Photostimulable phosphors for neutron imaging

SrBPO5:Eu、SrBPO5:Ce和CaBPO5:Ce是一种新型的低γ射线灵敏度光刺激荧光粉，研究了它们在中子辐照下的光刺激发光特性。由于Eu^<2+>的5d-4f跃迁，SrBPO5:Eu的PSL峰约为390 nm。PSL强度与E^<-1/2>呈线性关系，其中E为中子能量。SrBPO_5:Eu荧光粉的S_γ/S_n比市售中子成像板（NIPs）低一个数量级，其中S_n和S_γ分别是中子和伽马射线灵敏度。获得了空间分辨率为0.4 mm的准直中子束图像。SrBPO5:Ce和CaBPO5:Ce的PSL特性与SrBPO5:Eu基本相同。这些荧光粉的峰值和寿命分别为340nm和23.5 ns。此外，引入氟原子可显著提高PSL强度。SrBPO5:Eu和CaBPO5:Ce的探测量子效率（DQE）可达40%以上，而商用NIPS的探测量子效率低于40%。由于SrBPO5:Eu的PSL峰与市售NIPs相同，我们制作了新的SrBPO5:Eu的NIPs，使用传统的读取器清晰获取成像对象的图像。空间分辨率为0.3 mm，伽玛射线识别能力优于市售nip。

As new photostimulable phosphors with low gamma-ray sensitivities, SrBPO5:Eu, SrBPO5:Ce, and CaBPO5:Ce based phosphors have been prepared and their photostimulated luminescence (PSL) characteristics by neutron irradiation were investigated. The PSL peak of SrBPO5:Eu was about 390 nm due to 5d-4f transition of Eu^<2+>. The PSL intensity was linearly dependent on E^<-1/2>, where E is neutron energy. The S_γ/S_n ratio of SrBPO_5:Eu phosphor was one order magnitudes lower than that of commercially available neutron imaging plates (NIPs), where S_n and S_γ are neutron and gamma-ray sensitivities, respectively. A collimated neutron beam image was obtained with a spatial resolution of 0.4 mm. The PSL characteristics of SrBPO5:Ce and CaBPO5:Ce were almost the same as those of SrBPO5:Eu. The peak and lifetime of PSL of these phosphors was 340nm and 23.5 ns, respectively. Moreover, the PSL intensity was significantly increased by introducing fluorine atoms. The detective quantum efficiency (DQE) of SrBPO5:Eu and CaBPO5:Ce can be more than 40 %, while that of commercially NIPS was less than 40%. Since the PSL peak of SrBPO5:Eu was the same as that of commercially NIPs, new NIPs made of SrBPO5:Eu was made and the image of imaging subjects was clearly obtained by using a conventional reader. The spatial resolution was 0.3 mm and the gamma-ray discrimination ability was better than that of commercially NIPs.