For any application in liquid water based on the Geant4-DNA extension, we recommend the implementation of a Geant4-DNA physics list using the G4EmDNAPhysics* Physics constructors. The usage of such constructors is described in several Geant4-DNA extended examples (see examples section).

In order to implement a Geant4-DNA-based physics list, please follow the two steps indicated below for any G4EmDNAPhysics* physics constructor. For example, if you wish to use the "G4EmDNAPhysicsConstructor":

1) In your declaration file (eg. PhysicsList.hh)

#ifndef PhysicsList_h
#define PhysicsList_h 1

#include "G4VModularPhysicsList.hh"

class PhysicsList: public G4VModularPhysicsList
{
public:
PhysicsList();
virtual ~PhysicsList();
};

#endif

2) In your implementation file (eg. PhysicsList.cc)

#include "PhysicsList.hh"
#include "G4SystemOfUnits.hh"

#include "G4EmDNAPhysics.hh"

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

PhysicsList::PhysicsList()
: G4VModularPhysicsList()
{
SetDefaultCutValue(1*nanometer);
SetVerboseLevel(1);

// Geant4-DNA physics
RegisterPhysics(
new G4EmDNAPhysics());
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

PhysicsList::~PhysicsList()
{}

Important notes

  • The above physics list proposes a default production cut for secondaries (electrons, positrons, gammas) set to 1 nm. The Geant4-DNA processes are all discrete (that is, step-by step) processes; as such, they simulate explicitly all interactions and do not use any production cut, so this 1 nm cut will have no effect on the Geant4-DNA physics results. However, in the case users need to combine Geant4-DNA processes with other Geant4 electromagnetic processes (e.g. other electron processes) which use cuts for secondary particle production, we have indicated how to specify this cut value.
  • The user may want to write his/her own PhysicsList class based on Geant4-DNA physics processes and models. In order to do this, we recommend to use the method described above (creation of a PhysicsList class that uses the G4EmDNAPhysics* constructors) and then copy the Geant4 default G4EmDNAPhysics* class in his/her own application, so that he/she can modify this local copy of the G4EmDNAPhysics* class according to his/her needs.
  • The source code of all G4EmDNAPhysics* physics contructors may be found in the $G4INSTALL/source/physics_lists/constructors/electromagnetic directory.


List of available
Geant4-DNA Physics constructors for liquid water

We recommend several Physics constructors for simulations in liquid water, they are listed below.

  • G4EmDNAPhysics_option2 : accelerated default constructor, simulating electrons interactions up to 1 MeV, as well as all other particle interactions
  • G4EmDNAPhysics_option4 : contains electron elastic and inelastic models by D. Emfietzoglou, I. Kyriakou, S. Incerti, up to 10 keV
  • G4EmDNAPhysics_option6 : contains CPA100 electron elastic and inelastic models by M. C. Bordage, M. Terrissol, S. Incerti, up to 255 keV

These constructors are described in the following
publication. Other constructors are preliminary or obsolete constructors.