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 mfp example shows how to calculate mean free path of particles in liquid water using the Geant4-DNA physics processes and models.

It has been adapted from the spower and TestEm14 examples.

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

GEOMETRY SET-UP

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

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

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>

Use:

./mfp mfp.in

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

The computation of MFP and other quantities is performed in the SteppingAction::UserSteppingAction method.

The histo.in macro shows how to display several quantities (energy spectrum, scattering angle along x) of primary and secondaries.

PHYSICS

G4EmDNAPhysics* constructors are used.

SIMULATION OUTPUT AND RESULT ANALYSIS <br>

The accuracy of results may depend on incident statistics as well as on number of steps specified in the SteppingAction::UserSteppingAction method.

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

energy of incident particles (in eV)
mfp (in nm)
rms (i.e. standard deviation) on mfp (in nm)

Otherwise you may use histo.in to generate ROOT histograms of the other quantities.

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