GEANT4-DNA New physics models …from cell to DNA Christophe Champion FKPPL Workshop Seoul March 8-10, 2011

The classical Trajectory Monte Carlo - Classical Over Barrier model From water to DNA: The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) Input dynamical data : Each simulation starts and stops at large internuclear distance (≈100 a.u.) the projectile velocity (VP) the impact parameter (b) the initial conditions for the target

The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) The molecular binding energies

The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) General features of the classical models Movements of the particles described by Newton laws Initial targets information = the knowledge of the binding energies Classical criteria for describing the ionizing processes Total cross sections:

The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) COB (Classical Over Barrier) criteria

The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) COB (Classical Over Barrier) criteria

The Classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) COB (Classical Over Barrier) criteria Potential seen by the bound electron e1: where and where at the beginning of the simulation

The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) Propagation of the system At each step Δt (≈10-2 a.u.) COB and d conditions are tested: At each time step t and for each involved particle i (i = P, T and/or e-) For the next time step : t’ = t + Δt

The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) Conditions and criteria of the final state kinetic energy of the electron relatively to the target or the projectile potential energy of the electron relatively to the target or the projectile

The classical Trajectory Monte Carlo - Classical Over Barrier model (CTMC-COB) Total cross sections for the main ionizing processes induced by charged particles Abbas et al., Phys. Med. Biol. 53, N1-N11 (2008) Lekadir et al., NIM B 267, 1011-1014 (2009) Lekadir et al., Phys. Rev. A 79, 062710 (2009)

From water to DNA: Quantum mechanical approaches: Coulomb Born approximation (CB1) Continuum Distorted Wave – Eikonal Initial State (CDW-EIS) Champion et al., Phys. Med. Biol. 55, 6053-6067 (2010) Target description LCAO: Linear Combination of Atomic Orbitals Bernahrdt and Paretzke (Int. J. Mass Spectrom. 599 (2003))

Quantum mechanical /classical approaches: CB1, CDW-EIS / CTMC-COB Ionization of DNA bases impacted by light ions Abbas et al., Phys. Med. Biol. 53, N1-N11 (2008) Lekadir et al., NIM B 267, 1011-1014 (2009) Lekadir et al., Phys. Rev. A 79, 062710 (2009) Protons a-particles Carbon ions C6+

Quantum mechanical approaches: Continuum Distorted Wave – Eikonal Initial State (CDW-EIS) Capture on DNA bases impacted by light ions Protons Carbon ions C6+

DNA versus liquid water: GEANT4 simulations Results DNA 10 bp target Nucleosome target An increase of the mean energy value of energy deposits of the order of 25% for the 10 base pairs target and 25% for the nucleosome target