• Meter-scale spark X-ray spectrum statistics 

      Carlson, Brant Edward; Østgaard, Nikolai; Kochkin, Pavlo; Grøndahl, Øystein; Nisi, Ragnhild Schrøder; Weber, Kristian; Scherrer, Zack; LeCaptain, Kristian (Peer reviewed; Journal article, 2015-11-13)
      X-ray emission by sparks implies bremsstrahlung from a population of energetic electrons, but the details of this process remain a mystery. We present detailed statistical analysis of X-ray spectra detected by multiple ...
    • Modeling the relativistic runaway electron avalanche and the feedback mechanism with GEANT4 

      Skeltved, Alexander Broberg; Østgaard, Nikolai; Gjesteland, Thomas; Celestin, Sebastien; Carlson, Brant Edward (Peer reviewed; Journal article, 2014-11)
      This paper presents the first study that uses the GEometry ANd Tracking 4 (GEANT4) toolkit to do quantitative comparisons with other modeling results related to the production of terrestrial gamma ray flashes and high-energy ...
    • A new population of terrestrial gamma-ray flashes in the RHESSI data 

      Østgaard, Nikolai; Albrechtsen, Kjetil; Gjesteland, Thomas; Collier, Andrew B. (Peer reviewed; Journal article, 2015-12-23)
      Terrestrial gamma-ray flashes (TGFs) are the most energetic photon phenomenon occurring naturally on Earth. An outstanding question is as follows: Are these flashes just a rare exotic phenomenon or are they an intrinsic ...
    • Observation of intrinsically bright terrestrial gamma ray flashes from the Mediterranean basin 

      Gjesteland, Thomas; Østgaard, Nikolai; Laviola, Sante; Miglietta, M M; Arnone, Enrico; Marisaldi, Martino; Fuschino, F; Collier, Andrew B.; Fabro, F; Montanya, J (Peer reviewed; Journal article, 2015-12-14)
      We present three terrestrial gamma ray flashes (TGFs) observed over the Mediterranean basin by the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) satellite. Since the occurrence of these events in the ...
    • Search for Terrestrial Electron Beams in SAMPEX HILT data 

      Aamodt, Vegard (Master thesis, 2015-06-01)
      The Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) was a low polar orbiting satellite operating from 1992 to 2012. The goal of this master project has been to see if Terrestrial Electron Beams (TEBs), ~20 ...
    • Search for Terrestrial Gamma-ray Flashes in AGILE data by correlation with ground-based lightning measurements 

      Lindanger, Anders (Master thesis, 2018-06-16)
      Terrestrial Gamma-ray Flashes (TGFs) are sub-millisecond bursts of high energy photons, associated with lightning flashes produced inside thunderstorms. The Astro-Rivelatore Gamma a Immagini Leggero (AGILE) satellite is ...
    • Search for unidentified Terrestrial Gamma-ray Flashes 

      Albrechtsen, Kjetil Haakonseth (Master thesis, 2015-06-01)
      Terrestrial Gamma-ray Flashes (TGFs) are the most energetic natural phenomena on Earth with possible energies above 40MeV. They consist of large amounts of energetic photons ( 10^17 to 10^19 ) produced in thunderstorms at ...