Preparation method of organic glass scintillator

Abstract

The invention provides a preparation method of an organic glass scintillator, and aims to solve the problems that the preparation of an existing organic glass scintillator is easily influenced by multiple factors such as a mold and temperature, so that the sample performance discreteness is relatively high, and the yield level is difficult to improve. According to the invention, through the multi-factor optimization combination design of mold deposition of the SiO2 nano barrier layer, pre-melting and separate melting of the raw materials, constant-temperature vacuumizing, temperature gradient cooling and annealing treatment, the comprehensive performance of the organic glass scintillator is improved, the yield level of sample preparation is remarkably improved, and the requirement of large-scale application is met.

Description

Technical Field

[0001] This invention belongs to the field of radiation detection materials technology, specifically relating to a method for preparing large-scale organic glass scintillators. Background Technology

[0002] Radiation detection technology plays an indispensable role in fields such as nuclear physics, environmental monitoring, and space science. Among these, neutron-gamma discrimination technology has attracted significant attention due to its ability to effectively distinguish and accurately measure neutron and gamma signals in mixed radiation fields. Currently, materials capable of effective neutron-gamma discrimination fall into two main categories: inorganic scintillators and organic scintillators. Their working principle involves the interaction of ionizing radiation with characteristic elements within the material, converting neutron and gamma signals into detectable optical signals. The measured photoelectric signals are then used to invert and obtain information such as radiation dose and type. Compared to inorganic scintillators, organic scintillators not only achieve effective neutron-gamma discrimination but also possess advantages such as fast response time (nanosecond level), high degree of freedom in processing and shaping, good mechanical and environmental adaptability, and low intrinsic radioactivity. They are among the most widely used and abundant scintillator materials. However, low neutron-gamma discrimination figure of merit (FOM) and low scintillator light yield have consistently been technical challenges.

[0003] Organic glass scintillators (OGS) can achieve a neutron gamma discriminant figure of merit of up to 3.7 and a light yield of 16,000 Ph / MeV, which is 2-3 times higher than that of traditional organic scintillators (such as Stilbene, EJ-276, and BC-404). They are considered one of the most promising new scintillator materials and a current research hotspot in the field of radiation detection. However, the preparation of these materials is still in the laboratory exploration stage and is not yet ready for large-scale application. This is because the preparation of OGS is easily affected by multiple factors such as mold and temperature, resulting in large performance dispersion and difficulty in improving the yield. Therefore, proposing an OGS preparation scheme based on multi-factor optimized combination design is of great significance for improving its performance and sample yield.

[0004] Reference 1, “Taking advantage of disorder: Small-molecule organic glasses for radiation detection and particle discrimination[J]. Journal of the American Chemical Society, 2017, 139(28): 9621-9626,” reports an organic glass scintillator based on a mixture of (bis(9,9-dimethyl-9H-fluoren-2-yl)diphenylsilane, P2), (phenyltris(9,9'-dimethylfluoren-2-yl)silane, P3) and a fluorescent agent (1,4-bis(2-methylstyryl)benzene, Bis-MSB). The maximum size of the prepared sample is [missing information]. The highest light yield was 16,000 Ph / MeV. And in Effective discrimination of neutron gamma signals was achieved under source radiation conditions, with a PSD-FOM value of 3.7.

[0005] Document 2 "Organic glass scintillator (OGS) property comparisons toStilbene, EJ-276 and BC-404[J]. Nuclear Instruments and Methods in PhysicsResearch Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2021, 1018: 165778." reported and The preparation results of cylindrical OGS, and in Effective discrimination of neutron gamma signals was achieved under source radiation conditions. Measurement The OGS has a PSD-FOM value of 2.9, a rise time of 0.82 ns, and a maximum light yield of 15821 Ph / MeV.

[0006] Reference 3, "Adamowski L, Grodzicka-Kobylka M, Szczesniak T, et al. Influence of Self-Absorption on Pulse Shape Discrimination in Organic Glass Scintillators[J]. arxiv preprint arxiv: 2505.08513, 2025," reports the preparation results of cylindrical OGS with a diameter of 25.4 mm and heights of 25 mm, 55 mm, 78 mm, 102 mm, and 125 mm. The highest PSD-FOM value of 2.37 was measured under PuBe neutron source irradiation conditions. The highest light yield under gamma source conditions was 4730 Ph / Mev.

[0007] All of the above literature has achieved the preparation of plexiglass scintillator samples of a certain size, and the samples all have good neutron-gamma discrimination ability. However, the OGS test results in the above literature show that the neutron-gamma discrimination figure of merit (FOM) and light yield have strong dispersion, the number of samples is limited and the yield is low, which does not yet meet the requirements for large-scale application. Summary of the Invention

[0008] This invention addresses the problem that the preparation of acrylic scintillators is easily affected by multiple factors such as mold and temperature, resulting in large performance dispersion and difficulty in improving the yield. It provides a new method for preparing acrylic scintillators. By adopting an OGS preparation scheme based on multi-factor optimized combination design, the overall performance can be improved and the yield of sample preparation can be significantly increased, meeting the requirements of large-scale application.

[0009] The concept of this invention:

[0010] To address the problem that the preparation of acrylic scintillators is easily affected by multiple factors such as molds and temperature, resulting in large performance dispersion and difficulty in improving the yield rate, this invention, after careful analysis, found that the root cause is the residual internal stress of the acrylic scintillator and the surface interface bubble problem caused by casting molds and synthesis processes. This is the fundamental reason for the large performance dispersion and low yield rate. Therefore, this invention proposes to optimize the design in the following aspects:

[0011] I. Reduce mold-related factors

[0012] 1. Pre-deposited SiO2 nanobarrier layer

[0013] Pre-depositing a SiO2 nano barrier layer on the inner surface of the mold can effectively passivate defects such as scratches and micropores on the inner surface of the mold, significantly reduce the roughness of the inner surface of the mold, reduce the density of adhesion sites between the OGS surface and the inner surface of the mold, and avoid OGS cracking and surface damage caused by adhesion during demolding.

[0014] 2. Preheating and vacuum treatment

[0015] Preheating can effectively eliminate gas adsorption on the mold surface, and vacuum treatment can effectively remove gas from the molten raw material. The combination of the two can significantly reduce the gas content in the system, reduce the amount of bubbles generated during the curing process, and also reduce the internal stress caused by excessive temperature difference.

[0016] II. Reducing Process Influencing Factors

[0017] 1. The step-by-step pre-melting raw material method involves first pre-melting the high-melting-point raw material, which allows the system temperature to naturally reach a state higher than the melting point of all components. Then, when the low-melting-point components are added, they can melt quickly and uniformly.

[0018] 2. Reducing the cooling rate of the OGS melt can effectively remove bubbles present during the synthesis process, while also reducing and lowering residual internal stress generated during cooling.

[0019] 3. OGS melt isothermal vacuum treatment can slowly extract the gas generated during the casting process, effectively reduce the bubble content at the OGS surface interface, and also improve the transparency and light transmittance of the obtained OGS solid.

[0020] 4. OGS solid annealing treatment can almost completely eliminate the internal stress generated during melting, casting and cooling, which greatly improves the mechanical properties of OGS samples.

[0021] The optimized design combination of the above-mentioned mold treatment before melting, pre-melting and temperature rate treatment during melting, and solid treatment after casting can effectively solve the problems of residual internal stress and surface bubbles in plexiglass scintillators caused by multiple factors such as mold and temperature. This achieves the goal of improving its overall performance and significantly increasing the product preparation yield, so as to facilitate the large-scale production of plexiglass scintillators.

[0022] Based on the above inventive concept, and to achieve the above objectives, the technical solution provided by this invention is as follows:

[0023] A method for preparing an plexiglass scintillator, characterized by the following steps:

[0024] 1) Preprocessing

[0025] Pre-treatment includes mold preparation and raw material pre-melting and separation;

[0026] The mold treatment can be completed before OGS casting, aiming to prevent large internal stresses caused by rapid cooling during the casting of liquid acrylic glass, including the following steps:

[0027] A1. Low-temperature deposition of SiO2 nano-barrier layer on the clean and smooth inner surface of the mold;

[0028] A2. Place the mold in a drying oven for preheating to prevent the melt from cooling rapidly after being poured into the mold due to a large temperature difference. The preheating temperature is 130-150 ℃ (the preheating temperature varies slightly depending on the mold material, but it is all lower than the maximum temperature that the mold can withstand. The glass transition temperature Tg of OGS is around 80 ℃. Considering that there will be heat loss during the casting process after preheating, the preheating temperature is higher than the glass transition temperature of OGS). The preheating time is 10-30 min.

[0029] The pre-melting and partial melting of the raw materials includes the following steps:

[0030] B1. First, add the weighed tris(9,9-dimethylfluorene)butylsilane (P3) or tris(4-biphenyl)phenylsilane (PB3) to a capped glass bottle (other containers can also be used, but glass bottles are easier to observe). Connect the glass bottle to the vacuum pump and nitrogen cylinder, tighten the cap, turn on the vacuum pump, and evacuate the glass bottle until the vacuum degree is less than 100 mmHg. Then heat the glass bottle and continue to keep it warm for 10-30 minutes after P3 or PB3 has completely melted to make P3 or PB3 melt more fully.

[0031] B2. After heat preservation in step B1, reduce the temperature inside the glass bottle to 145-160 ℃, stop vacuuming, and introduce nitrogen into the glass bottle to balance the gas pressure inside and outside the glass bottle. After standing for 3-5 minutes, unscrew the bottle cap and add the weighed bis(9,9-dimethylfluorene)diphenylsilane (P2) into the glass bottle. After adding, quickly tighten the bottle cap and vacuum to a vacuum degree of less than 100 mmHg. Heat preservation at 145-160 ℃ to allow P2 to completely melt and mix with molten P3 or PB3. Then continue to heat preservation for 10-30 minutes.

[0032] B3. Turn off the vacuum pump and stop evacuation. Pour nitrogen into the glass bottle after the heat preservation in step B2 to balance the gas pressure inside and outside the glass bottle. After standing for 3-5 minutes, unscrew the bottle cap and add the weighed (1,4-bis(2-methylstyrene)benzene (Bis-MSB) into the glass bottle. After adding, quickly tighten the bottle cap and evacuate to a vacuum degree of less than 100 mmHg. Keep the temperature at 145-160 ℃ to completely melt Bis-MSB and mix it with the molten material obtained in step B2 (molten P2+P3, or molten P2+PB3) to form OGS melt. Then continue to keep the temperature for 10-30 minutes.

[0033] The three raw materials used to synthesize the organic glass scintillator have different melting points. The highest melting point P3 / PB3 is around 203 ℃ / 175 ℃, while the melting points of P2 and Bis-MSB are around 145 ℃. Therefore, the raw material pre-melting process involves first melting P3 / PB3, then melting P2, and finally melting Bis-MSB to adjust the melt mixture of the first two raw materials.

[0034] 2) OGS casting

[0035] Turn off the vacuum pump and stop vacuuming. Pour nitrogen into the insulated glass bottle to balance the gas pressure inside and outside the glass bottle. After standing for 3-5 minutes, slowly unscrew the bottle cap and pour the OGS melt into the preheated mold in time.

[0036] 3) Constant temperature vacuum

[0037] The mold containing the OGS melt is placed in a vacuum drying oven at a temperature of 135-155 ℃, and the vacuum drying oven is evacuated (vacuum degree less than 20 mmHg) to eliminate air bubbles in the plexiglass scintillator. The evacuation time is 1 h-6 h, and the evacuation time of the plexiglass scintillator varies depending on its size. Then the temperature is lowered to 105 ℃ at a rate of 1 ℃ every 0.5-1 hour.

[0038] 4) Gradient cooling

[0039] The mold containing the OGS melt was transferred to a forced-air drying oven for cooling to obtain an acrylic scintillator.

[0040] The cooling curve is as follows:

[0041] Starting from 105 ℃, for volumes V ≤ 2455 mm² 3 The cooling profile of the OGS melt was as follows: 105 °C, held for 0.3 h; 100 °C, held for 1 h; 95 °C, held for 1 h; 90 °C, held for 2 h; 85 °C, held for 2 h; 80 °C, held for 2 h; 75 °C, held for 1 h; 25 °C, held for 1 h; for every 500 mm increase in volume V... 3 Increase the heat preservation time at each temperature point by 10-20 minutes;

[0042] Taking OGS melt with a diameter of 25mm as an example, The entire cooling process for the OGS melt is as shown in the cooling curve above: 105 ℃ (0.3h) - 100 ℃ (1h) - 95 ℃ (1h) - 90 ℃ (2h) - 85 ℃ (2h) - 80 ℃ (2h) - 75 ℃ (1h) - 25 ℃ (1h). Based on this temperature gradient standard, for cylindrical OGS of the same diameter, the holding time increases by 10-20 min for every 1mm increase in thickness. The specific temperature gradient varies depending on the size, volume, shape, and temperature of the OGS melt.

[0043] 5) Annealing treatment

[0044] Remove the acrylic scintillator from the mold (be careful to avoid improper stress during removal to prevent cracking or breakage), place it in a drying oven and anneal at 50-60 ℃ for 5-10 h to reduce residual internal stress, and obtain the acrylic scintillator.

[0045] Furthermore, it also includes:

[0046] Step 6) Coating and Preservation

[0047] A protective film is formed by coating the surface of the plexiglass scintillator obtained in step 5 with a PVA solution and storing it in a glove box to prevent the plexiglass scintillator from aging.

[0048] Furthermore, A1 in the mold processing procedure specifically refers to:

[0049] A1.1 Place the mold in acetone or ethanol for ultrasonic cleaning to remove oil and particles;

[0050] A1.2 A SiO2 nano barrier layer with a thickness of 50-200 nm is deposited on the clean and smooth inner surface of the mold using plasma-enhanced chemical vapor deposition or plasma-enhanced physical vapor deposition.

[0051] A1.3 The mold is annealed in a vacuum environment to reduce internal stress. The annealing temperature is 180-230 ℃.

[0052] Furthermore, in A1.2, the process parameters for plasma-enhanced chemical vapor deposition are as follows:

[0053] The precursor, i.e., the gaseous reactant, forms a plasma upon excitation. This plasma is a 1:10 volume ratio of silane (SiH4) and nitrous oxide (N2O) or oxygen (O2). The radio frequency power is 50-300 W to excite the plasma; the temperature is 140-200 ℃, adjusted according to the heat resistance of the mold; the pressure is 50-500 Pa; and the time is 30-120 min. This yields a SiO2 nanolayer barrier with a thickness of 50-200 nm. Plasma-enhanced chemical vapor deposition (PECVD) is suitable for low-temperature deposition, below 200 ℃. This not only avoids mold deformation but also produces a dense, uniform SiO2 film with strong adhesion.

[0054] Furthermore, in B1, the heating temperature of P3 is 203-220 ℃, and the heating temperature of PB3 is 175-190 ℃.

[0055] Furthermore, the mold is made of ceramic, aluminum, silicone, Teflon, or graphite material, with silicone being preferred due to its low surface adhesion.

[0056] Furthermore, the PVA solution is an aqueous solution prepared from polyvinyl alcohol and silicone oil.

[0057] The present invention also provides an organic glass scintillator prepared by the above preparation method.

[0058] The principle of this invention:

[0059] This invention improves the residual internal stress of acrylic scintillators, the bubble condition at the surface interface of acrylic scintillators, and the difficulty of demolding after casting through the following four aspects, thereby improving the large-scale application of acrylic scintillators and enabling them to be mass-produced and applied to neutron gamma discrimination technology.

[0060] Firstly, for depositing SiO2 nano barrier layers on the surface of the selected mold, the main chemical vapor deposition (CVD) or physical vapor deposition (PVD) technologies are based on the principle of achieving deposition through chemical reactions or physical processes. This reduces the roughness of the acrylic scintillator, decreases its surface defects, lowers demolding resistance, avoids adhesion, and makes it easier for the acrylic scintillator to separate from the mold.

[0061] Secondly, regarding the temperature gradient cooling process and annealing treatment for reducing residual internal stress in acrylic scintillators, firstly, the temperature gradient is reduced; slow cooling decreases the temperature difference between the inside and outside of the glass, reducing shrinkage differences and thus avoiding severe stress concentration. Secondly, molecular structure is adjusted (relaxation); in the glass transition temperature region (Tg), molecules still have slight mobility; slow cooling provides sufficient time for molecules to rearrange and reach a more stable low-energy state, reducing structural stress. Thirdly, stress relaxation occurs; at high temperatures (close to Tg), the viscoelasticity of the glass allows stress to be gradually released through molecular motion.

[0062] Thirdly, the isothermal vacuum process for eliminating bubbles in plexiglass scintillators mainly involves reducing the ambient air pressure, thereby reducing the solubility of the gas in the liquid plexiglass and providing the impetus for the expansion and escape of the bubbles, ultimately causing the bubbles to burst and the gas to be pumped away by the vacuum pump.

[0063] Fourthly: Regarding the partial melting of P3 / PB3, P2, and Bis-MSB, as well as the pre-melting of P3 / PB3, P3 / PB3 has the highest melting point. The principle of pre-melting P3 / PB3 is based on both thermodynamics and kinetics. Thermodynamically, the system is heated to a temperature above the melting point of the high-melting-point substance to ensure sufficient heat capacity and intensity for the phase transition. Once the high-melting-point substance melts, the system temperature naturally becomes higher than the melting points of all components. Adding the low-melting-point component at this point allows for rapid and uniform melting. Kinetically, melting the high-melting-point substance first sets the necessary "starting temperature" for the entire reaction system, ensuring efficient execution of all subsequent steps.

[0064] Advantages of this invention:

[0065] This invention provides a novel method for the mass production of acrylic scintillators with low demolding resistance, low residual internal stress, and low surface bubble ratio.

[0066] 1. This invention provides a method for easily demolding acrylic scintillators by vapor-depositing a SiO2 nano-barrier layer on the mold surface. This method reduces the surface roughness of the acrylic scintillator, decreases surface defects, lowers demolding resistance, prevents adhesion, facilitates separation of the acrylic scintillator from the mold, promotes melt flow, reduces thermal stress and cracking risk, and avoids excessive bubble formation at the surface interface. Tests show that the surface roughness (Ra) of scintillators prepared using the SiO2 nano-barrier layer mold can be reduced to ≤0.1 µm, while the surface roughness (Ra) of samples prepared using traditional molds is 0.5-1.0 µm. Demolding force tests show that the method of this invention reduces the average demolding force from 150 N in traditional methods to 30 N, a reduction of 80%, completely avoiding adhesion and cracking during demolding. The product defect rate due to surface defects is also reduced from 70% to <10%.

[0067] 2. This invention provides a method that differs from the single-temperature melting method reported in the literature. Instead, P3 / PB3 is pre-melted at its melting point, the temperature is slowly increased to the melting point, and then held at that temperature for a certain period of time to ensure complete melting. Then, P2 and Bis-MSB are added to the fully molten P3 / PB3 under vacuum conditions, and the mixture is melted at the latter's melting point. Compared with the traditional direct mixing and melting method, the organic glass scintillator obtained by fractional melting has a more uniform composition, higher light transmittance (increasing from 50% to approximately 80%), reduced surface roughness, fewer defects, and more controllable structure. It also facilitates the elimination of bubbles and streaks.

[0068] 3. This invention provides a method for eliminating air bubbles in acrylic scintillators. Before the liquid acrylic cools and solidifies, air bubbles are removed using a constant-temperature vacuum process. Compared to directly cooling the liquid or placing it in a drying oven overnight, this method completely eliminates air bubbles at the surface interface of the acrylic scintillator, reduces surface defects, and makes the acrylic scintillator more complete and smooth. Polarizing microscopy observation and analysis showed that after the constant-temperature vacuum treatment, the number of air bubbles with a diameter greater than 50 µm inside the sample was zero. In contrast, samples cooled using traditional methods contained an average of [missing information - likely air bubbles]. The method of the present invention eliminates 100% of the surface area of ​​the plexiglass scintillator, free of bubble defects. Image analysis shows that the method of the present invention makes 100% of the surface area of ​​the plexiglass scintillator free of bubble defects.

[0069] 4. This invention provides a slow cooling temperature gradient procedure and annealing method to reduce residual internal stress. Before the liquid acrylic glass solidifies, the cast liquid acrylic glass is placed in a drying oven and subjected to a slow cooling temperature gradient procedure. After obtaining the solid acrylic scintillator, annealing is then performed. Compared with traditional cooling and solidification methods, this method significantly reduces the residual internal stress inside the acrylic scintillator, resulting in fewer stress fringes observed under an optical microscope, almost eliminating them. Under a polarizing microscope, samples treated with gradient cooling and annealing show almost no stress fringes, with an optical path difference of less than 10 nm / cm, meeting the standard for low-stress optical elements. In contrast, rapidly cooled samples have optical path differences exceeding 100 nm / cm. After 10 thermal cycles at 90-110 °C, 98% of the annealed samples remained intact, while the cracking rate of untreated samples exceeded 35%. After annealing, the dimensional stability of the acrylic scintillator is significantly improved, and its coefficient of thermal expansion decreases by 15%.

[0070] 5. Based on solving the problems of residual internal stress and surface bubbles, this invention also improves the PSD-FOM value of samples of the same size from 2.0 to 3.3, reduces the dispersion of the samples, and makes the PSD-FOM value of the samples ≥ 2.7. Attached Figure Description

[0071] Figure 1 This is an image of the plexiglass scintillator prepared in Comparative Example 1, which is filled with bubbles and impurities;

[0072] Figure 2 This is an image of the plexiglass scintillator prepared in Comparative Example 1, whose upper surface is filled with bubbles;

[0073] Figure 3 The image shows the plexiglass scintillator prepared in Comparative Example 1, which has some bubbles and impurities, but is highly transparent.

[0074] Figure 4 This is an image showing the large internal stress of the plexiglass scintillator prepared in Comparative Example 1 under a polarizing microscope;

[0075] Figure 5 These are images of the upper surface and the overall structure of the plexiglass scintillator prepared in Example 1 under a polarizing microscope;

[0076] Figure 6 This is a side view of the plexiglass scintillator prepared in Example 1;

[0077] Figure 7 These are PSD-FOM comparison images of samples of the same size from Example 3 and Comparative Example 6, where (a) is Comparative Example 6 and (b) is Example 3;

[0078] Figure 8 This is a comparison chart of PSD-FOM of three samples of the same size prepared in Example 2. Detailed Implementation

[0079] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0080] This invention provides a method for the large-scale preparation and synthesis of organic glass scintillators. The specific preparation and synthesis method is as follows:

[0081] Example 1:

[0082] A method for large-scale preparation of acrylic scintillators addresses issues such as demolding, surface bubbles, and residual internal stress, thereby reducing product dispersion and improving yield. The main preparation process includes pre-melting P3, adding P2 and Bis-MSB after P3 is completely melted, maintaining the melt temperature, casting it into a preheated mold, placing the mold in a vacuum drying oven for constant temperature vacuuming, and then placing it in a drying oven with a cooling program for slow gradient cooling. The resulting acrylic scintillator is annealed and then stored. The specific preparation steps are as follows:

[0083] 1) Choose one A cylindrical silicone mold.

[0084] 2) Deposit a SiO2 nano barrier layer on the inner surface of the mold.

[0085] Plasma-enhanced chemical vapor deposition (PECVD) was employed at a temperature of 180 °C. The PECVD process first involved pre-treating the silicone mold surface using acetone and ethanol via ultrasonic cleaning to remove oil and particles, followed by plasma treatment to activate the mold surface. The deposition parameters were: silane (SiH4) and oxygen (O2) as precursors, with a volume ratio of 1:10; RF power of 300 W to excite the plasma; temperature of 140 °C; pressure of 150 Pa; time of 60 min; and a film thickness of 100 nm. Subsequent annealing at 180 °C in a vacuum environment reduced internal stress, ultimately yielding a deposited SiO2 nanolayer barrier layer. Cylindrical silicone mold.

[0086] 3) Raw material melting

[0087] First, P3 is pre-melted. Using a balance and weighing paper, 400 mg of P3 is weighed with a spatula and poured into a capped glass bottle. The glass bottle is then connected to a vacuum pump and a nitrogen cylinder. The vacuum pump is turned on and the vacuum is evacuated until the vacuum level is less than 100 mmHg. The glass bottle is then heated. After the glass bottle is placed in a mold, it is placed on a heating table and heated to ensure that the actual heating temperature is 210 ℃, which is above the melting point of P3 to ensure complete melting. The temperature is then maintained for 15 min.

[0088] After P3 is completely melted, the temperature is set to 160 °C and cooling begins. During cooling, 3600 mg of P2 and 2 mg of Bis-MSB are weighed on weighing paper using a balance for later use. When the temperature reaches 160 °C, the vacuum pump is turned off, and the vacuuming process is stopped. Nitrogen gas is introduced into the insulated glass bottle to balance the pressure inside and outside the bottle. After standing for 3 minutes, the cap is slowly unscrewed, and the weighed bis(9,9-dimethylfluorene)diphenylsilane (P2) is added into the glass bottle. After adding the bis(9,9-dimethylfluorene)diphenylsilane (P2) is added, and the cap is quickly tightened. The vacuum is then evacuated to a vacuum level of less than 100 mmHg. The bottle is kept at 160 °C to allow P2 to completely melt and mix with the molten P3. The temperature is then maintained for another 10 minutes to allow P2 and P3 to fully melt. The vacuum pump is turned off, and the vacuuming process is stopped. Nitrogen gas is introduced into the insulated glass bottle to balance the pressure inside and outside the bottle. The bottle is then left to stand for 3 minutes. After min, slowly unscrew the cap and add the weighed Bis-MSB into the glass bottle. After adding, quickly tighten the cap and evacuate to a vacuum level of less than 100 mmHg. Keep the bottle at 160 ℃ to allow Bis-MSB to completely melt and mix with the molten P2 and P3 to form OGS melt. Then continue to keep the bottle at 15 min.

[0089] While waiting for the three raw materials to completely melt, preheat the mold at 145 ℃ for 10 min.

[0090] 4) After the raw material is melted and kept at a constant temperature for 15 minutes, turn off the vacuum pump and stop vacuuming. Introduce nitrogen into the glass bottle after it has been kept at a constant temperature to make the gas pressure inside the glass bottle equal to the atmospheric pressure. After standing for 3 minutes, slowly unscrew the bottle cap and take out the preheated mold at the same time. Use high-temperature gloves to quickly pour the OGS melt from the glass bottle into the preheated mold.

[0091] 5) Set the temperature in the vacuum drying oven to 145 ℃, quickly put the mold into the drying oven, and then slowly evacuate the vacuum until the vacuum degree is less than 20 mmHg. The evacuation time is 1 h, and then the temperature is lowered to 105 ℃.

[0092] 6) After vacuuming is complete, place it in a forced-air drying oven and set a temperature gradient cooling program. The entire cooling program is 105 ℃ (1h) - 100 ℃ (2h) - 95 ℃ (2h) - 90 ℃ (3h) - 85 ℃ (3h) - 80 ℃ (3h) - 75 ℃ (2h) - 25 ℃ (2h), and start cooling slowly.

[0093] 7) After the cooling process is complete, open the drying oven, remove the mold, and gently remove the acrylic scintillator from the mold to obtain... The cylindrical organic glass scintillator is then annealed in a drying oven at 50 ℃ for 8 h.

[0094] 8) After annealing, the resulting acrylic scintillator is photographed under a fluorescent plate and then coated with PVA before being stored in a glove box.

[0095] Ten samples were prepared using this method. Products, such as Figure 5 and Figure 6 As shown, the average demolding resistance is 30 N, the number of bubbles with a diameter greater than 50 μm inside the sample is 0, and the location of the bubbles is basically at the edge of the OGS surface. There are no bubbles in other locations. The transmittance is about 80%. After temperature gradient cooling time and annealing, almost no stress stripes can be observed in the sample. The occasional cracks are also basically at the edge of the OGS surface. There is no internal stress. Finally, there are 8-9 qualified samples.

[0096] Example 2:

[0097] A method for large-scale preparation of acrylic scintillators addresses issues such as demolding, surface bubbles, and residual internal stress, thereby reducing product dispersion and improving yield. The main preparation process includes pre-melting P3, adding P2 and Bis-MSB after P3 is completely melted, maintaining the melt temperature, casting it into a preheated mold, placing the mold in a vacuum drying oven for constant temperature vacuuming, and then placing it in a drying oven with a cooling program for slow gradient cooling. The resulting acrylic scintillator is annealed and then stored. The specific preparation steps are as follows:

[0098] 1) Choose one A cylindrical silicone mold.

[0099] 2) Deposit a SiO2 nano barrier layer on the inner surface of the mold.

[0100] Plasma-enhanced chemical vapor deposition (PECVD) was employed at a temperature of 180 °C. The PECVD process first involved pre-treating the silicone mold surface using acetone and ethanol via ultrasonic cleaning to remove oil and particles, followed by plasma treatment to activate the mold surface. The deposition parameters were: silane (SiH4) and oxygen (O2) as precursors, with a volume ratio of 1:10; RF power of 300 W to excite the plasma; temperature of 140 °C; pressure of 150 Pa; time of 60 min; and a film thickness of 100 nm. Subsequent annealing at 200 °C in a vacuum environment reduced internal stress, ultimately yielding a deposited SiO2 nanolayer barrier layer. Cylindrical silicone mold.

[0101] 3) Raw material melting

[0102] First, P3 is pre-melted. Using a balance and weighing paper, 400 mg of P3 is weighed with a spatula and poured into a capped glass bottle. The glass bottle is then connected to a vacuum pump and a nitrogen cylinder. The vacuum pump is turned on and the vacuum is evacuated until the vacuum level is less than 100 mmHg. The glass bottle is then heated. After the glass bottle is placed in a mold, it is placed on a heating table and heated to ensure that the actual heating temperature is 210 ℃, which is above the melting point of P3 to ensure complete melting. The temperature is then maintained for 15 min.

[0103] After P3 is completely melted, the temperature is set to 160 °C and cooling begins. During cooling, 3600 mg of P2 and 2 mg of Bis-MSB are weighed on weighing paper using a balance for later use. When the temperature reaches 160 °C, the vacuum pump is turned off, and the vacuuming process is stopped. Nitrogen gas is introduced into the insulated glass bottle to balance the pressure inside and outside the bottle. After standing for 3 minutes, the cap is slowly unscrewed, and the weighed bis(9,9-dimethylfluorene)diphenylsilane (P2) is added into the glass bottle. After adding the bis(9,9-dimethylfluorene)diphenylsilane (P2) is added, and the cap is quickly tightened. The vacuum is then evacuated to a vacuum level of less than 100 mmHg. The bottle is kept at 160 °C to allow P2 to completely melt and mix with the molten P3. The temperature is then maintained for another 10 minutes to allow P2 and P3 to fully melt. The vacuum pump is turned off, and the vacuuming process is stopped. Nitrogen gas is introduced into the insulated glass bottle to balance the pressure inside and outside the bottle. The bottle is then left to stand for 3 minutes. After min, slowly unscrew the cap and add the weighed Bis-MSB into the glass bottle. After adding, quickly tighten the cap and evacuate to a vacuum level of less than 100 mmHg. Keep the bottle at 160 ℃ to allow Bis-MSB to completely melt and mix with the molten P2 and P3 to form OGS melt. Then continue to keep the bottle at 15 min.

[0104] While waiting for the three raw materials to completely melt, preheat the mold at 135 ℃ for 15 min.

[0105] 4) After the raw material is melted and kept at a constant temperature for 15 minutes, turn off the vacuum pump and stop vacuuming. Introduce nitrogen into the glass bottle after it has been kept at a constant temperature to make the gas pressure inside the glass bottle equal to the atmospheric pressure. After standing for 3 minutes, slowly unscrew the bottle cap and take out the preheated mold at the same time. Use high-temperature gloves to quickly pour the OGS melt from the glass bottle into the preheated mold.

[0106] 5) Set the temperature in the vacuum drying oven to 155 ℃, quickly put the mold into the drying oven, and then slowly evacuate the vacuum until the vacuum degree is less than 20 mmHg. The evacuation time is 1 h, and then the temperature is lowered to 105 ℃.

[0107] 6) After vacuuming is complete, place it in a forced-air drying oven and set the temperature gradient cooling program: 105 ℃ (1h) - 100 ℃ (2h) - 95 ℃ (2h) - 90 ℃ (3h) - 85 ℃ (3h) - 80 ℃ (3h) - 75 ℃ (2h) - 25 ℃ (2h) and start to cool down slowly.

[0108] 7) After the cooling process is complete, open the drying oven, remove the mold, and gently remove the acrylic scintillator from the mold to obtain... The cylindrical acrylic scintillator was then annealed in a drying oven at 60 °C for 6 h.

[0109] 8) After annealing, the resulting acrylic scintillator is photographed under a fluorescent plate and then coated with PVA before being stored in a glove box.

[0110] Ten samples were prepared using this method. The product had an average demolding resistance of 29 N, zero bubbles with an internal diameter greater than 50 µm, and the bubbles were mainly located at the edge of the OGS surface, with no bubbles in other locations. The transmittance was around 82%. After temperature gradient cooling and annealing, almost no stress striations were observed in the samples. Occasional cracks were also mainly located at the edge of the OGS surface, and there was no internal stress. Finally, 8-9 samples passed the quality test.

[0111] Example 3:

[0112] A method for large-scale preparation of acrylic scintillators addresses issues such as demolding, surface bubbles, and residual internal stress, thereby reducing product dispersion and improving yield. The main preparation process includes pre-melting P3, adding P2 and Bis-MSB after P3 is completely melted, maintaining the melt temperature, casting it into a preheated mold, placing the mold in a vacuum drying oven for constant temperature vacuuming, and then placing it in a drying oven with a cooling program for slow gradient cooling. The resulting acrylic scintillator is annealed and then stored. The specific preparation steps are as follows:

[0113] 1) Choose one A cylindrical silicone mold.

[0114] 2) Deposit a SiO2 nano barrier layer on the inner surface of the mold.

[0115] Plasma-enhanced chemical vapor deposition (PECVD) was employed at a temperature of 180 °C. The PECVD process first involved pre-treating the silicone mold surface using acetone and ethanol via ultrasonic cleaning to remove oil and particles, followed by plasma treatment to activate the mold surface. The deposition parameters were: silane (SiH4) and oxygen (O2) as precursors, with a volume ratio of 1:10; RF power of 300 W to excite the plasma; temperature of 140 °C; pressure of 150 Pa; time of 60 min; and a film thickness of 100 nm. Subsequent annealing at 200 °C in a vacuum environment reduced internal stress, ultimately yielding a deposited SiO2 nanolayer barrier layer. Cylindrical silicone mold.

[0116] 3) Raw material melting

[0117] First, P3 was pre-melted. Using a balance and weighing paper, 833.4 mg of P3 was weighed with a spatula and poured into a capped glass bottle. The glass bottle was then connected to a vacuum pump and a nitrogen cylinder. The vacuum pump was turned on and the vacuum was evacuated until the vacuum level was less than 100 mmHg. The glass bottle was then heated. After the glass bottle was placed in a mold, it was placed on a heating table and heated to ensure that the actual heating temperature was 210 ℃, which is above the melting point of P3 to ensure complete melting. The temperature was then maintained for 20 minutes.

[0118] After P3 is completely melted, the temperature is set to 160 °C and cooling begins. During cooling, 7500 mg of P2 and 4.17 mg of Bis-MSB are weighed on weighing paper using a balance for later use. When the temperature reaches 160 °C, the vacuum pump is turned off, and the vacuuming process is stopped. Nitrogen gas is introduced into the insulated glass bottle to balance the pressure inside and outside the bottle. After standing for 3 minutes, the cap is slowly unscrewed, and the weighed bis(9,9-dimethylfluorene)diphenylsilane (P2) is added into the glass bottle. After adding the bis(9,9-dimethylfluorene)diphenylsilane (P2) is added, the cap is quickly tightened, and the vacuum is evacuated to a vacuum level of less than 100 mmHg. The bottle is kept at 160 °C to allow P2 to completely melt and mix with the molten P3. The temperature is then maintained for another 30 minutes to allow P2 and P3 to fully melt. The vacuum pump is turned off, and the vacuuming process is stopped. Nitrogen gas is introduced into the insulated glass bottle to balance the pressure inside and outside the bottle. The bottle is then left to stand for 3 minutes. After min, slowly unscrew the bottle cap and add the weighed Bis-MSB into the glass bottle. After adding, quickly tighten the bottle cap and evacuate to a vacuum degree of less than 100 mmHg. Keep the temperature at 160 ℃ to allow Bis-MSB to completely melt and mix with the molten P2 and P3 to form OGS melt. Then continue to keep the temperature for 20 min.

[0119] While waiting for the three raw materials to completely melt, preheat the mold at 145 ℃ for 30 min.

[0120] 4) After the raw material is melted and kept at a constant temperature for 20 minutes, turn off the vacuum pump and stop vacuuming. Introduce nitrogen into the glass bottle after it has been kept at a constant temperature to make the gas pressure inside the glass bottle equal to the atmospheric pressure. After standing for 3 minutes, slowly unscrew the bottle cap, take out the preheated mold, and use high-temperature gloves to quickly pour the OGS melt from the glass bottle into the preheated mold.

[0121] 5) Set the temperature in the vacuum drying oven to 150 ℃, quickly put the mold into the drying oven, and then slowly evacuate the vacuum until the vacuum degree is less than 20 mmHg. The evacuation time is 3 h, and then the temperature is reduced to 105 ℃.

[0122] 6) After vacuuming is complete, place it in a forced-air drying oven and set the temperature gradient cooling program: 105 ℃ (2h) - 100 ℃ (3h) - 95 ℃ (3h) - 90 ℃ (4h) - 85 ℃ (4h) - 80 ℃ (4h) - 75 ℃ (3h) - 25 ℃ (3h) and start to cool down slowly.

[0123] 7) After the cooling process is complete, open the drying oven, remove the mold, and gently remove the acrylic scintillator from the mold to obtain... The cylindrical organic glass scintillator was then annealed in a drying oven at 60 ℃ for 10 h.

[0124] 8) After annealing, the resulting acrylic scintillator is photographed under a fluorescent plate and then coated with PVA before being stored in a glove box.

[0125] Ten samples were prepared using this method. The average demolding resistance of the product is 35 N. The number of bubbles with an internal diameter greater than 50 µm is 0. The bubbles are mainly located at the edge of the OGS surface, and there are no bubbles in other locations. The transmittance is about 75%. After temperature gradient cooling time and annealing, almost no stress striations can be observed in the samples. The occasional cracks are also basically at the edge of the OGS surface, and there is no internal stress. Finally, there are 7-8 samples that meet the quality standards.

[0126] Comparative Example 1:

[0127] A method for preparing an acrylic scintillator includes melting and holding P3, P2, and Bis-MSB raw materials at a constant temperature, casting them into a preheated mold, and then placing the mold into a drying oven with a cooling program for gradient cooling. The resulting acrylic scintillator is then stored. The specific preparation steps are as follows:

[0128] 1) Choose one A cylindrical silicone mold.

[0129] 2) To melt the raw materials, first use a balance and weighing paper to weigh 400 mg of P3, 3600 mg of P2 and 2 mg of Bis-MSB with a spatula, and add them together to a glass bottle with a cap. Then connect the glass bottle to a vacuum pump and a nitrogen cylinder. Turn on the vacuum pump and evacuate to a vacuum degree of less than 100 mmHg. Heat the glass bottle and keep it at this temperature for 15 minutes after the raw materials are completely melted. Then turn off the vacuum pump and stop evacuating. Pour nitrogen into the glass bottle after it has been kept at this temperature so that the gas pressure inside the glass bottle is equal to the atmospheric pressure, that is, the vacuum gauge reading is 0.

[0130] 3) While waiting for the three raw materials to completely melt, preheat the mold at 145 ℃ for 10 min.

[0131] 4) After the raw material is melted and kept at a constant temperature for 15 minutes, turn off the vacuum pump and stop vacuuming. Introduce nitrogen into the glass bottle after it has been kept at a constant temperature to make the gas pressure inside the glass bottle equal to the atmospheric pressure. After standing for 3 minutes, slowly unscrew the bottle cap and take out the preheated mold at the same time. Use high-temperature gloves to quickly pour the OGS melt from the glass bottle into the preheated mold.

[0132] 5) Place the mold in a drying oven and let it cool from 105 ℃ to 25 ℃ for 6-8 hours;

[0133] 6) After the cooling process is complete, open the drying oven, remove the mold, and gently remove the acrylic scintillator from the mold to obtain the final product. The cylindrical acrylic scintillator was photographed under a fluorescent plate, then coated with PVA and stored in a glove box.

[0134] The above method is a traditional way to prepare and synthesize acrylic scintillators. Ten scintillators were obtained using this method. Samples, such as Figures 1-4 As shown, the same problem arises during the demolding process, with an average demolding resistance of 100 N; the sample contains an average of The samples contained bubbles, and the location and number of bubbles varied, showing a large dispersion and no regularity. The average transmittance was around 50%, and the cracking rate of the samples was 37%. The cracks and fractures were different at each location, and only 1-2 samples ultimately passed the quality test.

[0135] Comparative Example 2:

[0136] The difference between the preparation process of this comparative example and that of Example 1 is that the raw material pre-melting and separation process is not carried out, but rather co-melting is performed, while the rest of the operation process is the same.

[0137] Ten were prepared using this method. Compared to the product obtained in Example 1, the average demolding resistance of the product was 28 N. The number of bubbles with an internal diameter greater than 50 µm was zero, and the bubbles were primarily located at the edges of the OGS surface. The transmittance was approximately 60%. The obtained samples were slightly yellowish and contained some small black flakes. Stress striations were almost invisible in the samples treated with gradient cooling and annealing. Occasional cracks were also primarily located at the edges of the OGS surface. The lack of pre-melting and separation of the raw materials mainly affected the color and purity of the OGS samples, thus impacting the transparency. Excluding color and impurity factors, 8-9 samples ultimately met the quality standards.

[0138] Comparative Example 3:

[0139] The difference between this comparative example and Example 1 is that there is no temperature gradient cooling process; it is cooled naturally in the air. The rest of the operation process is the same.

[0140] Ten samples were prepared using this method. Compared to the product obtained in Example 1, the demolding resistance of the product averaged 20 N. The sample contained zero air bubbles, with no bubbles on the surface or inside, and a transmittance of approximately 85%. However, the sample without gradient cooling exhibited significant internal stress, resulting in small glass fragments during removal from the mold. Even intact samples showed considerable stress under a polarizing microscope, failing to meet the required internal stress levels. The lack of gradient temperature cooling primarily affected the internal stress of the OGS samples, ultimately resulting in only 3-5 samples meeting quality standards.

[0141] Comparative Example 4:

[0142] The difference between this comparative example and Example 1 is that there is no process of constant temperature vacuuming after casting; the rest of the operation process is the same.

[0143] Ten samples were prepared using this method. Compared with the product obtained in Example 1, the demolding resistance of the product averaged 35 N. The number of bubbles with a diameter greater than 50 µm inside the sample was occasionally present, and the location of the bubbles inside the sample was also different between samples. Bubbles were present on the edge of the sample surface. The transmittance was about 77%. The samples treated with gradient cooling and annealing showed almost no stress stripes. The individual cracks were basically located at the bottom where the bubbles were generated. The lack of constant temperature vacuuming mainly affected the bubble problem of the OGS sample. Finally, there were 3-5 samples that met the quality requirements.

[0144] Comparative Example 5:

[0145] The difference between this comparative example and Example 1 is that no SiO2 nano barrier layer is deposited on the mold, but the rest of the operation process is the same.

[0146] Ten samples were prepared using this method. Compared with the product obtained in Example 1, the average demolding resistance of the product was 85 N. The lack of SiO2 nano barrier layer deposition led to increased adsorption force of OGS on the mold. Some samples had bubbles with an internal diameter greater than 50 µm. The permeability was about 76%. The samples treated with gradient cooling and annealing showed almost no stress stripes. Some OGS with bubbles had certain internal stress. The lack of SiO2 nano barrier layer deposition on the mold surface mainly affected the demolding process. Finally, there were 5-7 samples with qualified quality.

[0147] Comparative Example 6

[0148] The difference between this and Comparative Example 1 is that the product size is different; the product size of this comparative example is [size missing]. .

[0149] Comparing Example 1 with Comparative Example 1, it can be clearly seen that by adding the following operations throughout the process: depositing a SiO2 nano barrier layer on the mold, pre-melting and separating the raw materials, temperature gradient cooling, and constant temperature vacuuming, the problems of bubble formation, residual internal stress, and demolding of the plexiglass scintillator were well resolved, resulting in reduced sample dispersion and significantly improved sample yield. Compared to Example 1, Comparative Examples 2-5 respectively reduced the processes of raw material pre-melting and separation, temperature gradient cooling, isothermal vacuuming, and the deposition of a SiO2 nano-barrier layer on the mold. Comparative Example 2 shows that raw material pre-melting and separation mainly affects the color and purity of the acrylic scintillator, reducing its transmittance. Comparative Example 3 shows that temperature gradient cooling is a key process for obtaining high-quality acrylic scintillators, as natural cooling in air leads to significant internal stress and poor mechanical properties. Comparative Example 4 shows that isothermal vacuuming is another crucial process for obtaining high-quality acrylic scintillators; otherwise, air bubbles cannot be completely eliminated, resulting in deteriorated mechanical properties. Comparative Example 5 shows that not depositing a SiO2 nano-barrier layer on the mold increases demolding resistance, making demolding difficult and causing damage to the acrylic scintillator. Therefore, through multi-factor optimization, this invention can completely solve the problems of difficult demolding of acrylic scintillators, surface bubbles, and residual internal stress, further reducing the dispersion performance of acrylic scintillators and improving sample yield. The comparison between Comparative Examples 2-5 and Example 1 illustrates that reducing any one operation will have a certain impact on the final sample's dispersion performance and yield.

[0150] from Figure 7 It can be seen that, for the same size, the PSD-FOM value of the product obtained by using the method of the present invention in Example 3 and the conventional method in Comparative Example 6 increased from 2.0 to 3.3; from Figure 8 As can be seen, for the same size, the PSD-FOM value of the product obtained by the method of this invention is ≥ 2.7, which shows good stability and overcomes the problem of large performance dispersion of existing products.

[0151] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an acrylic scintillator, characterized in that, Includes the following steps: 1) Preprocessing Pre-treatment includes mold preparation and raw material pre-melting and separation; The mold processing includes the following steps: A1. Low-temperature deposition of SiO2 nano-barrier layer on the clean and smooth inner surface of the mold; A2. Place the mold in a drying oven for preheating at a temperature of 130-150 ℃ for 10-30 min. The pre-melting and partial melting of the raw materials includes the following steps: B1. First, add the weighed tris(9,9-dimethylfluorene)butylsilane (P3) or tris(4-biphenyl)phenylsilane (PB3) to a glass bottle with a cap, tighten the cap, evacuate to a vacuum degree of less than 100 mmHg, then heat the glass bottle, and continue to keep it warm for 10-30 min after P3 or PB3 has completely melted. B2. After heat preservation in step B1, reduce the temperature inside the glass bottle to 145-160 ℃, stop vacuuming, and introduce nitrogen into the glass bottle to balance the gas pressure inside and outside the glass bottle. After standing for 3-5 minutes, unscrew the bottle cap and add the weighed bis(9,9-dimethylfluorene)diphenylsilane (P2) into the glass bottle. Then tighten the bottle cap, vacuum the bottle to a vacuum degree of less than 100 mmHg, and heat at 145-160 ℃ to allow P2 to completely melt and mix with molten P3 or PB3. Then continue to heat for 10-30 minutes. B3. Stop the vacuuming process, introduce nitrogen into the glass bottle after the heat preservation in step B2 to balance the gas pressure inside and outside the glass bottle, let it stand for 3-5 minutes, then unscrew the cap and add the weighed (1,4-bis(2-methylstyrene)benzene (Bis-MSB) into the glass bottle. Then tighten the cap, evacuate the vacuum to a vacuum degree of less than 100 mmHg, and heat at 145-160 ℃ to completely melt Bis-MSB and mix it with the molten material obtained in step B2 to form OGS melt. Then continue to heat for 10-30 minutes. 2) OGS casting Stop vacuuming, introduce nitrogen into the insulated glass bottle to balance the air pressure inside and outside the glass bottle, let it stand for 3-5 minutes, then unscrew the cap and pour the OGS melt into the preheated mold in time. 3) Constant temperature vacuum Place the mold containing the OGS melt in a vacuum drying oven at a temperature of 135-155 ℃, and perform a vacuuming operation on the vacuum drying oven to make the vacuum degree less than 20 mmHg. The vacuuming time is 1-6 h, and then the temperature is lowered to 105 ℃. 4) Gradient cooling The mold containing the OGS melt was transferred to a forced-air drying oven for cooling to obtain an acrylic scintillator. Starting from 105 ℃, for volumes V ≤ 2455 mm² 3 The cooling profile of the OGS melt was as follows: 105 °C, held for 0.3 h; 100 °C, held for 1 h; 95 °C, held for 1 h; 90 °C, held for 2 h; 85 °C, held for 2 h; 80 °C, held for 2 h; 75 °C, held for 1 h; 25 °C, held for 1 h; for every 500 mm increase in volume V... 3 Increase the heat preservation time at each temperature point by 10-20 minutes; 5) Annealing treatment Remove the acrylic scintillator from the mold and anneal it in a drying oven at 50-60 ℃ for 5-10 h to obtain the acrylic scintillator.

2. The method for preparing the plexiglass scintillator according to claim 1, characterized in that, Also includes: Step 6) Coating and Preservation A protective film is formed by coating the surface of the plexiglass scintillator obtained in step 5 with a PVA solution and storing it in a glove box.

3. The method for preparing the plexiglass scintillator according to claim 1 or 2, characterized in that: A1 in the mold processing process specifically refers to: A1.1 Place the mold in acetone or ethanol for ultrasonic cleaning to remove oil and particles; A1.2 A SiO2 nano barrier layer with a thickness of 50-200 nm is deposited on the clean and smooth inner surface of the mold using plasma-enhanced chemical vapor deposition or plasma-enhanced physical vapor deposition. A1.3 The mold is annealed in a vacuum environment at a temperature of 180-230℃.

4. The method for preparing the plexiglass scintillator according to claim 3, characterized in that: In A1.2, the process parameters for plasma-enhanced chemical vapor deposition are as follows: The precursor is silane (SiH4) and nitrous oxide (N2O) or oxygen (O2) in a volume ratio of 1:10; the radio frequency power is 50-300 W to excite the plasma; the temperature is 140-200 ℃; the pressure is 50-500 Pa; and the time is 30-120 min.

5. The method for preparing the plexiglass scintillator according to claim 4, characterized in that: In B1, the heating temperature of P3 is 203-220 ℃, and the heating temperature of PB3 is 175-190 ℃.

6. The method for preparing the plexiglass scintillator according to claim 5, characterized in that: The mold is made of silicone.

7. The method for preparing the plexiglass scintillator according to claim 6, characterized in that: The PVA solution is an aqueous solution prepared from polyvinyl alcohol and silicone oil.

8. An acrylic scintillator, characterized in that, It is prepared by any of the preparation methods described in claims 1-7.

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