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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= 235kradElectrons dominates.A 3D radiation transport simulation tools will be usefull during all JUICE mission phases.

Radiation simulation tools

3From ECSS-E-HB-10-12A (Calculation of radiation and its effects and margin policy handbook)

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Why GRAS*

* 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/

IRF need an engineering tool for radiation transport. GRAS includes all common analysis modules- Easy 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.

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Radiation modelling infrastructure at IRF

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Geometry production (Tesselation)

/gras/geometry/util/listLogicalVolumes

Checks for interference between parts

Checks the tesselation

Time consuming! But usefull!

Geometry: Working with multilayer

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For example:

Light shield: Vacuum – Vacuum – Aluminium – Aluminium

Heavy shield: Aluminium – Aluminium – Tantalum – Aluminium

First shielding estimates

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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 statisticsUse 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

GRAS RMC Example

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How small is the Shieldose solid sphere….if it had existed?

SHD2Q (4mm) GRAS 3.1 RMC (4mm) SHD2Q (10mm) GRAS 3.1 RMC (10mm)To Europa 113000 114440 25000 20020Europa phase 65000 55990 17000 10086Jupiter HL to Callisto 72000 80433 14000 13217To Ganymede 127000 159570 20000 25510Ganymede science 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.

Some Total dose result

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Without added shielding Added shielding

Mutal shielding in dense package

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Without added shielding Added shielding

Some fluence result

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Some internal charging result

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Phase Description

1 Transfer to Europa 2 Europa phase 3 Jupiter HL to Callisto 4 Transfer to Ganymede 5 Ganymede incl. shielding 6 Worst case e- fluence

[/cm2/sr/s] 7 Worst case e- fluence

[/cm2/sr/s] 12h 8 Worst case e- fluence

[/cm2/sr/s] 24h

Graded shields in the 3D model

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In this case:Only small reduction in electrom flux, 4%Good reduction for gamma, 15%

Lesson learned

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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