Gabriele Cosmo
132 lines
5.0 KiB
Plaintext
132 lines
5.0 KiB
Plaintext
-------------------------------------------------------------------
|
|
|
|
=========================================================
|
|
Geant4 - an Object-Oriented Toolkit for Simulation in HEP
|
|
=========================================================
|
|
|
|
amsEcal
|
|
-------
|
|
|
|
1- GEOMETRY DEFINITION
|
|
|
|
AMS Ecal calorimeter is described in the joined documument : ams_ecal.pdf
|
|
|
|
- A single layer is a plane of scintillating fibers within a box of
|
|
absorber material.
|
|
- Single layers are positionned (eg. placement) within Module
|
|
(called SuperLayer in the descriptive document),
|
|
alternatively with a relative offset of +- 0.25*distanceInterFibers.
|
|
- Modules are positionned within calorimeter, alternatively rotated of
|
|
90 deg around beam axis (X_axis).
|
|
Therefore all fibers are along Y_axis or Z_axis calorimeter.
|
|
|
|
The default geometry is constructed in DetectorConstruction class.
|
|
In addition a transverse uniform magnetic field can be applied.
|
|
|
|
2- PHYSICS LISTS
|
|
|
|
Physics lists can be local (eg. in this example) or from G4 kernel
|
|
(physics_lists subdirectory).
|
|
|
|
- "local" standard EM physics with current 'default' options.
|
|
|
|
From geant4/source/physics_lists/constructors:
|
|
- "emstandard_opt0" standard EM physics with all default options
|
|
- "emstandard_opt1" best CPU performance standard physics for LHC
|
|
- "emstandard_opt2"
|
|
- "emstandard_opt3"
|
|
|
|
Physics lists and options can be (re)set with UI commands
|
|
|
|
Please, notice that options set through G4EmProcessOPtions are global, eg
|
|
for all particle types. In G4 constructors, it is shown how to set options per
|
|
particle type.
|
|
|
|
3- PRIMARY GENERATOR : mono-energetic pencil beam
|
|
|
|
The primary kinematic is a single particle which hits the calorimeter
|
|
perpendicular to the input face (eg. along X_axis).
|
|
The type of particle and its energy are set in the PrimaryGeneratorAction,
|
|
and can be changed via the G4 build-in commands of ParticleGun class
|
|
(see the macros provided with this example).
|
|
|
|
One can choose randomly the tranverse position of the incident particle,
|
|
eg. the width of the beam. The associated interactive command is built
|
|
in PrimaryGeneratorMessenger.
|
|
|
|
4- DETECTOR RESPONSE
|
|
|
|
The program computes the 'visible' energy, eg. the energy deposited
|
|
in scintillating fibers.
|
|
|
|
It also computes the total energy deposited per layer, either in absorber
|
|
material or in scintillator material.
|
|
|
|
The list of fibers fired can be written event per event, on an ascii file.
|
|
The file is filled at EndOfEvent(); uncomment the function WriteFibers()
|
|
See EventAction::WriteFibers() and the format description : eventFormat.txt
|
|
|
|
NB: visible energy can be corrected for Birk's attenuation:
|
|
see the function SteppingAction::BirksAttenuation() (not activated)
|
|
|
|
5- HISTOGRAMS
|
|
|
|
The Program contains 5 built-in 1D histograms, managed by G4AnalysisManager.
|
|
These histograms can be activated individually with the command :
|
|
/analysis/h1/set id nbBins valMin valMax unit
|
|
where unit is the desired unit for the histo (MeV, keV, etc..)
|
|
(see the macros xxxx.mac).
|
|
|
|
1 total energy in calorimeter (eg. summed all layers)
|
|
2 vsible energy in calorimeter (eg. summed all layers)
|
|
3 total energy per layer (eg. longitudinal profile)
|
|
4 visible energy per layer (eg. longitudinal profile)
|
|
5 visible energy per fiber (eg. lateral profile)
|
|
|
|
Histograms can be viewed using ROOT.
|
|
|
|
One can control the name and format of the histograms file with the command:
|
|
/analysis/setFileName name (default amsEcal)
|
|
/analysis/setFileType type (choice: root(default), XML, csv)
|
|
|
|
It is also possible to print selected histograms on an ascii file:
|
|
/analysis/h1/setAscii id
|
|
All selected histos will be written on a file name.ascii (default amsEcal)
|
|
|
|
6- VISUALIZATION
|
|
|
|
Visualization Manager is set in the main().
|
|
Initialisation of the drawing is done via the commands :
|
|
/vis/... in the macro vis.mac. In interactive session:
|
|
PreInit or Idle > /control/execute vis.mac
|
|
|
|
Default view is a longitudinal view of the calorimeter.
|
|
|
|
Tracks are drawn at end of event, and erased at end of run.
|
|
Optionaly one can choose to draw all particles, only charged one, or none.
|
|
This command is defined in EventActionMessenger.
|
|
|
|
7- HOW TO START ?
|
|
|
|
- compile and link to generate an executable
|
|
% cd amsEcal
|
|
% gmake
|
|
|
|
- execute amsEcal in 'batch' mode from macro files
|
|
% amsEcal run1.mac
|
|
|
|
- execute amsEcal in 'interactive mode' with visualization
|
|
% amsEcal
|
|
....
|
|
Idle> type your commands. For instance:
|
|
Idle> /control/execute run1.mac
|
|
....
|
|
Idle> exit
|
|
|
|
8- HANDLE RANDOM NUMBER SEEDS
|
|
|
|
The macro rndmSeed.mac shows how to create a set of random number seeds.
|
|
Here we save the seed at begin of each run (the number of events per run
|
|
is arbitrary). The seeds are stored in subdirectory random.
|
|
|
|
Macro rndmSeed.mac shows also how to start a run from one of these seeds. |