KR101831627B1 - Plastic scintillator, method of menufacturing thereof, and detector for measurement of beta contamination level comprising the same - Google Patents

Abstract

The present invention relates to an epoxy resin composition comprising an epoxy resin; A first solute; A second solute; Wherein the weight ratio of the first solute to the second solute is in the range of 100: 1 to 2: 1. In contrast to the conventional plastic scintillator, Information can be obtained, the nuclide separation process is not necessary, and the measurement time can be shortened and the cost can be saved. More particularly, the present invention relates to a plastic scintillator capable of distinguishing between a high-energy beta ray and a low-energy beta ray, a method for producing the same, and a detector for measuring the beta ray contamination degree.

Description

TECHNICAL FIELD [0001] The present invention relates to a plastic scintillator, a method of manufacturing the same, and a detector for measuring the beta-ray including the plastic scintillator,

TECHNICAL FIELD The present invention relates to a plastic scintillator, a method of manufacturing the same, and a detector for measuring the degree of contamination of the plasticity. More particularly, the present invention relates to a detection material produced by mixing an organic scintillator into a polymer material, and a detector for measuring the contamination of the beta ray, which can detect the low energy beta ray and the high energy beta ray using the detection material.

Radiation sensors and materials have been growing in the markets of medical imaging, industrial non-destructive testing, and counter-terrorism security. In the field of medical imaging, semiconductor materials are mainly used because scintillators are required to have high sensitivity and high performance, and large area of low cost is required for the field of counterterrorism.

In order to measure the degree of residual radioactive contamination, it is necessary to rub the contaminated surface using smear paper in order to measure the contamination degree of the site and the building. (Gross Beta) contamination on the contaminated surface was measured using a gas-filled detector.

In addition to the above detection methods, radiation detectors have been developed using various materials, and in recent years, they have fused with various innovative technologies to achieve remarkable development.

As disclosed in Japanese Laid-Open Patent Application No. 2003-329775, a plastic scintillation detector is manufactured by adding an organic scintillating material to a polymer material and using a polymerization reaction.

However, according to the conventional measurement method, it is impossible to obtain information on the beta-ray emitting species, and the gas-filled detector is fabricated as a thin incidence window, so that the detector is often broken and the detection efficiency is low due to low gas density. There are many difficulties in measuring the residual pollution degree. The method of measuring and collecting the sample can accurately measure the radioactivity of the beta-ray emitting nuclide, but it requires a process of separation of the nuclide through chemical pretreatment, and thus takes a long time and a high cost.

Also, in the plastic flash detector, there is a problem that it is impossible to separately measure the high energy beta line and the low energy beta line contaminated on the site by using one detector. It is imperative that measures are taken to solve these problems.

TECHNICAL FIELD The present invention relates to a plastic scintillator, a method of manufacturing the same, and a detector for measuring the degree of contamination of the plasticity.

It is an object of the present invention to provide a detector for measuring the beta-ray contamination degree, which can obtain information of the beta-ray emitting nuclide and does not require a nuclide separation process, thereby shortening the measuring time and saving the cost.

It is another object of the present invention to provide a detector for measuring the beta-ray contamination degree which can discriminate between a high-energy beta ray and a low-energy beta ray.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In the drawings, the thickness and size of each layer are exaggerated for convenience and clarity of description, and the same reference numerals refer to the same elements in the drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

The scintillator of the present invention means a crystal which emits a flash when a radiation collides. Accordingly, the plastic scintillator of the present invention means a scintillator including a polymer material.

In one embodiment of the present invention, the present invention provides an epoxy resin composition comprising: an epoxy resin; A first solute; A second solute; And a curing agent. In the plastic scintillator of the present invention, the weight ratio of the first solute and the second solute is 100: 1 to 2: 1, preferably 30: 1 to 10: 1, but is not limited thereto. When the first solute and the second solute are contained in an amount of less than 2: 1, the scintillating substance is less contained, which may result in a problem of lowering the detection efficiency. When the first solute and the second solute are contained in an amount exceeding 100: 1, Is generated and the transmittance of the scintillation light generated by the interaction with the radiation is lowered and the detection efficiency is lowered.

In one embodiment of the present invention, the epoxy resin of the present invention is a bisphenol-A type epoxy resin, a bisphenol-F type epoxy resin, a UV curing type epoxy resin, a flame retardant epoxy, Novolac type epoxy resin, novolak type epoxy resin, polyfunctional amine epoxy, cycloaliphatic epoxy resin and low temperature curable epoxy resin, but the present invention is not limited to these examples.

In one embodiment of the present invention, the first solute and the second solute of the present invention are the same or different from each other and each independently selected from the group consisting of 2,5-diphenyloxazole (PPO), paraterphenyl (PT) 4-bis (2-methylstyryl) benzene (bis-MSB), P-terphenyl and 1,4-bis [ Phenyl-oxazole (BPO), 2-phenyl-5- (4-fluorophenyl) (4-biphenyl) -1,3,4-oxadiazole (PBD), 2- (1-naphthyl) -5-phenyloxazole Methyl-5-phenyl-2-oxazolyl) -benzene (dimethyl-POPOP), and 1,4-bis- (2-methylstyryl) benzene , Preferably the first solute is 2,5-diphenyloxazole (PPO) and the second solute is 1,4-bis [5-phenyl-2-oxazole] benzene (POPOP) But is not limited to.

In one embodiment of the present invention, when the thickness of the plastic scintillator of the present invention is 1 to 1.5 mm, a betaine of 450 to 800 keV can be measured. When the thickness of the scintillator is 3 to 3.5 mm, a betaine of 800 to 2300 keV is measured can do. That is, the range of the measurable beta ray differs depending on the thickness of the plastic scintillator.

Therefore, when the first plastic scintillator is less than 1 mm, there is a problem that the efficiency of detecting the beta rays of 450 to 800 keV is low. When the first plastic scintillator is more than 1.5 mm, the epoxy scintillator and scintillating material are less There is a problem that economical efficiency is lowered because a larger amount is required than when manufacturing. When the second plastic scintillator is less than 3 mm, the efficiency of measuring the beta rays of 800 to 2300 keV is inferior. When the second plastic scintillator is more than 3.5 mm, the epoxy scintillator and scintillating material are manufactured There is a problem in that the economical efficiency is lowered because a larger amount is required.

In one embodiment of the present invention, the present invention provides a process for preparing an epoxy resin composition comprising: 1) mixing an epoxy resin, a first solute and a second solute; 2) adding a curing agent to the mixture of step 1); 3) stirring the mixture of step 2) at 15 to 20 DEG C for 1 to 3 hours; And 4) placing the stirred mixture of step 3) in a mold and drying the plastic scintillator. The present invention relates to a method for producing the plastic scintillator. First, an epoxy resin, a first solute and a second solute are mixed. A curing agent is added to accelerate curing of the epoxy resin, the first solute and the second solute mixture. The mixture added up to the curing agent is stirred in a stirrer at 15 to 20 DEG C for 1 hour to 3 hours, preferably at 15 DEG C for 2 hours. After the stirring, if it is confirmed that there is no air bubble, the stirring step of step 3) is ended. Thereafter, the stirred mixture is put in a mold and dried to prepare a plastic scintillator.

In one embodiment of the invention, the mold of step 4) of the present invention may comprise a release agent. Generally, a plastic scintillator is manufactured by putting it in a mold and drying. In order to efficiently transfer the scintillation light generated by the interaction of radiation and plastic scintillation material, the plastic scintillation material thus manufactured is subjected to a polishing process . However, the polishing process involves costly and time-consuming additional manufacturing steps after the production of plastic scintillators. In order to solve such a problem, using a release agent makes it easy to separate the scintillator from the mold, and a transparent scintillator can be produced without polishing. The release agent is a polyethylene film, but is not limited to examples.

In one embodiment of the present invention, drying step 4) of the present invention comprises: 4-1) primary drying at 85 to 95 캜 for 11 to 13 hours; 4-2) secondary drying at 105 to 115 캜 for 4 hours to 6 hours; And 4-3) third drying at 125 to 135 占 폚 for 1 hour to 3 hours. The drying step in step 4) is to cause polymerization reaction of the polymer material, the first solute and the second solute. In addition, the drying step in the step 4) is a stepwise drying step as described above. When heating is carried out at a high temperature (120 ° C) for a short time, the drying time can be shortened, but there is a problem that deformation of the scintillator occurs during the drying process. Further, when the scintillator is prepared by first drying at a temperature lower than 85 ° C (60 ° C) and gradually changing the temperature, there arises a problem that the temperature does not become hard even after 12 hours, or even if hardening occurs, There was a problem that the scintillator broke even when given.

In one embodiment of the present invention, the curing agent of the present invention is selected from the group consisting of phenol-based, anhydride-based, and dicyanamide-based curing agents, and more specifically, phenol novolak, cresol novolak, bisphenol A novolac, Type, anhydride-based curing agent, and methylhexahydrophthalic anhydride, but the present invention is not limited to these examples.

In one embodiment of the present invention, the present invention provides a detector for measuring the beta ray contamination degree, which comprises a detecting section and a measuring section, wherein the detecting section comprises a plastic scintillator fabricated according to the above manufacturing method, a light guide, The present invention relates to a detector for measuring the contamination of a Beta wire to which a light guide is connected to one side of a scintillator and a light exhaust is connected to the opposite side of a light guide connected to the plastic scintillator.

In one embodiment of the present invention, the photoemission of the present invention is selected from the group consisting of a photomultiplier tube (PMT), silicon photomultipliers (SIPM) and a multi-pixel photon counter (MPPC) Preferably a photomultiplier tube (PMT), but is not limited to the example.

The photodiode of the present invention amplifies the high energy particles such as the radiation detected in the scintillator and the generated scintillation to convert the scintillation generated in the scintillator to photocurrent, such as a photomultiplier tube, a silicon spectrometer, a multipolar photon counter It is amplified by photo exhaust and converted to photocurrent.

In one embodiment of the present invention, the detecting section of the present invention includes a first detecting section and a second detecting section, wherein the first detecting section includes a first plastic scintillator and a second plastic scintillator, And a scintillator.

The plastic scintillator may be an epoxy resin; A first solute; A second solute; And a curing agent, the plastic scintillator comprising: 1) mixing an epoxy resin, a first solute and a second solute; 2) adding a curing agent to the mixture of step 1); 3) stirring the mixture of step 2) at 15 to 20 DEG C for 1 to 3 hours; And 4) placing the stirred mixture of step 3) in a mold and drying the plastic scintillator.

Specifically, the first detecting unit may include a first plastic scintillator and a second plastic scintillator, and a second plastic scintillator may be formed on one surface of the first plastic scintillator. More specifically, a second plastic scintillator may be disposed on the first plastic scintillator, And a structure in which a scintillator is stacked. The detecting unit includes a first detecting unit and a second detecting unit. The first detecting unit detects high-energy beta rays. The second detecting unit detects low-energy beta rays. Unlike the second detecting unit, The reason why the beta ray can be detected is that the first detection unit includes the first plastic scintillator and the second plastic scintillator. Energy beta rays are absorbed by the first plastic scintillator and the high energy beta rays are not absorbed by the first plastic scintillator and the high energy beta rays that have passed through the second plastic scintillator are absorbed by the second plastic scintillator. Energy beta lines can be detected. Therefore, the first plastic scintillator of the first detection unit is included in the second detection unit, and the second plastic scintillation material is not included.

In one embodiment of the invention, the first plastic scintillator of the present invention has a thickness of 1 to 1.5 mm, preferably 1 mm, but is not limited to an illustration. The second plastic scintillator is 3 to 3.5 mm thick, preferably 3 mm, but is not limited to the example.

Also, the first plastic scintillator may measure a betaine of 450 to 800 keV, and the second plastic scintillator may measure a betaine of 800 to 2300 keV. Generally, the beta ray of 450 to 800 keV is Tl-204 (0.7 MeV) with a low energy beta ray and the beta ray of 800 to 2300 keV is Sr-90 (Y-90, 2.3 MeV) with a high energy beta ray. Fig. 8 shows a spectrum that distinguishes between a high-energy beta line and a low-energy beta line. The first plastic scintillator can measure low energy beta rays and the second plastic scintillator can measure high energy beta rays. Accordingly, the detector for measuring the beta ray contamination degree according to the present invention includes a first plastic scintillator capable of measuring a low energy beta ray and a second plastic scintillator capable of measuring a high energy beta ray, have.

Therefore, when the first plastic scintillator is less than 1 mm, there is a problem that the efficiency of detecting the beta rays of 450 to 800 keV is low. When the first plastic scintillator is more than 1.5 mm, the epoxy scintillator and scintillating material are less There is a problem that economical efficiency is lowered because a larger amount is required than when manufacturing. When the second plastic scintillator is less than 3 mm, the efficiency of measuring the beta rays of 800 to 2300 keV is inferior. When the second plastic scintillator is more than 3.5 mm, the epoxy scintillator and scintillating material are manufactured There is a problem in that the economical efficiency is lowered because a larger amount is required.

In one embodiment of the present invention, the first detection portion of the present invention includes a first light guide and a first photo exhaust, and the second detection portion may include a second light guide and a second photo exhaust. That is, the first detection unit includes a first plastic scintillator, a second plastic scintillator, a first light guide, and a first photo exhaust, and the second detection unit includes a first plastic scintillator, a second light guide, and a second photo exhaust .

Specifically, the first detecting unit includes a plastic scintillator having a laminated structure in which a second plastic scintillator is formed on one surface of the first plastic scintillator, a first light guide is formed on an outer circumferential surface of the laminated plastic scintillator, The guide is directly connected to the first manifold exhaust. The second detection unit is formed with a second light guide on the outer circumferential surface of the first plastic scintillator, and the second light guide is directly connected to the second light evacuation unit.

The present invention can obtain the information of the beta emission radionuclide, and it is possible to shorten the measurement time and save the cost because the nuclide separation process is not required. More specifically, the high energy beta ray and the low energy beta ray can be discriminated and measured A method for producing the same, and a detector for measuring the beta-ray contamination degree.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart of a method for producing the plastic scintillator of the present invention.
2 is a view of a detector for measuring the beta ray contamination degree according to the present invention.
FIG. 3 shows a change in the amount of light according to the content of the first solute according to the present invention.
4 is a graph showing a change in the amount of light according to the content of the second solute according to the present invention.
5 is a photograph of a scintillator fabricated according to a change in temperature condition in a drying step according to an embodiment of the present invention.
6 is a photograph of a scintillator according to whether or not a release agent is used according to an embodiment of the present invention.
7 relates to the detection efficiency according to the thickness of the plastic scintillator of the present invention.
8 relates to the detection efficiency according to the thickness of the plastic scintillator of the present invention.
Fig. 9 relates to setting the measurement range of high energy and low energy beta rays.
100:
100 ': first detection unit
100 ": second detection section
110: first plastic scintillator
120: second plastic scintillator
130: Light guide
200:
210: Measurement system
300: Measuring site

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood that both the foregoing description and the following detailed description are exemplary, explanatory and are intended to be illustrative, and not restrictive. The scope of the invention is defined by the appended claims rather than by the foregoing description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart of a method of making a plastic scintillator of the present invention. 1) mixing the epoxy resin, the first solute and the second solute (S100). Epoxy resin, a bisphenol-A type epoxy resin, a bisphenol-F type epoxy resin, a UV curing type epoxy resin, a low temperature curing type epoxy resin, a flame retardant epoxy, a novolak type, A styrenic amine epoxy, and a cycloaliphatic. However, the present invention is not limited to these examples.

Wherein the first solute and the second solute are the same or different and are each independently selected from the group consisting of 2,5-diphenyloxazole (PPO), paraterphenyl (PT), 4-bis (2-methylstyryl) Benzene (bis-MSB), P-terphenyl and 1,4-bis [5-phenyl-2-oxazole] benzene (POPOP), anthracene anthracene, stilbene, tolan, 2- (4-biphenylyl) -5-phenyl-oxazole (BPO) (1-naphthyl) -5-phenyloxazole (? -NPO), 1,4-di- (4-methyl- ) -Benzene (dimethyl-POPOP), and 1,4-bis- (2-methylstyryl) benzene (bis-MSB), preferably the first solute is at least one selected from the group consisting of 2, 5-diphenyloxazole (PPO) and the second solute is 1,4-bis [5-phenyl-2-oxazole] benzene (POPOP), but is not limited to examples.

The weight ratio of the first solute to the second solute is 100: 1 to 2: 1, preferably 30: 1 to 10: 1, but is not limited to the examples. When the first solute and the second solute are contained in an amount of less than 2: 1, the scintillating substance is less contained, which may result in a problem of lowering the detection efficiency. When the first solute and the second solute are contained in an amount exceeding 100: 1, Is generated and the transmittance of the scintillation light generated by the interaction with the radiation is lowered and the detection efficiency is lowered.

The step of mixing the polymer material, the first solute and the second solute (S100), and then the step of adding a curing agent (S200). The curing agent is added in order to accelerate curing of the epoxy resin, the first solute and the second solute, and is selected from the group consisting of phenol-based, anhydride-based, and dicyanamide-based curing agents, and more specifically, phenol novolac, Novolak, bisphenol A novolac, naphthalene type, anhydride-based curing agent, and methylhexahydrophthalic anhydride, but the present invention is not limited to these examples.

After the step of adding the curing agent (S200), 3) the stirring step (S300), specifically, stirring is carried out at 15 to 20 ° C for 1 hour to 3 hours, preferably at 15 ° C for 2 hours. After the stirring, if it is confirmed that there is no air bubble, the stirring step of step 3) is ended. When the stirring step (S300) is completed, (4) the drying step is performed, and the polymerization reaction occurs due to drying at a certain temperature. Step 4) is not to dry at a constant temperature, and 4-1) to primary dry at 85 to 95 ° C for 11 hours to 13 hours; 4-2) secondary drying at 105 to 115 캜 for 4 hours to 6 hours; And 4-3) third drying at 125 to 135 占 폚 for 1 hour to 3 hours.

FIG. 2 is a view of a detector for measuring the contamination level of a Beta line according to the present invention, and is a detector for measuring a Beta line contamination degree including a detecting unit 100 and a measuring unit 200. The detection unit 100 detects the beta rays, amplifies the high energy particles such as the detected beta rays and the generated scintillation light, and converts the high energy particles into photocurrent. The measuring unit 200 measures the beta rays detected through the photocurrent switched by the detecting unit 100.

Specifically, the detection unit 100 includes plastic scintillators 110 and 120, a light guide 130, and a photoreceptor 140. A light guide 130 is connected to the outer circumferential surface of the plastic scintillators 110 and 120 and the light guide 130 is directly connected to the ambient light exhaust 140. The plastic scintillators 110 and 120 are for detecting the beta rays occurring in the site 300 and are characterized by a single layer or a multi-layer structure. FIG. 2 of the present invention is an example of the detector for measuring the contamination level of the beta rays of the present invention. The plastic scintillators 110 and 120 are composed of a single layer and a double layer structure, but are not limited to the examples.

2 of the present invention illustratively includes a first detection unit 100 'and a second detection unit 100 ". According to FIG. 2, the first detection unit 100' and the second detection unit 100 ' The detection unit 100 'includes a plastic scintillator having a multilayer structure of a first plastic scintillator 110 and a second plastic scintillator 120 while the second detection unit 100 "includes only a first plastic scintillator 110 . The first detecting unit 100 'and the second detecting unit 100' are different from each other in structure. Thus, the first detecting unit 100 'can detect a high-energy beta ray by changing the structure of the plastic scintillation member. , And the second detection unit 100 "can detect the low energy beta line. There is a difference in the beta rays detected by the first detector 100 'and the second detector 100'. For this reason, the detector for measuring the beta ray contamination degree according to the present invention can discriminate between the high energy beta ray and the low energy beta ray .

[Production Example 1]

Manufacture of plastic scintillators

Bisphenol-type epoxy resin and methylhexahydrophthalic anhydride anhydride-based curing agent were mixed so as to be 0.79 wt% (0.395 wt%: 0.395 wt%) and 0.2 wt% of 2.5-diphenyloxazole (PPO) And 0.01 wt% of 1,4-bis [5-phenyl-2-oxazole] benzene (POPOP) was mixed with the second solute.

The mixture was stirred at 15 DEG C for 2 hours, and the stirring step was completed after confirming that there was no air bubbles after stirring. After the stirring step was completed, the stirred mixture was put into a mold using a polyethylene film as a mold release agent.

The polymer mixture in the mold was first dried at 90 DEG C for 12 hours, then secondarily dried at 110 DEG C for 5 hours and then thirdly dried at 130 DEG C for 2 hours to prepare a plastic scintillator.

[Example 1]

Changes in the amount of light depending on the content of the first solute and the second solute

The preparation was carried out in the same manner as in Preparation Example 1, except that the contents of the first solute and the second solute were as shown in Tables 1 and 2 below.

The luminescence spectra of the products 1 to 7 prepared according to the contents of Tables 1 and 2 below were analyzed in the region of 420 nm.

PPO POPOP Production Example 1 0.2 0.01 Comparative Example 2 0.4 0.01 Comparative Example 3 0.6 0.01 Comparative Example 4 0.8 0.01 Comparative Example 5 1.0 0.01

PPO POPOP Production Example 1 0.2 0.01 Comparative Example 6 0.2 0.025 Comparative Example 7 0.2 0.05

FIG. 3 is a luminescence spectrum showing a change in the amount of light according to the content of PPO. As a result of varying the content of PPO from 0.1 to 1% by weight, the maximum is obtained when the content of PPO is 0.2% by weight and the mixing ratio of PPO is POPOP = 0.2% by weight: 0.01% by weight.

FIG. 4 is a luminescence spectrum showing the change in the amount of light according to the content of POPOP. As a result of varying the content of POPOP from 0.01 to 0.05% by weight, the amount of luminescence was decreased as the content of POPOP was increased. .

FIG. 5 is a graph showing the relationship between the content of PPO and the content of POPO in the scintillator, and FIG. 5 is a graph showing the detection efficiency of betaine according to the change of the content of PPO: POPOP. When the content of PPO is changed from 0.02 to 1 wt% The mixing ratio of possible scintillators was PPO: POPOP = 100: 1 to 2: 1, but optimum production conditions showed a weight ratio of PPO: POPOP = 30: 1 to 10: 1.

As a result, as the amount of PPO and POPOP decreases, the radiation detection efficiency becomes lower, and as the amount of PPO and POPOP increases, yellowing does not occur in the solvent and yellowing occurs. It is necessary to optimize the detection efficiency. Based on the above experimental results, it can be said that the optimal conditions for the production of the plastic scintillator is that the weight ratio of PPO: POPOP = 30: 1 to 10: 1 is the optimum condition for producing the plastic scintillator.

[Example 2]

Preparation of plastic scintillators according to drying conditions

A polymer scintillator was prepared by drying the polymer mixture in a mold and drying it under the temperature conditions shown in Table 3 below.

number Condition One 70 (12 hours) 90 (5 hours) 110 (2 hours) 2 90 (12 hours) 110 (5 hours) 130 (2 hours) 3 120 (2 hours)

The plastic scintillators produced according to the change of drying conditions are shown in Fig. As a result of the evaluation, condition 1 showed that the outer scintillator was not deformed, but the scintillator was dried at a low temperature, so that the strength was weak and the scintillator was broken even with a slight impact.

Condition 2 was higher than Condition 1, so that it was not damaged by external impact and had excellent strength, and the outer shape was not deformed.

Condition 3, the drying time was very short, but the scintillator twisted and distorted, making it impossible to use it as a plastic scintillator.

As a result, as in Condition No. 2, 1) primary drying at 85 to 95 캜 for 11 to 13 hours, 2) secondary drying at 105 to 115 캜 for 4 to 6 hours, 3) The plastic scintillator produced by the drying method in which the drying temperature is raised stepwise and the drying time is shortened in accordance with the rise of the temperature such as the third drying for one hour to three hours is not damaged by the external impact, However, as in condition 2, even if the temperature is gradually increased to three stages and dried, if the drying temperature is too low, it may not be sufficiently dried in the drying step, Even if it is dried, there is a concern that it may be easily broken by an external impact. In case of drying in a short time at a high temperature as in condition 3, the plastic scintillator is deformed This phenomenon caused by a problem that can not be used as a plastic scintillator.

[Example 3]

Comparison of properties of plastic scintillators manufactured with or without release agent

[Comparative Example 8]

A plastic scintillator was prepared in the same manner as in Preparation Example 1, except that the polyethylene film was not used in the mold.

FIG. 7 is a photograph of a scintillator according to an embodiment of the present invention. In the plastic scintillator manufactured by putting a polymer mixture in a mold without using a mold release agent, external strain was generated. On the other hand, in the case of Production Example 1 prepared using a polyethylene film as the release agent, the plastic scintillator was easily separated without being adhered to the mold after the completion of the drying step.

Generally, mold release agents are not used in the production of plastic scintillators, and external deformation is caused. Thus, a polishing process is essentially performed to produce plastic scintillators. However, unlike Comparative Example 8, when a release agent is used as in Production Example 1 of the present invention, it is possible to manufacture a transparent plastic scintillator without external deformation.

[Example 4]

Evaluation of beta ray measurements according to thickness of plastic scintillator

The beta line varies depending on the energy (distance traveled by the charged particle until the kinetic energy is lost in the material). Optimization of the thickness of plastic scintillators was performed to measure low energy and high energy beta lines by controlling the thickness of scintillators. In the evaluation method, the detection efficiency according to the change of the thickness of the scintillator was evaluated through an experiment with a computer code (MCNP). As the plastic scintillator, the plastic scintillator manufactured according to Production Example 1 was used and the evaluation was carried out with different thicknesses.

thickness Production Example 2 3mm Comparative Example 8 2mm

Referring to FIG. 8, the detection efficiency according to the thickness of the scintillator was measured using a computer code for the Bet-ray measurement of Sr-90 (high energy, maximum energy 2.3 MeV) As shown in Table 4, the test results for 3 mm and 2 mm also show that the detection efficiency is low at a thickness of 2 mm.

thickness Production Example 3 1mm Production Example 4 1.5mm Comparative Example 9 0.75mm Comparative Example 10 0.5mm

Referring to FIG. 9, in the case of Tl-204 (low energy, maximum energy 763 keV), the detection efficiency was increased up to 1 mm as a result of evaluation using a computer code for beta ray measurement. However, Giving. Experiments were carried out with the thickness of the scintillator varying from 0.5 to 1.5 mm, and the results were similar to those obtained with the computer code at 1 mm.

As a result, the thickness of the optimal plastic scintillator required for the detection of the beta rays is the same as the results of Figs. 7 and 8, through the change of the thicknesses of Tables 4 and 5. The detection efficiency of the high-energy beta ray is less than 3 mm, but the efficiency is excellent at a thickness of 3 mm or more. However, when the plastic scintillator is manufactured in a size of more than 3.5 mm, the detection efficiency is the same, but the problem that the amount of epoxy, hardening agent and scintillating material required to produce the plastic scintillator is larger have.

In addition, the low-energy beta ray has been found to exhibit excellent detection efficiency in the thickness range of 1 mm to 1.5 mm. When the particle size is less than 1 mm, the detection efficiency is inferior. When the particle size exceeds 1.5 mm, There is a problem that the amount of the hardener and the scintillating material is larger than that of the scouring agent and the scintillating material, and there is a problem that the distinction between the scintillator and the plastic scintillator for measuring the Gore-Nebi line is ambiguous.

Claims (17)

Epoxy resin;
A first solute;
A second solute;
A curing agent,
Wherein the weight ratio of the first solute to the second solute is 100: 1 to 2: 1,
Wherein the first solute and the second solute are the same or different and are each independently selected from the group consisting of 2,5-diphenyloxazole (PPO), paraterphenyl (PT), 4-bis (2-methylstyryl) Benzene (bis-MSB), P-terphenyl and 1,4-bis [5-phenyl-2-oxazole] benzene (POPOP), anthracene anthracene, stilbene, tolan, 2- (4-biphenylyl) -5-phenyl-oxazole (BPO) (1-naphthyl) -5-phenyloxazole (? -NPO), 1,4-di- (4-methyl- ) -Benzene (dimethyl-POPOP), and 1,4-bis- (2-methylstyryl) benzene (bis-MSB)
The plastic scintillator may be used to measure the energy of the beta-emitting nuclide
A beta ray having a thickness of 1 to 1.5 mm and measuring 450 to 800 keV is measured,
A plastic scintillator having a thickness of 3 to 3.5 mm and measuring a beta ray of 800 to 2300 keV.
The method according to claim 1,
Wherein the weight ratio of the first solute and the second solute is from 30: 1 to 10: 1. The method according to claim 1,
The epoxy resin may be at least one selected from the group consisting of a bisphenol-A type epoxy resin, a bisphenol-F type epoxy resin, a UV curing type epoxy resin, a low temperature curing type epoxy resin, a flame retardant epoxy, At least one selected from the group consisting of styrenic amine epoxy and cycloaliphatic. delete delete 1) mixing the epoxy resin, the first solute and the second solute;
2) adding a curing agent to the mixture of step 1);
3) stirring the mixture of step 2) at 15 to 20 DEG C for 1 to 3 hours; And
4) placing the stirred mixture of step 3) in a mold and drying,
Wherein the first solute and the second solute are the same or different and are each independently selected from the group consisting of 2,5-diphenyloxazole (PPO), paraterphenyl (PT), 4-bis (2-methylstyryl) benzene (bis-MSB), P-terphenyl and 1,4-bis [5-phenyl-2-oxazole] benzene (POPOP), anthracene anthracene, stilbene, tolan, 2- (4-biphenylyl) -5-phenyl-oxazole (BPO) (1-naphthyl) -5-phenyloxazole (? -NPO), 1,4-di- (4-methyl- ) -Benzene (dimethyl-POPOP), and 1,4-bis- (2-methylstyryl) benzene (bis-MSB). The method according to claim 6,
Wherein the mold of step 4) comprises a release agent. 8. The method of claim 7,
Wherein the releasing agent is a polyethylene film. The method according to claim 6,
The step of drying in step 4)
4-1) primary drying at 85 to 95 캜 for 11 to 13 hours;
4-2) secondary drying at 105 to 115 캜 for 4 hours to 6 hours; And
4-3) tertiary drying at 125 to 135 占 폚 for 1 hour to 3 hours. 1. A detector for measuring the contamination of a blood vessel,
Wherein the detection unit includes the plastic scintillator according to claim 1, a light guide,
A light guide is connected to an outer circumferential surface of the plastic scintillator,
The light guide connected to the plastic scintillator is a detector for measuring the contamination of the beta rays connected with the saturation exhaust. 11. The method of claim 10,
The detector is selected from the group consisting of a photomultiplier tube (PMT), a silicon photomultiplier (SIPM), and a Multi Pixel Photon Counter (MPPC). 11. The method of claim 10,
Wherein the detection unit includes a first detection unit and a second detection unit,
Wherein the first detecting unit includes a first plastic scintillator and a second plastic scintillator,
And the second detection unit includes a first plastic scintillator. 13. The method of claim 12,
And a second plastic scintillator laminated on top of the first plastic scintillator. 13. The method of claim 12,
Wherein the first plastic scintillator has a thickness of 1 to 1.5 mm. 13. The method of claim 12,
And the second plastic scintillator is 3 to 3.5 mm thick. delete 13. The method of claim 12,
Wherein the first detection portion includes a first light guide and a first photo-exhaust,
And the second detection unit includes a second light guide and a second photo-exhaust.

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