We present the results of Monte Carlo simulations of the microchannel plate (MCP) response to x rays in the 250 eV to 25 keV energy range as a function of both x-ray energy and impact angle and their comparisons with the experimental results from the X8A beamline at the National Synchrotron Light Source at Brookhaven National Laboratory. Incoming x rays interact with the lead glass of the microchannel plate, producing photoelectrons. Transport of the photoelectrons is neglected in this model, and it is assumed that photoelectrons deposit all their energy at the point they are created. This deposition leads to the generation of many secondary electrons, some fraction of which diffuse to the MCP pore surface where they can initiate secondary electron cascades in the pore under an external voltage bias. X-ray penetration through multiple MCP pore walls is increasingly important above 5 keV, and the effect of this penetration on MCP performance is studied. In agreement with past measurements, we find that the dependence of MCP sensitivity with angle relative to the pore bias changes from a cotangent dependence to angular independence and then proceeds to a secant dependence as the x-ray energy increases. We also find that with the increasing x-ray energy, the MCP gain sensitivity as a function of bias voltage decreases. The simulations also demonstrate that for x rays incident normal to the MCP surface, spatial resolution shows little dependence on the x-ray energy but degrades with the increasing x-ray energy as the angle of incidence relative to the surface normal increases. This agrees with experimental measurements. Simulation studies have also been completed for MCPs gated with a subnanosecond voltage pulse. We find that the optical gate profile width increases as the x-ray energy is increased above 5 keV, a consequence of increased x-ray penetration at energies >5 keV. Simulations of the pulsed dynamic range show that the dynamic range varies between ∼100 and 1000 depending on x-ray energy and peak voltage.

中文翻译：

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<25 keV x射线的基于微通道板的探测器的性能：蒙特卡罗模拟和与实验结果的比较

我们介绍了微通道板（MCP）对250 eV至25 keV能量范围内的x射线响应的蒙特卡罗模拟结果，该结果是x射线能量和冲击角的函数，并与X8A的实验结果进行比较Brookhaven国家实验室的National Synchrotron光源的光束线。入射的X射线与微通道板的铅玻璃相互作用，产生光电子。在此模型中忽略了光电子的传输，并假设光电子在其创建时将所有能量沉积。这种沉积导致许多二次电子的产生，其中一些电子扩散到MCP孔表面，在那里它们可以在外部电压偏置下在孔中引发二次电子级联。在5 keV以上时，穿过多个MCP孔壁的X射线穿透越来越重要，并且研究了这种穿透对MCP性能的影响。与过去的测量结果一致，我们发现MCP灵敏度随角度的变化（相对于孔隙偏差）的依赖关系从切线依赖关系变为角度独立性，然后随着X射线能量的增加而变为割线依赖关系。我们还发现，随着X射线能量的增加，MCP增益灵敏度随偏置电压的变化而降低。模拟还表明，对于垂直于MCP表面入射的X射线，空间分辨率几乎不依赖于X射线能量，但随着相对于表面法线的入射角增加，空间分辨率随X射线能量的增加而降低。这与实验测量结果一致。对用亚纳秒电压脉冲选通的MCP的仿真研究也已经完成。我们发现，随着x射线能量增加到5 keV以上，光闸轮廓宽度会增加，这是能量> 5 keV时x射线穿透增加的结果。脉冲动态范围的仿真表明，动态范围根据X射线能量和峰值电压在约100至1000之间变化。