Preliminary Results of the Summer 2022 Langmuir Energetic Radiation Campaign

There is a number of recently-discovered mechanisms by which lightning and thunderstorms may produce energetic photons, and in several of them X- and gamma-rays can be measured from ground level. Some examples include: (1) the stepped leader propagation stage of natural negative cloud-to-ground lightning seen in Florida; (2) downward terrestrial gamma ray flashes seen in the Utah Telescope Array, (3) in winter storms in Japan, or (4) at mountain level at Santis Tower; and (5) minute-long enhancements in gamma-ray fluxes at Mount Aragats. The Langmuir Laboratory mountain-top facility located at 3.3 km altitude above sea level in central New Mexico has played a central role in the discovery of energetic radiation by lightning [Moore et al., GRL, 2001]. In this presentation, we report on our efforts to make observations of X- and gamma-rays from thunderstorms at the very same place where these type of phenomena was discovered 20 years ago, but now with updated instrumentation. This location remains ideal for such type of investigation due to numerous types of co-located instruments, including: a lightning mapping array, an interferometer, field mills, and fast and slow antennas, all connected in a fully-networked mountain top. The X-ray detection system designed for the NSF project AGS-1917069 contains a LaBr detector with fast (16 ns) rise time and narrow pulse duration (100 ns). The system also contains a NaI detector, which has been the standard in the field for several years. Finally, the instrument also has a co-located fast antenna and GPS timing unit. Preliminary results of the Summer/2022 campaign include the detection of nearby strikes (within 2 km) of the X-ray instrument, and an analysis on what conditions these strikes can produce detectable X-rays. The facility also houses one of the UCSC THOR instruments, and we conclude by discussing possibilities for overlapping measurements.