Geant4 REMSIM application www.ge.infn.it/geant4/space/remsim: Geant4 REMSIM application www.ge.infn.it/geant4/space/remsim Susanna Guatelli, INFN Genova, Geant4 Workshop, 4th October 2004, Catania guatelli@ge.infn.it


Vision: Vision The project is defined in the context of AURORA - the European programme for the robotic and human exploration of the Solar System, with Mars, the Moon and the asteroids as the most likely targets The radiation hazard to crew is critical to the feasibility of interplanetary manned missions To protect crew shielding must be designed, the environment must be anticipated and monitored, a warning system must be put in place


Scope: Scope First quantitative evaluation of the physical effects of space radiation environment on astronauts in manned space missions The study is performed in a selected set of vehicle and surface habitats concepts with various shielding choices


Outline: Outline Software process Modeling the interplanetary space radiation Modeling the vehicle and surface habitats concepts Modeling the physics interactions Results first quantitative dosimetry in vehicle and surface habitats


Software process: Software process Iterative and incremental approach The Rational Unified Process (RUP) has been adopted as process framework Software process artifacts : User Requirement Document Design Project management at www.ge.infn.it/geant4/space/remsim


Project working group: Project working group P. Nieminen – European Space Agency, ESTEC, the Netherlands V. Guarnieri, C. Lobascio, P. Parodi, R. Rampini – ALENIA SPAZIO,Torino, Italy Model of vehicle concept and surface habitats S. Guatelli, M. G. Pia – INFN Genova, Italy Management and development of the Geant4 Remsim application


Strategy : Strategy The process consisted of a series of iterations Simplified geometrical configurations Essential characteristics for dosimetric studies kept Each iteration adds: a refinement in the experimental model the usage of further Geant4 functionality Physics processes


Space radiation environment: Space radiation environment Selected space radiation components: Galactic Cosmic rays Protons, alpha particles and heavy ions Solar Particle Events Protons and alpha particles GCR heavy ions considered: C-12, O-16, Si-28, Fe-52 The ions are completely stripped


Space radiation environment: Space radiation environment Envelope of CREME96 October 1989 and August 1972 spectra SPE particles: p and alpha Envelope of CREME96 1977 and CRÈME 86 1975 solar minimum spectra GCR: p, alpha, heavy ions Flux at 1 AU


Physics processes: Physics processes E.M. Physics Hadronic Physics for protons and alpha particles as incident particles


Selection of electromagnetic processes: Selection of electromagnetic processes Low Energy Package e-, photon, p, alpha particles, ions Standard Package e+ muons


E.M. physics validation: E.M. physics validation Validation of proton and alpha particles physics processes in the energy range of interest (1. MeV – 100. GeV) Comparison of Stopping power and CSDA range with respect to ICRU49 protocol Activity performed in the context of the Geant4 e.m. physics validation Look talk: Physics Validation – Electromagnetic, 5th October 2004, Catania


Selection of hadronic physics models: Selection of hadronic physics models For protons Two alternative models: Bertini and binary cascade Study and comparison of the dosimetric effect given by hadronic physics with the two alternative models For alpha particles IonBinary Model for E < 10 GeV Geant4 does not offer hadronic physics for higher energies


Selection of hadronic models (1): Selection of hadronic models (1) for p, n, pions – Bertini model Inelastic model 0 - 3.2 GeV : Bertini Cascade 2.8 – 25. GeV : Low Energy Parameterised (LEP) model 20. GeV -100. TeV: Quark Gluon String (QGS) model Elastic model


Selection of hadronic models (2): Selection of hadronic models (2) for p, n – Binary model Inelastic model 0. - 10. GeV : Binary Cascade 8. - 25. GeV : Low Energy Parameterised (LEP) model 20. GeV - 100. TeV: Quark Gluon String (QGS) model Elastic model for pions Inelastic model 0.- 25. GeV: LEP model 20. GeV – 100. TeV: QGS Elastic model


Slide16: Selection of hadronic models (3) alpha Inelastic model 0 – 100. MeV : LowEnergy Parameterised (LEP) 80. MeV – 10. GeV Binary Ion Model Alpha-nuclear cross sections: Tripathi, Shen Elastic model


Slide17: SIH consists of: Meteoroid and debris protection Structure Rebundant bladder The multilayer is the simplified model of the Simplified Inflatable Habitat concept (SIH) It retains the essential characteristics of the SIH relevant for a dosimetric study at this stage of the project Modeling SIH vehicle concept Geant4 model Astronaut shielding


Modeling the astronaut concept: Modeling the astronaut concept Optimisation of the max step allowed in the geometry (0.1 cm) Optimisation of the threshold of production of secondaries (0.1 cm) Voxel = 1 cm thick slice along the z Axis 30 voxels Astronaut - sensitive detector where the energy deposit is collected Simulation result: energy deposit with respect to the depth in the phantom


Results (1): Results (1) Thicker layer of shielding limit the exposure of the astronaut to the GCR The hadronic contribution to the dose calculation is relevant e.m. e.m. + binary e.m. + bertini


SPE shelter model: SPE shelter model The Geant4 model retains the essential characteristics of the vehicle concept relevant for a dosimetric study Geant4 model When SPE particles are detected by a warning system, the crew has to go inside the shelter Study the dosimetric effect of Galactic Cosmic Rays and Solar Particle Events in the Astronaut GCR and SPE particles


Results (2): Results (2) Energy deposit in the astronaut by GCR Energy deposit in the astronaut by SPE with E > 300 MeV Total equivalent dose in the astronaut given by GCR: em = 4.98 mSv/day em + hadronic (bertini) = 7.83 mSv/day em + hadronic (bynary) = 7.41 mSv/day


Modeling surface habitats: Modeling surface habitats On the moon, astronauts should build shelters by their own with moon soil Study the dosimetric effect of GCR and SPE particles with respect to x Add a log on top with variable height x x


Results (3): Results (3) The hadronic physics contribution is relevant in the dosimetric calculation e.m. e.m. + bertini e.m. + binary


Conclusions: Conclusions A first quantitative study has been performed in a set of vehicle and surface habitats Simple geometrical configurations, representing the essential features of vehicle concepts and moon surface habitats have been modeled Possible future developments: Refinement of the studies with angular dependencies of the incident beam Dosimetric studies with other options of shielding materials and thicknesses Geant4 advanced example: radioprotection Talk at the IEEE Nuclear Science Symposium Submission of the paper to the IEEE - Transactions On Nuclear Science