中子探测技术广泛用于国土安全、核材料安全检测以及高能物理等领域，由于3He资源紧缺，近年来急需开发出能够同时甄别中子/伽马的新型闪烁晶体，Cs2LaLiBr6∶Ce(CLLB∶Ce)晶体具有良好的中子/伽马甄别能力、优异的能量分辨率以及高的光输出，但其中子/伽马甄别性能有待进一步提高。本研究采用垂直布里奇曼法成功生长了Zr4+共掺杂的CLLB∶Ce晶体。通过不同表征手段研究了 Zr4+共掺杂CLLB∶Ce晶体的结构和组分，结果表明Zr4+成功掺入基质材料且对基质晶体结构不产生明显的影响，Zr4+共掺杂后没有产生新的发光中心，紫外衰减时间约为27。0 ns，仍具有较快的荧光衰减。Zr4+共掺杂CLLB∶Ce晶体的品质因子(Figure of Merit，FOM)从1。2提高到1。5，表明其中子/伽马甄别能力得到改善。结合热稳定性和闪烁衰减时间，探讨了衰减时间对FOM的影响机制，Zr4+共掺杂可以抑制浅电子陷阱和Vk中心，减少电子捕获和脱陷过程，使Ce3+直接捕获的概率大大增加，从而表现出更快的衰减速率。本研究显示，Zr4+共掺杂CLLB∶Ce晶体在中子/伽马探测领域具有潜在的应用前景。
Effect of Zr4+Co-doping on Neutron/Gamma Discrimination of Cs2LaLiBr6∶Ce Crystals
Neutron detection technology is widely used in homeland security,nuclear material security detection,and high energy physics,etc.Due to the shortage of 3He resources,it is urgent to develop a novel scintillator that can discriminate neutron and gamma.The Cs2LaLiBr6∶Ce(CLLB∶Ce)crystal has good neutron/gamma discrimination capacity,excellent energy resolution and high light yield,but its neutron/gamma discrimination performance needs further improvement.Here,the CLLB∶Ce crystals co-doped with Zr4+were grown successfully by the vertical Bridgman method.The results of different characterization methods prove that the Zr4+was successfully doped into the matrix and did not effect on the structure of host.Meanwhile,no new luminescence center was generated after Zr4+doping.The UV decay time is about 27 ns,presenting a fast fluorescence decay.Figure of merit(FOM)of CLLB∶Ce crystal is enhanced from 1.2 to 1.5 by co-doping Zr4+,which means that the neutron/gamma discrimination performance of CLLB∶Ce crystals is improved.Combined with the thermal stability and scintillation decay time,relationship between decay time and FOM was also analyzed.The co-doping of Zr4+can inhibit shallow electron trap and VK centers,reduce electron trapping-detrapping process,and greatly increase the probability of Ce3+direct capturing electron,which results in a shorter decay time.Data from this study indicate that the CLLB∶Ce crystals exhibit a huge application prospect in the field of neutron/gamma detection.
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