Barbara MascialinoGeant4 WorkshopCatania, October 4-9 2004 Electromagnetic physics validation...
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Transcript of Barbara MascialinoGeant4 WorkshopCatania, October 4-9 2004 Electromagnetic physics validation...
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
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
Geant4 Workshop Catania, October 4th-9th 2004
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
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.
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
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
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
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, U Energy range: 1 keV – 100 GeV
Testing activity has been automatised (thanks to Sandra Parlati and Koichi Murakami)
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photons: attenuation coefficient
χ2/ν stability study
Be Z dependency?
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photon attenuation coefficient: statistical results
χ2 /ν p-value χ2 /ν p-value χ2 /ν p-value
Be 1.26 0.16 0.08 1 1.01 0.45
Al 0.31 1 0.07 1 0.34 1
Si 0.32 1 0.10 1 0.56 0.97
Fe 0.11 1 0.08 1 0.20 1
Ge 0.15 1 0.05 1 0.28 1
Ag 0.22 1 0.15 1 0.45 1
Cs 0.19 1 0.37 1 0.81 0.75
Au 0.08 1 0.05 1 0.71 0.86
Pb 0.13 1 0.08 1 0.52 0.99
U 0.04 1 0.06 1 0.75 0.93
NIST – XCOMLowE Livermore
NIST – XCOMLowE Penelope
NIST – XCOMStandard
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photons: photoelectric cross section
χ2/ν stability study
Be Cs
Z dependency?
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photon photoelectric cross section: statistical results
χ2 /ν p-value χ2 /ν p-value χ2 /ν p-value
Be 0.05 1 0.05 1 0.82 0.63
Al 0.05 1 0.03 1 0.27 1
Si 0.07 1 0.02 1 0.17 1
Fe 0.09 1 0.05 1 0.11 1
Ge 0.21 1 0.08 1 0.07 1
Ag 0.07 1 0.05 1 0.07 1
Cs 0.52 0.94 0.21 1 1.18 0.27
Au 0.14 1 0.15 1 0.57 0.93
Pb 0.25 1 0.35 1 0.51 0.96
U 0.35 1 0.37 0.99 0.42 0.99
NIST – XCOMLowE Livermore
NIST – XCOMLowE Penelope
NIST – XCOMStandard
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photons: Compton cross section
The 1keV deviation effect is evident in both LowE Penelope and Standard packages
χ2/ν = with the
1 keV point
without the 1 keV point
LowE Penelope
17.30 0.46
Standard 9.0 1.65
As an example, let us consider Ag:
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photon Compton cross section: statistical results
χ2 /ν p-value χ2 /ν p-value χ2 /ν p-value
Be 0.12 1 0.07 1 0.53 0.85
Al 0.07 1 0.18 1 0.49 0.86
Si 1.61 0.09 0.15 1 0.60 0.77
Fe 0.30 1 0.69 0.75 0.27 0.99
Ge 0.13 1 1.68 0.07 0.38 0.96
Ag 0.09 1 0.65 0.79 0.46 0.92
Cs 0.14 1 0.36 0.97 0.62 0.72
Au 0.16 1 0.41 0.94 1.04 0.41
Pb 0.23 1 1.31 0.21 1.18 0.29
U 0.11 1 0.13 1 0.08 1
NIST – XCOMLowE Livermore
NIST – XCOMLowE Penelope
NIST – XCOMStandard
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Compton cross sections χ2/ν stability study
(without the E=1 keV point)
χ2/ν stability studySi
Pb
Ge
Au
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photons: pair production cross section
Beryllium
χ2/ν stability study
Be(not compatible with the NIST)
deviations
χ2/ν stability study
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photon pair production cross section: statistical results
χ2 /ν p-value χ2 /ν p-value χ2 /ν p-value
Be 0.05 1 8.07 <0.001 7.01 <0.001
Al 0.07 1 0.83 0.61 1.07 0.39
Si 0.09 1 0.76 0.69 0.93 0.52
Fe 0.07 1 0.32 0.99 0.30 0.99
Ge 0.04 1 0.25 1 0.18 1
Ag 0.06 1 0.15 1 0.23 1
Cs 0.24 1 0.54 0.89 0.30 0.99
Au 0.08 1 0.09 1 0.23 1
Pb 0.11 1 0.08 1 0.22 1
U 0.09 1 1.18 1 0.26 0.99
NIST – XCOMLowE Livermore
NIST – XCOMLowE Penelope
NIST – XCOMStandard
Rem
ovin
g th
e 1
keV
poi
nt
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photons: Rayleigh cross section
deviations
χ2/ν stability study
χ2/ν stability study
Ge
PbU
Au
Fe
Si
Al
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Photon Rayleigh cross section: statistical results
χ2 /ν p-value χ2 /ν p-value
Be 0.27 0.99 0.17 1
Al 1.15 0.97 24.86 <0.001
Si 0.68 0.77 25.08 <0.001
Fe 0.27 1 11.08 <0.001
Ge 17.97 <0.001 1.06 0.39
Ag 1.10 0.36 1.74 0.08
Au 1.90 0.05 18.99 <0.001
Pb 8.40 <0.001 22.10 <0.001
U 11.31 <0.001 28.19 <0.001
NIST – XCOMLowE Livermore
NIST – XCOMLowE Penelope
Tes
t re
sults
are
not
con
sist
ent
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
• 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 47 2722-35
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Electrons: stopping powerχ2/ν stability study
NIST – ESTARLowE Livermore
NIST – ESTARLowE Penelope
NIST – ESTARStandard
χ2/ν = -0.032 + 0.0074 Z R2=0.995 p<0.0001
χ2/ν = -0.032 + 0.0074 Z R2=0.995 p<0.0001
χ2/ν = -0.046 + 0.0073 Z R2=0.989 p<0.0001
The three models are equivalent
Strange effect (as a function of Z)
BESTFIT
BESTFIT
BESTFIT
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Electrons stopping power: statistical results
χ2 /ν p-value χ2 /ν p-value χ2 /ν p-value
Be 0.03 1 0.02 1 0.02 1
Al 0.06 1 0.05 1 0.06 1
Si 0.07 1 0.06 1 0.06 1
Fe 0.15 1 0.14 1 0.13 1
Ge 0.18 1 0.17 1 0.15 1
Cs 0.36 1 0.35 1 0.31 1
Au 0.57 0.96 0.56 0.96 0.54 0.97
Pb 0.58 0.95 0.57 0.96 0.56 0.97
U 0.65 0.91 0.64 0.92 0.64 0.92
NIST – ESTARLowE Livermore
NIST – ESTARLowE Penelope
NIST – ESTARStandard
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Electrons: CSDA range
χ2/ν stability study
Ag(to be explained)
The three models are equivalent
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
χ2 /ν p-value χ2 /ν p-value χ2 /ν p-value
Be 0.21 1 0.24 1 0.17 1
Al 0.05 1 0.05 1 0.04 1
Si 0.04 1 0.04 1 0.04 1
Fe 0.02 1 0.02 1 0.02 1
Ge 0.02 1 0.01 1 0.02 1
Ag 0.10 1 1.06 0.39 0.02 1
Cs 0.009 1 0.006 1 0.008 1
Au 0.005 1 0.004 1 0.005 1
Pb 0.005 1 0.004 1 0.004 1
U 0.004 1 0.003 1 0.003 1
NIST – ESTARLowE Livermore
NIST – ESTARLowE Penelope
NIST – ESTARStandard
Electrons CSDA range: statistical results
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
• LowE Ziegler 85• LowE Ziegler 2000• ICRU
• Standard
At low energies: free electron gas modelAt middle energies (~ MeV): parametrisationsAt 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
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Protons: stopping power
χ2/ν stability studyLowE ICRU StandardLowE Ziegler 85lOWe Ziegler 2000NIST - PSTAR
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Protons stopping power: statistical results
χ2 /ν p χ2 /ν p χ2 /ν p χ2 /ν p
Be 0.008 1 0.41 1 0.66 0.94 0.01 1
Al 0.02 1 0.05 1 0.06 1 0.02 1
Si 0.008 1 0.41 1 0.81 0.79 0.01 1
Fe 0.02 1 0.03 1 0.03 1 0.02 1
Ge 0.12 1 0.53 1 0.72 0.89 0.11 1
Ag 0.06 1 0.15 1 0.10 1 0.04 1
Au 0.08 1 0.27 1 0.17 1 0.09 1
Pb 0.06 1 0.12 1 0.17 0.21 0.05 1
U 0.10 1 1.28 0.12 1.28 0.12 0.09 1
NIST – PSTARLowE ICRU49
NIST – PSTARLowE Ziegler85
NIST – PSTARStandard
NIST – PSTARLowE Ziegler2000
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Protons: CSDA range
χ2/ν stability study
LowE ICRU StandardLowE Ziegler 85LowE Ziegler 2000NIST - PSTAR
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Protons CSDA range: statistical results
χ2 /ν p χ2 /ν p χ2 /ν p χ2 /ν p
Be 0.005 1 0.11 1 1.03 0.41 0.47 1
Al 0.03 1 0.01 1 0.01 1 0.27 1
Si 0.02 1 0.29 1 0.32 0.99 0.23 1
Fe 0.06 1 0.20 1 0.18 1 0.32 1
Ge 0.13 1 0.26 1 0.27 1 0.24 1
Ag 0.08 1 0.34 1 0.15 1 0.15 1
Au 0.09 1 0.91 0.62 0.47 1 0.14 1
Pb 0.09 1 0.21 1 0.17 0.99 0.12 1
U 0.11 1 1.23 0.16 1.18 0.21 0.13 1
NIST – PSTARLowE ICRU49
NIST – PSTARLowE Ziegler85
NIST – PSTARStandard
NIST – PSTARLowE Ziegler2000
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Alpha particles: stopping powerWORK IN PROGRESS
LowE ICRU StandardLowE Ziegler 77NIST - ASTAR
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
Alpha particles: CSDA rangeWORK IN PROGRESS
LowE ICRU StandardLowE Ziegler 77NIST - ASTAR
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
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.
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
• 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
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
• 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
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
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
Barbara Mascialino Geant4 Workshop Catania, October 4-9 2004
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