Radiation modelling infrastructure and methods
for JUICE at IRF
JUICE Radiation Modelling Workshop,
Aberystwyth
28-30 November 2012
Stefan Karlsson, Stas Barabash, Leif Kalla, Magnus Oja, Martin Wieser
Swedish Institute of Space Physics
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Jupiter is a challange
10mm => Bebi= 5krad JUICE= 235krad
Electrons dominates.
A 3D radiation transport simulation tools will be usefull
during all JUICE mission phases.
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Radiation simulation tools
From ECSS-E-HB-10-12A (Calculation of radiation and its effects and margin policy handbook)
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Why GRAS*
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IRF need an engineering tool for radiation transport.
GRAS includes all common analysis modulesEasy to use (REST-SIM will make use even easier and more
effective).
”Free software”
Development supported by ESA
Geant4 physics models has strong heritage
Validated.
* Geant4 Radiation for Space, G Santin, V Ivanchenko, H Evans, P Nieminen, and E Daly, “GRAS: a
general-purpose 3-D Modular Simulation tool for space environment effects analysis,” IEEE Trans Nucl
Sci, 52, no 6, pp2294–2299, 2005. URL:
http://space-env.esa.int/R_and_D/gras/
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Radiation modelling infrastructure at IRF
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Geometry production (Tesselation)
Checks for interference between parts
Checks the tesselation
Time consuming! But usefull!
/gras/geometry/util/listLogicalVolumes
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Geometry: Working with multilayer
For example:
Light shield: Vacuum – Vacuum – Aluminium – Aluminium
Heavy shield: Aluminium – Aluminium – Tantalum – Aluminium
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First shielding estimates
Using SSAT* to produce shielding maps is an effective way to discover
weknesses in the shielding of your 3D model.
*F.Lei, P.Truscott, G.Santin, M.Gadsson, SSAT “Sectoring Shielding Analysis Tool based
on Geant4” URL: http://reat.space.qinetiq.com/ssat/
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Dose distribution plots
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GRAS FMC
Add multiple detectors on Printed Ciruit board
Use sorce biasing, 1/E spectrum to increase statistics
Use loops to insert analysis modules setting histograms
/control/loop macros/analysis_dose.loop module 1 144 1
/control/loop macros/analysis_fluence.loop module 1 6 1
/control/loop macros/set_dose_histogram.loop module 0 292 1
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GRAS RMC
Make it possible to use very small sensitive detectors
Many simulation cases can be performed on a single computer.
Quite new feture in GRAS, some uncertainties exists, updated ongoing
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GRAS RMC Example
How small is the Shieldose solid sphere….if it had existed?
To Europa
Europa phase
Jupiter HL to Callisto
To Ganymede
Ganymede science
SHD2Q (4mm) GRAS 3.1 RMC (4mm) SHD2Q (10mm) GRAS 3.1 RMC (10mm)
113000
114440
25000
20020
65000
55990
17000
10086
72000
80433
14000
13217
127000
159570
20000
25510
782000
886090
156000
153500
Sum
1159000
1296523
232000
222333
Table 1: Data for 8um (Si) solid sphere, SHD2Q JES4.9 vs GRAS RMC 3.1.
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Particle Environment Package (PEP)
Particle Environment Package (PEP) is a particle instrument
being proposed for the JUICE mission
During AO work first radiation analysis was performed
This work covers the essential issues of Total Ionizing Dose, fluence of
particles at sensor level, and charging effects.
PEP uses mutal shieling by packing several instrument in a dense
package.
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Some Total dose result
Without added shielding
Added shielding
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Mutal shielding in dense package
Without added shielding
Added shielding
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Some fluence result
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Some internal charging result
Phase Description
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2
3
4
5
6
7
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Transfer to Europa
Europa phase
Jupiter HL to Callisto
Transfer to Ganymede
Ganymede incl. shielding
Worst case e- fluence
[/cm2/sr/s]
Worst case e- fluence
[/cm2/sr/s] 12h
Worst case e- fluence
[/cm2/sr/s] 24h
Energy range
[MeV]
0.02-1000
0.02-1000
0.02-1000
0.02-1000
0.02-1000
0.02-1000
0.02-1000
0.02-1000
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Graded shields in the 3D model
In this case:
Only small reduction in electrom flux, 4%
Good reduction for gamma, 15%
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Lesson learned
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Spend time to get your tessellated 3D geometry error
free before starting simulations, save time in the long
run.
During radiation iterative process useful with some
kind of parallel system.
Add more shielding than necessary, multi layered,
then it is no need for new geometry creation for every
simulation case.
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