1. Systematic validation of Geant4 electromagnetic and hadronic models against proton data
G.A.P. Cirrone1, G. Cuttone1, F. Di Rosa1, S. Guatelli1, A. Heikkinen3, B. Mascialino2, M.G. Pia1, G. Russo2
1INFN Laboratori Nazionali del Sud, Italy
2INFN Genova, Italy
3Helsinki Institute of Physics, Finland
CHEP 2006
Mumbai, February 2006

2. Geant4 physics Wide set of physics processes and models
Versatility of configuration according to use cases
How to best choose the most appropriate model for my simulation?
Provide objective criteria to evaluate Geant4 physics models
document their precision against established experimental data
evaluate all available Geant4 physics models systematically
publication-quality results, subject to peer-review process
Geant4 Physics Book
validation of basic Geant4 physics quantities (cross sections, final state distributions etc.)
demonstration of Geant4 validation in some typical use cases

3. Quantitative validation
K. Amako et al.,
Comparison of Geant4 electromagnetic physics models against the NIST reference data IEEE Trans. Nucl. Sci., Vol. 52, Issue 4, Aug. 2005, pp
Systematic approach
cover ALL available models
Quantitative validation
rigorous statistical methods for the comparison of simulated and experimental data distributions
Adopt the same method also for hadronic physics validation
address all modelling options
start from the bottom (low energy)
progress towards higher energy based on solid ground of previous assessments
statistical analysis of compatibility with experimental data
Guidance to users based on objective ground
not only “educated-guess” PhysicsLists

4. Proton Bragg peak Medical Physics High Energy Physics Space Science
Oncological radiotherapy
Medical Physics
LHC Radiation Monitors
High Energy Physics
Space Science
Astronauts’ radiation protection
Assess lowest energy range of hadronic interactions
pre-equilibrium + nuclear deexcitation
to build further validation tests on solid ground
Results directly relevant to various experimental use cases
see also talk on Simulation for LHC Radiation Background

5. Relevant Geant4 models Hadronic Electromagnetic
Parameterized (à la GHEISHA)
Nuclear Deexcitation
Default evaporation
GEM evaporation
Fermi break-up
Pre-equilibrium
Precompound model
Bertini model
Intra-nuclear cascade
Bertini cascade
Binary cascade
Elastic scattering
Parameterized
Bertini
Standard
Low Energy – ICRU 49
Low Energy – Ziegler 1977
Low Energy – Ziegler 1985
Low Energy – Ziegler 2000
New “very low energy” models

6. Markus Ionization chamber
Experimental data
CATANA hadrontherapy facility in Catania, Italy
high precision experimental data satisfying rigorous medical physics protocols
Geant4 Collaboration members
2 mm
Sensitive Volume = 0.05 cm3
Resolution 100 m
Markus Chamber
Markus Ionization chamber

7. Geant4 test application
Accurate reproduction of the experimental set-up in the simulation
This is the most difficult part to achieve a quantitative Geant4 physics validation
Geometry and beam characteristics must be known in detail and with high precision
GEANT4 simulation
Geant4 hadrontherapy Advanced Example

8. Software configuration
Geant4 7.1
Hadrontherapy-V
EMLOW Low Energy Electromagnetic data
CLHEP
Production Threshold = mm
MaxStep = cm
events

9. Preliminary results Work in progress
all the results presented here are PRELIMINARY
Realistic modelling of beam parameters and geometry details under verification and refinement
will affect the numerical results of the validation
current values presented here are subject to improvement
Statistical analysis with the Statistical Toolkit
see talk in the Core Libraries track

10. Preliminary! EM – ICRU 49 ENTIRE PEAK Exp G4 S 2.89 3.39 T 3.26 3.46
GoF test
CVM-AD
NE=149
NG4=150
Test statistics p KS
0.0368
CVM
0.0131 AD
0.0993

11. Preliminary! EM - Standard NE=149 NG4=150 Test statistics p KS 0.1035
CVM
0.1356 AD
0.7013

12. ICRU49 + Precompound Default
Preliminary!
NE=149
NG4=150
Test statistics p KS
0.0403
CVM
0.0134 AD
0.1079

13. Bragg- ICRU49 + Bertini model
Preliminary!
NE=149
NG4=150
Test statistics p KS
0.0420
CVM
0.0133 AD
0.1120

14. Bragg – ICRU49 – Binary Cascade
Preliminary!
NE=149
NG4=150
Test statistics p KS
0.0420
CVM
0.0123 AD
0.1096

15. Geant4 Parameterised (à la GHEISHA)
Preliminary!
NE=149
NG4=150
Test statistics p KS
0.0421
CVM
0.0214 AD
0.1366

16. ICRU49 + default evaporation + Fermi break-up
Preliminary!
NE=149
NG4=150
Test statistics p KS
0.0421
CVM
0.0144 AD
0.1160

17. ICRU49 + precompound + GEM evaporation
Preliminary!
NE=149
NG4=150
Test statistics p KS
0.0420
CVM
0.0137 AD
0.1148

18. ICRU49 + precompound + GEM evaporation + Fermi break up
Preliminary!
NE=149
NG4=150
Test statistics p KS
0.0487
CVM
0.0153 AD
0.1199

19. Outlook Work in progress
Precise reproduction of the experimental set-up
beam size, divergence, energy spread
details of the geometry
Other physics models under test
Low Energy Electromagnetic Ziegler parameterisations
Elastic scattering (Parameterised, Bertini)
Refined statistical analysis

20. Conclusion
A systematic, quantitative validation of ALL Geant4 electromagnetic and hadronic models against high precision experimental measurements in the energy range  100 MeV
Preliminary results available
Document Geant4 simulation accuracy
Provide guidance to users based on objective ground
Part of the Geant4 Physics Book project
To be submitted for publication in IEEE Trans. Nucl. Sci.

21. IEEE Transactions on Nuclear Science http://ieeexplore. ieee
Prime journal on technology in particle/nuclear physics
Review process reorganized about one year ago
Associate Editor dedicated to computing papers
Various papers associated to CHEP 2004 published on IEEE TNS
Papers associated to CHEP 2006 are welcome
Manuscript submission:
Papers submitted for publication will be subject to the regular review process
Publications on refereed journals are beneficial not only to authors, but to the whole community of computing-oriented physicists
Our “hardware colleagues” have better established publication habits…
Further info: