Geant4 estimation of relativistic runaway electron avalanche multiplication and relativistic feedback factors in a realistic thundercloud electric field

Geant4 simulation and analysis code for estimating the relativistic runaway electron avalanche (RREA) multiplication and the relativistic-feedback factor in a realistic, altitude-dependent thundercloud electric field and an NRLMSISE-00 atmosphere, and for locating the self-sustaining feedback threshold, where the feedback factor equals 1.

Seed electrons of 1 MeV are injected at the lower boundary of the region where the field exceeds the RREA threshold, in a vertical field profile derived from a charge-layer model and rescaled to a chosen peak field. Because direct transport of a full avalanche becomes infeasible near threshold, the analysis uses a factorized estimator: the avalanche length, the yield of feedback carriers (photons and positrons), the seed effectiveness and the response to single feedback carriers are measured in short Geant4 runs and combined into the multiplication and the one-generation feedback factor as functions of the peak field.

The package contains the C++ Geant4 application, the calibration and analysis scripts (Python standard library), the field profile and charge-layer model, the calibration files and results for 1 MeV seeds. It was run on Linux with Geant4 10.7.4, but should work with later Geant4 versin with minimal changes.

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