Author: S. Incerti (a, *), V. Ivantchenko (b), M. Karamitros (a)
a. Centre d'Etudes Nucleaires de Bordeaux-Gradignan (CENBG), IN2P3 / CNRS / Bordeaux 1 University, 33175 Gradignan, France
b. G4AI Ltd, UK
e-mail:incer.nosp@m.ti@c.nosp@m.enbg..nosp@m.in2p.nosp@m.3.fr

INTRODUCTION <br>

The microdosimetry example simulates the track of two 5 MeV protons in liquid water. Geant4 standard EM models are used in the World volume while Geant4-DNA models are used in a Target volume, declared as a Region.

This example is provided by the Geant4-DNA collaboration.

These processes and models are further described at: http://geant4-dna.org

Any report or published results obtained using the Geant4-DNA software shall cite the following Geant4-DNA collaboration publications:
Phys. Med. 31 (2015) 861-874 Med. Phys. 37 (2010) 4692-4708

We also suggest these other references related to this example:
Nucl. Instrum. and Meth. B 273 (2012) 95-97
Prog. Nucl. Sci. Tec. 2 (2011) 898-903

GEOMETRY SET-UP

The geometry is a 1 mm side cube (World) made of liquid water containing a smaller cubic Target volume of liquid water, which dimensions are twenty times smaller than the dimensions of the World volume.

SET-UP

Make sure G4LEDATA points to the low energy electromagnetic libraries.

The code can be compiled with cmake.

It works in MT mode.

HOW TO RUN THE EXAMPLE <br>

Normal mode, run:

./microdosimetry -mt 2 -out microdosimetry

(or more generally

./microdosimetry -mt 2 -out myRootFile

)

The macro microdosimetry.in is executed by default; to select another one:

./microdosimetry -mac myMacro.mac

To get visualization and interactivity:

./microdosimetry -gui

( OGL used by default)

or you may use your own visualization driver, for instance:

./microdosimetry -vis "DAWNFILE"

PHYSICS

This example shows:

how to use the Geant4-DNA processes,
how to count and save occurrences of processes
how to combine them with Standard EM Physics.

A simple electron capture process is also provided in order to kill electrons below a chosen energy threshold, set in the Physics list.

Look at the PhyscisList.cc file.

SIMULATION OUTPUT AND RESULT ANALYSIS <br>

The output results consists in a dna.root file, containing for each simulation step:

the type of particle for the current step
the type of process for the current step
the track position of the current step (in nanometers)
the energy deposit along the current step (in eV)
the step length (in nm)
the total energy loss along the current step (in eV)
the kinetic energy at PreStepPoint
the cos of the scattering angle
the event ID
the track ID
the parent track ID
the step number

This file can be easily analyzed using for example the provided ROOT macro file plot.C; to do so : be sure to have ROOT installed on your machine be sure to be in the microdosimetry directory launch ROOT by typing root under your ROOT session, type in : .X plot.C to execute the macro file alternatively you can type directly under your session : root plot.C

The naming scheme on the displayed ROOT plots is as follows (see SteppingAction.cc), as in the 'dnaphysics' example:

particles:
gamma : 0
e- : 1
proton : 2
hydrogen : 3
alpha : 4
alpha+ : 5
helium : 6
processes:
eCapture 1
(only if one uses G4EmDNAPhysicsActivator in PhysicsList)

e-_G4DNAElectronSolvation 10
e-_G4DNAElastic 11
e-_G4DNAExcitation 12
e-_G4DNAIonisation 13
e-_G4DNAAttachment 14
e-_G4DNAVibExcitation 15
msc 110
CoulombScat 120
eIoni 130

proton_G4DNAElastic 21
proton_G4DNAExcitation 22
proton_G4DNAIonisation 23
proton_G4DNAChargeDecrease 24
msc 210
CoulombScat 220
hIoni 230
nuclearStopping 240

hydrogen_G4DNAElastic 31
hydrogen_G4DNAExcitation 32
hydrogen_G4DNAIonisation 33
hydrogen_G4DNAChargeIncrease 35

alpha_G4DNAElastic 41
alpha_G4DNAExcitation 42
alpha_G4DNAIonisation 43
alpha_G4DNAChargeDecrease 44
msc 410
CoulombScat 420
ionIoni 430
nuclearStopping 440

alpha+_G4DNAElastic 51
alpha+_G4DNAExcitation 52
alpha+_G4DNAIonisation 53
alpha+_G4DNAChargeDecrease 54
alpha+_G4DNAChargeIncrease 55

msc 510
CoulombScat 520
hIoni 530
nuclearStopping 540
helium_G4DNAElastic 61
helium_G4DNAExcitation 62
helium_G4DNAIonisation 63
helium_G4DNAChargeIncrease 65

GenericIon_G4DNAIonisation 73
msc 710
msc 710
CoulombScat 720
ionIoni 730
nuclearStopping 740

Should you have any enquiry, please do not hesitate to contact: incer.nosp@m.ti@c.nosp@m.enbg..nosp@m.in2p.nosp@m.3.fr