Hadronic physics validation of Geant4 The study of radiation effects is fundamental to the feasibility of interplanetary missions Geant4 simulations are the primary tool to evaluate quantitatively the effects of the space radiation environment Crucial point: how to model physics interactions? The Geant4 Toolkit provides many alternative and complementary approaches and models (e.g. Parameterised and theory driven approaches, Bertini and Binary Cascade models, etc.) Which model is more suitable? Are these models reliable?

against reliable physics references Hadronic physics validation of Geant4 Systematic, rigorous, quantitative validation of Geant4 hadronic physics models As: Energy spectra Particle multiplicities Scattering angles etc. Similar approach as in Geant4 electromagnetic physics validation A systematic, statistically rigorous validation of Geant4 hadronic physics is missing at the present time. against reliable physics references

down to the electronvolt scale Geant 4 extension down to the electronvolt scale Simulation of electromagnetic interactions down to low energies is an important issue for space missions to Mars: Radiation effects on electronics and science instruments are critical to the successful operation of missions Possible biological effects of radiation on human tissues can compromise the astronauts’ health and the mission feasibility Currently, Geant4 provides a specialized package to simulate low energy electromagnetic interactions Models are based on the assumption that the atoms of the material subject to particle interaction are free This approximation is no more valid below 100-200 eV An extension of Geant4 physics capabilities below this energy range requires a novel modeling approach

Geant 4 electromagnetic physics validation Current models have been extensively validated w.r.t. the NIST database (cross sections and stopping powers) A rigorous statistical analysis has been performed with the Statistical Toolkit developed in the ESA SEPTIMESS project Extend rigorous validation of Geant4 for electromagnetic physics models Below 1 KeV Over 10/100 GeV (not covered by NIST) Final state generation (spectra, angular distributions) Provide guidance to users about the selection of electromagnetic physics models to be instantiated in a Physics List