CN106199681A - A kind of nuclear reaction radiation conversion target and preparation method thereof and a kind of offset-type neutron detector - Google Patents

Abstract

The invention provides a method for preparing a nuclear reaction radiation conversion target. The preparation method provided by the invention has strong operability, and the nuclear reaction radiation conversion target with good uniformity and stable performance can be prepared through simple operation steps. The invention provides a nuclear reaction radiation conversion target. The nuclear reaction radiation conversion target provided by the invention can realize energy response compensation in the fast neutron energy region, and is applied in a compensation type neutron detector, which is beneficial in the process of measuring the total number of neutrons It maintains relatively flat energy response, high neutron sensitivity and n/γ resolution, which lays the foundation for accurately measuring the total neutrons of low-intensity pulsed neutron sources. Theoretical calculations and experimental results show that the compensating neutron detector comprising the nuclear reaction radiation conversion target provided by the present invention, when the neutron energy is in the range of 1-15 MeV, its energy response is in the range of 1.01-1.44, and the neutron sensitivity is 10 ^{‑ 15} C cm, n/γ≥5.

Description

A nuclear reaction radiation conversion target and its preparation method and a compensation type neutron detector detector

technical field

The invention relates to the technical field of neutron detection, in particular to a nuclear reaction radiation conversion target, a preparation method thereof and a compensation type neutron detector.

Background technique

The total number of neutrons is an important part of low-intensity pulsed radiation detection. Low-intensity pulsed neutron sources have the characteristics of low neutron intensity, wide neutron energy range, short pulse duration, and serious mixing of neutrons and gamma rays. Therefore, to accurately measure the total number of neutrons in low-intensity pulsed neutron sources, neutron detectors are required to have higher neutron sensitivity, flatter energy response, higher n/γ resolution and faster time response, etc. performance. In the detection of low-intensity pulsed neutrons, the detectors used to measure the total number of neutrons mainly include scintillation film neutron detectors, scintillation fiber array neutron detectors, slit fission neutron detectors and compensation neutron detectors .

Scintillation thin-film neutron detectors use photomultiplier tubes to detect neutrons in organic thin-film scintillators, and the recoil protons generated in organic thin-film scintillators excite the scintillator to measure neutrons. It has the advantages of fast time response and high neutron sensitivity. However, since the luminescence efficiency of organic scintillators for electrons is higher than that for protons, the sensitivity of organic scintillators to γ-rays is also high, so their n/γ resolution is not high. Scintillation fiber array neutron detectors use photomultiplier tubes to detect neutrons. The recoil protons generated by the fiber scintillator excite the scintillator to emit light to realize the measurement of neutrons. The neutron sensitivity is high, but its energy spectrum response is not flat enough. The resulting n/γ resolution is not good enough. The slit fission neutron detector uses PIN to detect the fission fragments produced by neutron-induced fission target fission to measure neutrons, which has the advantage of flat energy response. However, in order to reduce the influence of n and γ direct illumination signals, it is necessary to arrange the PIN detector away from the radiation channel, so that only a small part of the fission fragments can be detected, so the neutron sensitivity is low, about 10 ^-17 ~ 10 ^-20 C cm, which cannot meet the measurement requirements of low-intensity pulsed neutron radiation field.

The compensation method neutron detector is to use the total signal current measured by PIN minus the n and γ direct light signal current measured by another PIN to measure neutrons. This measurement method adopts the method of switching target + PIN + PIN, switching The target is generally a uranium target or a polyethylene target: if the uranium target is selected as the conversion target, there is a problem that the direct irradiation sensitivity of PIN to neutrons is much greater than the fission sensitivity; if the polyethylene target is selected as the conversion target, the energy spectrum response is not flat enough The problem. Therefore, the neutron detectors existing in the prior art cannot actually accurately measure the total number of neutrons in the low-intensity pulsed neutron source.

Contents of the invention

The object of the present invention is to provide a nuclear reaction radiation conversion target and its preparation method and a compensating neutron detector. The compensating neutron detector prepared by using the nuclear reaction radiation conversion target provided by the present invention has relatively flat energy response, Higher neutron sensitivity and n/γ resolution capability lay the foundation for accurate measurement of the total number of neutrons in low-intensity pulsed neutron sources.

The invention provides a method for preparing a nuclear reaction radiation conversion target, comprising the following steps:

(1) pretreating the surface of the substrate;

(2) Coating is coated on the substrate surface after described step (1) pretreatment, and described coating comprises curing agent, resin, diluent and boron powder;

(3) drying and curing the substrate coated with the paint in the step (2) to obtain a nuclear reaction radiation conversion target.

Preferably, the mass ratio of curing agent, resin, diluent and boron powder in the coating in step (2) is 1: (2-3): (5-7): (3-4).

Preferably, the boron powder is amorphous ¹⁰ B powder.

Preferably, the boron powder is pretreated before use, and the pretreatment includes grinding, baking and secondary grinding.

Preferably, the particle size of the boron powder after the pretreatment is less than 1.0 μm.

Preferably, the drying and curing in step (3) includes drying treatment and baking treatment.

Preferably, the baking process adopts a gradient heating method, the initial temperature is 140-160°C, the end temperature is 440-460°C, the temperature increase range is 40-60°C each time, and the holding time after each temperature increase is 8-12min .

The invention provides a nuclear reaction radiation conversion target, which comprises a substrate and a cured coating on the surface of the substrate. The raw materials for forming the cured coating include curing agent, resin, diluent and boron powder.

Preferably, the thickness of the cured coating is 8-10 μm.

The invention provides a compensated neutron detector, comprising ⁴ He scintillator, pressure vessel, photomultiplier tube, high-voltage power supply and equipment for recording and transmitting signals, and also includes polyethylene nuclear recoil radiation located outside the incident window of the pressure vessel A conversion target and a nuclear reaction radiation conversion target located in the incident window of the pressure vessel, the nuclear reaction radiation conversion target being the nuclear reaction radiation conversion target described in the above technical solution.

The invention provides a method for preparing a nuclear reaction radiation conversion target. Firstly, the surface of a substrate is pretreated; then a coating is coated on the surface of the pretreated substrate, and the coating includes a curing agent, a resin, a diluent and Boron powder; finally drying and curing the coated substrate to obtain a nuclear reaction radiation conversion target. The preparation method provided by the invention has strong operability, and the nuclear reaction radiation conversion target with good uniformity and stable performance can be prepared through simple operation steps.

The invention provides a nuclear reaction radiation conversion target comprising a substrate and a cured coating on the surface of the substrate. The raw materials for forming the cured coating include curing agent, resin, diluent and boron powder. The nuclear reaction radiation conversion target provided by the present invention can realize energy response compensation in the fast neutron energy region, and is applied in a compensated neutron detector, which is conducive to maintaining relatively flat energy response and high neutron neutron total number measurement process. The neutron sensitivity and n/γ resolving power have laid the foundation for accurately measuring the total number of neutrons in low-intensity pulsed neutron sources. Theoretical calculations and experimental results show that the compensating neutron detector including the nuclear reaction radiation conversion target provided by the present invention, when the neutron energy is in the range of 1-15 MeV, its energy response is in the range of 1.01-1.44, and the neutron sensitivity is 10 ^{- 15} C cm, n/γ≥5.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic structural diagram of a compensation neutron detector provided by Embodiment 4 of the present invention.

detailed description

The invention provides a method for preparing a nuclear reaction radiation conversion target, comprising the following steps:

(1) pretreating the surface of the substrate;

(2) Coating is coated on the substrate surface after described step (1) pretreatment, and described coating comprises curing agent, resin, diluent and boron powder;

(3) drying and curing the substrate coated with the paint in the step (2) to obtain a nuclear reaction radiation conversion target.

The invention provides a method for preparing a nuclear reaction radiation conversion target. Firstly, the surface of a substrate is pretreated; then a coating is coated on the surface of the pretreated substrate, and the coating includes a curing agent, a resin, a diluent and Boron powder; finally drying and curing the coated substrate to obtain a nuclear reaction radiation conversion target. The preparation method provided by the present invention can obtain a nuclear reaction radiation conversion target with better uniformity, and the compensation type neutron detector comprising the nuclear reaction radiation conversion target provided by the present invention has relatively flat energy response, high neutron sensitivity and n The /γ resolution capability lays the foundation for accurately measuring the total number of neutrons in low-intensity pulsed neutron sources.

The invention pretreats the surface of the substrate. In the present invention, the thickness of the substrate is preferably 0.8-1.2 mm. In the present invention, there is no special limitation on the material of the substrate, and the material of the substrate well known to those skilled in the art can be used as a nuclear reaction radiation conversion target. Metal substrates are preferred for the present invention. In the embodiment of the present invention, an aluminum sheet is specifically used as the substrate. The present invention has no special requirements on the shape of the substrate, and the shape of the substrate well known to those skilled in the art can be adopted according to actual needs. In the embodiment of the present invention, a circular substrate is specifically used. In the present invention, the pretreatment on the surface of the substrate preferably includes grinding and polishing, cleaning and drying the surface of the substrate.

In the present invention, there is no special limitation on the grinding and polishing, and the technical solution of grinding and polishing well known to those skilled in the art can be adopted. In the embodiment of the present invention, specifically, 1200-grit sandpaper is used to grind and polish the surface of the substrate until the surface is smooth and free of burrs.

In the present invention, the ground and polished substrate is preferably cleaned. The present invention has no special limitation on the cleaning, and the technical solutions for cleaning well known to those skilled in the art can be adopted. In the present invention, ethanol is preferably used to clean the ground and polished substrate to remove dust and stains on the surface of the substrate.

In the present invention, the washed substrate is preferably dried. The present invention has no special limitation on the drying, and the technical solution of drying well known to those skilled in the art can be adopted. In the present invention, a hot air gun is preferably used to dry the cleaned substrate until the ethanol is completely volatilized.

After the pretreatment of the substrate is completed, the present invention coats the paint on the surface of the pretreated substrate, and the paint includes a curing agent, a resin, a diluent and boron powder. In the present invention, the mass ratio of curing agent, resin, diluent and boron powder in the coating is preferably 1: (2-3): (5-7): (3-4), more preferably 1:2 :6:3, 1:2:6:4, 1:3:6:3 or 1:3:6:4.

In the present invention, the coating includes curing agent, resin, diluent and boron powder. In the present invention, the boron powder is preferably amorphous ¹⁰ B powder. Natural boron consists of two stable isotopes, ¹⁰ B and ¹¹ B, with natural abundances of 19.3% and 80.7%, respectively. The thermal neutron absorption cross-section of ¹⁰ B is about 80,000 times that of ¹¹ B, and the absorption cross-section of boron with natural abundance is only 750b for thermal neutrons. In the present invention, in order to increase the reaction cross section between thermal neutrons and ¹⁰ B, it is preferred to use amorphous ¹⁰ B powder to prepare the nuclear reaction radiation conversion target. In the present invention, the purity of the amorphous ¹⁰ B powder is preferably >95.0%.

In the present invention, the boron powder is preferably pretreated before use, and the pretreatment includes grinding, baking and secondary grinding. In the present invention, there is no special limitation on the grinding, and the technical solution of grinding known to those skilled in the art can be adopted. In the present invention, a ball mill is preferably used to grind the boron powder. In the present invention, the grinding time is preferably 20-30 hours, more preferably 24-28 hours. In the present invention, the particle size of the ground boron powder is preferably less than 1.0 μm. In the present invention, a scanning electron microscope is preferably used to measure the particle size of the ground boron powder, so as to ensure that boron powder with a particle size of less than 1.0 μm is obtained.

In the present invention, the ground boron powder is preferably baked. In the present invention, the baking temperature is preferably 110-150° C., more preferably 120-135° C.; the baking time is preferably 0.5-2 hours, more preferably 1-1.5 hours. In the present invention, there is no special limitation on the equipment used for the baking, and the equipment for baking well known to those skilled in the art can be used. In the present invention, a muffle furnace is preferably used to bake the ground boron powder.

In the present invention, the baked boron powder is preferably subjected to secondary grinding. In the present invention, there is no special limitation on the secondary grinding, and the technical solution of grinding well known to those skilled in the art can be adopted. In the present invention, a ball mill is preferably used to perform secondary grinding on the boron powder. In the present invention, the secondary grinding time is preferably 10-18 hours, more preferably 12-15 hours. In the present invention, the particle size of the boron powder after secondary grinding is preferably less than 1.0 μm. In the present invention, a scanning electron microscope is preferably used to measure the particle size of the boron powder after secondary grinding, so as to ensure that boron powder with a particle size of less than 1.0 μm is obtained.

After the boron powder is pretreated, the present invention preferably mixes the pretreated boron powder with a curing agent, a resin, and a diluent to obtain a coating.

The present invention has no special limitation on the curing agent, and a curing agent well known to those skilled in the art can be used. In the present invention, the curing agent is preferably an amine curing agent, more preferably ethylenediamine or diethylenetriamine.

The present invention has no special limitation on the resin, and the resins well-known to those skilled in the art can be used. In the present invention, the resin is preferably epoxy resin, more preferably #601 epoxy resin, #604 epoxy resin or #607 epoxy resin.

The present invention has no special limitation on the diluent, and a diluent well known to those skilled in the art can be used. In the present invention, the diluent preferably includes isooctyl ether, oxiranylbenzene or butyl glycidyl ether.

In the present invention, there is no special limitation on the method of mixing the pretreated boron powder with curing agent, resin, and diluent, and a mixing technical solution well known to those skilled in the art can be used. In the present invention, the pretreated boron powder is preferably mixed with curing agent, resin and diluent under ultrasonic conditions. In the present invention, the duration of the ultrasound is preferably 8-12 minutes; the power of the ultrasound is preferably 18-22 kHz.

After the paint is obtained, the present invention coats the paint on the surface of the pretreated substrate. In the present invention, there is no special limitation on the coating method, and a coating technical solution well known to those skilled in the art can be used. In the present invention, the coating method is preferably spray coating. Specifically, the coating can be put into the spray gun in a clockwise direction, while keeping the angle between the spray direction and the plane where the pretreated substrate surface is located at 28° ~32 degrees, spraying on the surface of the pretreated substrate, rotating the pretreated substrate or the spray gun during the spraying process, so as to make the spraying even, and avoid the paint accumulation and cracking in the subsequent treatment.

After the coating is completed, the present invention dries and solidifies the coated substrate to obtain a nuclear reaction radiation conversion target. In the present invention, the drying curing preferably includes drying treatment and baking treatment.

In the present invention, there is no special limitation on the drying treatment, and a technical solution known to those skilled in the art that can dry the surface of the coated substrate can be used. The present invention preferably adopts a heat gun to carry out the drying treatment, specifically, the temperature of the heat gun is set to 100-250° C., the distance between the nozzle of the heat gun and the surface of the coated substrate is 5-10 cm, and the drying process is carried out for 1-3 minutes. Dry processing. In the present invention, the temperature of the heat gun is preferably 120-210°C, more preferably 150-180°C. In the present invention, the distance between the nozzle of the heat gun and the surface of the coated substrate is preferably 6-8 cm.

After the drying treatment is completed, the present invention preferably performs baking treatment on the substrate coated with the coating after the drying treatment. In the present invention, the baking treatment preferably adopts a gradient temperature rise method to prevent the sudden rise in temperature from cracking the paint coated on the surface of the substrate. In the present invention, the initial temperature in the gradient heating method is preferably 140-160°C, more preferably 145-155°C; the end point temperature is preferably 440-460°C, more preferably 445-455°C; The range is preferably 40-60°C, more preferably 45-55°C; the holding time after each temperature rise is preferably 8-12 minutes, more preferably 9-11 minutes. In the present invention, there is no special limitation on the equipment used for the baking treatment, and the equipment for baking treatment well known to those skilled in the art can be used. In the present invention, a muffle furnace is preferably used for the baking treatment.

In practical applications, the nuclear reaction radiation conversion target containing a single-layer cured coating can be continuously coated with multiple layers according to needs, and each layer needs to be coated and dried in sequence to obtain a multi-layer cured coating radiation conversion targets for nuclear reactions.

After the nuclear reaction radiation conversion target is prepared, the present invention preferably packages the nuclear reaction radiation conversion target for use. In order not to damage the cured coating of the nuclear reaction radiation conversion target, specifically, the cured coating surfaces of two nuclear reaction radiation conversion targets can be placed opposite each other. The middle is separated by a plastic ring, then wrapped with plastic wrap, and wrapped with tape for packaging; the thickness of the plastic ring is preferably 8-12mm, the outer diameter is equivalent to the size of the nuclear reaction radiation conversion target, and the difference between the inner and outer diameters is preferably 6-10mm .

The invention provides a nuclear reaction radiation conversion target, which comprises a substrate and a cured coating on the surface of the substrate. The raw materials for forming the cured coating include curing agent, resin, diluent and boron powder. In the present invention, the thickness of the cured coating is preferably 8-10 μm. In the present invention, the content of boron powder in the cured coating is preferably 68%-78%. In the present invention, the nuclear reaction radiation conversion target is preferably prepared by the preparation method described in the above technical solution.

In the present invention, the thickness of the cured coating of the nuclear reaction radiation conversion target and the content of boron powder in the cured coating can be accurately controlled, and the test methods for the thickness of the cured coating and the content of boron powder in the cured coating specifically include the following step:

(a) curing agent, resin and diluent in the coating are respectively baked, and the mass residual rate of curing agent, resin and diluent in the calculation is calculated, and the mass residual rate is the difference between the mass difference before and after the baking treatment and The mass ratio before baking treatment;

(b) According to the mass ratio of curing agent, resin, diluent and boron powder in the coating as b1:b2 _: b3: _b4 , _a nuclear reaction radiation conversion target is prepared _;

(c) calculate by the formula shown in formula I, obtain cured coating thickness; Calculate by the formula shown in formula II, obtain the boron powder content in the cured coating;

Among them, h is the cured coating thickness of the nuclear reaction radiation conversion target,

M is the mass of the nuclear reaction radiation conversion target,

m is the mass of the substrate after pretreatment,

a ₁ , a ₂ and a ₃ are the mass residual ratios of curing agent, resin and diluent in the paint respectively,

ρ is the density of boron powder in the paint,

s is the area of the substrate after pretreatment,

X is the boron powder content in the cured coating of the nuclear reaction radiation conversion target.

In the present invention, in the step (a), the curing agent, resin and diluent in the coating are subjected to baking treatment respectively, and the mass residual rate of the curing agent, resin and diluent in the coating is calculated, and the mass residual rate is described in the baking process. The mass ratio before and after roasting treatment to the mass ratio before roasting treatment. In the present invention, the baking treatment is preferably to heat the curing agent, resin and diluent in the coating at 230-250°C for 10-15 minutes, at 380-400°C for 10-15 minutes, and at 430-450°C for 10-10 minutes. 15min.

The invention provides a compensated neutron detector, comprising ⁴ He scintillator, pressure vessel, photomultiplier tube, high-voltage power supply and equipment for recording and transmitting signals, and also includes polyethylene nuclear recoil radiation located outside the incident window of the pressure vessel A conversion target and a nuclear reaction radiation conversion target located in the incident window of the pressure vessel, the nuclear reaction radiation conversion target being the nuclear reaction radiation conversion target described in the above technical solution.

The compensation type neutron detector provided by the invention includes a pressure vessel. In the present invention, there is no special limitation on the material of the pressure vessel, and materials known to those skilled in the art that can be used to prepare the pressure vessel can be used. In the present invention, the pressure vessel is preferably made of stainless steel, so as to ensure that the pressure in the pressure vessel can be kept stable. The present invention has no special requirements on the shape of the pressure vessel, and the shape of the pressure vessel well known to those skilled in the art can be used. The present invention preferably adopts a cylindrical pressure vessel to achieve the best anti-pressure effect.

The compensation type neutron detector provided by the present invention includes ⁴ He scintillator placed in a pressure vessel. In the present invention, the purity of the ⁴ He is preferably ≥99.99%. Helium ( ⁴ He ) is a gas scintillator with high luminous efficiency, and the gas density is small, it has the characteristics of small interaction cross section with γ-rays, low sensitivity of γ-rays, and fast time response. In the low-intensity pulse fission neutron measurement, ⁴ He is selected as the scintillator, which is beneficial to make the compensation neutron detector have higher sensitivity and better n/γ resolution ability.

The compensation type neutron detector provided by the invention includes a polyethylene nuclear recoil radiation conversion target placed outside the incident window of a pressure vessel. In the present invention, pure polyethylene is preferably used to prepare the polyethylene nuclear recoil radiation conversion target.

The compensation type neutron detector provided by the invention includes a nuclear reaction radiation conversion target placed in the incident window of a pressure vessel. In the present invention, the nuclear reaction radiation conversion target preferably adopts the nuclear reaction radiation conversion target provided by the above technical solution of the present invention.

The compensation type neutron detector provided by the invention includes a photomultiplier tube connected outside the exit window of the pressure vessel. In the present invention, the photomultiplier tube is preferably a 9215SB photomultiplier tube manufactured by British ET Company, with a spectral range of 290-630 nm and a gain of 10 ⁶ .

The compensation type neutron detector provided by the invention includes a recording and transmission signal device connected with a photomultiplier tube. The present invention has no special requirements for the recording and transmission signal equipment, and the recording and transmission signal equipment well-known to those skilled in the art can be used. The present invention preferably uses a galvanometer or an oscilloscope to record the transmission signal.

The compensation type neutron detector provided by the invention includes a high voltage power supply. The present invention has no special requirements for the high-voltage power supply, and a high-voltage power supply well known to those skilled in the art can be used. In the present invention, the output voltage of the high-voltage power supply is preferably ±5˜±50 kV; the maximum current of the high-voltage power supply is preferably 5 mA. The present invention has no special requirements on the connection mode of the high-voltage power supply, and the connection mode of the high-voltage power supply well-known to those skilled in the art can be used. In the present invention, the high voltage power supply is preferably connected to the photomultiplier tube.

The principle of the compensated neutron detector provided by the present invention to measure the total number of neutrons of the low-intensity pulsed neutron source is: in the low-intensity pulsed neutron radiation field, the neutron beam flows into the compensated neutron detector provided by the present invention In the process, the neutrons elastically scatter with the hydrogen nuclei in the polyethylene nuclear recoil radiation conversion target and the helium nuclei in the ⁴ He scintillator to produce recoil hydrogen nuclei and recoil helium nuclei, and transfer a part of the energy of the incident neutrons to the recoil Rush hydrogen nuclei and recoil helium nuclei; neutrons react with ¹⁰ B in the nuclear reaction radiation conversion target to generate ⁴ He and ⁷ Li, and transfer part of the energy of the incident neutrons to the reaction products ⁴ He and ⁷ Li; nuclear reactions and ^The charged particles generated by the nuclear recoil deposit energy into the 4He scintillator, excite ^4He to emit light, then use the photomultiplier tube to collect the light signal, and use the current meter or oscilloscope to record the output signal of the photomultiplier tube, so as to realize the detection of neutrons. Measurement. The compensated neutron detector provided by the present invention has an energy response of 1 to ^{15 MeV in the range of 1.01 to 1.44, a neutron sensitivity of 10-15 C} cm, and n/γ≥5, indicating that the nuclear reaction radiation conversion target provided by the present invention is included The compensated neutron detector has a relatively flat energy response, high neutron sensitivity and n/γ resolution, which lays the foundation for accurately measuring the total number of neutrons in low-intensity pulsed neutron sources.

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1:

(1) Take a circular aluminum sheet with a thickness of 1mm and a diameter of 50mm as the substrate, and use 1200 mesh sandpaper to polish the surface of the aluminum substrate until the surface is smooth and free of burrs; then use ethanol to polish the polished aluminum The substrate is cleaned to remove dust and stains on the surface; and then the cleaned substrate is dried with a heat gun until the ethanol is completely evaporated.

(2) Use a ball mill to grind the amorphous ¹⁰ B powder for 20 hours, and use a scanning electron microscope to measure the particle size of the ground boron powder to ensure that the boron powder with a particle size of less than 1.0 μm is obtained, and place the boron powder with a particle size of less than 1.0 μm in a muffle furnace Bake at 110°C for 2 hours, then use a ball mill to grind the baked boron powder for a second time for 18 hours, and use a scanning electron microscope to measure the particle size of the boron powder after the second grinding to ensure that the boron powder with a particle size of less than 1.0 μm is obtained, and the obtained particle size is less than 1.0 μm. The boron powder of μ m is mixed with ethylenediamine, #601 epoxy resin, and isooctyl ether to obtain a coating; the mass of amorphous ¹⁰ B powder, ethylenediamine, #601 epoxy resin, and isooctyl ether described in the coating The ratio was 3:1:2:5, and the mixture was sonicated for 8 min at 20 kHz ultrasonic power.

(3) Put the coating obtained in step (2) into the spray gun, clockwise, while keeping the plane angle between the spray direction and the aluminum substrate surface after the step (1) pretreatment is 30 degrees, to the described The surface of the pretreated aluminum substrate is sprayed.

(4) drying and curing the aluminum substrate coated with the coating in the step (3) to obtain a nuclear reaction radiation conversion target; specifically, a heat gun is used to dry the coated aluminum substrate, and the hot air The gun temperature was set at 100°C, the distance between the hot air gun nozzle and the coated substrate surface was 5 cm, and the drying treatment time was 3 minutes; the dried coated aluminum substrate was placed in a Baking treatment was carried out in a muffle furnace. In the gradient heating method, the initial temperature was 150° C., the end temperature was 450° C., the temperature increase range was 50° C., and the holding time after each temperature increase was 10 minutes.

Example 2:

(1) Take a circular aluminum sheet with a thickness of 0.8mm and a diameter of 50mm as the substrate, and use 1200 mesh sandpaper to polish the surface of the aluminum substrate until the surface is smooth and free of burrs; then use ethanol to polish the surface of the aluminum substrate. Clean the aluminum substrate to remove dust and stains on the surface; then use a heat gun to dry the cleaned substrate until the ethanol is completely evaporated.

(2) Use a ball mill to grind the amorphous ¹⁰ B powder for 30 hours, and use a scanning electron microscope to measure the particle size of the ground boron powder to ensure that the boron powder with a particle size of less than 1.0 μm is obtained, and place the boron powder with a particle size of less than 1.0 μm in a muffle furnace Bake at 150°C for 0.5h, then use a ball mill to grind the baked boron powder for a second time for 10h, use a scanning electron microscope to measure the particle size of the boron powder after the second grinding, to ensure that the boron powder with a particle size of less than 1.0μm is obtained, and the obtained particle size is less than The boron powder of 1.0 μ m is mixed with diethylenetriamine, #604 epoxy resin, epoxyethylbenzene to obtain a coating; the amorphous ¹⁰ B powder described in the coating is mixed with diethylenetriamine, #604 epoxy resin, epoxy The mass ratio of ethylbenzene is 4:1:3:7, and the mixture is sonicated at 22 kHz ultrasonic power for 10 min.

(3) Put the coating that step (2) obtains into the spray gun, along the clockwise direction, while keeping the plane angle between the spray direction and the aluminum substrate surface after the step (1) pretreatment is 30 degrees, to the described The surface of the pretreated aluminum substrate is sprayed.

(4) drying and curing the aluminum substrate coated with the coating in the step (3) to obtain a nuclear reaction radiation conversion target; specifically, a heat gun is used to dry the coated aluminum substrate, and the hot air The temperature of the gun was set at 250°C, the distance between the hot air gun nozzle and the coated substrate surface was 10 cm, and the drying treatment time was 1 min; the dried coated aluminum substrate was placed in a Baking treatment was carried out in a muffle furnace. In the gradient heating method, the initial temperature was 150° C., the end temperature was 450° C., the temperature increase range was 50° C., and the holding time after each temperature increase was 8 minutes.

Example 3:

(1) Take a circular aluminum sheet with a thickness of 1.2mm and a diameter of 50mm as the substrate, and use 1200 mesh sandpaper to polish the surface of the aluminum substrate until the surface is smooth and free of burrs; then use ethanol to polish the surface of the aluminum substrate. Clean the aluminum substrate to remove dust and stains on the surface; then use a heat gun to dry the cleaned substrate until the ethanol is completely evaporated.

(2) Use a ball mill to grind the amorphous ¹⁰ B powder for 25 hours, and use a scanning electron microscope to measure the particle size of the ground boron powder to ensure that the boron powder with a particle size of less than 1.0 μm is obtained, and place the boron powder with a particle size of less than 1.0 μm in a muffle furnace Bake at 120°C for 1.5h, then use a ball mill to grind the baked boron powder for a second time for 14h, use a scanning electron microscope to measure the particle size of the boron powder after the second grinding, to ensure that the boron powder with a particle size of less than 1.0μm is obtained, and the obtained particle size is less than The boron powder of 1.0 μ m is mixed with diethylenetriamine, #607 epoxy resin, butyl glycidyl ether to obtain a coating; the amorphous ¹⁰ B powder in the coating is mixed with diethylenetriamine, #607 epoxy resin, butyl The mass ratio of glycidyl ether was 4:1:2:6, and the mixture was sonicated for 12 min at 18 kHz ultrasonic power.

(3) Put the coating that step (2) obtains into the spray gun, along the clockwise direction, while keeping the plane angle between the spray direction and the aluminum substrate surface after the step (1) pretreatment is 30 degrees, to the described The surface of the pretreated aluminum substrate is sprayed.

(4) drying and curing the aluminum substrate coated with the coating in the step (3) to obtain a nuclear reaction radiation conversion target; specifically, a heat gun is used to dry the coated aluminum substrate, and the hot air The temperature of the gun was set at 160°C, the distance between the hot air gun nozzle and the coated substrate surface was 8 cm, and the drying treatment time was 2 min; the dried coated aluminum substrate was placed in a Baking treatment was carried out in a muffle furnace. In the gradient heating method, the initial temperature was 150° C., the end temperature was 450° C., the temperature increase range was 50° C., and the holding time after each temperature increase was 12 minutes.

Example 4

Using the nuclear reaction radiation conversion target prepared in Example ¹ to prepare a compensation type neutron detector, the compensation type neutron detector includes He scintillator, pressure vessel, polyethylene nuclear recoil radiation conversion target, nuclear reaction radiation conversion target, The structure of the photomultiplier tube, high voltage power supply and recording and transmission signal equipment is shown in Figure 1.

The Monte Cal program MCNPX is used to establish a theoretical calculation model based on the compensated neutron detector structure provided by the present invention, and perform energy response simulation calculations for neutrons of different energies. The calculation results show that the compensation type neutron detector provided by the invention has an energy response in the range of 1.01-1.44 when the neutron energy is 1-15 MeV.

The compensation type neutron detector provided by the present invention is tested for neutron sensitivity by using radial channels and thermal column channels of the Xi’an pulse reactor. The sub-sensitivity is 10 ^-15 C·cm.

The gamma sensitivity of the compensated neutron detector provided by the invention is tested by cobalt source and cesium source, and the result shows that n/γ≥5 of the compensated neutron detector provided by the invention.

It can be seen from the above examples that the preparation method provided by the present invention can obtain a nuclear reaction radiation conversion target with better uniformity, and the compensating neutron detector comprising the nuclear reaction radiation conversion target provided by the present invention has a relatively flat energy response, Higher neutron sensitivity and n/γ resolution capability lay the foundation for accurate measurement of the total number of neutrons in low-intensity pulsed neutron sources.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method for a nuclear reaction radiation conversion target, comprising the following steps: (1) pretreating the surface of the substrate; (2) Coating is coated on the substrate surface after described step (1) pretreatment, and described coating comprises curing agent, resin, diluent and boron powder; (3) drying and curing the substrate coated with the paint in the step (2) to obtain a nuclear reaction radiation conversion target. 2. The preparation method according to claim 1, characterized in that, the mass ratio of curing agent, resin, diluent and boron powder in the coating of step (2) is 1: (2～3): (5～7 ): (3~4). 3. The preparation method according to claim 1 or 2, characterized in that, the boron powder is an amorphous ¹⁰ B powder. 4. The preparation method according to claim 3, wherein the boron powder is pretreated before use, and the pretreatment includes grinding, baking and secondary grinding. 5. The preparation method according to claim 4, characterized in that the particle size of the boron powder after the pretreatment is less than 1.0 μm. 6 . The preparation method according to claim 1 , wherein the drying and curing in step (3) includes drying treatment and baking treatment. 7 . 7. The preparation method according to claim 6, characterized in that, the baking process adopts a gradient heating method, the initial temperature is 140-160°C, the end temperature is 440-460°C, and the heating range is 40-40°C each time. 60°C, the holding time after each temperature rise is 8-12 minutes. 8. A nuclear reaction radiation conversion target, characterized in that it comprises a substrate and a cured coating on the surface of the substrate, and the raw materials for forming the cured coating include curing agent, resin, diluent and boron powder. 9. The nuclear reaction radiation conversion target according to claim 8, characterized in that the thickness of the cured coating is 8-10 μm. 10. A compensated neutron detector, comprising ⁴ He scintillator, pressure vessel, photomultiplier tube, high-voltage power supply and recording and transmission signal equipment, characterized in that it also includes a polyethylene nuclear reactor positioned outside the incident window of the pressure vessel An impact radiation conversion target and a nuclear reaction radiation conversion target located in the incident window of the pressure vessel, the nuclear reaction radiation conversion target being the nuclear reaction radiation conversion target described in claim 8 or 9.