Ground‐based search for X rays generated by thunderstorms and lightning
Ground‐based search for X rays generated by thunderstorms and lightning
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地面搜索雷暴和闪电产生的 X 射线
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
G. Shaw
中科院分区：
文献类型：
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作者：
D. Suszcynsky;R. Roussel;G. Shaw
已经进行了一系列的地面实验，以调查与雷暴和闪电活动有关的伽马射线/X射线计数率的增加。NaI闪烁探测器被配置在长时间尺度通道中，以监测长期计数率变化（在1-104秒的时间尺度上）作为时间、压力、温度、湿度、电场、降雨量和一般的雷暴活动，并在一个短时间尺度的通道，由电场变化计触发，以监测个人计数的相关性（在10−7-10−2 s的时间尺度上），具有闪电的特定相位。长时间尺度的结果通常显示，在雷暴活动期间，计数率比背景水平高出百分之几到高达100%，这可能主要是由于氡子离子衰变产生的伽马射线发射，因为子离子通过降雨沉淀到地面。这些数据不能排除雷暴逃逸电子机制产生的韧致辐射X射线，但这些数据表明，如果该机制在运行，地面上的韧致辐射通量充其量是间歇性的和/或在背景水平以上几乎不可辨别。短时间尺度的结果并没有显示任何证据表明X射线是由单独的闪电产生的。然而，这些结果是不确定的，因为只有10例闪电在1公里的距离内记录。整体研究的结果相比，以前的研究声称计数率的增加与雷暴和闪电活动的正相关性。还从雷暴电场中失控电子加速和闪电引发的失控空气击穿机制方面进行了讨论。在引言中，我们回顾了雷暴和闪电的X射线辐射的物理和以前的研究。
A series of ground-based experiments have been performed to investigate gamma ray/X ray count rate increases that are associated with thunderstorm and lightning activity. NaI scintillation detectors were configured in a long-timescale channel to monitor long-term count rate variations (on timescales of 1–104 s) as a function of time, pressure, temperature, humidity, electric field, rainfall, and general thunderstorm activity and in a short-timescale channel that was triggered by an electric field change meter to monitor correlations of individual counts (on timescales of 10−7–10−2 s) with particular phases of a lightning flash. Long-timescale results typically show count rate increases of a few percent to as much as 100% above background levels during thunderstorm activity and are likely due primarily to gamma ray emissions from radon daughter-ion decay as the daughter ions are precipitated to the ground by rainfall. The production of bremsstrahlung X rays by a thunderstorm runaway electron mechanism cannot be ruled out by this data, but the data indicate that if the mechanism is in operation, the bremsstrahlung flux at the ground is at best intermittent and/or barely discernible above background levels. Short-timescale results do not show any evidence for the production of X rays by individual lightning flashes. However, these results are inconclusive since only 10 cases of lightning flashes within a 1 km distance were recorded. The results of the overall study are compared to previous studies which claim positive correlations of count rate increases with thunderstorm and lightning activity. They are also discussed in terms of runaway electron acceleration in thunderstorm electric fields and in terms of the runaway air breakdown mechanism for lightning initiation. A review of the physics of and previous studies of X ray emissions from thunderstorms and lightning is presented in the introduction.