$Id: README 92322 2015-08-27 14:54:05Z gcosmo $
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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AnaEx02
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Examples AnaEx01, AnaEx02 and AnaEx03 show the usage of histogram and tuple
manipulations using G4Analysis, ROOT and AIDA 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
ROOT system. Please install ROOT before building this example:
http://root.cern.ch
The example is an adaptation of examples/novice/N03. It describes a simple
sampling calorimeter setup.
1- 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 ||
======> || | || | || | ||
|| | || | || | ||
==========================================================================
2- 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.
3- 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.
4- 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.
5- Histograms
-------------
To produce histograms, ROOT system must be installed
AnaEx02 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 :
default name : AnaEx02
format : root
See HistoManager constructor
6- How to build
---------------
An additional step is needed when building the example with GNUmake
due to using the extra shared directory:
% cd path_to_AnaEx02/AnaEx02
% gmake setup
% gmake
This will copy the files from shared in the example include and src;
to remove these files:
% gmake clean_setup
Gabriele Cosmo