Example RE06

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 for a run
2. Changing calorimeter geometries without re-building a world volume
3. Defining geometrical regions and setting production thresholds for each region
4. Demonstrating the use of primitive scorer and filter classes without implementing sensitive detector class
5. Demonstrating the use of parallel scoring geometry and associating parallel world scoring process

6. Measuring the timing spent for each region, both for all particle types and for e+/e-

   It was moved in extended examples from novice/N07 with removal of novice examples.

   Note: Since this example utilizes its own RE06SteppingVerbose for the timing measurement, the user cannot get the ordinary verbosity with /tracking/verbose.

Utilizing a concrete run class derived from G4Run base class for accumulating physics quantities for 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, RE06Run is the class derived from G4Run. In the method RE06Run::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, RE06RunAction is the class which instantiating RE06Run class object. In RE06RunAction::EndOfRunAction(const G4Run*) method, RE06Run object is analized to output the run summary.

It should be noted that some information about generated secondaries are collected in RE06StackinAction instead of sensitive detector class. RE06StackingAction::ClassifyNewTrack(const G4Track*) method is used not for classifying tracks sent to the stack, but for accessing to all secondaries generated in an event.

Changing calorimeter geometries without re-building a world volume

In RE06DetectorConstruction, 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 RE06DetectorConstruction::SetNumberOfLayers(G4int) for changing the number of parameterized volumes, and also RE06DetectorConstruction::SetSerialGeometry(G4bool) for changing the position of placed volumes.

Defining geometrical regions and 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 RE06DetectorConstruction::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 RE06PhysicsList::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.

Demonstrating the use of primitive scorer and filter classes without implementing sensitive detector class

In RE06DetectorConstruction::SetupDetector() method, concrete classes G4PSEnergyDeposit, G4PSNofSecondary, G4PSTrackLength, G4PSNofStep and G4PSMinKinEAtGeneration, all of thich are derivalable of G4VPrimitiveScorer, are used to define the sensitivity of the calorimeter. All of them are registered to G4MultiFunctionalDetector and this detector object is set to the logical volume. G4SDParticleFilter is used to define the particle type(s) to be scored.

In RE06Run::RecordEvent() method, the way of retreiving G4THitsMap from each primitive scorer via G4HCofThisEvent is demonstrated. In RE06RunAction::EndOfRunAction(), Run is summarized with data kept in RE06Run class object.

Demonstrating the use of parallel scoring geometry and associating parallel world scoring process

In RE06PhysicsList::ConstructGeneral(), G4ParallelWorldScoringProcess is assigned to all the particle types. This process invokes sensitive detectors (and scorers) defined in the parallel world "ParallelScoringWorld", the name of the parallel world which is defined in main() (exampleRE06.cc) as an argument of RE06ParallelWorld constructor.

As implemented in RE06ParallelWorld::SetupGeometry(), the world volume of the parallel world is obtained by GetWorld() method as a clone copy of the world volume of the mass geometry. The user should not create the world volume.

RE06ParallelWorld defines three cylindrical volumes, each of them is located at the same position as three sandwitch calorimeters defined in the mass geometry (RE06DetectorConstruction). Each cylinder is replicated in Rho to define 20 layers, and scores the same quantities as the mass geometry. These three cylinders are relocated accordingly when the mass geometry is modified by RE06DetectorConstruction::SetSerialGeometry().

Measuring the timing spent for each region, both for all particle types and for e+/e-

RE06SteppingVerbose class has two G4SliceTimer class objects for each detector region. One G4SliceTimer is measuring the time spent by a step in a region for all types of particles, and another is measuring for e+/e- only.

RE06SteppingVerbose::InitializeTimers() is invoked by RE06RunAction:: BeginOfRunAction(), and checks the number of regions appear in the geometry and instantiates the necessary number of timers. Thus, this RE06SteppingVerbose class can be used for any kind of geometry the user defines without any modification. Given G4VSteppingVerbose is not invoked if the verbosity of G4SteppingManager is 0, this verbosity is set to 1.

NewStep() and StepInfo() are the methods defined in G4VSteppingVerbose base class, and they are invoked at the beginning and the end of every step, respectively, from G4SteppingManager. Thus, these methods are utilized in RE06SteppingVerbose to start/resume and pause the timer.

RE06SteppingVerbose::Report() method is used by RE06RunAction:: EndOfRunAction() to get the timing measured.

Macro files

• exampleRE06.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.

UI commands defined in this example

Command /RE06/setAbsMat
Guidance :
Select Material of the Absorber.

Parameter : choice
 Parameter type  : s
 Omittable       : False
 Candidates      : Aluminium liquidArgon Lead Water Scintillator Air Galactic 



Command /RE06/setGapMat
Guidance :
Select Material of the Gap.

Parameter : choice
 Parameter type  : s
 Omittable       : False
 Candidates      : Aluminium liquidArgon Lead Water Scintillator Air Galactic 



Command /RE06/numberOfLayers
Guidance :
Set number of layers.
 Range of parameters : nl>0

Parameter : nl
 Parameter type  : i
 Omittable       : False



Command /RE06/serialGeometry
Guidance :
Select calorimeters to be placed in serial or parallel.

Parameter : serialize
 Parameter type  : b
 Omittable       : False