Modeling Radiation Chemistry in the Geant4 Toolkit

Abstract

Simulation of biological effects of ionizing radiation at the DNA scale requires not only the modeling of direct damages induced on DNA by the incident radiation and by secondary particles but also the modeling of indirect effects of radiolytic products resulting from liquid water radiolysis. They can provoke single, double strand breaks and base damage by reacting with DNA. The Geant4 Monte Carlo toolkit is currently being extended for the simulation of biological damages of ionizing radiation at the DNA scale in the framework of the 'Geant4-DNA' project. Physics models for the modeling of direct effects are already available in Geant4. In the present paper, an approach for the modeling of radiation chemistry in pure liquid water within Geant4 is presented. In particular, this modeling includes Brownian motion and chemical reactions between molecules following water radiolysis. First results on time-dependent radiochemical yields from 1 picosecond up to 1 microsecond after irradiation are compared to published data and discussed.