Preliminary data on the energy distribution of X- and gamma-rays from
natural lightning
Abstract
During the 2022 New Mexico monsoon season, we deployed two X-ray
scintillation detectors, coupled with a 180 MHz data acquisition system
to detect X-rays from natural lightning at the Langmuir Lab mountain-top
facility, located at 3.3 km above mean sea level. Data acquisition was
triggered by an electric field antenna calibrated to pick up lightning
within a few km of the X-ray detectors. We report the energies of over
240 individual photons, ranging between 13 keV and 3.8 MeV, as
registered by the LaBr3(Ce) scintillation detector. These detections
were associated with four lightning flashes. Particularly, four stepped
leaders and seven dart leaders produced energetic radiation. The
reported photon energies allowed us to confirm that the X-ray energy
distribution of natural stepped and dart leaders follows a power-law
distribution with exponent ranging between 1.09 and 1.96, with stepped
leaders having a harder spectrum. Characterization of the associated
leaders and return strokes was done with four different electric field
sensing antennas, which can measure a wide-range of time scales, from
the static storm field to the fast change associated with dart leaders.