CAD interfaces for simulation and analysis tools in the space domain

Transcription

1 Geant4 CAD interface development meeting Orsay, 23 March 2010 CAD interfaces for simulation and analysis tools in the space domain Giovanni Santin* Space Environments and Effects Analysis Section European Space Agency ESTEC * on loan from RHEA System

2 Outline Radiation analyses in the space environment domain Geometry modelling issues Geant4 and CAD interfaces ESA developments

3 Simulations of the Space Radiation Environment Sources (Extra) Galactic and anomalous Cosmic Rays Protons and Ions <E> ~ 1 GeV, E max > ev Continuous low intensity Solar radiation Protons, some ions, electrons, neutrons, gamma rays, X-rays Softer spectrum Event driven occasional high fluxes over short periods. Trapped radiation Electrons ~< 10 MeV Protons ~< 10 2 MeV Spacecraft and payload geometry can significantly affect particle range and/or physical cross sections Impact on rate of degradation and single event effect Goals Component selection Ground tests Extrapolation to real life in space Science analyses Particle signal extraction Background Environment models Simulation of the emission and the propagation of radiation in space Cheaper than accelerator tests Calibration Effects Effects in components / sensors Single Event Effects (SE Upset, SE Latchup, ) Effects to science data Background (Spurious signals, Detector overload, ) Threats to life Dose (dose equivalent) and dose rate in manned space flights Degradation Charging Radiobiological effects (Ionisation, displacement, ) (internal, interferences, )

4 ECSS guidelines Engineering radiation analyses must insure conservatism of estimates still avoiding overdimensioned shielding (and margins) Use of detailed 3-D geometry models is encouraged

5 SREM Response (Proba-1) Directional response function for all output channels Geant4 / simulations Inner Belt Anisotropy Investigations AP-8 and Badhwar-Konradi pitch angle distribution model Comparison with observations onboard PROBA-1 Martin Siegl s Master s Thesis, 2009 Presented at RADECS 09, accepted IEEE TNS

6 Herschel and Planck

7 Tools at various detail levels along the ECSS guidelines SHIELDOSE-2 SHIELDOSE-J SHIELDOSE-2 Ray-tracing FASTRAD ESABASE SYSTEMA SSAT (Geant4) FASTRAD SSAT (Geant4) Full Monte Carlo MULASSIS (Geant4, 1.5-D) (Geant4, 3-D) MULASSISS (Geant4)

8 Geometry modelling practices Various strategies for obtaining analysis models from full CAD designs New model, copy by hand Common choice in long term HEP experiments Can be a significant part of simulation setup in space engineering ESABASE (v1) format (and similar SYSTEMA format) are rich with basic and more complex shapes (e.g. extrusions) ConeXpress, R.Lindberg, ESA Computer aided simplifications of original CAD model Even when CAD import works, the model might be unusable Open (or surface-like) shapes Wrongly oriented normals special tools for editing and simplifying the models in e.g. SYSTEMA, FASTRAD Full CAD model

9 Geant4 CAD interfaces Some history First releases of Geant4 used to include option for direct STEP conversion Based on obsolete library, limited applicability Abandoned Scepticism from the HEP community towards CAD models and related interfaces Boundary represented shapes Historically limited support from the Geant4 collaboration Potential complexity of surfaces Computing requirements CAD flat geometry VS Geant4 complex volume hierarchy tree Level of detail and precision in full-blown engineering models Hundreds of MB for sometime simple models Unneeded details (e.g. screws) Commercial tools, proprietary formats Development and maintenance of new CAD interface deemed beyond available resources

10 Geant4 renewed interest CAD interface requirement now clearer Need expressed by space, medical but also HEP users Discussion session at latest Geant4 collaboration meeting (Catania, Italy, Oct 2009)

11 Geant4 geometry interfaces C++ versus text formats GGE GUI and other tools produce C++ files to be compiled FASTRAD also has a proprietary Geant4 module producing C++ External files for geometry models Easier to exchange ASCII files (XML, or dedicated formats) Almost each big HEP experiment has own format / interface Difficulties in standardisation Potential standard formats for interfaces VRML Existing standard, can be produced and/or visualised with many tools GDML XML based, readable easily extensible Tailored for radiation transport TCAD formats, e.g. GDSII, Silvaco, Google SketchUp?

12 ESA funded CAD Geant4 interfaces (and 3D modelling GUI) Strategy: based on resources external to Geant4 External, established 3-D modelling tools / libraries STEP & IGES formats Combination w/ non CAD elements Geant4 via GDML outlut Synergy with space industry players Technical expertise Space user requirements oriented Link with non-hep resources Partners: QinetiQ (prime) TRAD (FASTRAD) Etamax (ESABASE2) FASTRAD, ESABASE2 GUI for 3D modelling Powerful and extremely useful GDML output ESA contract: REAT-MS (QinetiQ, TRAD, eta_max)

13 CAD Geant4 interface Implementation details CAD OpenCascade libraries STEP & IGES formats Geant4 G4TessellatedSolid by P.Truscott [Old prototype used to require ST-Viewer commercial S/W GDML to read ST-Viewer files] GDML format Upgrade by Witek Pokorski, CERN Tetrahedron and Tessellated volumes, modular models, loops Open issues Some limitations (e.g. hierarchy) are being addressed Continuous funding from ESA not guaranteed License, distribution policies are showing some constraints for wide use by Geant4 user community Significant interest from users in space, medical and HEP domain ESA contract: REAT-MS (QinetiQ, TRAD, eta_max)

14 STEP format extensions for plasma and radiation transport ESA contract: STEP-SPE STEP for Space Environment standard (STEP-SPE) Built upon already established extensions for thermal analyses STEP-TAS Includes placeholders for parameters needed for high energy radiation transport and plasma simulations, e.g. Materials with chemical composition Density Surface properties Developed by INCKA (F) Includes new format and library for reading and writing of STEP-SPE files FASTRAD (TRAD) and ESABASE2 (etamax) now include STEP-SPE interfaces

15 External geometries GDML, CAD (via GDML) Radiation Environment (e.g. SPENVIS, CREME96) via GPS Requirements: Ready-To-Use tool Built-in geometries MULASSIS, GEMAT, C++, Reverse MC RMC Multi-mission approach Geant4 Physics EM & Hadronic options Transport, Scoring Quick assessments Ray-tracing MC 1D 3D Physics interfaces: PHITS, JQMD, DPMJET2.5 Analysis output: Scalars, Histograms, Tuples (CSV, AIDA, ROOT, log) EM Hadronics LET SV details G Santin, V Ivantchenko et al, IEEE Trans. Nucl. Sci. 52,

16 (v2.4) Modular progress C++ GEMAT (QQ) MULASSIS (QQ) Geometry GDML 2.10 & 3 (CAD) ESA facility Being augmented with support of ESA external contracts (e.g. REAT-MS, RRMC, REST-SIM) Open to collaborations and contributions (modules, infrastructure) Dose Dose Dose Analysis Analysis Analysis Modules Modules Modules Ray-Tracing (QQ) GPS Primary Generator New EM e.g. e-, ion Single.Sc. DPMJET2.5 interface Previous physics elements Physics Firsov Scattering (QQ) Adjoint physics Run Manager Adjoint manager Run Action Event Action Tracking Action Stepping Action Analysis Manager Dose Dose Analysis Analysis Analysis Modules Modules Modules Ray- Dose Dose Analysis Analysis tracing Modules Modules Analysis Modules Charge Dose Collection Dose Analysis (GEMAT,QQ) Analysis Modules Analysis Modules Modules

17 Enabling technologies: Reverse MC Requirement from space industry Tallying in sub-micron SV inside macroscopic geometries Simulation approach: Implemented Reverse Processes: Ionisation for e -, protons, ions (with delta-ray production, continuous energy loss and multiple scattering) e - Bremsstrahlung Gamma: Compton scattering, Photo-electric effect Laurent Desorgher (Space IT) Reverse tracking from the boundary of the sensitive region to the external source Based on adjoint transport equations Forward tracking trough the SV to compute the detector signal Same code than in a forward MC simulation Computing time focused on tracks that contribute to the detector signal Capability added to ESA REAT-MS and RRMC contracts Included in Geant4 9.3

18 Summary Successful development of CAD interfaces for Geant4 based on OpenCascade libraries in external tools FASTRAD ESABASE-2 License, distribution policies and wide Geant4 user community CAD interfaces in the global picture for space radiation environment analyses at ESA STEP-SPE Reverse-MC Acknowledgements LPC Clermont-Ferrand for the support for this meeting