geant4/examples/extended/analysis/AnaEx01/README.md

\page ExampleAnaEx01 Example AnaEx01

Examples AnaEx01 and AnaEx02 show the usage of histogram and tuple manipulations using G4Analysis and ROOT compliant systems on the same scenario. All analysis manipulations (histo booking, filling, saving histos in a file, etc...) are located in one class : HistoManager, implementation of which is different in each example. All the other classes are same in all three examples.

This example shows the usage of histogram and tuple manipulations using G4Analysis system.

The example is an adaptation of examples/novice/N03. It describes a simple sampling calorimeter setup.

Detector description

The calorimeter is a box made of a given number of layers. A layer consists of an absorber plate and of a detection gap. The layer is replicated.

Six parameters define the calorimeter : - the material of the absorber, - the thickness of an absorber plate, - the material of the detection gap, - the thickness of a gap, - the number of layers, - the transverse size of the calorimeter (the input face is a square).

The default geometry is constructed in DetectorConstruction class, but all of the above parameters can be modified interactively via the commands defined in the DetectorMessenger class.

        |<----layer 0---------->|<----layer 1---------->|<----layer 2---------->|
        |                       |                       |                       |
        ==========================================================================
        ||              |       ||              |       ||              |       ||
        ||              |       ||              |       ||              |       ||
 beam   ||   absorber   |  gap  ||   absorber   |  gap  ||   absorber   |  gap  ||
======> ||              |       ||              |       ||              |       ||
        ||              |       ||              |       ||              |       ||
        ==========================================================================

Physics list

The particle's type and the physic processes which will be available in this example are set in the FTFP_BERT physics list.

Action Initialization

A newly introduced class, ActionInitialization, instantiates and registers to Geant4 kernel all user action classes which are defined thread-local and a run action class which is defined both thread-local and global.

The thread-local action classes are defined in ActionInitialization::Build() and the global run action class is defined in ActionInitialization::BuildForMaster(). Note that ActionInitialization::Build() is also used to instatiate user action clasess in sequential mode.

An event : PrimaryGeneratorAction

The primary kinematic consists of a single particle which hits the calorimeter perpendicular to the input face. The type of the particle and its energy are set in the PrimaryGeneratorAction class, and can be changed via the G4 build-in commands of ParticleGun class.

Histograms

AnaEx01 can produce 4 histograms :

• EAbs : total energy deposit in absorber per event
• EGap : total energy deposit in gap per event
• LAbs : total track length of charged particles in absorber per event
• LGap : total track length of charged particles in gap per event

And 2 Ntuples :

• Ntuple1:
  • one row per event : EnergyAbs EnergyGap
• Ntuple2:
  • one row per event : TrackLAbs TrackLGap

These histos and ntuples are booked in HistoManager and filled from EventAction.

One can control the name of the histograms file and its format:

• default name : AnaEx01 The format of the histogram file can be : root (default), xml, csv.

We can define the default file type and set it to the analysis manager via

/analysis/setDefaultFileType root    # or csv hdf5 xml

The file names then need not to be provided with the file extension and the same macro can be used with different output types.

Macros

• The AnaEx01.in macro uses the defaultFileType parameter (alias), which default value, "root" is defined in main().

• AnaEx01-csv.in, AnaEx01-hdf5.in, AnaEx01-root.in, AnaEx01-xml.in: \n In these macros, the default value of the defaultFileType is overritten with

/control/alias defaultFileType cvs   # or hdf5 root xml

and then the AnaEx01.in macro is called.

How to build

An additional step is needed when building the example with GNUmake due to using the extra shared directory:

% cd path_to_AnaEx01/AnaEx01
% gmake setup
% gmake

This will copy the files from shared in the example include and src; to remove these files:

% gmake clean_setup

HOW TO RUN

• Execute AnaEx01 in the 'interactive mode' with visualization

% ./AnaEx01
and type in the commands from run.mac line by line:
Idle> /control/verbose 2
Idle> /tracking/verbose 1
Idle> /run/beamOn 10
Idle> ...
Idle> exit

  or

Idle> /control/execute run.mac
....
Idle> exit

• Execute AnaEx01 in the 'batch' mode from macro files (without visualization)

% ./AnaEx01 run.mac
% ./AnaEx01 run.mac > run.out

The AnaEx01.in macro is used in Geant4 testing.