084] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0085] In the description of this invention, the terms "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, 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.

[0086] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0087] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A GM counter tube suitable for measuring α / β / γ rays and neutrons, characterized in that, include: Cathode housing (1); The first detection window (5) and the second detection window (6) are respectively sealed and connected to the left and right ends of the cathode housing (1); A boron neutron-sensitive coating is applied to a portion of the outer surface of the first detection window (5) and / or a portion of the outer surface of the second detection window (6); The insulating base (4) is sealed to the side wall of the cathode housing (1); The first anode wire (2) is disposed inside the cathode housing (1); The second anode wire (3) has a hole (31) in the middle. The first end of the second anode wire (3) is connected to the middle of the first anode wire (2), and its second end passes through the insulating seat (4) and is led out to the outside of the cathode housing (1).

2. The GM counter tube for measuring α / β / γ rays and neutrons according to claim 1, characterized in that, The cathode housing (1) is made of stainless steel and has a cylindrical structure.

3. The GM counter tube for measuring α / β / γ rays and neutrons according to claim 2, characterized in that, The boron neutron sensitive coating includes a first boron neutron sensitive coating (7) and a second boron neutron sensitive coating (8). Both the first boron neutron sensitive coating (7) and the second boron neutron sensitive coating (8) are annular and are coated on the outer surfaces of the first detection window (5) and the second detection window (6), respectively.

4. A method for manufacturing a GM counter tube suitable for α / β / γ ray and neutron measurement as described in any one of claims 1 to 3, characterized in that, include: An insulating base (4) is installed on the cathode housing (1); Install the first anode wire (2) and the second anode wire (3); Connect the first detection window (5) and the second detection window (6) to the cathode housing (1); Preparation of coating solution; A first boron neutron sensitive coating (7) and a second boron neutron sensitive coating (8) are formed by spraying a coating solution onto the first detection window (5) and the second detection window (6); Vacuuming and inflation.

5. The method for manufacturing a GM counter tube suitable for α / β / γ ray and neutron measurement according to claim 4, characterized in that, The coating solution comprises the following components in parts by weight: 10-12 parts of amorphous nano-boron powder, 1.5-2.0 parts of polyvinylpyrrolidone, 45-50 parts of N,N-dimethylformamide, 38-43 parts of ethanol, and 0.3-0.5 parts of dispersant.

6. The method for manufacturing a GM counter tube suitable for α / β / γ ray and neutron measurement according to claim 5, characterized in that, The coating solution preparation includes: Take N,N-dimethylformamide and anhydrous ethanol, pour them into a beaker, stir and mix them evenly to obtain a mixed solvent; Slowly add the weighed polyvinylpyrrolidone powder to the mixed solvent and stir continuously for ≥2 h until the polyvinylpyrrolidone is completely dissolved and a uniform viscous solution is formed. Add the dispersant and continue stirring for ≥30 min. While stirring, slowly add the weighed amorphous nano boron powder in small batches and stir for ≥2 h to achieve preliminary dispersion. Place the beaker in an ice-water bath with a water temperature of <25°C, immerse the ultrasonic disperser probe below the liquid surface for intermittent dispersion, and maintain the total ultrasonic dispersion time for ≥15 min to obtain a monodisperse nano boron powder suspension. The prepared coating solution is allowed to stand, stirred, and then set aside to achieve degassing.

7. The method for manufacturing a GM counter tube suitable for α / β / γ ray and neutron measurement according to claim 6, characterized in that, The process of spraying a coating solution onto the first detection window (5) and the second detection window (6) to form a first boron neutron-sensitive coating (7) and a second boron neutron-sensitive coating (8) includes: The mask (23) is placed on the first detection window (5) and the second detection window (6) respectively. The coating solution is sprayed onto the outer surface of the first detection window (5) and the second detection window (6) using an ultrasonic nozzle (21) to form annular first boron neutron sensitive coating (7) and second boron neutron sensitive coating (8).

8. The method for manufacturing a GM counter tube suitable for α / β / γ ray and neutron measurement according to claim 7, characterized in that, Before placing the mask (23) on the first detection window (5) and the second detection window (6) respectively, and using an ultrasonic nozzle (21) to spray the coating solution onto the outer surfaces of the first detection window (5) and the second detection window (6) to form annular first boron neutron-sensitive coating (7) and second boron neutron-sensitive coating (8), the following steps are included: The outer surfaces of the first detection window (5) and the second detection window (6) to be sprayed are swept by a nitrogen gas stream. The first detection window (5) and the second detection window (6) are ultrasonically cleaned; The uncoated GM counter tubes were placed in a cleanroom oven, baked, and then stored. A base (22) is provided on a substrate (24), and a GM counter tube is mounted on the base (22). The substrate temperature is set to 80-90°C, and heat is conducted to the GM counter tube through the base (22).

9. The method for manufacturing a GM counter tube suitable for α / β / γ ray and neutron measurement according to claim 8, characterized in that, Also includes: Place the coated GM counter tube in a drying oven and maintain it at 170-190°C for 20-40 minutes to remove residual solvent from the coating solution and allow the polyvinylpyrrolidone polymer to undergo slight crosslinking.

10. The method for manufacturing a GM counter tube suitable for α / β / γ ray and neutron measurement according to claim 9, characterized in that, Also includes: When the boron neutron sensitive layer of the coated GM counter tube is worn, consumed, or its condition changes, the boron neutron sensitive layer is removed using a cleaning solution, and the boron neutron sensitive layer is recoated onto the detection window. The cleaning solution includes the following components by weight: 8-9 parts N,N-dimethylformamide, 1 part deionized water, 0.3-0.5 parts benzotriazole, and 0.5-1 part ultrasonic cleaner.

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