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Electromagnetic physics validation. Katsuya Amako,Susanna Guatelli, Vladimir Ivanchenko, Michel Maire, Barbara Mascialino, Koichi Murakami, Sandra Parlati, Andreas Pfeiffer, Maria Grazia Pia, Takashi Sasaki, Lazslo Urban. IEEE - NSS Rome, October 2004. - Evaluation of Geant4 physics goodness

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## Electromagnetic physics validation

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**Electromagnetic physicsvalidation**Katsuya Amako,Susanna Guatelli, Vladimir Ivanchenko, Michel Maire, Barbara Mascialino, Koichi Murakami, Sandra Parlati, Andreas Pfeiffer, Maria Grazia Pia, Takashi Sasaki, Lazslo Urban IEEE - NSS Rome, October 2004**- Evaluation of Geant4 physics goodness**• How the various Geant4 models behave in the same experimental condition • - Systematic data analysis allows to improve the physics models and guarantees the reliability Scope Aim of the project • Validation of Geant4 electromagnetic models against established references (ICRU - NIST) • Simulation of physics quantities in the same experimental set-up as reference data • Rigorous quantitative statistical comparison Quantitative statistical analysis PHYSICAL TEST GOODNESS-OF-FIT TESTING**Alternative models for the same physics process**High energy models fundamental for LHC experiments, cosmic ray experiments etc. Low energy models fundamental for space and medical applications, neutrino experiments, antimatter spectroscopy etc. two “flavours” of models: model based on Livermore libraries à la Penelope multiple scattering bremsstrahlung ionisation annihilation photoelectric effect Compton scattering Rayleigh effect gamma conversion e+e- pair production synchrotron radiation transition radiation Cherenkov refraction reflection absorption scintillation fluorescence Auger It handles electrons and positrons, gamma, X-ray and optical photons, muons, charged hadrons, ions Geant4 Electromagnetic Physics models Standard Package Geant4 Electromagnetic Package LowEnergy Package Muon Package Optical photon Package**Physics quantities under study**• Photon Attenuation Coefficient • Photon Cross Sections(attenuation coefficients with only one process activated) • ElectronCSDA range and Stopping Power (no multiple scattering, no energy fluctuations) • ProtonCSDA range and Stopping Power (no multiple scattering, no energy fluctuations) • AlphaCSDA range and Stopping Power (no multiple scattering, no energy fluctuations) Elements: Be, Al, Si, Fe, Ge, Ag, Cs, Au, Pb, U + water Energy range: 1 keV – 10 GeV Testing activity has been automatised (INFN Gran Sasso Laboratory and KEK)**p < 0.05: Geant4 simulations and NIST data**differ significantly p > 0.05: Geant4 simulations and NIST data do not differ significantly The p-value represents the probability that the test statistics has a value at least as extreme as that observed, assuming the null hypothesis is true 0 ≤ p ≤ 1 Statistical analysis • The statistical analysis has been performed by means of a Goodness-of-Fit Statistical Toolkit • The two hypothesis under study are the following: • H0: Geant4 simulations = NIST data • H1: Geant4 simulations ≠ NIST data Distance between Geant4 simulations and NIST reference data GoF Toolkit GoF test (χ2 test) Test result (p-value)**Physics models under test:**• Geant4 Standard • Geant4 Low Energy – EPDL • Geant4 Low Energy – Penelope • Reference data: • NIST - XCOM p-value stability study Transmitted photons (I) Photon beam (Io) p-value H0 ACCEPTANCE AREA H0 REJECTION AREA Z Photon attenuation coefficient Experimental set-up Geant4 LowE Penelope Geant4 Standard Geant4 LowE EPDL NIST - XCOM • The three Geant4 models reproduce total attenuation coefficients with high accuracy • The two Geant4 LowE models exhibit the best agreement**Physics models under test:**• Geant4 Standard • Geant4 Low Energy – EPDL • Geant4 Low Energy – Penelope • Reference data: • NIST - XCOM p-value H0 REJECTION AREA Z Photoelectric cross section • The three Geant4 models reproduce photoelectric cross sections with high accuracy • The two Geant4 LowE models exhibit the best agreement p-value stability study Geant4 LowE Penelope Geant4 Standard Geant4 LowE EPDL NIST - XCOM Geant4 LowE Penelope Geant4 Standard Geant4 LowE EPDL**Compton scattering cross section**• Physics models under test: • Geant4 Standard • Geant4 Low Energy – EPDL • Geant4 Low Energy – Penelope • Reference data: • NIST - XCOM p-value stability study Geant4 LowE Penelope Geant4 Standard Geant4 LowE EPDL p-value H0 REJECTION AREA Z • The three Geant4 models reproduce Compton scattering cross sections with high accuracy • The Geant4 LowE – EPDL model exhibits the best agreement Geant4 LowE Penelope Geant4 Standard Geant4 LowE EPDL NIST - XCOM**Pair production cross section**• Physics models under test: • Geant4 Standard • Geant4 Low Energy – EPDL • Geant4 Low Energy – Penelope • Reference data: • NIST - XCOM p-value H0 REJECTION AREA • The three Geant4 models reproduce pair production cross sections with high accuracy • The Geant4 LowE – EPDL model exhibits the best agreement p-value stability study Geant4 LowE Penelope Geant4 Standard Geant4 LowE EPDL Geant4 LowE Penelope Geant4 Standard Geant4 LowE EPDL NIST - XCOM Z**Physics models under test:**• Geant4 Standard • Geant4 Low Energy – EPDL • Geant4 Low Energy – Penelope • Reference data: • NIST - XCOM Geant4 Penelope Geant4 LowE EPDL p-value H0 REJECTION AREA Rayleigh scattering cross section The Geant4 models seem to be in disagreement with the reference data p-value stability study Geant4 Penelope Geant4 LowE EPDL NIST - XCOM Z**Rayleigh scattering cross section**• The NIST database and the EPDL97 evaluated data library give Rayleigh cross section data in disagreement for E < 1 MeV • EPDL97 is the most up-to- date, complete and consistent data library available at the moment (Zaidi, 2000). NIST EPDL 97 * Zaidi H., 2000, Comparative evaluation of photon cross section libraries for materials of interest in PET Monte Carlo simulation IEEE Transaction on Nuclear Science 47 2722-35**Electron Stopping Power**• Physics models under test: • Geant4 Standard • Geant4 Low Energy – Livermore • Geant4 Low Energy – Penelope • Reference data: • NIST ESTAR - ICRU 37 Experimental set-up centre p-value stability study Geant4 LowE Penelope Geant4 Standard Geant4 LowE EEDL NIST - XCOM p-value Geant4 LowE Penelope Geant4 Standard Geant4 LowE EEDL The three Geant4 models are equivalent H0 REJECTION AREA Z**Physics models under test:**• Geant4 Standard • Geant4 Low Energy – Livermore • Geant4 Low Energy – Penelope • Reference data: • NIST ESTAR - ICRU 37 p-value H0 REJECTION AREA Electron CSDA Range CSDA range: particle range without energy loss fluctuations and multiple scattering p-value stability study Geant4 LowE Penelope Geant4 Standard Geant4 LowE EEDL NIST - XCOM Geant4 LowE Penelope Geant4 Standard Geant4 LowE EEDL The three Geant4 models are equivalent Z**Protons**Alpha particles • Geant4 models under test: • Geant4 models under test: • Standard • Low Energy – ICRU 49 • Low Energy – Ziegler 85 • Low Energy – Ziegler 2000 • Standard • Low Energy – ICRU 49 • Low Energy – Ziegler 77 • Reference data: • Reference data: NIST PSTAR – ICRU 49 NIST ASTAR – ICRU 49 Protons and alpha particles • Comparison of Geant4 models with respect to ICRU 49 protocol • Geant4 LowE Package has ICRU 49 parameterisations as one of its models verification, not validation • The Ziegler parameterisations are as authoritative as the ICRU 49 reference • comparison rather than validation**Stopping Power and CSDA Range**Proton stopping power Proton CSDA range Geant4 LowE ICRU Geant4 Standard Geant4 LowE Ziegler 85 Geant4 LOWe Ziegler 2000 NIST PSTAR - ICRU 49 p>0.05 Geant4 LowE ICRU Geant4 Standard Geant4 LowE Ziegler 85 Geant4 LOWe Ziegler 2000 NIST PSTAR - ICRU 49 Geant4 LowE ICRU Geant4 Standard Geant4 LowE Ziegler 85 Geant4 LOWe Ziegler 2000 NIST PSTAR - ICRU 49 p>0.05 Similar results for alpha particles**Conclusions**• Systematic validationof Geant4 electromagnetic models against ICRU protocols and NIST reference data • Validation based on arigorous, quantitative statistical analysis of test results • All Geant4 electromagnetic models are in agreement with the reference data • The Geant4 Low Energy Package is the most accurate with respect to the ICRU protocol • More results: http://www.ge.infn.it/geant4/analysis/book • Future: extend the validation test to other physics quantities

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