This example is intended to check implementation of the processes of muon interactions: ionization, direct (e+,e-) production, mu+mu- pair production, bremsstrahlung, and mu-nuclear interaction. It allows to compute differential cross sections (as function of the energy transfered to secondaries), total cross sections, and to compare with analytic calculations.
It is a single box of homogeneous medium. Two parameters define the geometry :
The default geometry (1 m of Iron) is constructed in DetectorConstruction, but the above parameters can be changed interactively via the commands defined in DetectorMessenger.
The Physics List of the example uses the main physics constructor (builder) called "local", which includes only muon, pion, and proton processes under study. As an alternative standard "emstandard_opt0" and "emstandard_opt4" constructors may be used.
Optionally "muNucl" builder, MuNuclearBuilder, may be added activating muon-nuclear inelastic interaction.
The primary kinematic consists of a single particle starting at the edge of the box. The type of the particle and its energy are set in PrimaryGeneratorAction (mu+ 10 TeV), and can be changed via the G4 build-in commands of ParticleGun class (see the macros provided with this example).
The incident particle is a muon. During the tracking, secondary particles are killed.
The number of interactions are plotted as a function of the energy transfered to the secondaries. The total number of interactions is recorded, and the total cross section computed from this.
At RunAction::EndOfRun(..), the above results are compared with analytical calculations. The functions computing the theoretical cross sections have been provided by the G4 MEPhI group, and implemented in MuCrossSections class.
The test contains 4 built-in 1D histograms, which are managed by the HistoManager class and its Messenger, HistoMessenger.
The histos can be activated individually with the command :
/testem/histo/setHisto id nbBins valMin valMax
min and max values of log10(eps/Emu kin).
At RunAction::EndOfRunAction() the corresponding histos for analytic calculations are automatically created and filled (histo 11 to 14, and 18).
One can control the name and the type of the histograms file with the command:
/testem/histo/setFileName name (default testem17)
It is possible to choose the format of the histogram file : root (default), xml, csv, by using namespace in HistoManager.hh
The Visualization Manager is set in the main () (see TestEm17.cc). The initialisation of the drawing is done via the commands /vis/... in the macro vis.mac. To get visualisation:
> /control/execute vis.mac
The detector has a default view which is a longitudinal view of the box.
The tracks are drawn at the end of event, and erased at the end of run.
% TestEm17 allproc.mac
% TestEm17 Idle> control/execute vis.mac .... Idle> type your commands .... Idle> exit