Investigating the Correlation Between Lightning and High-Energy Particles in the Earth's Atmosphere

该项目支持闪电测绘阵列（LMA）数据的操作和分析，该阵列与北方半球最大的天体粒子物理观测站望远镜阵列（TA）配合使用。这些阵列的合并允许（1）使用能够重建雷击产生的伽马簇射的宽孔径探测器研究已知的闪电伽马射线发射现象，以及（2）寻找长期推测的宇宙射线空气簇射的雷击“播种”。智力优点：十多年来，人们一直知道雷击会发出x射线和伽马辐射（约100 keV至10 MeV）。地面探测器与自然闪电和感应闪电以及太空探测器都观察到了这种现象。最近，物理学家研究了美国犹他州西部700平方公里的TA表面探测器（SD）收集的数据，观察到与雷击一致的高能基本粒子。在这些事件的一个子集中，“阵雨”已经被重建，它指向地球大气中粒子的起源。这是以前从未见过的，这意味着高能辐射可以追溯到特定的时间和特征内的雷击。LMA是理想的仪器，以配合TA SD进行这些研究。用于现场测试目的的该仪器的一个版本已暂时位于TA现场。LMA由九个VHF探测器组成，分布在数百平方公里的范围内，用于探测闪电的脉冲辐射。这些脉冲可以重建10微秒的时间精度和优于100米的位置精度，并用于创建闪电的三维GPS定时重建。TA/LMA的合并也是寻找粒子天体物理学和气候之间更投机但更深刻的联系的理想工具：宇宙射线空气簇射引发闪电。由于雷暴中存在的电场通常比空气介电击穿所需的30 kV/cm小一个数量级，因此很明显，必须有其他东西来辅助这一过程。TA/LMA的协同作用将具有搜索宇宙射线与闪电重合的独特能力，为其能力增加了一项诱人的推测性研究。更广泛的影响：协同作用将为粒子天体物理学研究创造一个难得的机会，对国家气象研究的优先事项产生直接影响。大气中的电风暴对地球上生命的发展产生了深远的影响，并继续塑造着人类的生活和社会。然而，闪电的原因和性质仍然是个谜。一个大型的宇宙射线观测站与闪电探测器是探测其中两个谜团的理想配对：（1）在雷击中高能粒子是从哪里产生的？(2)宇宙线空气簇射能提供大气介质击穿的“种子”吗？由于维护闪电映射阵列的成本相对较低，TA/LMA天文台将成为展示NSF粒子天体物理学对整个社会的好处的重要展示品。

This project supports for the operation and analysis of data from a Lightning Mapping Array (LMA), collocated with the Telescope Array (TA), the largest astroparticle physicsobservatory in the Northern Hemisphere. The merger of these arrays allows (1) study of the known phenomenon of gamma ray emission by lightning with a wide aperture detector capable of reconstructing gamma showers generated by lightning strikes, and (2) a search for the long-speculated "seeding" of lightning strikes by cosmic ray air showers. Intellectual Merit:It has been known for over a decade that x-ray and gamma radiation (~100 keV to 10 MeV) is emitted by lightning strikes. This phenomenon has been observed by ground-based detectors in association with both natural and induced lightning, and by space-based detectors. Recently, physicists studying data collected by the 700 square kilometer TA Surface Detector (SD) in Western Utah, U.S.A. have observed energetic elementary particles in coincidence with lightning strikes. In a subset of these events, "showers" have been reconstructed which point back to the particles' origin in the Earth's atmosphere. This has not been seen before, and it implies that the energetic radiation may be traced to particular times and features within the lightning strike.The LMA is the ideal instrument to couple with the TA SD in order to perform these studies. A version of this instrument used for site testing purposes has been temporarily located at the TA site. The LMA consists of nine VHF detectors, spread over hundreds of square kilometers, which detect impulsive radiation from lightning. These impulses may be reconstructed with 10 microsecond timing accuracy and better than 100 meter position accuracy, and used to create a 3-dimensional GPS-timed reconstruction of a lightning strike.The merger of TA/LMA is also the ideal instrument to search for evidence of a more speculative - but more profound - connection between particle astrophysics and climate: The seeding of lightning strikes by cosmic ray air showers. Since the electric fields present in thunderstorms are typically an order-of-magnitude less than the 30 kV/cm needed for dielectric breakdown of air, it is evident that something else must be assisting the process. The TA/LMA synergy will have the unique ability to search for cosmic ray coincidences with lightning, adding a tantalizing piece of speculative research to its capabilities.Broader Impacts:The synergy will create a rare opportunity for particle astrophysics research to have such a direct impact on the national priority of meteorological research. Electrical storms in the atmosphere have had a profound impact on the development of life on Earth, and continue to shape individual human lives and society. Yet mysteries remain as to the causes and nature of lightning. A large cosmic ray observatory is the ideal pairing with a lightning detector to probe two of these mysteries: (1) From where within a lightning strike do high-energy particles arise? (2) Can cosmic ray air showers provide the "seed" of atmospheric dielectric breakdown? For the relatively modest cost of maintaining a lightning mapping array, the TA/LMA observatory will become an important showpiece illustrating the benefits of NSF Particle Astrophysics to society as a whole.