Collaborative Research: Strategic Observations of Terrestrial Gamma-Ray Flashes and Related Phenomena

该奖项支持对雷暴内部产生的一小部分闪电中产生的地面伽马射线闪光（TGFs）的理解。TGF是非常强大的伽马辐射爆发;伽马射线是不可见光的粒子，类似于X射线，但在这种情况下，能量比医生和牙医使用的X射线高出约100倍。虽然TGF很罕见，但这些闪光直接击中一架满载人员的飞机的后果是重大的。机组人员和乘客可能会突然受到非常高剂量的危险辐射，可能足以立即引起辐射病，并在以后的生活中有患癌症的重大风险。 大气物理学中关于TGF的一个未解决的有趣问题是TGF是如何，为什么以及何时产生的。研究小组试图了解伽马射线是如何变得如此明亮的，以及为什么（幸运的是）它们只发生在千分之一的闪电中，这是基于他们目前对TGF的“构建块”的理解，以及高能辐射如何在闪电中自然发生。这项调查可能使研究小组能够预测TGF参与与飞机相互作用的闪电，并为公共安全提供有关航空风险的宝贵信息。在该项目中，研究小组将在地面站点、飞机和高空气球上部署一些伽马射线探测器（以前由NSF、NASA和空军资助建造），以便在以前见过的地方收集有关TGF的新数据，例如冬季的日本西海岸，夏季的佛罗里达雷暴和飓风的眼墙。 每个站点和观察方法都被选择用于靠近其生产地点的TGF测量。其中一个关键的观测结果将是TGF能有多亮，以及它们能有多暗。目前主要模式预测的TGF辐射强度的时间变化有很大的不确定性。为了解决这种不确定性，同时考虑到辐射强度随时间的一系列可能的快速爆发，将使用用于观察每个伽马射线相互作用的塑料闪烁器的快速响应探测器来确定正确的模型物理。雷电特性的综合测量（主要通过无线电发射）与补充的气象数据一起，该团队不仅能够了解产生TGFs的闪电的详细行为，还能够了解在未产生TGFs的情况下类似的高质量闪电数据，这个奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准。

This award supports investigation of understanding terrestrial gamma-ray flashes (TGFs) generated among a small fraction of lightning flashes generated inside thunderstorms. TGFs are extraordinarily powerful bursts of gamma radiation; gamma-rays are particles of invisible light, similar to x-rays but in this case with energies up to about 100 times higher than the x-rays used by doctors and dentists. Although TGFs are rare, the consequences of a direct hit by one of these flashes to a plane full of people are significant. The crew and passengers could receive a very high, sudden dose of dangerous radiation, possibly enough to cause immediate radiation sickness and a significant risk of cancer later in life. An unsolved and interesting problem in atmospheric physics regarding to TGFs is how, why, and when TGFs are produced. The research team seeks understanding of how the gamma-rays get as bright as they do and why (fortunately) they only happen in maybe one out of a thousand lightning flashes based on their current understanding of the ``building blocks'' of a TGF and how high-energy radiation might naturally happen during lightning. The investigation will potentially enable the team to predict involvement of TGFs in lightning flashes that interact with aircraft and provide valuable information on aviation risks for public safety. In this project, the research team will deploy a number of gamma-ray detectors (previously constructed under funding from NSF, NASA, and the Air Force) to ground-based sites, aircraft, and high-altitude balloons in order to gather new data on TGFs in places they have been seen before, such as the western coast of Japan in winter, summer thunderstorms in Florida, and the eyewalls of hurricanes. Each site and the method of observation have been chosen for measurements of TGFs close to their production locations. One of the key observations will be how bright TGFs can get and how faint they get. Currently temporal variations of TGF radiation intensity predicted by leading models have significant uncertainty. To address this uncertainty with consideration of a possible series of rapid bursts of radiation intensity with time, the fast response detector of plastic scintillators for observing each gamma-ray interaction will be used to determine the correct model physics. Combining measurements of lightning characteristics (mostly via radio emission) with complementary meteorological data, the team would be able to understand not only the detailed behavior of lightning that produces TGFs, but also lightning data of similar high quality for situations where a TGF did not get produced, which is equally important to understand.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.