1. 1 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

2. 2 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.

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

4. 4 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.

5. 5 Radiation modelling infrastructure at IRF

6. 6 Geometry production (Tesselation) /gras/geometry/util/listLogicalVolumes Checks for interference between parts Checks the tesselation Time consuming! But usefull!

7. Geometry: Working with multilayer 7 For example: Light shield: Vacuum – Vacuum – Aluminium – Aluminium Heavy shield: Aluminium – Aluminium – Tantalum – Aluminium

8. First shielding estimates 8 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/http://reat.space.qinetiq.com/ssat/

9. 9 Dose distribution plots

10. 10 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

11. 11 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

12. GRAS RMC Example 12 How small is the Shieldose solid sphere….if it had existed? Table 1: Data for 8um (Si) solid sphere, SHD2Q JES4.9 vs GRAS RMC 3.1.

13. 13 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.

14. Some Total dose result 14 Without added shielding Added shielding

15. Mutal shielding in dense package 15 Without added shielding Added shielding

16. Some fluence result 16

17. Some internal charging result 17

18. Graded shields in the 3D model 18 In this case: Only small reduction in electrom flux, 4% Good reduction for gamma, 15%

19. 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. 19