Quantifying electron cascade size in various irradiated materials for free-electron laser applications

Area of Science:

• Physics
• Materials Science
• Computational Science

Background:

• Electron and X-ray induced cascades are vital for free-electron laser (FEL) research.
• Understanding cascade dynamics is key for applications like X-ray imaging and material damage studies.

Purpose of the Study:

• Investigate factors influencing electron cascade duration and spatial size in solids.
• Analyze electron propagation in ten materials relevant to X-ray laser applications.

Main Methods:

• Employed classical Monte Carlo simulations in the atomic approximation.
• Studied electron propagation and cascade development in various solids (Au, B4C, diamond, Ni, polystyrene, Ru, Si, SiC, Si3N4, W).
• Examined the dependence of cascade size on incident electron/photon energy and target properties.

Main Results:

• Electron-induced cascades are consistently larger than photon-induced cascades.
• Maximal cascade size is not always equivalent to the electron range, contrary to common assumptions.
• Cascade size can be effectively tuned by selecting specific photon energies relative to ionization potentials.

Conclusions:

• Tailoring photon energy, especially near ionization thresholds, can significantly reduce cascade size by splitting energy between photo- and Auger electrons.
• Findings provide a method for controlling electron cascade dimensions for specific applications, enabling high-density or low-density electron excitation.
• This research offers insights into managing electron cascade phenomena in materials for advanced scientific applications.