Study On Preparation And Properties Of Novel Plastic Scintillator And Wavelength Shifter

With the continuous development of science and technology, there is an everincreasing demand for the scintillator detector in the detection of energy particle and nuclear radiation, and novel plastic scintillators with different performance advantages should be prepared to meet the detection requirements of different areas and different application places. The relationship between the property of plastic scintillator and each component was deeply discussed in this paper. Then a novel UV-curable plastic scintillator was first prepared in a short time by using the technology of photosensitivity rapid prototyping, the proportion of each component and the preparation technology were also discussed. In the end, a novel wavelength shifer with a maximum absorption wavelength in 450 nm was synthesized and applied to the plastic scintillator.A series of polystyrene-based plastic scintillator had been prepared using AIBN as an initiator by thermal polymerization. Three first luminescent additives(PPO, p-TP and b-PBD) and four wavelength-shifters(POPOP, Bis-MSB, Me-MSB and DPA) were added to plastic scintillators respectively. The comparison results of performance test showed that PPO and POPOP were the most adequate fluorescent dyes for the polystyrene-based plastic scintillator. Then the effect of the concentration of PPO, POPOP and AIBN on the performance of plastic scintillator was investigated. The final results showed that the fluorescence intensity and light yield were increased firstly and then decreased with the increase of the concentration of PPO and POPOP; increase the concentration of AIBN would degrade the performance of plastic scintillator; the polystyrene-based plastic scintillator containing 2% PPO, 0.02% POPOP and 0.1% AIBN had the highest fluorescence intensity and light yield.The novel UV-curable plastic scintillator was first successfully prepared under the irradiation of UV curing machine using the copolymer of 621A-80, TPGDA and styrene as the matrix doped with the first luminescent additive PPO, wavelength shifter POPOP and photoinitiator 184. The best conditions for preparing novel UV-curable plastic scintillator was determined by changing process conditions and the proportion of each component. The UV-curable plastic scintillator used the copolymer of oligomer 621A-80, TPGDA and styrene(its mass ratio was 7:3:3) as the matrix containing 2% PPO, 0.02% POPOP and 3% photoinitiator 184 had the best performance. The maximum wavelength of the UV-curable plastic scintillator is 420 nm. Its light yield was 7.1% of anthracene on the basis of a comparison with ST-401.The as-prepared plastic scintillator displayed a fast scintillation decay. Its decay time is 2.58 ns.In order to obtain a plastic scintillator with longer emission wavelength, the molecular formulas of new wavelength shifter was designed based on the molecular structure of POPOP and Bis-MSB. The new wavelength shifter was synthesized by 2-methyl benzoxazole and 1,4-phthalaldehyde. By analyzing the FTIR spectroscopy and 1H NMR spectroscopy of the synthesis product which was purified by recrystallization, we confirmed that the molecular formula of the synthesis product was consistent with the theoretic molecular structure. The maximum absorption wavelength of the new wavelength shifter was 375 nm, the maximum emission wavelength was 446 nm and the melting point was 337.73°C. The polystyrene-based plastic scintillator containing 2% PPO, 0.1% AIBN and 0.02% new wavelength shifter had a maximum wavelength in 450 nm. The light yield of the plastic scintillator was approximately 60.1% of anthracene. Its decay time is 2.54 ns.