Physics processes & models


This page describes the list of physical interactions that can be modeled using Geant4-DNA for the simulation of track structures in liquid water and other materials, in Geant4 version 11.2.

A) Models applicable to liquid water, main component of biological medium


These models are available in Geant4-DNA physics constructors as described in the Physics lists section.

They use the « G4_WATER » Geant4 NIST material.

Please refer to the publication section of this web site for more details about the physics models (in particular this review).

The corresponding process classes, model classes, low energy and high energy limits of applicability of models (the kinetic energy of the particle must be less than this strict high energy limit), energy threshold (also called "tracking cut") below which the incident particle is killed (stopped and the kinetic energy is locally deposited) and type of model (analytical or based on interpolated data tables), and the corresponding physics constructor are indicated in the list below.

The low and high energy applicability limits used during the simulation are directly set by the corresponding model classes (and not by process classes).

ELECTRONS (Geant4 electron name is "e-")

  • Elastic scattering : G4DNAElastic process class
    • G4DNAChampionElasticModel model class
      • applicable energy range : 7.4 eV - 1 MeV
      • cut at 7.4 eV (1)
      • type : interpolated
      • in the following Geant4-DNA physics constructors : default, option2 (*)
    • G4DNAScreenedRutherfordElasticModel
      • applicable energy range : 0 eV - 1 MeV
      • cut at 9 eV (1)
      • type : analytical
      • constructors : none
    • G4DNAUeharaScreenedRutherfordElasticModel
      • applicable energy range : 10 eV - 1 MeV
      • cut at 10 eV (1)
      • type : analytical
      • constructors : option4 (*)
    • G4DNACPA100ElasticModel (2)
      • applicable energy range : 11 eV - 250 keV
      • cut at 11 eV (1)
      • type : interpolated
      • constructors : option6 (*)

  • Electronic excitation : G4DNAExcitation
    • G4DNABornExcitationModel
      • applicable energy range : 9 eV - 1 MeV
      • type : interpolated
      • constructors : default, option2, and up to 1 MeV for option4 and option6
    • G4DNAEmfietzoglouExcitationModel (3)
      • applicable energy range : 8 eV - 10 keV
      • type : interpolated
      • constructors : option4
    • G4DNACPA100ExcitationModel (3)
      • applicable energy range : 11 eV - 250 keV
      • type : interpolated
      • constructors : option6

  • Ionisation : G4DNAIonisation
    • G4DNABornIonisationModel
      • applicable energy range : 10 eV - 1 MeV
      • type : interpolated
      • constructors : default, option2, and up to 1 MeV for option4 and option6
    • G4DNAEmfietzoglouIonisationModel (4)
      • applicable energy range : 11 eV - 10 keV
      • type : interpolated
      • constructors : option4
    • G4DNACPA100IonisationModel (4)
      • applicable energy range : 11 eV - 250 keV
      • type : interpolated
      • constructors : option6

  • Vibrational excitation : G4DNAVibExcitation
    • G4DNASancheExcitationModel
      • applicable energy range : 2 eV - 100 eV
      • type : interpolated
      • constructors : default, option2

  • Attachment : G4DNAAttachment
    • G4DNAMeltonAttachmentModel
      • applicable energy range : 4 eV - 13 eV
      • type : interpolated
      • constructors : default, option2

(1) indicates the default tracking cut for electrons as set in the Geant4-DNA physics constructors and handled by the G4DNAElectronSolvation process, when chemistry simulation is not activated.

(2) the G4DNAScreenedRutherfordElasticModel, G4DNAUeharaScreenedRutherfordElasticModel and G4DNACPA100ElasticModel are alternative models for the simulation of elastic scattering.

(3) the G4DNAEmfietzoglouExcitationModel and G4DNACPA100ExcitationModel are alternative models for the simulation of electronic excitation.

(4) the G4DNAEmfietzoglouIonisationModel and G4DNACPA100IOnisationModel are alternative models for the simulation of ionisation.

(*) constructors differ by electron models - see all constructors in the Physics lists section.

PROTONS (named "proton")

  • Nuclear scattering : G4DNAElastic
    • G4DNAIonElasticModel
      • applicable energy range : 100 eV - 1 MeV
      • cut at 100 eV (5)
      • type : interpolated
      • Geant4-DNA physics constructors : default, option2, option4, option6

  • Electronic excitation : G4DNAExcitation
    • G4DNAMillerGreenExcitationModel
      • applicable energy range : 10 eV - 500 keV
      • type : analytical
      • constructors : default, option2, option4, option6
    • G4DNABornExcitationModel (3)
      • applicable energy range : 500 keV - 100 MeV
      • type : interpolated
      • constructors : default, option2, option4, option6
    • G4DNARPWBAExcitationModel
      • applicable energy range : 100 MeV - 300 MeV
      • type : interpolated
      • constructors : default, option2, option4, option6

  • Ionisation : G4DNAIonisation
    • G4DNARuddIonisationModel (G4DNARuddIonisationExtendedModel is also usable, (6))
      • applicable energy range : 100 eV - 500 keV
      • cut at 100 eV for both models (5)
      • type : interpolated
      • constructors : default, option2 (6), option4, option6
    • G4DNABornIonisationModel
      • applicable energy range : 500 keV - 100 MeV
      • type : interpolated
      • constructors : default, option2, option4, option6
    • G4DNARPWBAIonisationModel
      • applicable energy range : 100 MeV - 300 MeV
      • type : interpolated
      • constructors : default, option2, option4, option6

  • Electron capture : G4DNAChargeDecrease
    • G4DNADingfelderChargeDecreaseModel
      • applicable energy range : 100 eV - 100 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

(5) indicates the tracking cut applied by the corresponding model.

(6) a preliminary updated version of the G4DNARuddIonisationExtendedModel has been released in Geant4 11.2. It is significantly faster than the G4DNARuddIonisationModel for the sampling of secondary electrons. It is used in the option2 constructor for protons, hydrogen atoms, alpha particles and their charge states, and in all constructors for heavier ions.


HYDROGEN ATOMS (named "hydrogen")

  • Nuclear scattering : G4DNAElastic
    • G4DNAIonElasticModel
      • applicable energy range : 100 eV - 1 MeV
      • cut at 100 eV (5)
      • type : interpolated
      • Geant4-DNA physics constructors : default, option2, option4, option6

  • Electronic excitation : G4DNAExcitation
    • G4DNAMillerGreenExcitationModel
      • applicable energy range : 10 eV - 500 keV
      • type : analytical
      • constructors : default, option2, option4, option6

  • Ionisation : G4DNAIonisation
    • G4DNARuddIonisationModel (G4DNARuddIonisationExtendedModel is also usable, (6))
      • applicable energy range : 100 eV - 100 MeV
      • type : interpolated
      • constructors : default, option2 (6), option4, option6

  • Electron loss : G4DNAChargeIncrease
    • G4DNADingfelderChargeIncreaseModel
      • applicable energy range : 100 eV - 100 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

HELIUM ATOMS IONISED TWICE (named "alpha")

  • Nuclear scattering : G4DNAElastic
    • G4DNAIonElasticModel
      • applicable energy range : 100 eV - 1 MeV
      • cut at 100 eV (5)
      • type : interpolated
      • Geant4-DNA physics constructors : default, option2, option4, option6

  • Electronic excitation : G4DNAExcitation
    • G4DNAMillerGreenExcitationModel
      • applicable energy range : 1 keV - 400 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

  • Ionisation : G4DNAIonisation
    • G4DNARuddIonisationModel (G4DNARuddIonisationExtendedModel is also usable, (6))
      • applicable energy range : 100 eV - 400 MeV
      • cut at 1 keV (5) for default, option4, option6 constructors
      • type : interpolated
      • constructors : default, option2 (6), option4, option6

  • Electron capture : G4DNAChargeDecrease
    • G4DNADingfelderChargeDecreaseModel
      • applicable energy range : 1 keV - 400 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

HELIUM ATOMS IONISED ONCE (named "alpha+")

  • Nuclear scattering : G4DNAElastic
    • G4DNAIonElasticModel
      • applicable energy range : 100 eV - 1 MeV
      • cut at 100 eV (5)
      • type : interpolated
      • Geant4-DNA physics constructors : default, option2, option4, option6

  • Electronic excitation : G4DNAExcitation
    • G4DNAMillerGreenExcitationModel
      • applicable energy range : 1 keV - 400 MeV
      • type : analytical
      • constructors : default, option2 (*), option4, option6

  • Ionisation : G4DNAIonisation
    • G4DNARuddIonisationModel (G4DNARuddIonisationExtendedModel is also usable, (6))
      • applicable energy range : 100 eV - 400 MeV
      • cut at 1 keV (5) for default, option4, option6 constructors
      • type : interpolated
      • constructors : default, option2 (6), option4, option6

  • Electron capture : G4DNAChargeDecrease
    • G4DNADingfelderChargeDecreaseModel
      • applicable energy range : 1 keV - 400 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

  • Electron loss : G4DNAChargeIncrease
    • G4DNADingfelderChargeIncreaseModel
      • applicable energy range : 1 keV - 400 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

NEUTRAL HELIUM ATOMS (named "helium")

  • Nuclear scattering : G4DNAElastic
    • G4DNAIonElasticModel
      • applicable energy range : 100 eV - 1 MeV
      • cut at 100 eV (5)
      • type : interpolated
      • Geant4-DNA physics constructors : default, option2, option4, option6

  • Electronic excitation : G4DNAExcitation
    • G4DNAMillerGreenExcitationModel
      • applicable energy range : 1 keV - 400 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

  • Ionisation : G4DNAIonisation
    • G4DNARuddIonisationModel (G4DNARuddIonisationExtendedModel is also usable, (6))
      • applicable energy range : 100 eV - 400 MeV
      • cut at 1 keV (5) for default, option4, option6 constructors
      • type : interpolated
      • constructors : default, option2 (6), option4, option6

  • Electron loss : G4DNAChargeIncrease
    • G4DNADingfelderChargeIncreaseModel
      • applicable energy range : 1 keV - 400 MeV
      • type : analytical
      • constructors : default, option2, option4, option6

IONS
  • Geant4-DNA can simulate ionisation by the following incident ions, dominant in the cosmic spectrum : Li (3,7), Be (4,9), B (5,11), C (6,12), N (7,14), O (8,16), Si (14,28), Fe (26,56). For all other ions, a scaling based on proton cross section is applied from Geant4 11.2.
  • Ionisation : G4DNAIonisation process class
    • G4DNARuddIonisationExtendedModel model class
      • valid down to 0.5 MeV/u and up to about 1E6 MeV/u (see ref.)
      • type : interpolated
      • constructors : option2 (this model is also used for protons, alphas and all charge states, and for ions), option4 (for ions only), option6 (for ions only)
  • Refer to the dnaphysics.in macro file of the "dnaphysics" example to see how to shoot ions

GAMMAS (named "gamma")

Gamma interactions are based on the Geant4 Livermore/EADL97 models and they are included by default in all G4EmDNAPhysics* constructors. Please see more on Physics lists.


B) Models applicable to materials other than liquid water


  • Models for DNA components

CPA100 models are also applicable for the simulation of physical interactions (elastic, excitation, ionisation) in adenine, cytosine, guanine, thymine, deoxyribose and phosphoric acid (respectively identified as the following Geant4 materials: « G4_ADENINE », « G4_CYTOSINE », « G4_GUANINE », « G4_THYMINE », « G4_DEOXYRIBOSE » and « G4_PHOSPHORIC_ACID »).
They are applicable to electrons (from 11 eV to 1 MeV).

  • G4DNACPA100ExcitationModel
  • G4DNACPA100IonisationModel
  • G4DNACPA100ElasticModel

They are available in the G4EmDNAPhysics_option6 physics constructor.

  • Models for DNA precursors and N2

Additional models are available for the simulation of physical interactions (elastic, excitation, ionisation) in tetrahydrofuran (THF), trimethylphosphate (TMP), pyrimidine (PY) and purine (PU), serving as precursors for the deoxyribose and phosphate groups in the DNA backbone, as well as for the pyrimidine nucleobases. Nitrogen material is also available.

The models are described by the classes:

  • G4DNAPTBAugerModel
  • G4DNAPTBExcitationModel
  • G4DNAPTBIonisationModel
  • G4DNAPTBElasticModel

They are applicable to electrons (from 12 eV to 1 keV) and to protons (70 keV - 10 MeV) and their usage is illustrated in the "icsd" Geant4-DNA example. Note that for protons, only the ionisation process is currently available.

  • Models for solid gold

Additional models are available for the simulation of track structures of electrons in solid gold material.

The models are described by the classes:

  • G4DNADiracRMatrixExcitationModel
  • G4DNAQuinnPlasmonExcitationModel
  • G4DNARelativisticIonisationModel
  • G4DNAELSEPAElasticModel

They are applicable to electrons (from 10 eV to 1 GeV) and their usage is illustrated in the "AuNP" Geant4-DNA example.

C) Notes


  • From Geant4 version 11.2, do not use these constructors for incident energies exceeding the upper energy limit of the Geant4-DNA physics models (that is, 1 MeV for electrons, 300 MeV for protons, 400 MeV for alphas)
  • A preliminary updated version of the G4DNARuddIonisationExtendedModel has been released in Geant4 11.2. It is significantly faster than the G4DNARuddIonisationModel for the sampling of secondary electrons. It is used in the option2 constructor for protons, hydrogen atoms, alpha particles and their charge states, and in all constructors for heavier ions.