Author: S. Incerti et al. (a, *)
a. Centre d'Etudes Nucleaires de Bordeaux-Gradignan
(CENBG), IN2P3 / CNRS / Bordeaux University, 33175 Gradignan, France
e-mail:incer.nosp@m.ti@c.nosp@m.enbg..nosp@m.in2p.nosp@m.3.fr

INTRODUCTION. <br>

The wvalue example shows how to calculate w in liquid water for e- using the Geant4-DNA physics processes and models.

w is computed as the ratio of the incident particle energy and the total number of ionisations.

It is adapted from svalue.

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 publication: Phys. Med. 31 (2015) 861-874 Med. Phys. 37 (2010) 4692-4708

This example is presented in the following paper, which shall also be cited: Med. Phys. 42 (2015) 3870-3876

GEOMETRY SET-UP

The geometry is a 1 m radius sphere of liquid water (G4_WATER material). Particles are shot randomly from the sphere centre.

Radius of the sphere, physics constructor and energy can be controlled by the wvalue.in macro file.

The PrimaryGeneratorAction class is adapted (G4 state dependent) in order to enable generic physics list usage (empty modular physics list).

SET-UP

Make sure G4LEDATA points to the low energy electromagnetic data files.

The code can be compiled with cmake.

It works in MT mode.

HOW TO RUN THE EXAMPLE <br>

In interactive mode, run:

./wvalue wvalue.in

The wvalue.in macro allows a full control of the simulation.

PHYSICS

You can select Geant4-DNA physics constructor in wvalue.in.

A tracking cut can be applied if requested.

SIMULATION OUTPUT AND RESULT ANALYSIS <br>

The output results consist in a text file (wvalue.txt), containing :

the energy of incident particles (in eV)
the mean number of ionisations
its rms
the w value (in eV)
its rms (in eV)

Note: rms values correspond to standard deviation.

In addition, another macro (histo.in) is also provided including a series of histograms :

histogram #1 : nb of ionisation interactions per event
histogram #2 : total energy deposited in absorber
histogram #3 : true track length of the primary particle
histogram #4 : true step size of the primary particle
histogram #5 : projected range of the primary particle
histogram #6 : true track length of charged secondaries
histogram #7 : true track length of charged secondaries

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