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

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
Susanna Guatelli
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
Susanna Guatelli
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
Susanna Guatelli
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
Susanna Guatelli
Geant4 Workshop 2004

7. Strategy The process consisted of a series of iterations
Each iteration adds:
a refinement in the experimental model
the usage of further Geant4 functionality
Vehicle concepts
Moon surface habitats
Simplified geometrical configurations
Essential characteristics for dosimetric
studies kept
Electromagnetic physics
+ hadronic physics
Physics processes
Susanna Guatelli
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
Susanna Guatelli
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 CREME and CRÈME solar minimum spectra
Susanna Guatelli
Geant4 Workshop 2004

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

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

14. Selection of hadronic models (1)
for p, n, pions – Bertini model
Inelastic model
GeV : Bertini Cascade
2.8 – 25. GeV : Low Energy Parameterised (LEP) model
20. GeV TeV: Quark Gluon String (QGS) model
Elastic model
Susanna Guatelli
Geant4 Workshop 2004

15. Selection of hadronic models (2)
for p, n – Binary model
Inelastic model
GeV : Binary Cascade
GeV : Low Energy Parameterised (LEP) model
20. GeV TeV: Quark Gluon String (QGS) model
Elastic model
for pions
GeV: LEP model
20. GeV – 100. TeV: QGS
Susanna Guatelli
Geant4 Workshop 2004

16. Selection of hadronic models (3)
alpha
Inelastic model
0 – MeV : LowEnergy Parameterised (LEP)
80. MeV – 10. GeV Binary Ion Model
Alpha-nuclear cross sections: Tripathi, Shen
Elastic model
Susanna Guatelli
Geant4 Workshop 2004

17. 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
GCR particles
vacuum
Air
Astronaut
multilayer
SIH model
Astronaut
Geant4 model
Susanna Guatelli
Geant4 Workshop 2004
shielding

18. 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
30 cm
incident
radiation Z
Voxel = 1 cm thick slice along the z Axis
30 voxels
Optimisation of the max step allowed in the geometry (0.1 cm)
Optimisation of the threshold of production of secondaries (0.1 cm)
Susanna Guatelli
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
Susanna Guatelli
Geant4 Workshop 2004

20. SPE shelter model shelter Geant4 model Air vacuum Multilayer phantom
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
vacuum
Air
Multilayer (28 layers)
phantom
shelter
Multilayer
Geant4 model
GCR and SPE
particles
Study the dosimetric effect
of Galactic Cosmic Rays and Solar Particle Events in the Astronaut
Susanna Guatelli
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 = mSv/day
em + hadronic (bertini) = 7.83 mSv/day
em + hadronic (bynary) = mSv/day
Susanna Guatelli
Geant4 Workshop 2004

22. Modeling surface habitats
Vacuum
Moon
soil
Beam
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
Susanna Guatelli
Geant4 Workshop 2004

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