cad interfaces for simulation and analysis tools in the...

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


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


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


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)


Herschel and Planck


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)


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


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


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)


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

?


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)


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)


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


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

http://space-env.esa.int/index.php/geant4-radiation-analysis-for-space.html


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





…Analysis Modules



Ray- tracingAnalysis 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


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


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

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