cad interfaces for simulation and analysis tools in the...
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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 SectionEuropean Space Agency
ESTEC* on loan from RHEA System
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Outline
Radiation analyses in the space environment domain–
Geometry modelling issues
Geant4 and CAD interfaces –
ESA developments
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Simulations of the Space Radiation Environment
Spacecraft and payload geometry can significantly affect particle range and/or physical cross sections
Impact on rate of degradation and single event effect
Protons, some ions, electrons, neutrons, gamma rays, X-rays…
Softer spectrum
Event driven –
occasional high fluxes over short periods.
Solar radiation Electrons ~< 10 MeV
Protons ~< 102
MeV
Trapped radiation
Sou
rces
Protons and Ions
<E> ~ 1 GeV, Emax
> 1021
eV
Continuous
low intensity
(Extra) Galactic and anomalous Cosmic Rays
Effe
cts
Single Event Effects
(SE Upset, SE Latchup, …)
Degradation
(Ionisation, displacement,…)
Effects in components / sensorsBackground
(Spurious signals, Detector overload,…)
Charging
(internal, interferences, …)
Effects to science dataDose (dose equivalent) and dose rate in
manned space flights
Radiobiological effects
Threats to life
Ground tests
Extrapolation to real life in space
Cheaper than accelerator tests
Component selection
Goa
ls
Particle signal extraction
Background
Calibration
Science analysesSimulation of the emission and the
propagation of radiation in space
Environment models
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
ECSS guidelines
Engineering radiation analyses must
–
insure conservatism of estimates
–
still avoiding over-
dimensioned shielding (and margins)
Use of detailed 3-D geometry models is encouraged
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Directional response function for all output channels
Geant4 / GRAS 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
SREM Response (Proba-1)
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Herschel and Planck
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Tools at various detail levels along the ECSS guidelines
SHIELDOSE-2–
SHIELDOSE-J
Ray-tracing–
FASTRAD–
ESABASE–
SYSTEMA–
SSAT (Geant4)
Full Monte Carlo–
MULASSIS (Geant4, 1.5-D)–
GRAS (Geant4, 3-D)
SH
IELD
OSE
-2
FAS
TRA
D
SSA
T (G
eant
4)M
ULA
SS
ISS
(G
eant
4)
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Geometry modelling practicesVarious 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
“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
–
ESABASE (v1) format (and similar SYSTEMA format) are rich with basic and more complex shapes (e.g. extrusions)
Con
eXpr
ess,
R.L
indb
erg,
ES
A
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
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
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
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)
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
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
?
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
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)
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
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)
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
STEP format extensions for plasma and radiation transport
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
ESA contract:
STEP-SPE
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
GRAS
Requirements:
Ready-To-Use toolMulti-mission
approach
Quick assessmentsRay-tracing ↔ MC
1D ↔ 3D
EM ↔ Hadronics
LET ↔ SV detailshttp://space-env.esa.int/index.php/geant4-radiation-analysis-for-space.html
G Santin, V Ivantchenko et al, IEEE Trans. Nucl. Sci. 52, 2005
GRAS
Transport,Scoring
Radiation Environment(e.g. SPENVIS, CREME96)
via GPS
Geant4 PhysicsEM & Hadronic options
Built-in geometriesMULASSIS,
GEMAT, C++,
Analysis output:Scalars, Histograms, Tuples
(CSV, AIDA, ROOT, log)
External geometriesGDML, CAD (via GDML)
Reverse MCRMC
Physics interfaces:PHITS, JQMD, DPMJET2.5
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
GRAS (v2.4) Modular progress
ESA facility
Being augmented with support of ESA external contracts (e.g. REAT-MS, RRMC, REST-SIM)
Open to collaborations and contributions (modules, infrastructure)
GRAS Analysis Manager
DoseAnalysis Modules
DoseAnalysis Modules
DoseAnalysis Modules
DoseAnalysis Modules
DoseAnalysis Modules
…Analysis Modules
DoseAnalysis Modules
DoseAnalysis Modules
Ray- tracingAnalysis Modules
DoseAnalysis Modules
DoseAnalysis Modules
Charge Collection
(GEMAT,QQ)Analysis Modules
GRAS Run
ActionGRAS Event ActionGRAS
Tracking ActionGRAS
Stepping Action
GRASRun
ManagerGRAS
PrimaryGenerator
GPS
Ray-Tracing(QQ)
GRAS Geometry
GDML 2.10 &
3(CAD)
MULASSIS(QQ)
GEMAT(QQ)
C++
GRASPhysics
Previous physics
elementsNew EM
e.g. e-, ion Single.Sc.
DPMJET2.5interface Adjoint
physicsFirsov
Scattering (QQ)
Adjoint manager
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Enabling technologies: Reverse MC
Requirement from space industry
Tallying in sub-micron SV inside macroscopic geometries
Simulation approach:
Reverse tracking from the boundary of the sensitive region to the external sourceBased on “adjoint”
transport equations
Forward tracking trough the SV to compute the detector signalSame code than in a forward MC simulation
Computing time focused on tracks that contribute to the detector signal
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
Capability added to GRAS
ESA REAT-MS
and RRMC contracts
Laurent Desorgher (Space IT)
Included in Geant4 9.3
Giovanni Santin - (Geant4) CAD interfaces in the space domain - Orsay, 23 March 2010
Summary
Successful development of CAD interfaces for Geant4 based on OpenCascade
libraries in external tools–
FASTRAD–
ESABASE-2License, distribution policies and wide Geant4 user community
CAD interfaces in the global picture for space radiation environment analyses at ESA
–
STEP-SPE–
Reverse-MC–
GRAS
Acknowledgements–
LPC Clermont-Ferrand for the support for this meeting