The scope of the
radioprotection example is to study shielding solutions to protect the crews of
shuttles from space radiation hazards in interplanetary space missions.
The example calculates the energy deposit in an astronaut
in selected vehicle configurations and Moon surface habitats, in a set of interplanetary space radiation environments.
This application has been developed in the context of the
ESA
REMSIM project of the
AURORA
Programme.
The primary objective of Aurora is to create, and then implement, a European
long-term plan for the robotic and human exploration of the solar system,
with Mars, the Moon and the asteroids as the most likely targets.
The REMSIM Geant4 Simulation
web site provides more information concerning this Geant4
advanced example and all the related
software process
documents.
Authors: S. Guatelli (INFN Genova),
M. G. Pia (INFN Genova)
The radioprotection example encompasses components, that have different responsibilities and cooperate to achieve the goals of the application defined in the User Requirement Documents. The implementation of the sofware reflects the design model.
This element
has the responsibility of generation of primary particles, that can be protons,
alpha particles, ions, electrons, photons, neutrons, etc..
Primary particles can be generated as monochromatic beams or on the basis
of a given energy spectrum, that can be supplied in an ASCII file.
The user can generate primary particles from a fixed point in the experimental
set-up or from a plane or from the surface of a hemisphere.
The direction of the primary particles can be fixed or randomised on the
basis of a given algorithm. The user can choose the conditions of the generation
of primary particles interactively.
The example provides ASCII files with the energy spectrum
of selected Galactic Cosmic Rays (GCR) components and Solar Particle Events
(SPE).
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||
Envelope of CREME 96 1977
and CREME 86 1975. The fluxes are predicted for 1 AU and correspond to the
solar minimum activity. |
SPE protons ( blue) and SPE
alpha (pink). Envelope of CREME96 October 1989 and August 1972 spectra. The fluxes are predicted for 1 AU. |
||
ASCII file containing GCR
energy spectra |
ASCII file containg the SPE
energy spectra |
||
First column: energy (MeV) |
|||
p alpha carbon ion oxygen ion silicon ion iron ion |
gcrZ=1.txt gcrZ=2.txt gcrZ=6.txt gcrZ=8.txt gcrZ=14.txt gcrZ=26.txt |
p alpha |
speZ=1.txt speZ=2.txt |
This component
has the responsibility of the configuration of the experimental set-up in
terms of volumes and materials. The vehicle and Moon surface habitats and
the Astronaut are defined in this component. The available geometry configurations
are listed in the following table.
Vehicle concept |
![]() |
Geometrical set-up 1 A particle beam impinges on a multilayer box structure, that represents a model of a Simplified Inflatable Habitat (SIH). The energy deposit is collected in the Astronaut. The user can add a shielding to the multilayer structure. The shielding is a layer of water, whose purpose it to protect the astronaut from Galactic Cosmic Rays (GCR). The user can add, delete this element in the geometrical configuration, change its thickness through UI comands. |
Vehicle concept |
![]() |
Geometrical set-up 2 A SPE shelter is added to the multilayer structure. The SPE shelter is a water layer (thickness = 75.cm along Z axis), its purpose is to protect the astronaut from Solar Particle Events (SPE). The user can add, delete this element in the geometrical configuration through UI comands. |
Moon
Surface habitat |
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Geometrical set-up 3 The astronaut habitat is a box of air placed under the surface of the Moon (first picture). The astronaut is positioned inside the habitat. The user can add, delete a pyramid log placed on top of the habitat (second picture). The purpose of the pyramid log is to protect the astronaut from the space radiation environment. The pyramid log is made of moon soil; the user can change its height interactively. |
The Astronaut is
the geometrical component where the energy deposit is collected (sensitive
detector). The energy
deposit results from the interactions of the primary and secondary particles
in the associated volume.
The user can retrieve the information of energy
deposit with respect to the depth of penetration in the Astronaut.
The user can retrieve
the type and energy of primary particles reaching and traversing the Astronaut.
This component has the responsibility of the instantiation of particles involved in the simulation study. The Geant4 pre-defined particles (for example electrons, positrons, photons, protons, alpha particles) are just instantiated. Carbon, Oxygen, Silicon and Iron ions have been created for the application, providing information of their mass, atomic and mass numbers. These ions are completely stripped of their electrons.
The physics component has the responsibility of the activation of Geant4 physics processes. It is modularised in sub-components: each component controls the activation of the processes for a given particle type. The user can activate both electromagnetic and hadronic physics processes.
This component manages information regarding the steps of particles in the experimental set-up. The user can retrieve the information about the type of a particle, its energy, its initial energy, etc..
The messengers allow to change simulation parameters in interactive sessions or through macros. The application is provided of messengers to change primary particle configuration and geometry experimental set-ups. Please look in the README file for details about the available UI commands.
The application is interfaced to external visualisation tools to visualise the experimental set-up and the particle tracks. The user can use OpenGL, DAWN, WRML as graphics tools.
The application
is interfaced to external analysis tools through AIDA 3.2.1 and PI 1.2.1.
The use of these analysis tools allows to store the results of the simulations
in histograms, ntuples, data sets.
If the ANALYSIS_USE environment
variable is
set to 1, the simulation produces a remsim.hbk analysis output file,
containing the following histograms:
The analysis tools can be downloaded from the AIDA
and PI web sites.
A standard Geant4 example GNUmakefile is provided.
The example has been tested on the platform Linux RedHat 7.3, with
compiler = gcc-3.2.3 (corresponding to Geant4 environment variable G4SYSTEM = linux-g++).
The following environment variables concerning physics must be set:
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pointing to low energy data G4EMLOW2.3 |
![]() |
pointing to PhotoEvaporation data |
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pointing to Radioactive Decay data |
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pointing to neutron data G4NDL3.7 |
Setup for analysis: AIDA 3.2.1, PI 1.2.1.
Example macros are provided:
To run in
batch mode:
To run in
interactive mode:
For
further information please look into:
For questions not covered by Geant4 or
REMSIM documentation, please contact
Susanna Guatelli.