A 5D, polarised, Bethe-Heitler event generator for $\gamma \to e^+e^-$ conversion

TL;DR

This paper introduces a new 5D, polarised Bethe-Heitler event generator for gamma-ray to electron-positron conversion, enabling efficient, precise simulations across a wide energy range for advanced gamma-ray telescopes.

Contribution

A novel 5D, exact, polarised event generator for gamma-ray conversion that efficiently simulates multiple events across diverse energies and targets without significant CPU overhead.

Findings

Extended verification range down to 1 keV above threshold

Simulates events up to 1 EeV energy range

Mitigates kinematic correlations via Lorentz frame transformations

Abstract

We describe a new version of the 5D, exact, polarised, Bethe-Heitler event generator of $\gamma$-ray conversions to $e^+e^-$, developed in the context of the HARPO project, that is able to simulate successive events with different photon energies and on different atomic targets without any substantial CPU overhead. The strong correlation between kinematic variables in the divergence of the five-dimensional differential cross section are mitigated by performing each step of the conversion in the appropriate Lorentz frame. We extend the verification range down to 1 keV above threshold and up to 1 EeV. This work could pave the way to the precise simulation of the high-performance $\gamma$-ray telescopes and polarimeters of the post-Fermi-LAT area.