Gabriele Cosmo
176 lines
6.1 KiB
Plaintext
176 lines
6.1 KiB
Plaintext
$Id: README,v 1.22 2004/11/23 14:05:24 maire Exp $
|
|
-------------------------------------------------------------------
|
|
|
|
=========================================================
|
|
Geant4 - an Object-Oriented Toolkit for Simulation in HEP
|
|
=========================================================
|
|
|
|
TestEm3
|
|
-------
|
|
|
|
This example simulates a simple Sampling Calorimeter setup.
|
|
|
|
1- GEOMETRY DEFINITION
|
|
|
|
The calorimeter is a box made of a given number of layers.
|
|
A layer consists of a sequence of various absorbers (maximum MaxAbsor=9).
|
|
The layer is replicated.
|
|
|
|
Parameters defining the calorimeter :
|
|
- the number of layers,
|
|
- the number of absorbers within a layer,
|
|
- the material of the absorbers,
|
|
- the thickness of the absorbers,
|
|
- the transverse size of the calorimeter (the input face is a square).
|
|
|
|
In addition a transverse uniform magnetic field can be applied.
|
|
|
|
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.
|
|
|
|
NB. Numbering scheme (for histograms):
|
|
layer : from 1 to NbOfLayers (inclued)
|
|
absorbers : from 1 to NbOfAbsor (inclued)
|
|
planes : from 1 to NbOfLayers*NbOfAbsor + 1 (inclued)
|
|
|
|
NB. The number of absorbers and the number of layers can be set to 1.
|
|
In this case we have a unique homogeneous block of matter, which looks like
|
|
a bubble chamber rather than a calorimeter ...
|
|
(see the macro of commands: newgeom.mac)
|
|
|
|
2- PHYSICS LISTS
|
|
|
|
Physics Lists are subdivided on 4 following modules:
|
|
1. "particles" - particle definitions
|
|
2. "general" - decays and transportation
|
|
3. "standard" (alternative) - standard EM physics
|
|
4. "g4v52" (alternative) - standard EM physics version G4 5.2
|
|
|
|
Notice that there is an example of definition of a static ion : IonC12
|
|
(see PhysListParticle.cc) and an example of use : ionC12.mac
|
|
|
|
3- AN EVENT : THE PRIMARY GENERATOR
|
|
|
|
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 (see the macros provided with this
|
|
example).
|
|
|
|
In addition one can choose randomly the impact point of the incident particle.
|
|
The corresponding interactive command is built in PrimaryGeneratorMessenger.
|
|
|
|
A RUN is a set of events.
|
|
|
|
4- VISUALIZATION
|
|
|
|
The Visualization Manager is set in the main().
|
|
The 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
|
|
|
|
The default view is a longitudinal view of the calorimeter.
|
|
|
|
The tracks are drawn at the end of event, and erased at the end of run.
|
|
Optionaly one can choose to draw all particles, only the charged one, or none.
|
|
This command is defined in EventActionMessenger class.
|
|
|
|
5- PHYSICS DEMO
|
|
|
|
The particle's type and the physic processes which will be available
|
|
in this example are set in PhysicsList class.
|
|
|
|
In addition a build-in interactive command (/process/inactivate processName)
|
|
allows to activate/inactivate the processes one by one.
|
|
Then one can well visualize the processes one by one, especially
|
|
in the bubble chamber setup with a transverse magnetic field.
|
|
|
|
As a homework try to visualize a gamma conversion alone,
|
|
or the effect of the multiple scattering.
|
|
|
|
Notice that one can control the maximum step size in each absorber, via the
|
|
StepMax process and the command /testem/stepMax/absorber
|
|
(see StepMax and PhysicsList classes)
|
|
|
|
6- HOW TO START ?
|
|
|
|
- compile and link to generate an executable
|
|
% cd TestEm3
|
|
% gmake
|
|
|
|
- execute TestEm3 in 'batch' mode from macro files
|
|
% TestEm3 run01.mac
|
|
|
|
- execute TestEm3 in 'interactive mode' with visualization
|
|
% TestEm3
|
|
....
|
|
Idle> type your commands. For instance:
|
|
Idle> /control/execute run01.mac
|
|
....
|
|
Idle> exit
|
|
|
|
7- HISTOGRAMS
|
|
|
|
Testem3 can produce histograms :
|
|
histo 1 : energy deposit in absorber 1
|
|
histo 2 : energy deposit in absorber 2
|
|
...etc...........
|
|
|
|
One can control the binning of the histo with the command:
|
|
/testem/histo/setHisto idAbsor nbin Emin Emax unit
|
|
...etc...........
|
|
where unit is the desired energy unit for that histo (see TestEm3.in).
|
|
|
|
histo 11 : longitudinal profile of energy deposit in absorber 1 (MeV)
|
|
histo 12 : longitudinal profile of energy deposit in absorber 2 (MeV)
|
|
...etc...........
|
|
|
|
histo 21 : forward energy flow of primary particle (MeV)
|
|
histo 22 : forward energy flow of all secondary particles (MeV)
|
|
|
|
One can control the name of the histograms file with the command:
|
|
/testem/histo/setFileName name (default testem3.aida)
|
|
|
|
Note that, by default, histograms are disabled. To activate them, uncomment
|
|
the flag G4ANALYSIS_USE in GNUmakefile.
|
|
|
|
|
|
8- Using histograms
|
|
-------------------
|
|
|
|
By default the histograms are not activated. To activate histograms
|
|
the environment variable G4ANALYSIS_USE should be defined. For instance
|
|
uncomment the flag G4ANALYSIS_USE in GNUmakefile.
|
|
|
|
To use histograms any of implementations of AIDA interfaces should
|
|
be available (see http://aida.freehep.org).
|
|
|
|
A package including AIDA and extended interfaces also using Python
|
|
is PI, available from: http://cern.ch/pi .
|
|
|
|
Once installed PI or PI-Lite in a specified local area $MYPY, it is
|
|
required to add the installation path to $PATH, i.e. for example,
|
|
for release 1.2.1 of PI:
|
|
|
|
setenv PATH ${PATH}:$MYPI/1.2.1/app/releases/PI/PI_1_2_1/rh73_gcc32/bin
|
|
|
|
CERN users can use the PATH to the LCG area on AFS.
|
|
|
|
Before compilation of the example it is optimal to clean up old
|
|
files:
|
|
|
|
gmake histclean
|
|
gmake
|
|
|
|
Before running the example the command should be issued:
|
|
|
|
eval `aida-config --runtime csh`
|
|
|
|
It is possible to choose the format of the output file with
|
|
histograms using UI command:
|
|
|
|
/testem/histo/setFileType type
|
|
|
|
The following types are available: hbook, root, xml.
|