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Charged Particle Track-Structure Simulations: Interaction Cross Sections for Gold

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M Dingfelder

M Dingfelder*, J Teller , East Carolina University, Greenville, NC


SU-I-GPD-T-109 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Provide quality interaction cross sections for charged particle Monte Carlo (MC) track structure codes for non biological targets like gold.

Methods: Track-structure simulations are often used to model the physical and chemical stages of radiation action with matter and the initial radiation damage to biological systems. Available MC track structure codes are limited to a few materials of biological interest, mainly water (vapor and liquid) and DNA-like bases; they use mass density scaling to simulate different materials, which is justified for low Z biological matter. However, this method cannot be used for high Z materials like gold nano-particles. Interaction cross-sections for charged particles (e.g., electrons, protons, alpha particles, light and heavy ions) are calculated using the dielectric formalism and the first Born approximation. This method combines first principles with theoretical modeling and available experimental information and is applicable to condensed phase targets. It uses measured optical constants, theoretical inner shell cross-sections and a simple separation into excitations, detailed inner shell ionizations, and average outer shell ionization channels. The cross-sections and a transport model for charged particles including secondary electron emission, elastic scattering for electrons, and non-Born effects will be implemented into the MC track structure code PARTRAC.

Results: Total and energy differential cross sections for excitations, outer shell and inner shell ionizations for electrons and protons in gold are presented as well as transport models on secondary electron emission.

Conclusion: The availability of gold as a target material will allow the detailed simulation and study of gold nano-particles as radiation enhancers on a micro- or nano-dosimetric scale and include the effects into radiation damage simulations.

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