Seminario Geant4 INFN

1
Precision Validation of Geant4 Electromagnetic
Physics
Susanna Guatelli Barbara Mascialino
G.A.P. Cirrone (INFN LNS), G. Cuttone (INFN LNS),
S. Donadio (INFN,Genova), S. Guatelli (INFN
Genova) , M. Maire (LAPP), A. Mantero (ESA) , B.
Mascialino (INFN Genova), P. Nieminen (ESA), L.
Pandola(INFN LNGS), S. Parlati (INFN LNGS) , A.
Pfeiffer (CERN), M.G. Pia (INFN Genova), L. Urban
(Budapest)
1st Workshop on Italy-Japan Collaboration on
Geant4 Medical Application
2
Electromagnetic Physics

• It handles
• electrons and positrons
• gamma, X-ray and optical photons
• muons
• charged hadrons
• ions

• multiple scattering
• Bremsstrahlung
• ionisation
• annihilation
• photoelectric effect
• Compton scattering
• Rayleigh effect
• gamma conversion
• ee- pair production
• synchrotron radiation
• transition radiation
• Cherenkov
• refraction
• reflection
• absorption
• scintillation
• fluorescence
• Auger

3
E.M. Physics Validation

• Validation is fundamental in Geant4
• Validations at different levels
• Comparisons to experimental measurements and
  recognised standard references

• Unit, integration, system testing
• Microscopic physics validation
• Macroscopic validation experimental use cases

4
Microscopic Validation

• Validation of Geant4 electromagnetic physics
  models
• Attenuation coefficients, CSDA ranges, Stopping
  Power, distributions of physics quantities
• Quantitative comparisons to experimental data and
  recognised standard references

5
Photon Mass Attenuation Coefficient
x-ray attenuation coeff in U
NIST data Penelope
c219.3 n22 p0.63
Absorber Materials Be, Al, Si, Ge, Fe, Cs, Au,
Pb, U
6
X-ray Attenuation Coefficient - Al
7
X-ray Attenuation Coefficient - Al
?2N-P15.9 ?19 p0.66
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X-ray Attenuation Coefficient - Ge
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X-ray Attenuation Coefficient - Ge
?2N-P10.1 ?21 - p0.98
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X-ray Attenuation Coefficient - U
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X-ray Attenuation Coefficient - U
?2N-P19.3 ?22 - p0.63
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Compton Scattering - Al
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Compton Scattering - Al
?2N-P2.5 ?6 - p0.87
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Compton Scattering - Cs
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Compton Scattering - Cs
?2N-P4.6 ?8 - p0.80
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Rayleigh Scattering - Al
?2N-L13.6 ?11 - p0.26
17
Rayleigh Scattering - Al
?2N-P7.2 ?8 - p0.52
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Rayleigh Scattering - Cs
19
Rayleigh Scattering - Cs
20
Photoelectric Effect - Fe
21
Photoelectric Effect - Fe
22
Pair Production - Si
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Pair Production - Si
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Electrons - Stopping Power and CSDA Range
G4 Standard G4 LowE-EPDL NIST
Absorber Materials Be, Al, Si, Ge, Fe, Cs, Au,
Pb, U
G4 Standard G4 LowE-EPDL NIST
CSDA range particle range without energy loss
fluctuations and multiple scattering
Experimental set-up
centre
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Electrons - CSDA Range - Al
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Electrons - CSDA Range - Pb
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Electrons - Stopping Power - Al
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Electrons - Stopping Power - Pb
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Electrons - CSDA Range Al G4LowE
Regression testing
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Electrons - CSDA Range Pb G4Standard
Regression testing
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Protons - CSDA Range Al
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Protons - CSDA Range Pb
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Protons - Stopping Power Al
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Protons - Stopping Power - Pb
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Protons - CSDA Range Al G4LowE
Regression testing
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Protons - CSDA Range Al G4LowE Ziegler
Regression testing
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Protons - CSDA Range Al G4Standard
Regression testing
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Protons - CSDA Range Pb G4LowE
Regression testing
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Protons - CSDA Range Pb G4LowE Ziegler
Regression testing
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Protons - CSDA Range Pb G4Standard
Regression testing
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Electrons Transmission Tests
Experimental set-up
e- beam
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Electrons Backscattering Coefficient E100keV
Backscattered e-
Experimental set-up
Incident e- beam
Angle of incidence (with respect to the normal
to the sample surface) 0
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Electrons Backscattering Coefficient E1MeV
Angle of incidence (with respect to the normal
to the sample surface)0
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Positrons - Backscattering coefficient 30keV
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Positrons - Backscattering coefficient 30keV
Regression testing
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Auger Effect, X-Ray Fluorescence
Anderson-Darling Test Ac (95) 0.752
Detector response
Simulation of Auger emission from pure materials
irradiated by an electron beam with continuous
spectrum
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Much more available or in progress
ions
Barkas Effect
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Macroscopic Validation

• Experimental set-up validation
• Collaboration of Geant4 developers
• and research groups of different experiments

Medical Physics
Space science
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The Problem of Validation Finding Reliable Data
Note Geant4 validation is not always
easy experimental data often exhibit large
differences!
Backscattering low energies - Au
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Conclusions

• Geant4 electromagnetic package encompasses an
  ample set of physics models, specialised for
  particle type, energy range and detector
  applications
• Geant4 Physics Reference Manual
  (www.cern.ch/geant4)
• Geant4 e.m. physics is subject to a rigorous
  testing and validation process
• Many detailed results are available for the
  validation of basic physics distributions
• (http//www.ge.infn.it/geant4/analysis/test)
• Many significant contributions to the validation
  of Geant4 e.m. physics from test beams and
  application in the experiments

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Geant4 Physics Book

• A project has been recently launched for a Geant4
  Physics Book
• To have a solid and comprehensive reference on
  Geant4 physics
• Collaborative effort involving Geant4 physics
  groups, experiments
• Main focus of the project is Geant4 physics
  models validation

Collaboration with detector experts valuable and
welcome!