Comparison and assessment of electron cross sections for Monte Carlo track structure codes

Area of Science:

• Radiation Physics
• Biophysical Modeling
• Computational Science

Background:

• Electron track structure codes are essential for understanding radiation effects in biological systems.
• Variations in input data and physical assumptions can lead to discrepancies in biophysical modeling outcomes.

Purpose of the Study:

• To intercompare and assess electron cross sections in water for use in electron track structure codes.
• To investigate the influence of cross-section data and assumptions on biophysical modeling of radiation effects.

Main Methods:

• Calculated ionization cross sections and secondary electron spectra using various theories.
• Analyzed water vapor cross sections due to data availability.
• Fitted experimental total ionization cross sections and compared excitation cross sections and mean excitation energy.
• Generated electron tracks using a Monte Carlo code with different cross-section combinations.
• Compared radial distributions and point kernels of generated tracks.

Main Results:

• The spectrum of secondary electrons from ionization had the most significant influence on track structure.
• Variations in excitation and elastic scattering cross sections had less impact than ionization cross sections.
• Codes showed similar energy deposition for larger targets but differed for B-DNA-sized targets.
• Most codes agreed on macroscopic quantities like stopping power and strand break yield.

Conclusions:

• Recommended using fitted functions for experimental total ionization and elastic cross sections.
• Predicted differences in track clustering frequencies among various models despite macroscopic agreement.
• Highlighted the critical role of ionization cross sections and secondary electron spectra in electron track structure simulations.