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Susanna Guatelli Geant4 Workshop 2004
Geant4 REMSIM application www.ge.infn.it/geant4/space/remsim
Susanna Guatelli, INFN Genova, Geant4 Workshop,4th October 2004,Catania
Moonhabitat
guatelli@ge.infn.it
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
Strategy
The process consisted of a series of iterations
Simplified geometrical configurations
EssentialEssential characteristics for dosimetric studies kept
Each iteration adds: • a refinement in the experimental model • the usage of further Geant4 functionality
Vehicle concepts
Moon surface habitats
Physics processesElectromagnetic physics
+ hadronic physics
Susanna Guatelli Geant4 Workshop 2004
Space radiation environmentSelected 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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
Physics processes
E.M. Physics
Hadronic Physics for protons and alpha particles as incident particles
Susanna Guatelli Geant4 Workshop 2004
Selection of electromagnetic processes
Low Energy Package- e-, photon, p, alpha particles, ions
- Standard Package- e+- muons
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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 SIHrelevant for a dosimetric study at this stage of the project
Modeling SIH vehicle concept
GCR particles
vacuum Air
Astronaut
multilayer
SIH model
Geant4 model
Astronaut
shielding
Susanna Guatelli Geant4 Workshop 2004
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
30 cm
incidentradiation Z
Astronaut - sensitive detector where the energy deposit is collected
Simulation result: energy deposit with respect to the depth in the phantom
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
SPE shelter model
vacuum
Air
Multilayer (28 layers) phantom
shelter
vacuum
Multilayer
• 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 effectof Galactic Cosmic Rays and Solar Particle Events in the Astronaut
GCR and SPEparticles
Susanna Guatelli Geant4 Workshop 2004
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
Susanna Guatelli Geant4 Workshop 2004
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
Vacuum Moonsoil
Beam
Add a log on top with variable height x
x
Susanna Guatelli Geant4 Workshop 2004
Results (3)
• The hadronic physics contribution is relevant in the dosimetric calculatione.m.
e.m. + bertini
e.m. + binary
Susanna Guatelli Geant4 Workshop 2004
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