X射线二极管在2～6keV能区的灵敏度退化研究

Sensitivity degradation of X-ray diodes in 2 to 6 keV

利用北京同步辐射装置4B7B束线,在2.1-5.9 keV能区,对＂强光一号＂加速器Z箍缩实验中常用的Al和Au阴极X射线二极管进行了谱响应标定。对比了不同阴极材料（Au和Al）、加工方式（蒸镀Al和机械加工固体Al）及使用条件（参与实验发次）对探测器谱响应分散性及退化程度的影响。长期储存后的镀Au阴极仍有较好的谱响应一致性,但灵敏度退化明显,比文献报道新鲜Au阴极数据低70%以上,使用中还会进一步降低。Al阴极在保存和使用中的灵敏度退化相对较轻。新鲜的固体Al阴极谱响应分散性较小,灵敏度较文献报道数据略高,使用过10-40发次并保存9个月后灵敏度平均下降约20%-30%。镀Al阴极的谱响应分散性较大,相对偏差可达20%。初步探讨了定期更换以减轻灵敏度退化影响的可行性。

Spectral responses of aluminum-and gold-cathode X-ray diodes,commonly used in Z-pinch experiments of Qiangguang-I generator,have been calibrated on the 4B7B beamline of Beijing Synchrotron Radiation Facility,with a spectral range of 2.1 to 5.9 keV.Results of different kinds of cathodes,as well as other published data,are compared to check the effect of cathode material,preparation process and usage conditions on the degradation and dispersivity of the sensitivity.Evaporated gold cathodes stored in dry air for several years still have quite uniform spectral responses,while also with a large fall that their responses are only 20% to 25% of those reported data for fresh gold cathodes.Used gold cathodes even show a further fall in sensitivities.The aluminum cathodes exhibit much less degradation in response.Newly-prepared solid aluminum cathodes also have responses with low dispersivity,and the sensitivities are a little higher than those reported data.When used for 10～40 shots in a month and stored for 9 months,the responses fall by 20%～30%.Evaporated aluminum cathodes show larger response variation that the standard deviation may reach 20%.The method,which uses solid,sufficiently oxidated aluminum cathodes and changes them every 10～20 shots,is proposed to mitigate the sensitivity degradation effects.