BaF_(2)纳米复合闪烁体的闪烁特性研究

Scintillation Properties of BaF_(2) Nanocomposite Scintillator

为研究基于BaF_(2)无机纳米颗粒复合闪烁体的闪烁特性,将粒径约为20 nm的BaF_(2)无机纳米颗粒与塑料闪烁体结合,制作了不同质量分数的BaF_(2)纳米复合闪烁体。通过闪烁光谱测量系统、时间关联单光子计数系统、基于钴源的γ射线辐照系统,实验测量了BaF_(2)纳米复合闪烁体在低能X射线和γ射线(1.25 MeV)辐射下的闪烁效率、闪烁光谱和发光衰减时间。实验结果表明,在低能X射线和γ射线激发下,基于BaF_(2)纳米颗粒的复合闪烁体可以将发光效率分别提升83.1倍和16.4倍;同时由于BaF_(2)无机纳米颗粒的尺寸效应有效地压制了其慢衰减时间的发光成分(来源于自陷态激子效应),从而使得该BaF_(2)纳米复合闪烁体具有与塑料闪烁体相近的闪烁光谱,快衰减时间约为2 ns。

To study the scintillation characteristics of BaF_(2) inorganic nanoparticle composite scintillators,BaF_(2) nanoparticles with a particle size of about 20 nm are combined with plastic scintillators to fabricate BaF_(2) nanocomposite scintillators with different mass fractions.The scintillation efficiency,scintillation spectra and luminescence decay time of these BaF_(2) nanocomposite scintillators under low-energy X-ray and gamma-ray(1.25 MeV)radiation are experimentally measured by scintillation spectroscopy measurement system,time-correlated single-photon counting system and gamma-ray irradiation system of 60 Co source.The experimental results show that the composite scintillator based on BaF_(2) nanoparticles can increase the luminous efficiency by 83.1 times and 16.4 times under low-energy X-ray and gamma-ray excitation,respectively.At the same time,the size effect of BaF_(2) inorganic nanoparticles effectively suppresses the luminescence component with slow decay time(from the self-trapping exciton effect),so that the BaF_(2) nanocomposite scintillators have scintillation spectra similar to that of the plastic scintillator and a fast decay time(about 2 ns).