Kruschwitz Craig A, Wu Ming, Rochau Greg A
National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544, USA.
Rev Sci Instrum. 2011 Feb;82(2):023102. doi: 10.1063/1.3530451.
This paper is the second part of a continuing study of straight-channel microchannel plate (MCP)-based x-ray detectors. Such detectors are a useful diagnostic tool for two-dimensional, time-resolved imaging and time-resolved x-ray spectroscopy. To interpret the data from such detectors, it is critical to develop a better understanding of the behavior of MCPs biased with subnanosecond voltage pulses. The subject of this paper is a Monte Carlo computer code that simulates the electron cascade in a MCP channel under an arbitrary pulsed voltage, particularly those pulses with widths comparable to the transit time of the electron cascade in the MCP under DC voltage bias. We use this code to study the gain as a function of time (also called the gate profile or optical gate) for various voltage pulse shapes, including pulses measured along the MCP. In addition, experimental data of MCP behavior in pulsed mode are obtained with a short-pulse UV laser. Comparisons between the simulations and experimental data show excellent agreement for both the gate profile and the peak relative sensitivity along the MCP strips. We report that the dependence of relative gain on peak voltage is larger in pulsed mode when the width of the high-voltage waveform is smaller than the transit time of cascading electrons in the MCP.
本文是对基于直通道微通道板（MCP）的X射线探测器持续研究的第二部分。此类探测器是用于二维、时间分辨成像和时间分辨X射线光谱学的有用诊断工具。为了解释从此类探测器获取的数据，更深入地了解用亚纳秒电压脉冲偏置的MCP的行为至关重要。本文的主题是一个蒙特卡罗计算机代码，它模拟在任意脉冲电压下MCP通道中的电子级联，特别是那些宽度与直流电压偏置下MCP中电子级联的渡越时间相当的脉冲。我们使用此代码研究各种电压脉冲形状下增益随时间的变化（也称为门控曲线或光学门控），包括沿MCP测量的脉冲。此外，用短脉冲紫外激光获得了MCP在脉冲模式下行为的实验数据。模拟结果与实验数据之间的比较表明，在门控曲线和沿MCP条带的峰值相对灵敏度方面都有很好的一致性。我们报告，当高压波形的宽度小于MCP中级联电子的渡越时间时，脉冲模式下相对增益对峰值电压的依赖性更大。
