Radioprotection advanced example


Introduction

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)


Example components

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.

Primary particles

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).



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)
Second column: flux

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

Experimental set-up

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

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.

Particles

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.

Physics

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.

Stepping

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..

Messengers

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.

Visualisation

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.

Analysis

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.


Set-up

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:

G4LEDATA  pointing to low energy data G4EMLOW2.3
G4LEVELGAMMADATA  pointing to PhotoEvaporation data
G4RADIOACTIVEDATA  pointing to Radioactive Decay data
NeutronHPCrossSections  pointing to neutron data G4NDL3.7

Setup for analysis: AIDA 3.2.1, PI 1.2.1.


How to run the example

Example macros are provided:

To run in batch mode:

To run in interactive mode:


Additional documentation

For further information please look into:

For questions not covered by Geant4 or REMSIM documentation, please contact Susanna Guatelli.



Last modified 9-7-2004 - Susanna Guatelli