Geant4 REMSIM application gefn.it/geant4/space/remsim

1. Moon habitat guatelli@ge.infn.it Geant4 REMSIM applicationwww.ge.infn.it/geant4/space/remsim Susanna Guatelli, INFN Genova, Geant4 Workshop, 4th October 2004, Catania Geant4 Workshop 2004

2. Vision • The project is defined in the context of AURORA - the European programme for the robotic and human exploration of the SolarSystem, 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 Geant4 Workshop 2004

3. 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 Geant4 Workshop 2004

4. 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 Geant4 Workshop 2004

5. 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 Geant4 Workshop 2004

6. 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 Geant4 Workshop 2004

7. Vehicle concepts Moon surface habitats Electromagnetic physics + hadronic physics Strategy The process consisted of a series of iterations • Each iteration adds: • a refinement in the experimental model • the usage of further Geant4 functionality • Simplified geometrical configurations Essentialcharacteristics for dosimetric studies kept • Physics processes Geant4 Workshop 2004

8. 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 Geant4 Workshop 2004

9. Space radiation environment Flux at 1 AU GCR: p, alpha, heavy ions SPE particles: p and alpha Envelope of CREME96 October 1989 and August 1972 spectra Envelope of CREME96 1977 and CRÈME 86 1975 solar minimum spectra Geant4 Workshop 2004

10. Physics processes • E.M. Physics • Hadronic Physics for protons and alpha particles as incident particles Geant4 Workshop 2004

11. Selection of electromagnetic processes • Low Energy Package • e-, photon, p, alpha particles, ions • Standard Package • e+ • muons Geant4 Workshop 2004

12. 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 Geant4 Workshop 2004

13. 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 Geant4 Workshop 2004

14. 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 Geant4 Workshop 2004

15. 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 Geant4 Workshop 2004

16. 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 Geant4 Workshop 2004

17. vacuum Air GCR particles Astronaut SIH model multilayer Modeling SIH vehicle concept • 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 Astronaut Geant4 model Geant4 Workshop 2004 shielding

18. incident radiation Z 30 cm Modeling the astronaut concept • Astronaut - sensitive detector where the energy deposit is collected • Simulation result: energy deposit with respect to the depth in the phantom • 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 Geant4 Workshop 2004

19. Results (1) e.m. + binary e.m. + bertini e.m. • Thicker layer of shielding limit the exposure of the astronaut to the GCR • The hadronic contribution to the dose calculation is relevant Geant4 Workshop 2004

20. vacuum shelter Air vacuum Multilayer phantom Multilayer (28 layers) SPE shelter model • When SPE particles are detected by a warning system, the crew has to go inside the shelter • The Geant4 model retains the essential characteristics of the vehicle concept relevant for a dosimetric study Geant4 model GCR and SPE particles Study the dosimetric effect of Galactic Cosmic Rays and Solar Particle Events in the Astronaut Geant4 Workshop 2004

21. 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 Geant4 Workshop 2004

22. Moon soil Vacuum Beam Modeling surface habitats Add a log on top with variable height x • 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 x Geant4 Workshop 2004

23. Results (3) e.m. + binary • The hadronic physics contribution is relevant in the dosimetric calculation e.m. + bertini e.m. Geant4 Workshop 2004

24. 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 Geant4 Workshop 2004