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Barbara MascialinoGeant4 WorkshopCatania, October 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 Geant4 Workshop Catania, October 4 th -9 th 2004

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Barbara MascialinoGeant4 WorkshopCatania, October The project The project is based on a geographically spread collaboration: INFN Genova INFN Gran Sasso Standard Group KEK THANKS TO KOICHI MURAKAMI, TAKASHI SASAKI, KATSUYA AMAKO FOR THE VERY FRUITFUL COLLABORATION! Preliminary results were presented at last Geant4 Workshop and at IEEE-NSS in Portland. Now the project has reached a mature state.

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Barbara MascialinoGeant4 WorkshopCatania, October Aim of the project Project for the validation of all Geant4 electromagnetic models against established references The project s made-up by two parts: PHYSICAL TEST GOODNESS-OF-FIT TESTING test50 Goodness-of-Fit statistical toolkit Quantitative statistical comparisons allow: - an evaluation of Geant4 physics goodness - how the specific models behave in the same experimental condition POSSIBILITY OF CHOOSING THE MOST APPROPRIATE MODEL Chi-squared stability study

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Barbara MascialinoGeant4 WorkshopCatania, October Photon Attenuation Coefficient Photon Cross Sections (attenuation coefficients with only one process activated) Electrons CSDA range and Stopping Power (no multiple scattering, no energy fluctuations) Protons CSDA range and Stopping Power (no multiple scattering, no energy fluctuations) Alpha particles CSDA range and Stopping Power (no multiple scattering, no energy fluctuations) First phase: validation against the NIST database Elements: Be, Al, Si, Fe, Ge, Ag, Cs, Au, Pb, UEnergy range: 1 keV – 100 GeV Testing activity has been automatised (thanks to Sandra Parlati and Koichi Murakami)

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Barbara MascialinoGeant4 WorkshopCatania, October Photons: attenuation coefficient χ 2 /ν stability study BeZ dependency?

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Barbara MascialinoGeant4 WorkshopCatania, October Photon attenuation coefficient: statistical results χ 2 /ν p-value χ 2 /ν p-value χ 2 /ν p-value Be Al Si Fe Ge Ag Cs Au Pb U NIST – XCOM LowE Livermore NIST – XCOM LowE Penelope NIST – XCOM Standard

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Barbara MascialinoGeant4 WorkshopCatania, October Photons: photoelectric cross section χ 2 /ν stability study Be Cs Z dependency?

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Barbara MascialinoGeant4 WorkshopCatania, October Photon photoelectric cross section: statistical results χ 2 /ν p-value χ 2 /ν p-value χ 2 /ν p-value Be Al Si Fe Ge Ag Cs Au Pb U NIST – XCOM LowE Livermore NIST – XCOM LowE Penelope NIST – XCOM Standard

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Barbara MascialinoGeant4 WorkshopCatania, October Photons: Compton cross section The 1keV deviation effect is evident in both LowE Penelope and Standard packages χ 2 /ν = with the 1 keV point without the 1 keV point LowE Penelope Standard As an example, let us consider Ag:

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Barbara MascialinoGeant4 WorkshopCatania, October Photon Compton cross section: statistical results χ 2 /ν p-value χ 2 /ν p-value χ 2 /ν p-value Be Al Si Fe Ge Ag Cs Au Pb U NIST – XCOM LowE Livermore NIST – XCOM LowE Penelope NIST – XCOM Standard

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Barbara MascialinoGeant4 WorkshopCatania, October Compton cross sections χ 2 /ν stability study (without the E=1 keV point) χ 2 /ν stability study Si Pb Ge Au

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Barbara MascialinoGeant4 WorkshopCatania, October Photons: pair production cross section Beryllium χ 2 /ν stability study Be (not compatible with the NIST) deviations χ 2 /ν stability study

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Barbara MascialinoGeant4 WorkshopCatania, October Photon pair production cross section: statistical results χ 2 /ν p-value χ 2 /ν p-value χ 2 /ν p-value Be < <0.001 Al Si Fe Ge Ag Cs Au Pb U NIST – XCOM LowE Livermore NIST – XCOM LowE Penelope NIST – XCOM Standard Removing the 1 keV point

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Barbara MascialinoGeant4 WorkshopCatania, October Photons: Rayleigh cross section deviations χ 2 /ν stability study Ge Pb U Au Fe Si Al

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Barbara MascialinoGeant4 WorkshopCatania, October Photon Rayleigh cross section: statistical results χ 2 /ν p-value χ 2 /ν p-value Be Al <0.001 Si <0.001 Fe <0.001 Ge17.97< Ag Au <0.001 Pb8.40< <0.001 U11.31< <0.001 NIST – XCOM LowE Livermore NIST – XCOM LowE Penelope Test results are not consistent

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Barbara MascialinoGeant4 WorkshopCatania, October The disagreement between NIST reference data and data coming from the recent library EPDL97 (provided by Lawrence Livermore National Laboratory) within the range of energies between 1 keV and 1 MeV has been already underlined and discussed in a recent paper by Zaidi *. In his paper Zaidi concluded that EPDL97 is the most up-dated, complete and consistent data library available at the moment. For these features, it should be considered as a standard. Critical discussion of this result * Zaidi H., 2000, Comparative evaluation of photon cross section libraries for materials of interest in PET Monte Carlo simulation IEEE Transaction on Nuclear Science

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Barbara MascialinoGeant4 WorkshopCatania, October Electrons: stopping power χ 2 /ν stability study NIST – ESTAR LowE Livermore NIST – ESTAR LowE Penelope NIST – ESTAR Standard χ 2 /ν = Z R 2 =0.995 p< χ 2 /ν = Z R 2 =0.989 p< The three models are equivalent Strange effect (as a function of Z) BEST FIT BEST FIT BEST FIT

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Barbara MascialinoGeant4 WorkshopCatania, October Electrons stopping power: statistical results χ 2 /ν p-value χ 2 /ν p-value χ 2 /ν p-value Be Al Si Fe Ge Cs Au Pb U NIST – ESTAR LowE Livermore NIST – ESTAR LowE Penelope NIST – ESTAR Standard

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Barbara MascialinoGeant4 WorkshopCatania, October Electrons: CSDA range χ 2 /ν stability study Ag (to be explained) The three models are equivalent

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Barbara MascialinoGeant4 WorkshopCatania, October χ 2 /ν p-value χ 2 /ν p-value χ 2 /ν p-value Be Al Si Fe Ge Ag Cs Au Pb U NIST – ESTAR LowE Livermore NIST – ESTAR LowE Penelope NIST – ESTAR Standard Electrons CSDA range: statistical results

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Barbara MascialinoGeant4 WorkshopCatania, October LowE Ziegler 85 LowE Ziegler 2000 ICRU Standard At low energies: free electron gas model At middle energies (~ MeV): parametrisations At high energies: Bethe Bloch Statistical comparison cannot lead to a real physics validation, but we can only compare two different models (NIST – Ziegler) Protons and alpha particles NIST database

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Barbara MascialinoGeant4 WorkshopCatania, October Protons: stopping power χ 2 /ν stability study LowE ICRU Standard LowE Ziegler 85 lOWe Ziegler 2000 NIST - PSTAR

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Barbara MascialinoGeant4 WorkshopCatania, October Protons stopping power: statistical results χ 2 /ν p p p p Be Al Si Fe Ge Ag Au Pb U NIST – PSTAR LowE ICRU49 NIST – PSTAR LowE Ziegler85 NIST – PSTAR Standard NIST – PSTAR LowE Ziegler2000

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Barbara MascialinoGeant4 WorkshopCatania, October Protons: CSDA range χ 2 /ν stability study LowE ICRU Standard LowE Ziegler 85 LowE Ziegler 2000 NIST - PSTAR

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Barbara MascialinoGeant4 WorkshopCatania, October Protons CSDA range: statistical results χ 2 /ν p p p p Be Al Si Fe Ge Ag Au Pb U NIST – PSTAR LowE ICRU49 NIST – PSTAR LowE Ziegler85 NIST – PSTAR Standard NIST – PSTAR LowE Ziegler2000

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Barbara MascialinoGeant4 WorkshopCatania, October Alpha particles: stopping power WORK IN PROGRESS LowE ICRU Standard LowE Ziegler 77 NIST - ASTAR

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Barbara MascialinoGeant4 WorkshopCatania, October Alpha particles: CSDA range WORK IN PROGRESS LowE ICRU Standard LowE Ziegler 77 NIST - ASTAR

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Barbara MascialinoGeant4 WorkshopCatania, October Statistical comparisons (II) Concerning alpha particles, this is the second iteration of production and analysis since last July. This because thanks to the quantitative analysis we could detect a conceptual flaw in physics tables treatment for both protons and alpha particles. Systematic data analysis allowed to improve the physical models.

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Barbara MascialinoGeant4 WorkshopCatania, October Low Energy Livermore is the most compatible with the NIST reference (Rayleigh scattering is a special case) Low Energy Penelope is quite compatible with NIST reference except for some problems exhibited in Compton scattering and pair production cross sections Standard electrons are compatible with NIST, photons are quite compatible, but exhibit some problems SUMMARY: photons and electrons

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Barbara MascialinoGeant4 WorkshopCatania, October While NIST represents an established reference for photon and electron processes, the reference for protons and alpha processes in controversial at least in the lower energy ranges. Two reference data compilations ICRU/NIST and Ziegler. Quantitative comparisons available for all NIST quantities for protons and alpha particles. SUMMARY: protons and alpha particles

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Barbara MascialinoGeant4 WorkshopCatania, October Conclusions Validation of all Geant4 Electromagnetic models against the NIST database Quantitative statistical analysis on all the comparisons Fully automated testing system (thanks to Sandra Parlati and Koichi Murakami) Objective comparison among Geant4 models (with respect to the NIST reference) Mature project and results will be presented at IEEE-NSS – paper submitted for publication next month

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Barbara MascialinoGeant4 WorkshopCatania, October Future perspectives Final states angular distributions and spectra The first results will be shown and discussed in the parallel section Physics Book introductory talk by Susanna Guatelli

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