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