$Id: README,v 1.2 2003/04/09 23:20:58 asaim Exp $
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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ExampleN07
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This example simulates three simplified sandwitch calorimeters.
The main features demonstrated in this example are :
1. Utilizing a concrete run class derived from G4Run base class for
accumulating physics quantities and hits as a run
2. Changing calorimeter geometries without re-building a world volume
3. Changing materials used in parameterized volumes
4. Instantiating more than one sensitive detectors with different
module names from one concrete sensitive detector class
5. Defining geometrical regions ans setting production thresholds
for each region
1- Utilizing a concrete run class derived from G4Run base class for
accumulating physics quantities and hits as a run
G4Run is a class the user can inherit and create his/her own concrete
class for accumulating information useful to him/her. It has a virtual
method RecordEvent(const G4Event*), which will be invoked by G4RunManager
at the end of processing each event. By implemeting this method in the
user'r concrete run class, he/she can store information associating with
G4Event class itself and hits collections attached with G4Event. In this
example, ExN07Run is the class derived from G4Run. In the method
ExN07Run::RecordEvent(const G4Event*), in addition to counting the
number of events, all hits collections are accessed to accumulate
energy depositions, step lengths and number of steps.
In case the user create his/her own run class, an object of this class
must be instantiated in the method GenerateRun() of his/her concrete
class derived from G4UserRunAction base class. The pointer to this run
object must be returned by this method. In this example, ExN07RunAction
is the class which instantiating ExN07Run class object. In
ExN07RunAction::EndOfRunAction(const G4Run*) method, ExN07Run object
is analized to output the run summary.
It should be noted that some information about generated secondaries
are collected in ExN07StackinAction instead of sensitive detector class.
ExN07StackingAction::ClassifyNewTrack(const G4Track*) method is used
not for classifying tracks sent to the stack, but for accessing to all
secondaries generated in an event.
2- Changing calorimeter geometries without re-building a world volume
In ExN07DetectorConstruction, all solids, logical and physical volumes
are constructed only once at the first invocation of Constuct() method.
Positions and number of slices are changed not by re-constructing another
objects but by modifying data members of already existing objects as
it is implemented in ExN07DetectorConstruction::SetNumberOfLayers(G4int)
for changing the number of parameterized volumes, and also
ExN07DetectorConstruction::SetSerialGeometry(G4bool) for changing the
position of placed volumes.
3- Changing materials used in parameterized volumes
Materials of absorber and sensitive gap in calorimeters are defined by
ExN07GapParameterisation::ComputeMaterial(const G4int,G4VPhysicalVolume*),
as well as positions of each layer to be defined by
ExN07GapParameterisation::ComputeTransformation(const G4int,
G4VPhysicalVolume*).
4- Instantiating more than one sensitive detectors with different
module names from one concrete sensitive detector class
ExN07CalorimeterSD is constructed three times with deferent module names
in ExN07DetectorConstruction::Construct(). In addition, each detector
create two hits collections of ExN07CalorHit. Thus, in total, six hits
collections of same type are created for each event. To access to each
of these collections in ExN07EventAction, both module name and collection
name are combinedly used.
5- Defining geometrical regions ans setting production thresholds
for each region
Setting production thresholds (so-called production cuts) to individual
region of a detector geometry is the new feature provided by Geant4 5.1
release. This feature is also called as "Cuts per region".
Please note that this new feature is supporsed to be used only by the
users,
a) who is simulating most complex geometry such as an LHC detector,
b) and who has enough experience of simulating EM showers in matter.
We strongly recommend to compare the simulated results of this new
feature with the results of the same geometry but having uniform
production thresholds. Setting completely different cut values for
individual region may break the coherent and comprehensive accuracy
of the simulation. Thus such cut values should be carefully optimized
by the user with comparison with results of uniform cuts.
In ExN07DetectorConstruction::Construct(), Three objects of G4Region
class are instantiated and set to the logical volumes of each of three
calorimeter modules. Also, these individual logical volumes are
registered as "root logical volume" so that all daghter volumes in
these logical volumes are also affected by the corresponding regions.
In ExN07PhysicsList::SetCuts(), in addition to set the default threshold
values for the world volume, three threshold values are set to three
calorimeter regions respectively. By setting production thresholds to
a region, gamma, electron or positron will not be generated as a
secondary if its range is shorter than the production threshold of that
particular region. Please note that some EM processes still generate
such secondary below threshold.
6- Macro files
exampleN07.in
To be used for batch mode. The reference output file is made by this
macro file.
sample.mac
To be used for interactive mode. Issue "/control/execute sample.mac"
when "Idle>" prompt appears.
vis.mac
Setting visualization parameters. This macro file will be called
automatically when interactive execution starts.
7- UI commands defined in this example
Command /N07/setAbsMat
Guidance :
Select Material of the Absorber.
Parameter : choice
Parameter type : s
Omittable : False
Candidates : Aluminium liquidArgon Lead Water Scintillator Air Galactic
Command /N07/setGapMat
Guidance :
Select Material of the Gap.
Parameter : choice
Parameter type : s
Omittable : False
Candidates : Aluminium liquidArgon Lead Water Scintillator Air Galactic
Command /N07/numberOfLayers
Guidance :
Set number of layers.
Range of parameters : nl>0
Parameter : nl
Parameter type : i
Omittable : False
Command /N07/serialGeometry
Guidance :
Select calorimeters to be placed in serial or parallel.
Parameter : serialize
Parameter type : b
Omittable : False
Command /N07/verbose
Guidance :
Set verbosity of each event.
Range of parameters : vl>=0 && vl<10
Parameter : vl
Parameter type : i
Omittable : True
Default value : taken from the current value
Gabriele Cosmo