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In‐Flight Observation of Positron Annihilation by ILDAS
Author(s) -
Kochkin P.,
Sarria D.,
Skeie C.,
Deursen A. P. J.,
Boer A. I.,
Bardet M.,
Allasia C.,
Flourens F.,
Østgaard N.
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd028337
Subject(s) - physics , thunderstorm , photon , gamma ray , positron , lightning (connector) , annihilation , monte carlo method , electron , nuclear physics , computational physics , meteorology , optics , power (physics) , statistics , mathematics , quantum mechanics
We report a 511‐keV photon flux enhancement that was observed inside a thundercloud and is a result of positron annihilation. The observation was made with the In‐flight Lightning Damage Assessment System (ILDAS) on board of an A340 test aircraft. The aircraft was intentionally flying through a thunderstorm at 12‐km altitude over Northern Australia in January 2016. Two gamma ray detectors showed a significant count rate increase synchronously with fast electromagnetic field variations registered by an on‐board antenna. A sequence of 10 gamma ray enhancements was detected, each lasted for about 1 s. Their spectrum mainly consists of 511‐keV photons and their Compton component. The local electric activity during the emission was identified as a series of static discharges of the aircraft. A full‐scale Geant4 model of the aircraft was created to estimate the emission area. Monte Carlo simulation indicated that the positrons annihilated in direct vicinity or in the aircraft body.