WO2024198169A1 - Composite neutron scintillator, preparation method therefor, and use thereof - Google Patents

Abstract

Embodiments of the present application provide a composite neutron scintillator, a preparation method therefor, and use thereof, relating to the field of radiation detection. The composite neutron scintillator comprises: an organic polymer matrix; and a perovskite material powder and a neutron absorption material powder which are dispersed in the organic polymer matrix. The perovskite material is selected from at least one of Cs₃Cu₂I₅ and CsCu₂I₃, and the neutron absorption material is selected from at least one of Gd₂O₃, ⁶LiF, and ¹⁰B₂O₃. The preparation method mainly comprises: uniformly grinding the organic polymer, the perovskite material and the neutron absorption material to obtain a mixed powder; stirring and mixing the mixed powder with a solvent until the mixed powder is dissolved; and pouring the mixture into a mold for molding. The composite neutron scintillator is characterized by high light yield, shorter decay life, and capability of effectively performing neutron/gamma discrimination, and features a simple preparation process and low cost.

Description

A composite neutron scintillator and its preparation method and application Technical Field

The present application relates to the field of radiation detection, and in particular, to a composite neutron scintillator and a preparation method and application thereof.

Background Art

Neutron detection plays an important role in basic physics, nuclear power, radioactive waste storage, homeland security, nuclear medicine and material analysis. Since neutrons are not charged and cannot be detected directly, indirect detection of neutrons is usually achieved by using nuclides that can react with neutrons. At present, most neutron detection uses ³ He neutron detectors, which are expensive. Neutron scintillator is the best solution to replace the expensive ³ He neutron detector. Its principle is to use the nuclides ⁶ Li, ¹⁰ B, ¹⁵⁷ Gd contained in the scintillator material or composite material to absorb neutrons and produce high-energy particles, or use gamma rays to excite the scintillator material to produce photons, and collect signals through photomultiplier tubes and electronic systems to achieve neutron detection.

However, the existing neutron scintillators have low light yield and high cost, which makes it difficult to meet the actual application needs, especially for large scientific facilities such as spallation neutron sources. For example, ⁶ Li glass:Ce (represented by GS20) has a short decay life and high transparency, but its light yield is low. Ce-doped potassium cryolite structure A ₂ LiMX ₆ :Ce (Cs ₂ LiYCl ₆ :Ce, Cs ₂ LiYBr ₆ :Ce, etc.) has a relatively high light yield, but its growth and preparation process is complex and the production cost is relatively high. The synthesis process of eutectic composite scintillators (LiF/SrF ₂ :Ce, LiF/CaF ₂ :Eu, etc.) mostly requires a high temperature and high pressure environment, and the preparation cost is also very high. In addition, the Eu-doped eutectic scintillator has a long life and is difficult to be applied to position neutron detectors. The most mature technology currently used is the ZnS:Ag/ ^6LiF neutron scintillator screen, which has a relatively high light yield, but a relatively long attenuation life, and is bonded with an adhesive, so it has poor toughness and strength and is easy to break. Therefore, a neutron scintillator with a simple preparation process and that meets the needs of neutron detection is needed.

Summary of the invention

The purpose of the embodiments of the present application is to provide a composite neutron scintillator and a preparation method and application thereof. The neutron scintillator has the characteristics of high light yield, short decay life, and can effectively perform neutron/gamma discrimination, and the preparation process is simple and the cost is low.

In a first aspect, the present invention provides a composite neutron scintillator, which includes an organic polymer matrix and a Perovskite material powder and neutron absorption material powder are dispersed in an organic polymer matrix, the perovskite material is selected from at least one of Cs ₃ Cu ₂ I ₅ and CsCu ₂ I ₃ , and the neutron absorption material is selected from at least one of Gd ₂ O ₃ , ⁶ LiF and ¹⁰ B ₂ O ₃ .

In the above technical solution, the luminescent material of the composite neutron scintillator is a perovskite material, which is composited with a neutron absorbing material and embedded in an organic polymer matrix to form a large-area scintillator film with good plasticity.

In a possible implementation, the perovskite material is Cs ₃ Cu ₂ I ₅ , and the neutron absorption material is ⁶ LiF.

In a possible implementation, the mass ratio of the perovskite material powder to the organic polymer matrix is 0.05-1:1.

In the above technical solution, if the amount of perovskite material used is too large, the transparency of the formed scintillator will decrease, resulting in severe light scattering, reduced transmittance, and reduced final light yield or detection efficiency.

In a possible implementation, the mass ratio of the perovskite material powder to the neutron absorption material powder is 0.05-1:1.

In the above technical solution, if the amount of perovskite material is too small relative to the neutron absorbing material, the energy emitted by the neutron absorbing material cannot be completely absorbed, resulting in a decrease in the final light yield of the scintillator or the neutron detection efficiency.

In a possible implementation manner, the material of the organic polymer matrix is selected from at least one of polymethyl methacrylate, polystyrene, polyvinyl chloride and polyphenylene oxide.

In a possible implementation, the composite neutron scintillator has a thickness of 0.2-2 mm, a light transmittance of 30%-90%, and a light yield of more than 20,000 photon/MeV.

In the above technical solution, the light transmittance of the scintillator is guaranteed to ensure its detection efficiency.

In a second aspect, an embodiment of the present application provides a method for preparing the composite neutron scintillator provided in the first aspect, comprising the following steps:

Grinding the organic polymer, the perovskite material and the neutron absorbing material uniformly to obtain a mixed powder;

The mixed powder is stirred with the solvent until dissolved, and then poured into a mold for molding.

In the above technical solution, the preparation process is simple, and compared with the traditional neutron scintillator, it does not require high-temperature preparation and has low cost.

In a possible implementation, the solvent is selected from at least one of dichloromethane, N,N-dimethylformamide, dimethyl sulfoxide, and alcohols;

And/or, the molding method is to allow the solvent to evaporate naturally, or to place the mixture at 10-24°C to allow the solvent to evaporate.

In a possible implementation, the method for preparing the perovskite material includes the following steps:

Adding CuI, CsI and a stabilizer into a solvent, stirring with ultrasound until all of them are dissolved in the solvent, to obtain a solution;

Allow the solvent in the solution to evaporate naturally until it is completely evaporated.

In a third aspect, an embodiment of the present application provides an application of the composite neutron scintillator provided in the first aspect, and the composite neutron scintillator can be used as a neutron scintillation material for wave-shifting optical fiber, Anger camera, imaging system, and neutron detector.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic diagram of the structure of a composite neutron scintillator provided in an embodiment of the present application;

FIG2 is a schematic diagram of a microscopic photograph of the perovskite Cs ₃ Cu ₂ I ₅ crystal prepared in Example 1;

FIG3 is an XRD pattern of the perovskite Cs ₃ Cu ₂ I ₅ crystal prepared in Example 1;

FIG4 is a graph showing the fluorescence quantum efficiency of the perovskite material Cs ₃ Cu ₂ I ₅ prepared in Example 1;

FIG5 is a luminescence spectrum of the perovskite material Cs ₃ Cu ₂ I ₅ prepared in Example 1 under X-ray irradiation;

FIG6 is a comparison diagram of the light yield of the neutron scintillator of Example 1 and the commercial GS20 scintillator;

FIG7 is a neutron scintillator decay life curve of Example 1;

FIG. 8 is a neutron scintillator neutron gamma in Example 1 Identification chart;

FIG9 is a physical photograph of different neutron scintillator samples;

FIG10 is the absorption spectra of different neutron scintillator samples.

DETAILED DESCRIPTION

In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

The composite neutron scintillator and its preparation method and application according to the embodiment of the present application are described in detail below.

Referring to FIG. 1 , an embodiment of the present application provides a composite neutron scintillator, which includes an organic polymer matrix, and a perovskite material powder and a neutron absorption material powder dispersed in the organic polymer matrix. At least one selected from polymethyl methacrylate, polystyrene, polyvinyl chloride and polyphenylene oxide; the perovskite material is selected from at least one selected from Cs ₃ Cu ₂ I ₅ and CsCu ₂ I ₃ , and the neutron absorption material is selected from at least one selected from Gd ₂ O ₃ , ⁶ LiF and ¹⁰ B ₂ O _3. The perovskite material is Cs ₃ Cu ₂ I ₅ , and the neutron absorption material is ⁶ LiF.

In some embodiments of the present application, the mass ratio of the perovskite material powder to the organic polymer matrix is generally 0.05-1:1, and can be optionally 0.5:1.

The mass ratio of the perovskite material powder to the neutron absorption material powder is 0.05-1:1, and can be optionally 1:1.

The mass ratio of the organic polymer matrix to the perovskite material powder and the neutron absorption material powder is 1:0.05-1:0.05-1. Exemplarily, the mass ratio of the three materials is: organic polymer/perovskite material/neutron absorption material=2:1:1.

The smaller the particle size of the perovskite material powder and the neutron absorption material powder, the better the effect. Considering the comprehensive cost, the particle size of the perovskite material powder is generally 20-500μm, which is easy to prepare; the particle size of the neutron absorption material powder is 1-5μm, which can be directly purchased and obtained by grinding.

The composite neutron scintillator has a thickness of 0.2-2 mm, a light transmittance of 30%-90%, and a light yield of more than 20,000 photon/MeV, illustratively, about 23,000 photon/MeV.

In addition, an embodiment of the present application provides a method for preparing the above-mentioned composite neutron scintillator, which comprises the following steps:

S1. Preparation of perovskite materials:

Adding CuI, CsI and a stabilizer to a solvent, stirring with ultrasound until all of them are dissolved in the solvent, to obtain a solution, wherein the solvent may be N,N-dimethylformamide or dimethyl sulfoxide;

Allow the solvent in the solution to evaporate naturally until it is completely evaporated.

S2, grinding the organic polymer, the perovskite material and the neutron absorbing material uniformly to obtain a mixed powder;

S3. Stirring the mixed powder and the solvent until dissolved, the solvent is selected from at least one of dichloromethane, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and alcohols. The mixed powder is dissolved in the solvent, subjected to ultrasonic dispersion treatment until uniformly dispersed, and poured into a mold for molding. The molding method is to allow the solvent to evaporate naturally, or to place the solvent at a certain temperature (such as 10-24°C) to evaporate.

The embodiment of the present application provides an application of the above-mentioned composite neutron scintillator, and the composite neutron scintillator can be used as a neutron scintillation material for wave-shifting optical fiber, Anger camera, imaging system, and neutron detector.

The features and performance of the present application are further described in detail below in conjunction with the embodiments.

Example 1

This embodiment provides a neutron scintillator, and the preparation process thereof is as follows:

(1) Material preparation

S1. Add CuI, CsI and stabilizer into N,N-dimethylformamide (DMF) solvent in sequence.

Among them, the ratio of CuI and CsI is 2:3.

The stabilizer may be one of Tween 80, citric acid, oleic acid, ethylenediaminetetraacetic acid, polyvinylpyrrolidone, etc., and in this embodiment, Tween 80 is used.

S2. Ultrasonicate the above solution until the solvent is completely dissolved.

S3. Pour the above solution into a culture dish and place it in a fume hood to evaporate naturally.

S4. After the solvent is evaporated, a dry solid powder is obtained.

The solid powder was tested, and a micrograph of the solid powder is shown in FIG2 , and an XRD pattern is shown in FIG3 .

As can be seen from FIG3 , the phase structure of the crystal is Cs ₃ Cu ₂ I ₅ (corresponding to card PDF#45-0077), belonging to the Pbnm (62) space group.

The fluorescence quantum efficiency of the perovskite material Cs ₃ Cu ₂ I ₅ was tested using an integrating sphere with BaSO ₄ built in. The test graph is shown in FIG4 . After calculating the test results, the quantum efficiency was obtained to be 60.3%.

The luminescence spectrum of the perovskite material Cs ₃ Cu ₂ I ₅ under X-ray irradiation is shown in FIG5 . The luminescence peak is located at about 440 nm, which is a typical blue luminescence (bright blue light is emitted under X-ray irradiation). This luminescence band corresponds to the high quantum efficiency band of PMT, which is conducive to neutron detection.

(2) The generated powder was mixed with organic polymer PMMA powder and ⁶ LiF powder in a mass ratio of PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:1, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in a solvent and poured into a mold for molding.

The type of solvent can be dichloromethane, DMF, DMSO, alcohols, etc. The solvent in this embodiment is dichloromethane.

The molding process can be a natural volatilization of the solvent, or volatilization at a certain temperature. The volatilization temperature is determined by the boiling point of the selected solvent. In this embodiment, natural volatilization is used.

The shape of the mold can be cylindrical, square, etc. In this embodiment, the mold used is cylindrical.

(4) After the molded sample is demolded, the desired neutron scintillator is obtained.

The light yield comparison diagram of the neutron scintillator and the commercial GS20 scintillator is shown in FIG6 , where the radiation source is ²⁵² Cf, and the commercial GS20 (whose light yield is about 6000 photons/MeV) is used as the calibration object. The test results show that the neutron scintillator in this embodiment The light output of the neutron scintillator Cs ₃ Cu ₂ I ₅ / ⁶ LiF/PMMA is about 4 times that of GS20, which is equivalent to a light output of about 23,000 photons/MeV.

The decay lifetime curve of the neutron scintillator is shown in FIG7 . The radiation source is ²⁵² Cf. The radiation decay lifetime is fitted and the decay lifetime is obtained to be about 253 ns.

The neutron gamma The discrimination diagram is shown in Figure 8. The discrimination method uses image Non-negative matrix method: First, the radiation reaction events are measured under different radiation sources ( ⁶⁰ Co, ²⁵² Cf, ¹³⁷ Cs, background (Bg)), and the measured events are formed into image signals, and a two-dimensional image is formed through an algorithm. The different shades of color in Figure 8 represent the signals formed by different events. From Figure 8, it is easy to distinguish the signals formed by neutron radiation and the signals formed by gamma radiation.

It can be seen that the neutron scintillator has a high light yield, a short lifespan, and a high neutron gamma discrimination rate (2×10 ⁵ ).

Example 2

This embodiment provides a neutron scintillator, and its preparation process is different from that of embodiment 1 in that:

(2) The generated powder was mixed with organic polymer PDMS (polydimethylsiloxane) and ⁶ LiF powder in a mass ratio of PDMS/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ =2:1:1, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in ethyl acetate, poured into a cylindrical mold and placed at 60° C. for volatilization and molding.

(4) After the molded sample is demolded, the desired neutron scintillator is obtained.

Example 3

This embodiment provides a neutron scintillator, and its preparation process is different from that of embodiment 1 in that:

(2) The generated powder was mixed with organic polymer PMMA powder and Gd ₂ O ₃ powder in a mass ratio of PMMA/Gd ₂ O ₃ /Cs ₃ Cu ₂ I ₅ =2:0.1:1, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in dichloromethane solvent and poured into a cylindrical mold to evaporate naturally.

Example 4

This embodiment provides a neutron scintillator, and its preparation process is different from that of embodiment 1 in that:

(2) The generated powder was mixed with organic polymer PMMA powder and ⁶ LiF powder in a mass ratio of PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:0.1, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in dichloromethane solvent and poured into a cylindrical mold to evaporate naturally.

(4) After the molded sample is demolded, the desired neutron scintillator is obtained.

Example 5

This embodiment provides a neutron scintillator, and its preparation process is different from that of embodiment 1 in that:

(2) The generated powder was mixed with organic polymer PMMA powder and ⁶ LiF powder in a mass ratio of PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:0.3, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in dichloromethane solvent and poured into a cylindrical mold to evaporate naturally.

(4) After the molded sample is demolded, the desired neutron scintillator is obtained.

Example 6

This embodiment provides a neutron scintillator, and its preparation process is different from that of embodiment 1 in that:

(2) The generated powder was mixed with organic polymer PMMA powder and ⁶ LiF powder in a mass ratio of PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:0.5, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in dichloromethane solvent and poured into a cylindrical mold to evaporate naturally.

(4) After the molded sample is demolded, the desired neutron scintillator is obtained.

Example 7

This embodiment provides a neutron scintillator, and its preparation process is different from that of embodiment 1 in that:

(2) The generated powder was mixed with organic polymer PMMA powder and ⁶ LiF powder in a mass ratio of PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:2, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in dichloromethane solvent and poured into a cylindrical mold to evaporate naturally.

(4) After the molded sample is demolded, the desired neutron scintillator is obtained.

Example 8

This embodiment provides a neutron scintillator, and its preparation process is different from that of embodiment 1 in that:

(2) The generated powder was mixed with organic polymer PMMA powder and ⁶ LiF powder in a mass ratio of PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:1.5, and the mixture was poured into a mortar and ground.

(3) The uniformly ground powder is dissolved in dichloromethane solvent and poured into a cylindrical mold to evaporate naturally.

(4) After the molded sample is demolded, the desired neutron scintillator is obtained.

Embodiment 1, Embodiment 4-6, and Embodiment 8 are neutron scintillator samples prepared by using different addition ratios of perovskite materials. FIG. 9 shows different addition ratios of perovskite materials Cs ₃ Cu ₂ I ₅ (PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:0.1, 2:1:0.3, 2:1:0.5, As can be seen from Figure 9, if the addition ratio of perovskite material is too large, the transparency of the scintillator will be reduced.

Embodiment 1, Embodiment 4-6, and Embodiment 8 are neutron scintillator samples prepared by using different addition ratios of perovskite materials. Figure 10 is the absorption spectra of neutron scintillator samples with different addition ratios of perovskite material Cs ₃ Cu ₂ I ₅ (PMMA/ ⁶ LiF/Cs ₃ Cu ₂ I ₅ = 2:1:0.1, 2:1:0.3, 2:1:0.5, 2:1:1, 2:1:1.5). It can be seen from Figure 10 that with the increase of Cs ₃ Cu ₂ I ₅ content in the composite neutron scintillator, its transmittance becomes lower and lower.

In summary, the composite neutron scintillator of the embodiment of the present application has the characteristics of high light yield, short decay life, and can effectively perform neutron/gamma discrimination, and has a simple preparation process and low cost.

The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims (10)

A composite neutron scintillator, characterized in that it comprises an organic polymer matrix, and perovskite material powder and neutron absorption material powder dispersed in the organic polymer matrix, the perovskite material is selected from at least one of Cs ₃ Cu ₂ I ₅ and CsCu ₂ I ₃ , and the neutron absorption material is selected from at least one of Gd ₂ O ₃ , ⁶ LiF, and ¹⁰ B ₂ O ₃ . The composite neutron scintillator according to claim 1, characterized in that the perovskite material is Cs ₃ Cu ₂ I ₅ , and the neutron absorption material is ⁶ LiF. The composite neutron scintillator according to claim 1, characterized in that the mass ratio of the perovskite material powder to the organic polymer matrix is 0.05-1:1. The composite neutron scintillator according to claim 1, characterized in that the mass ratio of the perovskite material powder to the neutron absorption material powder is 0.05-1:1. The composite neutron scintillator according to claim 1 is characterized in that the material of the organic polymer matrix is selected from at least one of polymethyl methacrylate, polystyrene, polyvinyl chloride and polyphenylene oxide. The composite neutron scintillator according to claim 1 is characterized in that the composite neutron scintillator has a thickness of 0.2-2 mm, a transmittance of 30%-90%, and a light yield of more than 20,000 photon/MeV. A method for preparing a composite neutron scintillator according to claim 1, characterized in that it comprises the following steps: Grinding the organic polymer, the perovskite material and the neutron absorbing material uniformly to obtain a mixed powder; The mixed powder is stirred and mixed with a solvent until dissolved, and poured into a mold for molding. The method for preparing a composite neutron scintillator according to claim 7, characterized in that the solvent is selected from at least one of dichloromethane, N,N-dimethylformamide, dimethyl sulfoxide, and alcohols; And/or, the molding method is to allow the solvent to evaporate naturally, or to place the solvent at 10-24°C to evaporate. The method for preparing a composite neutron scintillator according to claim 7, characterized in that the method for preparing the perovskite material comprises the following steps: Adding CuI, CsI and a stabilizer into a solvent, and stirring with ultrasound until all of them are dissolved in the solvent, to obtain a solution; The solvent in the solution is allowed to evaporate naturally until it is completely evaporated. An application of the composite neutron scintillator as claimed in claim 1, characterized in that the composite neutron scintillator can be used as a neutron scintillation material for wave-shifting optical fibers, Anger cameras, imaging systems, and neutron detectors.