Geant4-DNA development for atmospheric applications: N₂, O₂ and CO₂ models implementation.

Area of Science:

• Atmospheric Chemistry
• Computational Physics
• Radiation Physics

Background:

• Cosmic rays ionize atmospheric gases, influencing chemical reactions and atmospheric composition.
• Accurate particle-molecule interaction models are essential for quantifying these effects.
• The Geant-DNA toolkit is being expanded for atmospheric science applications.

Purpose of the Study:

• To extend the Geant-DNA toolkit with validated electron impact interaction models for atmospheric molecules.
• To incorporate electron cross sections for carbon dioxide, a key greenhouse gas.
• To enable quantitative analysis of ion-molecule reactions in the atmosphere.

Main Methods:

• Extended validation of electron impact interaction models for nitrogen (N2) and oxygen (O2) up to 10 MeV.
• Introduced new electron cross sections for carbon dioxide (CO2).
• Implemented these cross section models in the Geant4-DNA toolkit and validated them using stopping power and range simulations.

Main Results:

• Differential cross sections showed good agreement with analytical calculations and literature data for N2, O2, and CO2.
• Simulations of stopping power and range for N2, O2, CO2, and air demonstrated agreement within 6% of ESTAR database reference data.
• Successful implementation and validation of the new models within Geant4-DNA.

Conclusions:

• The implemented cross section models for N2, O2, and CO2 are now available in the Geant4-DNA toolkit.
• This advancement is critical for quantitatively studying atmospheric ionic reactive chemical networks.
• The toolkit enables better assessment of ionization's impact on atmospheric chemistry and climate implications.