Modeling and constraining a gamma-ray glow observed at 20 km altitude during the FEGS/ALOFT campaign
Creators: name: Sarria, D.
Publisher: name: Zenodo
Year: 2018
Subjects: photon electron positron gamma ray glow cosmic ray high energy atmospheric physics x gamma ray detector thunderstorm er-2

description: Slides of the presentation held during the 2018 AGU Fall Meeting in Washington, D.C. . See full information here. The associated journal article is available here. <strong>Abstract :</strong> In the spring of 2017 the «GOES-R Validation Flight Campaign» was undertaken with an ER-2 aircraft over the continental United States. The plane, flying at a cruise altitude of 20km, had a scientific payload designed to detect optical signals, electric fields and gamma rays from thunderstorms. On May 8, 2017, the on-board gamma-ray spectrometers could detect a gamma-ray glow event lasting for about 4 minutes over Colorado. It was detected by several spectrometers, including three BGO-based detectors, similar to the ones on-board of the ASIM instrument docked to the international space station. The glow showed a gamma-ray count increase on top of the background of 10 to 40 %, which was rather unexpected from such high altitude (20 km). We present a detailed analysis and modeling of this glow event, by building a model based on the GEANT4 toolkit [1] (for particle propagation and detector simulation), associated with the PARMA code [2] (for cosmic ray generation). We evaluate two hypotheses for the glow generation: - <strong>A</strong>: large scale (tens of kilometers) electric field starting from the top of the cloud (13 km) towards higher altitudes, exponentially decaying. - <strong>B</strong>: kilometer scale constant electric field inside the thundercloud (8 to 13 km altitude) with positive or negative polarity. We conclude that some of the type <strong>B</strong> configurations can give good spectrum fits and compatible photon flux increases, but require a polarity that is incompatible with the cloud charge structure deduced from other measurements (LMA, E-field antennas). Type <strong>A</strong> scenarios can also reproduce compatible increase in gamma-ray flux and good spectral fits, but require electric fields above the thundercloud that are several times larger than the ones measured during the event. References: [1] Allison, J., K. Amako, J. Apostolakis, H. Araujo, P. A. Dubois, M. Asai, G. Barrand, R. Capra, S. Chauvie, R. Chytracek, et al. (2006), Geant4 developments and applications, IEEE Transac- tions on Nuclear Science, 53, 270–278, doi:10.1109/TNS.2006.869826. [2] Sato, T. (2016), Analytical model for estimating the zenith angle dependence of terrestrial cosmic ray fluxes, PLOS ONE, 11(8), 1–22, doi:10.1371/journal.pone.0160390
description: {"references": ["\u00d8stgaard N., et al., (2019) \"Gamma\u2010ray glow observations at 20 km altitude\" https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JD030312", "Allison, J., K. Amako, et al. (2006), Geant4 developments and applications, IEEE Transac- tions on Nuclear Science, 53, 270\u2013278, doi:10.1109/TNS.2006.869826.", "Sato, T. (2016), Analytical model for estimating the zenith angle dependence of terrestrial cosmic ray fluxes, PLOS ONE, 11(8), 1\u201322, doi:10.1371/journal.pone.0160390", "Sarria D. et al. (2018) Evaluation of Monte Carlo tools for high energy atmospheric physics II : relativistic runaway electron avalanches Geoscientific Model Development", "Smith D. M., et al. (2018) Characterizing upward lightning with and without a terrestrial gamma-ray flash Journal of Geophysical Research, Atmospheres"]}