Maria Grazia Pia

Systematic validation of Geant4 Systematic validation of Geant4

electromagnetic and hadronic models electromagnetic and hadronic models against proton dataagainst 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 2006Mumbai, 13-17 February 2006

Maria Grazia Pia

Geant4 physicsGeant4 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 precisionprecision against established experimental data– evaluate all available Geant4 physics models systematicallysystematically– publication-qualitypublication-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

Maria Grazia Pia

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

K. Amako et al., Comparison of Geant4 electromagnetic physics models against the NIST reference dataIEEE Trans. Nucl. Sci., Vol. 52, Issue 4, Aug. 2005, pp. 910-918

Maria Grazia Pia

Proton Bragg peakProton Bragg peak

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

Oncological radiotherapy

Medical Physics

LHC Radiation Monitors

High Energy PhysicsHigh Energy PhysicsSpace Science

Astronauts’ radiation protection

Maria Grazia Pia

Relevant Geant4 modelsRelevant Geant4 models

StandardLow Energy – ICRU 49Low Energy – Ziegler 1977Low Energy – Ziegler 1985Low Energy – Ziegler 2000New “very low energy” models

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

HadronicElectromagnetic

Maria Grazia Pia

Experimental dataExperimental data

CATANA hadrontherapy facility in Catania, Italy– high precision experimental data satisfying rigorous medical physics protocols– Geant4 Collaboration members

Markus Ionization chamber

2 mm

Sensitive Volume = 0.05 cm3

Resolution 100 m

Markus Chamber

Maria Grazia Pia

Geant4 test applicationGeant4 test application

GEANT4 simulation

Accurate reproduction of the experimental set-up in the simulation

This is the most difficult part to achieve a quantitative quantitative Geant4 physics validation

GeometryGeometry and beambeam characteristics must be known in detail and with high precision

Geant4 hadrontherapy Advanced Example

Maria Grazia Pia

Software configurationSoftware configuration

Geant4 7.1

Hadrontherapy-V07-01-07

EMLOW 3.0 Low Energy Electromagnetic data

CLHEP 1.9.1.2

Production Threshold = 0.001 mm

MaxStep = 0.002 cm

3000000 events

Maria Grazia Pia

Preliminary resultsPreliminary 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

Maria Grazia Pia

EM – ICRU 49EM – ICRU 49

NE=149

NG4=150

Test statistics

p

KS 0.0368 0.999944

CVM 0.0131 0.999887

AD 0.0993 0.999974

ENTIRE

PEAK

Exp G4

S 2.89 3.39

T 3.26 3.46

GoF test CVM-AD

Preliminary!

Maria Grazia Pia

EM - StandardEM - Standard

NE=149

NG4=150

Test statistics

p

KS 0.1035 0.380591

CVM 0.1356 0.436725

AD 0.7013 0.557752

Preliminary!

Maria Grazia Pia

ICRU49 + Precompound ICRU49 + Precompound DefaultDefault

NE=149

NG4=150

Test statistics

p

KS 0.0403 0.999646

CVM 0.0134 0.999865

AD 0.1079 0.999933

Preliminary!

Maria Grazia Pia

Bragg- ICRU49 + Bertini Bragg- ICRU49 + Bertini modelmodel

NE=149

NG4=150

Test statistics

p

KS 0.0420 0.999218

CVM 0.0133 0.999871

AD 0.1120 0.999900

Preliminary!

Maria Grazia Pia

Bragg – ICRU49 – Binary Bragg – ICRU49 – Binary CascadeCascade

NE=149

NG4=150

Test statistics

p

KS 0.0420 0.999218

CVM 0.0123 0.999939

AD 0.1096 0.999921

Preliminary!

Maria Grazia Pia

Geant4 Parameterised Geant4 Parameterised (à la (à la GHEISHA)GHEISHA)

NE=149

NG4=150

Test statistics

p

KS 0.0421 0.999189

CVM 0.0214 0.995490

AD 0.1366 0.999455

Preliminary!

Maria Grazia Pia

ICRU49 + default evaporation + Fermi ICRU49 + default evaporation + Fermi break-upbreak-up

NE=149

NG4=150

Test statistics

p

KS 0.0421 0.999203

CVM 0.0144 0.999734

AD 0.1160 0.999857

Preliminary!

Maria Grazia Pia

ICRU49 + precompound + GEM ICRU49 + precompound + GEM evaporationevaporation

NE=149

NG4=150

Test statistics

p

KS 0.0420 0.999218

CVM 0.0137 0.999831

AD 0.1148 0.999871

Preliminary!

Maria Grazia Pia

ICRU49 + precompound + GEM evaporation + Fermi ICRU49 + precompound + GEM evaporation + Fermi break upbreak up

NE=149

NG4=150

Test statistics

p

KS 0.0487 0.993171

CVM 0.0153 0.999561

AD 0.1199 0.999801

Preliminary!

Maria Grazia Pia

OutlookOutlookWork in progressWork 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

Maria Grazia Pia

ConclusionConclusion

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.

Maria Grazia Pia

IEEE Transactions on Nuclear ScienceIEEE Transactions on Nuclear Sciencehttp://ieeexplore.ieee.org/xpl/RecentIssue.jsp?puNumber=23

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 welcomePapers associated to CHEP 2006 are welcome

Manuscript submission: http://tns-ieee.manuscriptcentral.com/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: Maria.Grazia.Pia@cern.ch