Photostimulable phosphors for neutron imaging

制备了SrBPO_5：Eu、SrBPO_5：Ce和CaBPO_5：Ce三种新型低γ射线灵敏度的光激励荧光粉，研究了它们的中子辐照光激励发光特性。SrBPO_5：Eu的光致发光峰位于390 nm左右，这是由于Eu ~（2+）的5d-4f跃迁所致。PSL强度与E^<-1/2>成线性关系，其中E是中子能量。SrBPO_5：Eu荧光粉的S_γ/S_n比市售的中子成像板（NIP）低一个数量级，其中S_n和S_γ分别为中子和γ射线灵敏度。获得了空间分辨率为0.4mm的准直中子束像，SrBPO_5：Ce和CaBPO_5：Ce的光释光特性与SrBPO_5：Eu的光释光特性基本相同。荧光粉的发光峰值和寿命分别为340 nm和23.5ns。此外，通过引入氟原子，PSL强度显著增加。SrBPO_5：Eu和CaBPO_5：Ce的探测量子效率（DQE）可达40%以上，而商品化的NIPS的DQE低于40%。由于SrBPO 5：Eu的PSL峰与市售NIP的PSL峰相同，因此制备了由SrBPO 5：Eu制成的新NIP，并且通过使用常规读取器清晰地获得成像对象的图像。空间分辨率为0.3mm，γ射线分辨能力优于市售NIPs。

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.