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Communication Dans Un Congrès Année : 2019

Modeling Downward Terrestrial Gamma Ray Flashes Detected by Ground-Based Particle Arrays

Résumé

Terrestrial gamma-ray flashes (TGFs) are sub-millisecond bursts of high-energy photons that originate in the electric fields of thunderclouds. Since their discovery by the Compton Gamma-ray Observatory in 1994, observations of TGFs have routinely been made from space. TGFs have been shown to happen in association with the propagation of upward intra-cloud lightning. Until recently, ground-based observations of TGFs were uncommon. The few detections made were found in association with rocket triggered or cloud-to-ground (CG) lightning. Since the Telescope Array Surface Detector in Utah, USA started making detections of high-energy particles during CG lightning activity, the number of potential TGFs seen from the ground has greatly increased.

Observations of TGFs on the ground pose a valuable addition to space-borne detectors. The combination of having detectors much closer to the event and having several detectors registering each event allows us to obtain unprecedented information about the geometry and time structure of TGFs.

We simulate downward-directed TGFs using a Monte Carlo model of photons propagating through the atmosphere. Using this tool, we show how the footprints of downward TGFs would present on ground given different initial geometries, and how time structures observed on ground could be detectable by space-borne instruments. We also show the impact different initial energy spectra have on the number of photons observed on ground and in space.

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Dates et versions

hal-03563825 , version 1 (10-02-2022)

Identifiants

Citer

N. Berge, S. J. Celestin. Modeling Downward Terrestrial Gamma Ray Flashes Detected by Ground-Based Particle Arrays. American Geophysical Union, 2019, San Francisco, United States. ⟨hal-03563825⟩
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