摘要:
为了测量脉冲时间宽度小于20 ns时的γ射线时间分辨图像,发展了新型无机闪烁体Yb:YAG,并实验测量了晶体的发光衰减时间、X射线激发发光光谱、相对发光效率和空间分辨等性能,研究了Yb:YAG晶体的发光性能.实验表明,Yb:YAG发光有三种衰减成分,快成分衰减常数为1.2 ns,慢成分衰减常数与射线种类有关;X射线激发发光光谱在250~800 nm范围,有三个发光峰,分别为320,380和500 nm,且320 nm处强度最大;相对发光效率为1900 ph/MeV;使用钨分辨卡测得Yb: YAG空间分辨能力为2 lp/m,使用刀口法测得空间调制传递函数为0.5时的频率为0.7 lp/mm.结果说明Yb:YAG晶体性能能够满足所需测量要求.
Abstract:
In order to acquire time resolution image of γ-ray while impulse pulse width is under 20 ns, a new scintillator named Yb:YAG is developed, and its characteristics of luminescence decay time, excited luminescence spectrum of X-ray, relative luminescence efficiency and spatial resolution are measured.The measurement shows that there are three decay components.The fast decay constant comes to 1.2 ns, but the slow decay constant depends on radiation category.The excited luminescence spectrum ranges from 250 nm to 800 nm, and three peaks, 320 nm, 380 nm, 500 nm, exist.Meanwhile, the strongest intensity spectrum is located at 320 nm.The relative luminescence efficiency reaches 1900 ph/MeV.The spatial resolution is 2 lp/mm in the test with W resolution chart.The frequency is 0.7 lp/mm when the MTF is 0.5 in the test with edge image.The result shows that the characteristics of Yb:YAG crystal could satisfy the measurement demand.
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