CN115902990A - Scintillation composite material for neutron-gamma discrimination and preparation method and application thereof - Google Patents

Scintillation composite material for neutron-gamma discrimination and preparation method and application thereof Download PDF

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CN115902990A
CN115902990A CN202110900621.5A CN202110900621A CN115902990A CN 115902990 A CN115902990 A CN 115902990A CN 202110900621 A CN202110900621 A CN 202110900621A CN 115902990 A CN115902990 A CN 115902990A
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scintillation
neutron
composite material
gamma
single crystal
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吴云涛
李云云
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Shanghai Institute of Ceramics of CAS
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Shanghai Institute of Ceramics of CAS
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Abstract

The invention relates to a scintillation composite material for neutron-gamma discrimination and a preparation method and application thereof. The scintillation composite for neutron-gamma screening comprises: the device comprises a plastic scintillator and inorganic scintillation single crystals which are embedded in the plastic scintillator and arranged in an array; the volume ratio of the inorganic scintillation single crystal is 1-95 vol%, preferably 10-50 vol%; the size of the inorganic scintillation single crystal is at least 0.1mm.

Description

Scintillation composite material for neutron-gamma discrimination and preparation method and application thereof
Technical Field
The invention relates to a scintillation composite material which is low in cost, can be prepared in a large size and has the advantages of simultaneous neutron-gamma detection and discrimination, and a preparation method and application thereof, and belongs to the field of multi-mode radiation detection.
Background
A scintillator is a component of a scintillator detector that interacts with particles to convert high energy radiation or high energy particles into visible or ultraviolet light through the action of ionizing radiation. As an optical functional material, the material is widely applied to the fields of high-energy physics, medical imaging, security inspection, industrial exploration and the like. In recent years, with the requirements of national important strategic applications such as national defense and military industry, nuclear energy utilization, nuclear physics experiments and the like, the nuclear radiation detector is required to be capable of realizing effective synchronous detection and discrimination of multiple particles or rays in a radiation mixed field with coexistence of neutrons and gamma radiation, so that the used scintillation material is required to have multimode detection and discrimination capability.
The plastic scintillator is a solid solution of organic scintillating substances in plastics, has the advantages of no deliquescence, stable performance, irradiation resistance, fast attenuation, easy processing, large-size preparation, low cost and the like, has the capability of fast neutron detection due to rich hydrogen content, but is lack of the capability of energy spectrum detection due to the small effective atomic number of the plastic scintillator, and only can realize gamma ray counting detection. Scintillation crystals that have been discovered so far to detect both neutron and gamma rays and have excellent properties include LiI, eu and Li 6 Gd(BO 3 ) 3 :Ce(LGBO)、LiCaAlF 6 :Ce(LiCAF)、Cs 2 LiYCl 6 :Ce(CLYC)、Cs 2 LiLaBr 6 Ce (CLLB), naI: tl, li, etc., have the advantages of excellent energy response linearity, high energy resolution and high light output in the aspect of gamma ray detection, and are concentrated 6 Li (the content reaches 95 percent) can also realize slow neutron detection by utilizing nuclear reaction, and realize synchronous detection and discrimination of gamma rays and slow neutrons. However, from the perspective of crystal growth, the preparation of large-size crystals of this type is not only extremely costly, but also has great growth difficulty. So far, no multi-mode nuclear detection scintillation material which can realize low cost and large-size preparation is available.
The existing composite scintillating material is generally prepared by physically mixing an organic plastic scintillator and inorganic scintillating powder. Because the inorganic scintillating powder is easy to agglomerate, the luminous uniformity of the scintillating composite material is influenced. In addition, the inorganic scintillation powder has a large number of surface defects, the prepared scintillation composite material has poor transparency and serious self-absorption, and can only be made into a detection film or a detection sheet, the thickness is small, and the stopping capability of high-energy rays is poor, so that the scintillation composite material can only be used for low-energy ray detection.
Disclosure of Invention
In view of the above problems, the present invention aims to develop a scintillation composite material with high performance, low cost and large size, which can be prepared for neutron-gamma detection and screening, and can realize synchronous and efficient detection and screening of fast neutrons, slow neutrons and gamma rays for a radiation mixed field with coexistence of neutrons and gamma radiation.
In one aspect, the present invention provides a scintillating composite material for neutron-gamma screening, comprising: the device comprises a plastic scintillator and inorganic scintillation single crystals which are embedded in the plastic scintillator and arranged in an array; the volume ratio of the inorganic scintillation single crystal is 1-95 vol%, preferably 5-50 vol%, more preferably 10-50 vol%; the size of the inorganic scintillation single crystal is at least 0.1mm. If the volume ratio of the inorganic scintillation single crystal is insufficient, the counting rate of gamma rays or thermal neutrons of the scintillation composite material is low, and the detection efficiency is low; as the volume ratio of the inorganic scintillation single crystal is increased, the detection efficiency of gamma rays or thermal neutrons is improved, but the cost is also correspondingly and greatly improved, so that the advantages and disadvantages of the preparation cost and the detection efficiency of the scintillation composite material are balanced, and an ideal value of the volume ratio of the inorganic scintillation single crystal can be obtained.
In the invention, the organic-inorganic composite scintillation material prepared from the organic plastic scintillator and the large-size inorganic scintillation single crystal integrates the advantages of the organic plastic scintillator and the inorganic scintillation single crystal, has high light transmittance, and can still realize excellent scintillation performance in large size, so that the novel scintillation composite material has the advantages of low cost, large-size preparation, high light yield, high energy resolution, and neutron-gamma synchronous detection and discrimination capability, and is an ideal multi-mode nuclear radiation detection scintillation material.
Preferably, the inorganic scintillation single crystal is selected from the group consisting of NaI: 6 Li,Tl、CsI: 6 Li,Tl、NaI: 6 Li、CsI: 6 Li、 6 LiI:Eu、Cs 3 Cu 2 I 5 、Cs 3 Cu 2 I 5 :Tl、Cs 3 Cu 2 I 5 : 6 Li,Tl、CsCu 2 I 3 、CsCu 2 I 3: Tl、CsCu 2 I 3: 6 Li,Tl、LaBr 3 、CeBr 3 at least one of; the thickness of the scintillation composite material for neutron-gamma screening is at least 0.1mm.
Preferably, the inorganic scintillation single crystal includes irregular bulk scintillation single crystal (average size corresponding to size) and regular bulk single crystal; the regular block single crystal has a geometric structure of one of a cube (corresponding to the side length), a cuboid (corresponding to the length/width/height), a cylinder (corresponding to the diameter and the height), a prism (corresponding to the bottom side length and the height), a sphere (corresponding to the diameter), and a hemisphere (corresponding to the diameter); the size of the inorganic scintillation single crystal is at least 0.1mm, preferably at least 1mm, more preferably at least 2mm, and most preferably at least 5mm. The size and the geometric structure of the inorganic scintillation single crystal are kept consistent as much as possible, the light yield and the energy resolution ratio are close as much as possible, and the arrangement mode, the aspect ratio and the volume ratio of the inorganic scintillation single crystal are further optimized by adopting Monte Carlo simulation so as to ensure that the prepared scintillation composite material has excellent scintillation properties such as light-emitting uniformity and the like. The size of the inorganic scintillation single crystal depends on the size of the scintillation composite material, and the size of the scintillation composite material is increased correspondingly; the height of the inorganic scintillation single crystal is smaller than that of the scintillation composite material, and the height of the inorganic scintillation single crystal is correspondingly increased along with the increase of the height of the scintillation composite material; the size and the geometric structure of the inorganic scintillation single crystal are kept consistent, and the arrangement mode of the further inorganic scintillation single crystal is uniformly distributed in the plastic scintillator of the covering layer as far as possible, so that the prepared scintillation composite material has excellent scintillation properties such as light-emitting uniformity and the like.
Preferably, the plastic scintillator consists of a plastic matrix, an initiator, a primary fluorescent dye and a wave-shifting agent; the content of the initiator is 0-1 wt%; the content of the primary fluorescent dye is 1-40 wt%; the content of the wave-shifting agent is 0.01-10 wt%.
Preferably, the plastic matrix is selected from at least one of polyvinyl toluene, polymethyl methacrylate, polystyrene, polydimethylsiloxane, poly (9-vinylcarbazole), and polyethylene terephthalate.
Preferably, the initiator is at least one selected from azo initiators, peroxide initiators and photoinitiators; preferably at least one selected from the group consisting of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, benzoyl peroxide t-butyl peroxide, methyl ethyl ketone peroxide, photoinitiator 184, and photoinitiator BAPO.
Preferably, the primary fluorescent dye is at least one selected from 2, 5-diphenyl oxazole, p-terphenyl, 2- (4 '-tert-butylbenzene) -5- (4' -biphenyl) -1,3, 4-oxadiazole and 2- (4-biphenyl) -5-phenyl oxadiazole.
Preferably, the wave-shifting agent is selected from one of 1, 4-bis (5-phenyl-2-oxazolyl) benzene, 1, 4-bis (2-methylstyrene) benzene, 1, 4-bis (4-methylstyrene) benzene, 9, 10-diphenylanthracene, coumarin dye or a combination thereof.
On the other hand, the invention provides a preparation method of the scintillation composite material for neutron-gamma discrimination, which comprises the following steps:
(1) In an inert atmosphere, adding a monomer of a plastic matrix, an initiator (0-1 wt%), a primary fluorescent dye (1-40 wt%) and a wave-shifting agent (0.01-10 wt%) into a reaction mold to obtain a uniform clear solution, and then sealing the reaction mold;
(2) Sealing the reaction mould in the step (1), heating and pre-polymerizing to enable the substrate layer to be micro-cured and capable of supporting the scintillation crystal, and obtaining a partially polymerized substrate layer;
(3) In an inert atmosphere, placing a plurality of inorganic scintillation single crystals on the partially polymerized substrate layer in an array arrangement mode, sealing, and continuously heating and polymerizing to ensure that the inorganic scintillation single crystals and the partially polymerized substrate layer are completely adhered to form a whole;
(4) Pouring clear solution formed by monomers of a plastic matrix, an initiator (0-1 wt%), a primary fluorescent dye (1-40 wt%) and a wave-shifting agent (0.01-10 wt%) into a reaction mold to form a covering layer (the height of the covering layer solution at least exceeds a substrate layer and an inorganic scintillation single crystal), sealing the reaction mold, heating until the covering layer is completely cured, then heating to a higher temperature, keeping the temperature for 1-7 days to ensure that the residual monomers are completely cured, and finally slowly cooling to room temperature to obtain the scintillation composite material for neutron-gamma discrimination.
In another aspect, the invention provides an application of a scintillation composite for neutron-gamma screening, wherein the scintillation composite for neutron-gamma screening is used for detecting and screening gamma rays, fast neutrons and slow neutrons; the scintillation composite material for neutron-gamma discrimination is used for detectors in the fields of border security inspection, homeland security, environmental detection and nuclear energy utilization radiation mixed fields.
Has the advantages that:
the scintillation composite material prepared by the invention has the advantages of low cost, large size, no deliquescence and the like, has excellent scintillation performance, comprises the advantages of high light yield, high energy resolution, neutron-gamma detection and discrimination and the like, can be used for detecting gamma rays, fast neutrons and thermal neutrons, and has important application prospect in the security and safety inspection field involving the coexistence of neutron radiation and gamma radiation such as nuclear weapon test, nuclear nondiffusion and the like.
Drawings
FIG. 1 is a photograph of a sample of the scintillating composite material prepared in example 1 under natural light;
FIG. 2 is a photograph of a sample of the scintillating composite material prepared in example 2 under natural light;
FIG. 3 is a fluorescence spectrum of the prepared inorganic scintillating crystal, plastic scintillator and a transmission spectrum of the plastic scintillator;
FIG. 4 is an X-ray excitation emission spectrum of the prepared inorganic scintillation crystal and plastic scintillator;
FIG. 5 is a scintillation composite prepared 137 (ii) pulse height spectrum under Cs source;
FIG. 6 is a scintillation composite prepared 137 (ii) pulse height spectrum under Cs source;
FIG. 7 is a scintillation composite prepared 137 Scintillation decay time under a Cs source;
fig. 8 is a neutron-gamma pulse shape discrimination spectrum of the scintillation composite prepared.
Detailed Description
The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.
The scintillation composite material which is low in cost, large in size, high in light yield, high in energy resolution and capable of neutron-gamma detection and discrimination is developed, and has high practical value in the field of radiation detection of neutrons and gamma radiation in coexistence.
In one embodiment of the invention, a scintillation composite includes a plastic scintillator and an insert. The plastic scintillator comprises a substrate layer (A) and a cover layer (B) which are polymerized in advance, wherein the substrate layer (A) and the cover layer (B) are substantially integrated. The insert is an inorganic scintillation single crystal (C). Compared with the conventional scintillation powder, the scintillation single crystal has the advantages of complete structure, small light scattering degree and high transmittance, can enable scintillation light to be completely transmitted, and has ideal scintillation performance. Moreover, the inorganic scintillation single crystal has good light transmission, and the large size can still realize high light output, so that low-energy and high-energy ray detection can be realized. The following illustrates an exemplary method for preparing a novel scintillating composite material for high performance, low cost, large size neutron-gamma screening.
Sequentially using deionized water, ethanol and acetone, cleaning the glass reaction vessel for at least three times, and then putting the glass reaction vessel into an oven for vacuum heating. Wherein the vacuum heating temperature is 120 deg.C, and the time can be more than 24 hr.
In an inert atmosphere, adding a monomer of a plastic scintillator, an initiator (0-1 wt%), a primary fluorescent dye (1-40 wt%) and a wave-shifting agent (0.01-10 wt%) into a cleaned reaction mold, dissolving to obtain a uniform solution system, and sealing the reaction mold. As a further preferable scheme, the monomers of the plastic scintillator are purified to remove the stabilizer and the water, the purity of the initiator, the fluorescent dye and the wave shifter is more than 99%, and the batching environment is an inert gas environment (a glove box filled with argon or nitrogen).
And (3) putting the sealed reaction die into an oven or heating the sealed reaction die to a certain temperature (70-120 ℃) by using heat transfer fluid (oil, water and the like), and carrying out heat preservation and prepolymerization (2-120 hours) until the sealed reaction die can support the inorganic scintillation single crystal to form a substrate layer (A) of the scintillation composite material. If the step is completely solidified, the base layer and the inorganic scintillation single crystal cannot be integrally adhered, and further the base layer and the covering layer cannot be integrally formed into the scintillation composite material. If the prepolymerization time in the step is insufficient, the substrate layer cannot support the inorganic scintillation single crystal, the inorganic single crystal can incline and even fall to the bottommost part of the substrate layer, the arrangement mode of the inorganic single crystal is uneven and even deliquescence is caused, and the scintillation performances of the scintillation composite material, such as light yield, energy resolution and the like, can be further degraded.
In an inert atmosphere, placing a plurality of inorganic scintillation single crystals (C) with similar light yield and energy resolution, same size and geometric structure on a substrate layer (A), sealing a reaction mould, placing the reaction mould into an oven or heating the reaction mould to a certain temperature (70-120 ℃) by using heat transfer fluid (oil, water and the like), and carrying out heat preservation polymerization until the inorganic scintillation single crystals (C) and the substrate layer (A) are completely adhered to form a whole. Preferably, the surface of the inorganic scintillation single crystal is also required to be pretreated, and the surface of the single crystal is thoroughly cleaned, so that unsaturated bonds on the surface and oil stains on the surface are eliminated as much as possible.
Monomer of plastic scintillator, initiator (0-1 wt%), primary fluorescent dye (1-40 wt%) and wave-shifting agent (0.01-10 wt%) are premixed and dissolved to obtain homogeneous clear solution. And pouring the clear solution into a reaction mold to form a covering layer (B), wherein the covering layer solution at least submerges the substrate layer and the inorganic scintillation single crystal to ensure that the deliquescent inorganic scintillation single crystal (C) is encapsulated in the plastic scintillator. After the reaction mold is sealed, it is placed in an oven or heated to a certain temperature (70-120 ℃) using a heat transfer fluid (oil, water, etc.) and polymerized for several weeks (e.g., 1-8 weeks) at an elevated temperature until the cover layer is fully cured. Then raising the polymerization temperature to 80-130 ℃ and keeping the temperature for 1-7 days to achieve the purpose of removing a small amount of unpolymerized monomer by post curing. As a further preferable scheme, when the base layer and the covering layer are polymerized to a certain degree, a vacuumizing mode is adopted to remove air bubbles in the system, and the size and the geometric structure of the inorganic scintillation monocrystal of the embedded body are completely consistent, and the inorganic scintillation monocrystal has similar energy resolution and light yield. After the polymerization is finished, the temperature is slowly reduced to room temperature so as to reduce internal stress. And taking the cured scintillation composite material out of the reaction mould, and cutting and polishing to obtain the required scintillation composite material.
In the present invention, a plastic scintillator is used to detect fast neutrons, and an inorganic scintillation single crystal is used to detect slow neutrons and gamma rays. The novel scintillation composite material provided by the invention has the advantages of low cost, large-size preparation, high sensitivity, multimode detection and discrimination and the like, can be used for detecting and discriminating gamma rays, fast neutrons and slow neutrons, and has important application prospects in the fields of radiation mixing fields such as border security, homeland security, environmental detection, nuclear energy utilization and the like.
The present invention will be described in further detail with reference to examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that insubstantial modifications and adaptations of the invention by those skilled in the art based on the foregoing description are intended to be included within the scope of the invention. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.
Example 1:
the matrix of the scintillation composite material in this example 1 is a plastic scintillator PVT, wherein the plastic scintillator comprises two parts of a base layer (a) and a cover layer (B) which are polymerized in advance, and the embedded body is 4 inorganic scintillating single crystals NaI with the size of 12 × 12 × 20 mm: 6 Li,Tl。
in this embodiment 1, the scintillation composite material PVT-NaI for neutron-gamma detection and discrimination: 6 the preparation method of Li and Tl comprises the following steps:
step 1: deionized water, ethanol and acetone are sequentially used for cleaning a glass reaction vessel with the diameter of 53mm for three times, and then the glass reaction vessel is placed into an oven for vacuum heating at 120 ℃ and drying for more than 24 hours.
Step 2: in an inert atmosphere, adding a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-10 wt%) and a wave-shifting agent (0.01-2 wt%) into the glass reaction vessel cleaned in the step 1, dissolving to obtain a uniform solution system, and sealing the glass reaction vessel.
And step 3: and (3) putting the sealed glass reaction vessel in the step (2) into an oven or heating the sealed glass reaction vessel at 70-90 ℃ by using a heat transfer fluid (oil, water and the like), and carrying out thermal prepolymerization for 12-120 hours to the extent that the sealed glass reaction vessel can support the inorganic scintillation single crystal to form a substrate layer (A) of the scintillation composite material.
And 4, step 4: in an inert atmosphere, 4 pieces of 12 × 12 × 20mm inorganic scintillation single crystals NaI with similar light yield and energy resolution: 6 and (3) placing Li and Tl on the substrate layer (A) in the step 3, sealing the reaction glass container, putting the reaction glass container into an oven or heating the reaction glass container at 70-90 ℃ by using heat transfer fluid (oil, water and the like), and carrying out thermal insulation polymerization until the inorganic scintillation single crystal NaI: 6 li, tl are completely adhered to the substrate layer (A) and integrated therewith.
And 5: premixing and dissolving a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-20 wt%) and a wave-shifting agent (0.01-2 wt%) to obtain a uniform clear solution, and pouring the solution into the reaction glass container in the step 4 to form a covering layer (B) so as to ensure that the deliquescent inorganic scintillation single crystal (C) is packaged in the plastic scintillator. After the reaction glass container is sealed, the reaction glass container is put into an oven or heated by using heat transfer fluid (oil, water and the like) at 70-90 ℃, and polymerization is carried out for 2-6 weeks under the condition of heat preservation until the covering layer is completely cured. The polymerization temperature is then raised to 80-100 ℃ and held for 1-7 days to achieve post-cure with the exclusion of small amounts of unpolymerized monomer.
And 6: after the polymerization is finished, the temperature is slowly reduced to room temperature so as to reduce internal stress. And taking the cured scintillation composite material out of the glass reaction vessel, and cutting and polishing to obtain the required scintillation composite material. The obtained scintillation composite material has the diameter of 53mm and the height of 30mm, wherein the ratio of inorganic scintillation single crystal NaI: 6 the content of Li and Tl was 17.4vol%.
Example 2:
the matrix of the scintillating composite material in the embodiment 2 is plastic scintillator PVT, wherein the plastic scintillator comprises two parts of a base layer (A) and a covering layer (B) which are polymerized in advance, and the embedded body is 4 inorganic scintillating single crystals NaI with the diameter of 8 multiplied by 20 mm: 6 Li,Tl。
in this embodiment 2, the scintillation composite material PVT-NaI for neutron-gamma detection and discrimination: 6 the preparation method of Li and Tl comprises the following steps:
step 1: deionized water, ethanol and acetone are sequentially used for cleaning a glass reaction vessel with the diameter of 53mm for three times, and then the glass reaction vessel is placed into an oven for vacuum heating at 120 ℃ and drying for more than 24 hours.
And 2, step: in an inert atmosphere, adding a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-10 wt%) and a wave-shifting agent (0.01-2 wt%) into the glass reaction container cleaned in the step 1, dissolving to obtain a uniform solution system, and sealing the glass reaction container.
And 3, step 3: and (3) putting the sealed glass reaction vessel in the step (2) into an oven or heating the sealed glass reaction vessel at 70-100 ℃ by using a heat transfer fluid (oil, water and the like), and carrying out thermal prepolymerization for 12-96 hours to the extent that the sealed glass reaction vessel can support the inorganic scintillation single crystal to form a substrate layer (A) of the scintillation composite material.
And 4, step 4: in an inert atmosphere, 4 pieces of 8 × 8 × 20mm inorganic scintillation single crystals NaI with similar light yield and energy resolution: 6 and (3) placing Li and Tl on the substrate layer (A) in the step 3, sealing the reaction glass container, putting the reaction glass container into an oven or heating the reaction glass container at 70-100 ℃ by using heat transfer fluid (oil, water and the like), and carrying out heat preservation polymerization until the ratio of inorganic scintillation single crystal NaI: 6 li, tl are completely adhered to the substrate layer (A) and integrated therewith.
And 5: premixing and dissolving a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-20 wt%) and a wave-shifting agent (0.01-2 wt%) to obtain a uniform clear solution, and pouring the solution into the reaction glass container in the step 4 to form a covering layer (B) so as to ensure that the deliquescent inorganic scintillation single crystal (C) is packaged in the plastic scintillator. After the reaction glass container is sealed, the reaction glass container is put into an oven or heated by using heat transfer fluid (oil, water and the like), and polymerization is carried out for 2 to 5 weeks under the condition of heat preservation until the covering layer is completely solidified. The polymerization temperature is then raised to 80-100 ℃ and held for 1-7 days to achieve post-cure with the exclusion of small amounts of unpolymerized monomer.
Step 6: after the polymerization is finished, the temperature is slowly reduced to room temperature so as to reduce internal stress. And taking the cured scintillation composite material out of the glass reaction vessel, and cutting and polishing to obtain the required scintillation composite material. The obtained scintillation composite material has the diameter of 53mm and the height of 30mm, wherein the ratio of inorganic scintillation single crystal NaI: 6 the content of Li and Tl was 7.7vol%.
Example 3:
in this example 3, the matrix of the scintillating composite material is PVT plastic scintillator, wherein the plastic scintillator comprises two parts of a base layer (A) and a cover layer (B) which are polymerized in advance, and the embedded bodies are 9 inorganic scintillating bodies with the diameter of 11mm and the height of 20mmScintillation single crystal CsCu 2 I 3 。
In this embodiment 3, the scintillation composite material PVT-CsCu for neutron-gamma detection and discrimination 2 I 3 The preparation method comprises the following steps:
step 1: the glass reaction vessel with the diameter of 53mm is washed three times by deionized water, ethanol and acetone in sequence, and then is put into an oven to be dried for more than 24 hours under vacuum heating at 120 ℃.
And 2, step: in an inert atmosphere, adding a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-10 wt%) and a wave-shifting agent (0.01-2 wt%) into the glass reaction vessel cleaned in the step 1, dissolving to obtain a uniform solution system, and sealing the glass reaction vessel.
And step 3: and (3) putting the sealed glass reaction vessel in the step (2) into an oven or heating the sealed glass reaction vessel at 70-90 ℃ by using a heat transfer fluid (oil, water and the like), and carrying out thermal prepolymerization for 24-96 hours to the extent that the inorganic scintillation single crystal can be supported to form a substrate layer (A) of the scintillation composite material.
And 4, step 4: in an inert atmosphere, 9 inorganic scintillation single crystals CsCu with the diameter of 11mm and the height of 20mm and similar light yield and energy resolution are put into 2 I 3 Placing on the substrate layer (A) in step 3, sealing the reaction glass container, placing in an oven or heating with heat transfer fluid (oil, water, etc.) at 70-90 deg.C, and polymerizing under heat preservation to obtain inorganic scintillation monocrystal CsCu 2 I 3 Completely adhered to the substrate layer (A) and integrated therewith.
And 5: premixing and dissolving a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-20 wt%) and a wave-shifting agent (0.01-2 wt%) to obtain a uniform clear solution, and pouring the solution into the reaction glass container in the step 4 to form a covering layer (B) so as to ensure that the deliquescent inorganic scintillation single crystal (C) is packaged in the plastic scintillator. After the reaction glass container is sealed, the reaction glass container is put into an oven or heated by using heat transfer fluid (oil, water and the like), and polymerization is carried out for 2 to 6 weeks under the condition of heat preservation until the covering layer is completely solidified. The polymerization temperature is then raised to 80-100 ℃ and held for 1-4 days to achieve postcure with exclusion of small amounts of unpolymerized monomer.
Step 6: after the polymerization is finished, the temperature is slowly reduced to room temperature so as to reduce internal stress. And taking the cured scintillation composite material out of the glass reaction vessel, and cutting and polishing to obtain the required scintillation composite material. The obtained scintillation composite material has a diameter of 53mm and a height of 30mm, wherein the inorganic scintillation single crystal CsCu 2 I 3 The content of (B) was 25.8vol%.
Example 4:
in this example 4, the matrix of the scintillating composite material is PVT plastic scintillator, wherein the plastic scintillator comprises two parts of a base layer (A) and a covering layer (B) which are polymerized in advance, and the embedded bodies are 9 inorganic scintillating single crystals Cs with the diameter of 11mm and the height of 20mm 3 Cu 2 I 5 :Tl。
In this embodiment 3, the scintillation composite material PVT-Cs for neutron-gamma detection and discrimination 3 Cu 2 I 5 The preparation method of Tl comprises the following steps:
step 1: the glass reaction vessel with the diameter of 53mm is washed three times by deionized water, ethanol and acetone in sequence, and then is put into an oven to be dried for more than 24 hours under vacuum heating at 120 ℃.
Step 2: in an inert atmosphere, adding a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-10 wt%) and a wave-shifting agent (0.01-2 wt%) into the glass reaction container cleaned in the step 1, dissolving to obtain a uniform solution system, and sealing the glass reaction container.
And step 3: and (3) putting the sealed glass reaction vessel in the step (2) into an oven or heating the sealed glass reaction vessel at 70-100 ℃ by using a heat transfer fluid (oil, water and the like), and carrying out thermal prepolymerization for 24-96 hours to the extent that the inorganic scintillation single crystal can be supported to form a substrate layer (A) of the scintillation composite material.
And 4, step 4: in an inert atmosphere, 9 inorganic scintillating single crystals Cs with the diameter of 11mm and the height of 20mm and with similar light yield and energy resolution 3 Cu 2 I 5 Tl is placed on the substrate layer (A) in the step 3, the reaction glass container is sealed, and then is placed into an oven or heated by using heat transfer fluid (oil, water and the like) at 70-100 ℃, and is subjected to heat preservation polymerization until inorganic scintillation monocrystal Cs is polymerized 3 Cu 2 I 5 Tl is completely adhered to the substrate layer (A)And is formed integrally.
And 5: premixing and dissolving a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-20 wt%) and a wave-shifting agent (0.01-2 wt%) to obtain a uniform clear solution, and pouring the solution into the reaction glass container in the step 4 to form a covering layer (B) so as to ensure that the deliquescent inorganic scintillation single crystal (C) is packaged in the plastic scintillator. After the reaction glass container is sealed, the reaction glass container is put into an oven or heated by using heat transfer fluid (oil, water and the like), and polymerization is carried out for 2 to 6 weeks under the condition of heat preservation until the covering layer is completely solidified. The polymerization temperature is subsequently raised to 80-110 ℃ and maintained for 1-7 days in order to achieve postcuring with exclusion of small amounts of unpolymerized monomers.
And 6: after the polymerization is finished, the temperature is slowly reduced to room temperature so as to reduce internal stress. And taking the cured scintillation composite material out of the glass reaction vessel, and cutting and polishing to obtain the required scintillation composite material. The obtained scintillation composite material has a diameter of 53mm and a height of 30mm, wherein the inorganic scintillation single crystal Cs 3 Cu 2 I 5 The content of Tl is 25.8vol%.
Example 5:
in this example 5, the matrix of the scintillating composite material is PVT plastic scintillator, wherein the plastic scintillator comprises two parts of a base layer (A) and a covering layer (B) which are polymerized in advance, and the embedded body is 4 inorganic scintillating single crystals Cs with the size of 20X 20mm 3 Cu 2 I 5 。
In this embodiment 3, the scintillation composite material PVT-Cs for neutron-gamma detection and discrimination 3 Cu 2 I 5 The preparation method comprises the following steps:
step 1: deionized water, ethanol and acetone are sequentially used for cleaning a glass reaction vessel with the diameter of 53mm for three times, and then the glass reaction vessel is placed into an oven for vacuum heating at 120 ℃ and drying for more than 24 hours.
Step 2: in an inert atmosphere, adding a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-10 wt%) and a wave-shifting agent (0.01-2 wt%) into the glass reaction vessel cleaned in the step 1, dissolving to obtain a uniform solution system, and sealing the glass reaction vessel.
And 3, step 3: and (3) putting the sealed glass reaction vessel in the step (2) into an oven or heating the sealed glass reaction vessel at 80-100 ℃ by using a heat transfer fluid (oil, water and the like), and carrying out thermal prepolymerization for 24-96 hours to the extent that the sealed glass reaction vessel can support the inorganic scintillation single crystal to form a substrate layer (A) of the scintillation composite material.
And 4, step 4: 4 pieces of 20X 20mm inorganic scintillating single crystals Cs with similar light yield and energy resolution are put into an inert atmosphere 3 Cu 2 I 5 Placing on the substrate layer (A) in the step 3, sealing the reaction glass container, placing in an oven or heating with heat transfer fluid (oil, water, etc.) at 80-100 deg.C, and polymerizing under heat preservation to obtain inorganic scintillation monocrystal Cs 3 Cu 2 I 5 Is completely adhered and integrated with the substrate layer (A).
And 5: premixing and dissolving a matrix monomer, an initiator (0-1 wt%), a primary fluorescent dye (1-20 wt%) and a wave-shifting agent (0.01-2 wt%) to obtain a uniform clear solution, and pouring the solution into the reaction glass container in the step 4 to form a covering layer (B) so as to ensure that the deliquescent inorganic scintillation single crystal (C) is packaged in the plastic scintillator. After the reaction glass container is sealed, the reaction glass container is put into an oven or heated by using heat transfer fluid (oil, water and the like), and polymerization is carried out for 2 to 6 weeks under the condition of heat preservation until the covering layer is completely solidified. The polymerization temperature is then raised to 90-110 ℃ and held for 1-3 days to achieve post-cure with the exclusion of small amounts of unpolymerized monomer.
Step 6: after the polymerization is finished, the temperature is slowly reduced to room temperature so as to reduce internal stress. And taking the cured scintillation composite material out of the glass reaction vessel, and cutting and polishing to obtain the required scintillation composite material. The obtained scintillating composite material has a diameter of 53mm and a height of 30mm, wherein the inorganic scintillating single crystal Cs 3 Cu 2 I 5 The content of (B) was 48.4vol%.
FIG. 8 is a neutron/gamma pulse shape discrimination spectrum of a scintillating composite material provided by the present invention. The diameter of the scintillation composite material is 53mm, the height of the scintillation composite material is 30mm, wherein the ratio of inorganic scintillation single crystal NaI: 6 the content of Li and Tl was 17.4vol%. The neutron-gamma pulse shape discrimination spectrum test result shows that the PVT-NaI: 6 the Li and Tl composite scintillating material has better neutron-gamma discrimination quality factor. The obtained organic-inorganic composite scintillation material can be used as a scintillation materialThe field of neutron-gamma detection and discrimination.
FIG. 1 is a photograph of a sample of a scintillating composite material provided in example 1 of the present invention under natural light. The scintillation composite material is PVT-NaI: 6 li, tl composite scintillation material with a diameter of 53mm and a height of 30mm, wherein NaI: 6 the content of Li and Tl was 17.4vol%.
FIG. 2 is a photograph of a sample of scintillating composite material provided in example 2 of the present invention under natural light. The scintillation composite material is PVT-NaI: 6 li, tl composite scintillation material with a diameter of 53mm and a height of 30mm, wherein NaI: 6 the content of Li and Tl was 7.7vol%.
FIG. 3 shows the inorganic scintillation single crystal NaI: 6 li, tl, fluorescence spectra of plastic scintillator PVT and transmission spectra of plastic scintillator PVT.
FIG. 4 shows the inorganic scintillation single crystal NaI: 6 x-ray excitation emission spectra of Li, tl and plastic scintillator PVT. Fig. 4 shows that the inorganic scintillation single crystal NaI: 6 li, tl have emission peaks at 341nm and 417nm under X-ray excitation, and the plastic scintillator PVT has emission peaks at 422nm and 440nm under X-ray excitation.
FIG. 5 is a scintillating composite material provided by the invention 137 Pulse height spectrum under Cs source. PVT-NaI: 6 the Li, tl composite scintillating material has a diameter of 53mm and a height of 30mm, wherein the ratio of NaI: 6 the content of Li and Tl is 17.4vol%; tl is a standard NaI with a size of 25mm diameter and 25mm height and a light yield of 44,600phototons/MeV. PVT-NaI: 6 li, tl composite scintillating material in 137 Under the excitation of Cs source gamma ray, the light yield is 45,300photons/MeV, and the energy resolution is 13.6% @662keV.
FIG. 6 shows a scintillating composite material provided by the present invention 137 Pulse height spectrum under Cs source. PVT-NaI: 6 the Li and Tl composite scintillating material has a diameter of 53mm and a height of 30mm, wherein the ratio of NaI: 6 the content of Li and Tl is 7.7vol%; tl is a standard NaI with a size of 25mm diameter and 25mm height and a light yield of 44,600phototons/MeV. PVT-NaI: 6 li, tl composite scintillating material in 137 The number of the lower channels of the Cs source gamma ray excitation is 491, the number of the channels of the standard sample NaI and Tl is 642, so the composite scintillating materialRelative light yield of 34,100photos/MeV. In addition, when both the composite scintillation material and the standard NaI: tl full energy peak count reached 500, the time taken was 450 seconds and 96 seconds, respectively, so the NaI: 6 PVT-NaI with Li, tl content of 7.7 vol%: 6 the gamma ray detection efficiency of the Li, tl composite scintillation material is about 21 percent of NaI to Tl of a standard sample with the diameter of 25mm and the height of 25 mm.
FIG. 7 shows a scintillating composite material provided by the present invention 137 Scintillation decay time under Cs source. PVT-NaI: 6 the Li and Tl composite scintillating material has a diameter of 53mm and a height of 30mm, wherein the ratio of NaI: 6 the content of Li and Tl was 17.4vol%. FIG. 7 shows PVT-NaI: 6 li, tl composite scintillating material in 137 The decay time under Cs source gamma irradiation can be fitted by an exponential function, where the fast component of the decay time is 4.84ns, 66% by percentage, and the slow component is 263.58ns, 34% by percentage.
Finally, it is necessary to explain here: the above embodiments are only used for further detailed description of the technical solutions of the present invention, and should not be understood as limiting the scope of the present invention, and the insubstantial modifications and adaptations made by those skilled in the art according to the above descriptions of the present invention are within the scope of the present invention.

Claims (10)

1. A scintillating composite material for neutron-gamma screening, comprising: the device comprises a plastic scintillator and inorganic scintillation single crystals which are embedded in the plastic scintillator and arranged in an array; the volume ratio of the inorganic scintillation single crystal is 1-95 vol%, preferably 10-50 vol%; the size of the inorganic scintillation single crystal is at least 0.1mm.
2. The scintillation composite for neutron-gamma screening according to claim 1, wherein the inorganic scintillation single crystal is selected from the group consisting of NaI: 6 Li,Tl、CsI: 6 Li,Tl、NaI: 6 Li、CsI: 6 Li、 6 LiI:Eu、Cs 3 Cu 2 I 5 、Cs 3 Cu 2 I 5 :Tl、Cs 3 Cu 2 I 5 : 6 Li,Tl、CsCu 2 I 3 、CsCu 2 I 3: Tl、CsCu 2 I 3: 6 Li,Tl、LaBr 3 、CeBr 3 one or more of (a); the thickness of the scintillation composite material for neutron-gamma screening is at least 0.1mm.
3. The scintillation composite for neutron-gamma screening according to claim 1 or 2, wherein the inorganic scintillation single crystal comprises an irregular bulk scintillation single crystal and a regular bulk single crystal; the regular block single crystal has a geometric structure of one of a cube, a cuboid, a cylinder, a prism, a sphere and a hemisphere.
4. The scintillating composite material for neutron-gamma screening according to any one of claims 1 to 3, wherein the plastic scintillator consists of a plastic matrix, an initiator, a primary fluorescent dye, and a wave shifter; the content of the initiator is 0-1 wt%; the content of the primary fluorescent dye is 1-40 wt%; the content of the wave-shifting agent is 0.01-10 wt%.
5. The scintillation composite for neutron-gamma screening according to claim 4, wherein the plastic matrix is selected from at least one of polyvinyltoluene, polymethylmethacrylate, polystyrene, polydimethylsiloxane, poly (9-vinylcarbazole), polyethylene terephthalate.
6. The scintillating composite material for neutron-gamma screening according to claim 4 or 5, wherein the initiator is selected from at least one of azo initiators, peroxide initiators, and photoinitiators; preferably at least one selected from the group consisting of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, benzoyl peroxide, benzoyl tert-butyl peroxide, methyl ethyl ketone peroxide, photoinitiator 184, and photoinitiator BAPO.
7. The scintillating composite material for neutron-gamma screening according to any one of claims 4 to 6, wherein the primary fluorescent dye is selected from at least one of 2, 5-diphenyloxazole, p-terphenyl, 2- (4 '-tert-butylbenzene) -5- (4' -biphenyl) -1,3, 4-oxadiazole, and 2- (4-biphenyl) -5-phenyloxadiazole.
8. The scintillation composite for neutron-gamma screening according to any one of claims 4 to 7, wherein the wave-shifting agent is selected from one of 1, 4-bis (5-phenyl-2-oxazolyl) benzene, 1, 4-bis (2-methylstyrene) benzene, 1, 4-bis (4-methylstyrene) benzene, 9, 10-diphenylanthracene, coumarin dye, or a combination thereof.
9. A method of making a scintillating composite material for neutron-gamma screening according to any one of claims 1 to 8, comprising:
(1) In an inert atmosphere, adding a monomer of a plastic matrix, an initiator, a primary fluorescent dye and a wave-shifting agent into a reaction mold to obtain a uniform clear solution, and then sealing the reaction mold;
(2) Sealing the reaction mould in the step (1) and heating for prepolymerization to ensure that the plastic matrix is micro-cured and can support the scintillation crystal to obtain a partially polymerized substrate layer;
(3) In an inert atmosphere, placing a plurality of inorganic scintillation single crystals on the partially polymerized substrate layer in an array arrangement mode, sealing the reaction mould, and continuing heating and polymerizing to ensure that the inorganic scintillation single crystals and the partially polymerized substrate layer are completely adhered to form a whole;
(4) And (3) pouring a clear solution formed by a monomer of a plastic matrix, an initiator, a primary fluorescent dye and a wave-shifting agent into the reaction mould in the step (3) to form a covering layer, sealing the reaction mould, heating until the covering layer is completely cured, heating to a higher temperature, keeping the temperature for 1-7 days, and finally slowly cooling to room temperature to obtain the scintillation composite material for neutron-gamma discrimination.
10. Use of the scintillating composite material of any one of claims 1 to 8 for neutron-gamma screening for detecting and screening gamma rays, fast neutrons and slow neutrons; the scintillation composite material for neutron-gamma discrimination is used for detectors in the fields of border security inspection, homeland security, environmental detection and nuclear energy utilization radiation mixed fields.
CN202110900621.5A 2021-08-06 2021-08-06 Scintillation composite material for neutron-gamma discrimination and preparation method and application thereof Pending CN115902990A (en)

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