X-ray tracing using Geant4

We describe an extension to the Geant4 software package that allows it to be used as a general purpose X-ray tracing package. We demonstrate its use by building a model of the X-ray optics of the XMM-Newton, calculating its effective area, and comparing the results with the published calibration curves.

💡 Research Summary

The paper presents a novel extension to the Geant4 Monte‑Carlo toolkit that equips it with the capability to perform general‑purpose X‑ray ray‑tracing. While Geant4 is widely used for high‑energy particle transport, its standard physics libraries lack the detailed treatment of X‑ray reflection, refraction, and surface‑roughness effects that are essential for grazing‑incidence optics. To fill this gap, the authors develop a new process class, “G4XrayReflectivity,” derived from the G4VProcess interface. This class reads complex refractive‑index data (n + ik) for coating materials, computes angle‑dependent reflectivity using Fresnel equations, and incorporates a Gaussian roughness correction factor exp