Preparation method and application of novel benzyl cinnamate-vinyl toluene mixed matrix neutron / gamma discrimination plastic scintillator

Abstract

The invention discloses a preparation method and application of a novel benzyl cinnamate-vinyl toluene (PVT) mixed matrix neutron / gamma discrimination plastic scintillator. The plastic scintillator is composed of a polymer matrix, a main fluorescent dye, a secondary fluorescent dye, a cross-linking agent and an initiator, the polymer matrix is benzyl cinnamate (RG) and vinyl toluene, the main fluorescent dye is 2, 5-diphenyloxazole (PPO), the secondary fluorescent dye is 7-diethylamino-4-methylcoumarin (MDAC), and the initiator is an initiator. The crosslinking agent is divinyl benzene (DVB), and the initiator is azodiisobutyronitrile (AIBN). The prepared plastic scintillator is polymerized based on a novel organic polymer matrix, and has good transparency. Compared with a plastic scintillator of the same type, the preparation time is greatly shortened by using the substrate, and the preparation efficiency is improved.

Description

Technical Field

[0001] This invention relates to a novel benzyl cinnamate-vinyl toluene mixed matrix neutron / gamma discriminant plastic scintillator, its preparation method, and its application, belonging to the field of nuclear technology radiation detection. Background Technology

[0002] Neutron / gamma discrimination is a key technology for neutron energy spectrum and neutron parameter diagnosis in nuclear physics experiments, nuclear reactor monitoring, and nuclear radiation protection. In recent years, plastic scintillators have become increasingly popular and widely used in various fields due to their fast decay time, low manufacturing cost, ease of cutting into arbitrary shapes, and excellent neutron / gamma discrimination capabilities. When charged particles (such as recoil protons generated by the interaction of neutrons with matter, or electrons generated by the interaction of gamma rays with matter) pass through the scintillator material, they are excited and ionized, producing photons, i.e., scintillating light. Plastic scintillators are mainly composed of a scintillator matrix and scintillator material. They possess excellent mechanical properties, can be processed into arbitrary shapes, and can be used in various physical environments. Compared to liquid scintillators and inorganic crystal scintillators, they have advantages such as low cost, ease of large-scale fabrication, low leakage risk, and high efficiency in detecting fast neutrons. These characteristics make plastic scintillators an important choice for neutron detection technology. Neutrons and detector materials suffer from problems such as radiation trapping and inelastic scattering. Therefore, neutron measurement is inevitably accompanied by gamma-ray background interference. Thus, neutron detection technology involves n / γ discrimination technology under strong gamma-ray background radiation.

[0003] Currently, commercially available plastic scintillators have emerged abroad. For example, the fast neutron detection system developed by the Japan Atomic Energy Agency (JAEA) uses the EJ-299-33M plastic scintillator, which significantly reduces gamma background interference through PSD technology, enabling the identification of the radiation source direction. Plastic scintillators primarily use polystyrene, polyvinyl toluene, or polysiloxane as matrix materials. However, using these matrix materials results in long polymerization times, insufficient mechanical properties, and a tendency for brittle fracture. Therefore, this invention introduces benzyl cinnamate (RG) into polyvinyl toluene to form a mixed matrix, which is expected to develop a neutron / gamma discrimination plastic scintillator based on a novel organic polymer matrix RG and possessing high optical transparency. Compared to similar plastic scintillators, using this matrix significantly shortens the preparation time and improves preparation efficiency. Summary of the Invention

[0004] To address the problems of long preparation time and low chemical stability in existing plastic scintillators, the present invention aims to provide a novel plastic scintillator preparation method and its application that features short preparation time, low cost, high mechanical strength, high chemical stability, and good neutron / gamma discrimination capability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention relates to a novel benzyl cinnamate-vinyl toluene mixed matrix neutron / gamma discrimination plastic scintillator. The plastic scintillator is composed of a mixed matrix of two polymers, a primary fluorescent dye, a secondary fluorescent dye, a crosslinking agent, and an initiator. The polymer matrix is ​​benzyl cinnamate (RG) and vinyl toluene (PVT). The primary fluorescent dye is 2,5-diphenyloxazole (PPO). The secondary fluorescent dye is 7-diethylamino-4-methylcoumarin (MDAC). The crosslinking agent is divinylbenzene (DVB). The initiator is azobisisobutyronitrile (AIBN).

[0007] The neutron / gamma discrimination plastic scintillator of the present invention uses benzyl cinnamate and vinyltoluene as a mixed organic matrix. The inventors have found that the use of benzyl cinnamate can significantly reduce the preparation time of the plastic scintillator and greatly improve the brittleness of the plastic scintillator. The prepared scintillator has high hardness and good optical transparency and neutron / gamma discrimination capability.

[0008] In plastic scintillators, the matrix material plays a crucial role, serving not only as the physical framework of the entire scintillator but also as the starting point for the radiative energy conversion process. Primary and secondary fluorescent dyes are essential components of plastic scintillators, key to their ability to convert high-energy radiation into visible light. They primarily provide the interaction network for the transfer and collision of singlet and triplet excited states of scintillator molecules, thus providing the pathway for excitation energy transfer. When particles enter the scintillator, energy is continuously lost, exciting the plastic matrix molecules. The excited molecular excitation energy is transferred to the primary fluorescent dye, emitting fluorescence. The main function of these primary dye molecules is to effectively absorb ultraviolet or short-wavelength visible light generated by the polymer matrix and convert it into longer-wavelength visible light emission. However, most primary fluorescent dyes exhibit significant self-absorption, necessitating the addition of secondary fluorescent dyes. Secondary fluorescent dyes can absorb photons emitted by the primary fluorescent dyes and emit fluorescence at longer wavelengths, thereby maximizing the number of externally coupled photons emitted by the scintillator, increasing its luminescence yield, and optimizing the spectral output to match the sensitive spectral range of detectors such as photomultiplier tubes (PMTs).

[0009] This invention uses benzyl cinnamate as a mixed matrix variable, PPO with a fluorescence emission peak at 365 nm as the main fluorescent dye, MDAC as the secondary fluorescent dye, divinylbenzene (DVB) as the crosslinking agent, and azobisisobutyronitrile (AIBN) as the initiator to prepare a plastic scintillator, and investigates the effect of benzyl cinnamate content from low to high concentration on the polymerization time and performance of the plastic scintillator.

[0010] This invention provides a novel hybrid matrix plastic scintillator with short molding time, neutron / gamma discrimination capability, and good antioxidant stability, mechanical hardness, optical transmittance and radioluminescence yield.

[0011] In a preferred embodiment, the polymer matrix is ​​a mixture of benzyl cinnamate and vinyltoluene.

[0012] The inventors discovered that when the organic polymer matrix is ​​selected with a benzyl cinnamate mass fraction of 30 wt.%, the resulting novel plastic scintillator has the shortest molding time and the best neutron / gamma discrimination capability.

[0013] In a preferred embodiment, the benzyl cinnamate has a mass fraction of 30 wt.% in the novel hybrid matrix neutron / gamma-detection plastic scintillator. The primary fluorescent dye PPO has a mass fraction of 30 wt.% in the novel hybrid matrix neutron / gamma-detection plastic scintillator. The secondary fluorescent dye MDAC has a mass fraction of 0.4 wt.% in the novel hybrid matrix neutron / gamma-detection plastic scintillator.

[0014] In a preferred embodiment, the crosslinking agent DVB has a mass fraction of 4 wt.% in the novel neutron / gamma discrimination plastic scintillator, and the initiator AIBN has a mass fraction of 0.08 wt.% in the novel neutron / gamma discrimination plastic scintillator.

[0015] The inventors discovered that when the mass fraction of benzyl cinnamate is 30 wt.%, the mass fraction of the primary fluorescent dye PPO is 30 wt.%, and the mass fraction of the secondary fluorescent dye MDAC is 0.2–0.4 wt.%, the prepared benzyl cinnamate-vinyl toluene mixed matrix plastic scintillator has good optical transparency, high luminescence yield, and good neutron / gamma ray discrimination ability.

[0016] In this invention, adding an appropriate amount of main fluorescent dye can improve the discrimination ability of the scintillator, but the amount still needs to be controlled. When the content of main fluorescent dye is too high, its self-absorption effect is obvious, which leads to a decrease in luminous efficiency and light yield. In addition, the sample with excessive PPO will have dye precipitation after being placed for a period of time, which will lead to a decrease in stability.

[0017] In a preferred embodiment, after the precursor solution is prepared and sealed in a tube, it is placed in a vacuum drying oven. The temperature is increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it is allowed to cool naturally to room temperature. Finally, the process is stopped, and the sample is allowed to cool to room temperature in the oven before being removed. The fully polymerized sample is then removed from the glass tube and polished to obtain the final product.

[0018] Principles and advantages

[0019] This invention uses a novel aromatic organic compound, benzyl cinnamate, as one of the matrix materials for plastic scintillators, which greatly shortens the polymerization molding time of the scintillator. Furthermore, by adding the primary fluorescent dye PPO in combination with the secondary fluorescent dye MDAC, the self-absorption of high-concentration primary fluorescent dye is avoided.

[0020] The energy transfer process and principle of this invention are as follows: benzyl cinnamate and vinyltoluene act as energy donors, the main fluorescent dye PPO acts as the first energy receiver, and then the energy is transferred to the second energy receiver MDAC, finally outputting photons that are received and converted by a photomultiplier tube. When particles are incident on the scintillator, energy is continuously lost and excited the molecules in the plastic matrix. Depending on the composition, plastic scintillators can be used to detect high-energy (fast) neutrons and low-energy (thermal) neutrons. In plastic scintillator detectors, the interaction between neutrons and organic matter is mainly of two types: neutrons are scattered or absorbed by atomic nuclei. For gamma rays, secondary electrons are generated in the matrix mainly through Compton scattering, the photoelectric effect, or the electron-pair effect. For fast neutrons, they mainly interact with hydrogen atoms in the matrix (abundant in polymers) through elastic scattering, generating recoil protons. When these secondary charged particles (electrons or protons) travel through the matrix, they ionize and excite polymer molecules, converting the energy of the incident radiation into the excitation energy of the matrix molecules. Under equivalent energy capture, "fast neutron pulses" have a longer decay time than "gamma pulses," thus enabling neutron / gamma discrimination.

[0021] The advantages of this invention are: under the action of benzyl cinnamate molecules, the molding time is short, reducing synthesis costs and lowering the brittleness of the material. The prepared scintillator has excellent stability, transmittance, light yield, and neutron-gamma discrimination ability, showing broad application prospects. Attached Figure Description

[0022] Figure 1 These are sample images taken under visible light for Examples 1, 3, 5, 7, and 9 of this invention.

[0023] Figure 2 Neutron / gamma pulse shape discrimination spectra for Examples 1, 3, 5, 7, and 9 of this invention ( 238 (Pu-Be neutron source irradiation)

[0024] Figure 3 The following are the excitation (EX)-emission (EM) spectra of the scintillator samples in Examples 1 and 7 of this invention (λem=435 nm, λex=300 nm).

[0025] Figure 4 The ultraviolet-visible transmittance spectra of RG-doped scintillators in Examples 1, 3, 5, and 7 of this invention (10 wt.%, 20 wt.%, 40 wt.%, and 50 wt.%) are shown.

[0026] Figure 5 The pulse height spectra of RG-doped scintillator samples (10 wt% ~ 50 wt%) and commercial EJ-276 samples in Examples 1, 3, 5, 7, and 9 of this invention, and are shown below. 137 Cs gamma source radiation). Detailed Implementation

[0027] The preparation of the novel plastic scintillator of the present invention will be further explained below through specific embodiments.

[0028] Example 1

[0029] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.012 g (0.4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 0.3 g (10 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0030] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0031] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0032] Example 2

[0033] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.12 g (0.4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 0.45 g (15 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0034] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0035] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0036] Example 3

[0037] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.12 g (4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 0.60 g (20 wt.%) of benzyl cinnamate (RG), and 3 g of vinyltoluene (PVT) according to their mass percentages and stir until homogeneous; then, sonicate the dye molecules in the homogeneous mixture to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0038] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0039] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0040] Example 4

[0041] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.012 g (0.4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 0.75 g (25 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0042] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0043] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0044] Example 5

[0045] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.012 g (0.4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 0.9 g (30 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0046] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0047] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0048] Example 6

[0049] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.012 g (0.4 wt.%) of the wave-shifting agent ethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 1.05 g (35 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0050] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0051] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0052] Example 7

[0053] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.012 g (0.4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 1.2 g (40 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution. The precursor solution is added to a glass tube of a custom diameter, and then the glass tube is placed in a container filled with liquid nitrogen to solidify the precursor solution. The tube is then vacuum-treated using a Hickley apparatus and a vacuum pump, and nitrogen gas is introduced. This process is repeated five times before the tube is sintered and sealed.

[0054] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0055] Example 8

[0056] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.012 g (0.4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 1.35 g (45 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0057] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0058] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0059] Example 9

[0060] (1) Mix 0.90 g (30 wt.%) of the main fluorescent dye 2,5-diphenyloxazole (PPO), 0.012 g (0.4 wt.%) of the wave-shifting agent 7-diethylamino-4-methylcoumarin (MDAC), 0.12 g (4 wt.%) of divinylbenzene (DVB), 0.0024 g (0.08 wt.%) of the initiator azobisisobutyronitrile (AIBN), 1.50 g (50 wt.%) of benzyl cinnamate (RG) and 3 g of vinyltoluene (PVT) according to mass percentage and stir until homogeneous; disperse the dye molecules in the homogeneous mixture by ultrasonication to obtain the RG / PVT / PPO / MDAC / DVB / AIBN precursor solution.

[0061] (2) Add the precursor solution into a glass tube of a custom diameter, and then place the glass tube into a container filled with liquid nitrogen to solidify the precursor solution into a solid. Then use a Hickley apparatus and a vacuum pump to vacuum it and introduce nitrogen gas. Repeat the above treatment five times and then sinter and seal the tube.

[0062] (3) After sealing, the glass tube was placed in an oven for a gradient reaction. The temperature was increased from room temperature to 50°C at a rate of 60°C / h and held for 1 hour; then increased to 70°C at a rate of 10°C / h and held for 12 hours; then increased to 80°C at a rate of 5°C / h and held for 24 hours; then decreased to 75°C at a rate of 5°C / h and held for 12 hours; then decreased to 50°C at a rate of 5.56°C / h and held for 3 hours. Afterward, it was allowed to cool naturally to room temperature. The fully polymerized sample was removed from the glass tube and polished to obtain the final product.

[0063] The following is an analysis of the pulse shape discrimination performance of the novel plastic scintillators obtained in Examples 1-9.

[0064] Figure 1 These are sample images of Examples 1, 3, 5, 7, and 9 taken under visible light.

[0065] Figure 2 These are the neutron / gamma pulse shape discrimination (PSD) spectra for Examples 1, 3, 5, 7, and 9. A 14-bit 500MS / s flash ADC waveform digitizer (CAEN DT5730S) and a Hamamatsu H1949-51 photomultiplier tube (Japan) were used. 238 The scintillator samples were irradiated with a Pu-Be neutron source, and neutron / gamma pulse shape discrimination spectra were obtained for each scintillator sample. The distribution of neutron and gamma-ray energy bands can be clearly seen in the PSD spectra; the upper band represents the pulse signal generated by neutrons, and the lower band represents the pulse signal generated by gamma rays. This demonstrates that this novel polybenzyl cinnamate-based plastic scintillator exhibits excellent neutron / gamma resolution.

[0066] Figure 3 These are the excitation-emission spectra of Examples 1 and 7. In this experiment, excitation-emission spectra of the samples (10 wt.% and 40 wt.% RG doped) were analyzed using a steady-state-transient fluorescence spectrometer (FLS1000). An excitation peak appeared at approximately 300 nm, corresponding to the fluorescence absorption of benzyl cinnamate. The characteristic emission peak of the primary fluorescent dye PPO appeared at 370 nm, and the characteristic emission peak of the secondary fluorescent dye MDAC was observed at 435 nm. The low intensity of the PPO characteristic peak at 370 nm indicates efficient energy resonance transfer of scintillation fluorescence within the fluorescent dye molecules.

[0067] Figure 4 These are the UV-Vis transmission spectra of Examples 1, 3, 7, and 9. This experiment used a UV-Vis spectrophotometer (Shimadzu UE-3600i Plus) to measure the UV-Vis transmission spectra of the scintillators in the 200-800 nm wavelength range. The results show that from 410 nm to 800 nm, the transmittance increases with increasing RG addition; the scintillators with a small amount of RG have similar transparency to those without RG.

[0068] Figure 5 The implementation methods 1, 3, 5, 7, and 9 are adopted. 137 Pulse height spectra obtained by irradiating scintillator samples with a Cs standard gamma radiation source. The scintillator doped with benzyl cinnamate has 60-70% of the optical yield of the commercial EJ276, and the optical yield increases slightly with increasing RG content (<30 wt.%).

[0069] Comparative Example 1

[0070] All other conditions were the same as in Example 5, except that the heating rate was changed. The sample was placed in an oil bath and heated at a higher rate. During the polymerization process, the temperature was unstable and the sample was not in a vacuum environment, which resulted in incomplete polymerization. The sample produced after polymerization within the same time period had very low hardness, was thin, and had residual liquid phase.

[0071] Comparative Example 2

[0072] All other conditions were the same as in Example 5. After the sample was cooled to room temperature from the drying oven, it was placed back into a vacuum drying oven at 60°C for annealing to increase its stability, and kept at that temperature for two hours. After removal, it was found that although the scintillator had high hardness, it showed slight whitening, decreased transparency, and a decline in performance.

Claims

1. A novel plastic scintillator of benzyl cinnamate-vinyl toluene (PVT) mixed matrix neutron / gamma discrimination capability, characterized by: The plastic scintillator is composed of a mixed matrix of two polymers, a primary fluorescent dye and a secondary fluorescent dye, a crosslinking agent, and an initiator, wherein the polymer matrix is benzyl cinnamate (RG) and vinyltoluene (PVT), the primary fluorescent dye is 2,5-diphenyloxazole (PPO), the secondary fluorescent dye is 7-diethylamino-4-methylcoumarin (MDAC), the crosslinking agent is divinylbenzene (DVB), and the initiator is azobisisobutyronitrile (AIBN).

2. A novel mixed matrix neutron / gamma discriminating plastic scintillator according to claim 1, characterized in that: The plastic scintillator matrix is obtained by free radical polymerization of benzyl cinnamate monomers and vinyltoluene monomers, wherein the mass fraction of benzyl cinnamate in the neutron / gamma discrimination plastic scintillator is 10-50 wt.%.

3. A novel neutron / gamma discriminating plastic scintillator according to claim 1, characterized in that: The mass fraction of the primary fluorescent dye PPO in the neutron / gamma discrimination plastic scintillator is 30 wt.%.

4. A novel neutron / gamma discriminating plastic scintillator according to claim 1, characterized in that: The mass fraction of the secondary fluorescent dye MDAC in the neutron / gamma discrimination plastic scintillator is 0.4 wt.%.

5. The method of producing a novel plastic scintillator with neutron / gamma discrimination ability according to claim 5, characterized by: The mass fraction of the crosslinking agent DVB is 4 wt.%.

6. The method for preparing a novel plastic scintillator with neutron / gamma discrimination capability according to claim 5, characterized in that: The mass fraction of the initiator AIBN is 0.08 wt.%.

7. A method of producing a novel neutron / gamma discriminating plastic scintillator according to any one of claims 1 to 6, characterized in that The following steps: weigh benzyl cinnamate (RG), PVT, PPO, MDAC, DVB, AIBN, etc. to configure a mixed solution. In order to obtain a plastic scintillator with good performance, the prepared solution needs to be pretreated; the pretreatment is to move the solution into a customized glass tube, then put it into liquid nitrogen, so that the precursor solution solidifies into a solid under the cooling of liquid nitrogen, preventing the loss of raw materials under vacuum operation; at the same time, the solution is made oxygen-free by using a Hickley device through five times of "vacuum pumping, nitrogen replacement" repeated operation, then the glass tube is sealed, and then the glass tube is placed in a vacuum drying box for heat polymerization reaction at a certain temperature, finally a new type of neutron / gamma discrimination plastic scintillator is obtained.

8. The method for preparing a novel plastic scintillator with neutron / gamma discrimination capability according to claim 7, characterized in that: The polymerization reaction process is as follows: heating from room temperature to 50 DEG C at a rate of 60 DEG C / h, keeping for 1 h; then heating to 70 DEG C at a rate of 10 DEG C / h, keeping for 12 h; then heating to 80 DEG C at a rate of 5 DEG C / h, keeping for 24 h; then cooling to 75 DEG C at a rate of 5 DEG C / h, keeping for 12 h, then cooling to 50 DEG C at a rate of 5.56 DEG C / h, keeping for 3 h, and then naturally cooling to room temperature.

9. The method for preparing the novel neutron / gamma discrimination plastic scintillator according to claim 7, characterized in that: The new benzyl cinnamate-vinyltoluene plastic scintillator can be applied to neutron detection in a pulse radiation field mixed with neutrons and gamma rays.

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