geant4

exgps is created to demonstrate the usage of G4GeneralParticleSource for generating primary particle according to user defined distributions. These range from simple monocromatic point source to complicated mutiple sources with various biasing schemes.

GEOMETRY

Simple geometry consists of a "Vacuum" world and, in it, two other components: - An alunimium box : 20 x 20 x 20 cm in size, cerntered at the origin. - A SiO2 sphere (radius 5 cm) is placed at the centre of the aluminium box.

PHYSICS

Tranportation process only for all particles.

EVENT

The event generator is the G4GeneralParticleSource (GPS). The instantiation of G4GeneralParticleSource is same as that for G4ParticleGun. See the exGPSPrimaryGeneratorAction.cc file for details.

VISUALIZATION

Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An example of displaying the geometry and tracks using OGL is given in the macro vis.mac.

HISTOGRAMS

This example implements an histo manager which creates histograms and ntuples using Geant4 analysis tools.

The output file can contain the following histograms and one ntuple:

histo1D 1: energy spectrum.
histo1D 2: vertex: radial distribution dN/dv.
histo1D 3: angular distribution: cos(theta).
histo1D 4: angular distribution: phi.
histo2D 1: vertex position in the X-Y plane.
histo2D 2: vertex position in the X-Z plane.
histo2D 3: vertex position in the Y-Z plane.
histo2D 4: angular distribution: phi-cos(theta).
histo2D 5: angular distribution: of phi-theta.

In the ntuple the following data are recorded for each incident particle:

Particle ID
Kinetic energy (Ekin);
Incident Position (x,y,z);
Incident Angle (theta,phi);
Particle weight;

The histograms are managed by G4AnalysisManager class and its Messenger. The histos, not activated by default, can be individually activated with the command :

  /analysis/h1/set id nbBins  valMin valMax unit

where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)

One can control the name of the histograms file with the command:

  /analysis/setFileName  name  (default exgps)

It is possible to choose the format of the histogram file : root (default), xml, csv, by using namespace in HistoManager.hh

GETTING STARTED

Execute exgps in 'batch' mode from macro files

% ./exgps exgps.in
% ./exgps exgps_MT.in   # larger number of events

Execute exgps in 'interactive mode' with visualization

% ./exgps
....
Idle> type your commands
....
Idle> exit

FURTHER EXAMPLES of MACRO FILES

There are a number of mac files in the ./macros subdirectory, to show the various features of GPS.

test01.mac : point source, isotropic radiation, monoenergetic
test02.mac : square plane source, cosine-law radiation, linear energy
test03.mac : rectangular plane source, isotropic radiation, power-law energy
test04.mac : circular plane source, cosine-law radiation, exponential energy
test05.mac : elliptical plane source, isotropic radiation, bremsstrahlung energy
test06.mac : spherical surface source, isotropic radiation, black-body energy
test07.mac : cylindrical surface source, cosine-law radiation, Cosmic diffuse energy
test08.mac : elliptical surface source, isotropic radiation, linear energy
test09.mac : parallepiped surface source, isotropic radiation, linear energy
test10.mac : spherical volume source, isotropic radiation, linear energy
test11.mac : cylindrical volume source, isotropic radiation, power-law energy
test12.mac : elliptical volume source, isotropic radiation, power-law energy
test13.mac : parallelepiped volume source, cosine-law radiation, exponential energy
test14.mac : rotated circular plane source, isotropic radiation, exponential energy
test15.mac : rotated surface cylinder source, isotropic radiation, bremsstrahlung energy
test16.mac : rotated parallelepiped volume source, isotropic radiation, bremsstrahlung energy
test17.mac : confined spherical volume source, isotropic radiation, exponential energy
test18.mac : square plane source, cosine-law radiation, user-defined energy histogram
test19.mac : square plane source, cosine-law radiation, arbitrary point-wise energy function with linear interpolation.
test20.mac : square plane source, cosine-law radiation, arbitrary point-wise energy function with logarithmic interpolation.
test21.mac : square plane source, cosine-law radiation, arbitrary point-wise energy function with exponential interpolation.
test22.mac : square plane source, cosine-law radiation, arbitrary point-wise energy function with spline interpolation.
test23.mac : square plane source with x and y biasing, user-defined theta and phi distributions, user-defined EPN energy distribution.
test24.mac : spherical volume source with z biasing, isotropic radiation with theta and phi biasing, arbitrary point-wise energy function with linear interpolation.
test25.mac : spherical volume source, isotropic radiation with theta and phi biasing, user-defined energy histogram.
test26.mac : square plane source, cosine-law radiation with lower and upper theta and phi limits, linear energy with biasing.
test27.mac : square plane source, user-defined theta, arbitrary point-wise energy function with linear interpolation.
test28.mac : particle=ion, square plane source, isotropic radiation, monoenergetic energy.
test29.mac : plane source of type annulus, cosine-law radiation, exponential energy
test30.mac : rotated 1d beam source, Gaussian beam energy.
test31.mac : two-beam incidence, i.e. multiple sources with relative intensities.
test32.mac : Sphere volume source, with biasing in theta and phi Isotropic directional distribution with theta and phi biasing.
test33.mac : Focused angular distribution.
test34.mac : Two simultaneous sources, both fired at the same time.
test35.mac : automatic biasing of the energy distribution sampling, original in power-law.
test36.mac : automatic biasing of the energy distribution sampling, original in arbitrary data points.
test37.mac : automatic biasing of the energy distribution sampling, original in exponential form.
test38.mac : arbitrary energy distribution, defined using the ascii input file: spectrum.dat

All these test macros can be run via the runall.csh script and the resulting ROOT files can be then analysed with the 'plotall.py' macro, calling internally 'plotfiles.py':

% ./macros/runall.csh
% python3 macros/plotall.py

In addition, the examples of ROOT macros plotHisto.C and plottest35.C are also available.

More information is available at: https://geant4-userdoc.web.cern.ch/UsersGuides/ForApplicationDeveloper/html/GettingStarted/generalParticleSource.html