geant4

This example demonstrating usage 'gflash' shower parameterisation in homogeneous calorimeter. Compare with glash1,2,3 the histograms have been added in this example. This makes it possible to use this example for fine tuning of GFLASH parameters.

This example allows to compare the shower profiles from fast simulation with full simulation by histograming of longitudinal (slice) and radial profiles with different "binning". Then GFlash fast simulation can be "tuned" via modification of the model parameters file:

include/ExGflashHomoShowerTuning.hh

in this example.

Physics List

The Physics list factory is used in this example. The default physics list is FTFP_BERT which has EM opt0. Additionally, the G4FastSimulationPhysics physics constructor was created to insert the G4FastSimulationManagerProcess that is making the interface between the fast simulation and the tracking.

The default PHYSICS list may be changed via setting of the PHYSLIST environment variable, e.g.:

export PHYSLIST=FTFP_BERT_EMZ # for FTFP_BERT with opt 4 EM physics

Geometry Definition

In this example the calorimeter is a simple cube, which consists of 10 x 10 crystals of PbWO4 (CMS like).

Geometry, sensitive detector and hits are defined respectively in:

ExGflashDetectorConstruction
ExGflashSensitiveDetector
ExGflashHit

The geometry can be redefined in PreInit state via commands:

/exgflash/det/setNbCrys ncrys
/exgflash/det/setCrysWidth width [cm]
/exgflash/det/setCrysLength length [cm]

Materials can be chosen from Nist Materials: G4_Air G4_WATER ... e.g.:

/exgflash/det/setMat G4_PbWO4

Hit Scoring

The virtual cylinder sliced longitudinally (slice) and radially (ring) was used. The size of the slices and rings are expressed in radiation length units and Moliere radius (Rm) units for rings. The number of division and division size in fraction of units and can be changed. e.g.:

/exgflash/det/setLbin 20   1.    ---> 20 slices of 1. radl
/exgflash/det/setRbin  5   0.25  --->  5 rings of 0.25 Rm
     (MaxBin = 500 in both directions)

In ExGflashEventAction class the arrays corresponded slices and rings was created and filled with hists information. These arrays where use to fill histograms later.

Visualization

The Visualization Manager is set in the main(). The initialization of the drawing is done via the commands /vis/... in the macro vis.mac. To get visualization use:

/control/execute vis.mac

How to start ?

Execute ExGflasha in 'batch' mode from macro files

 % ./ExGflasha   test.mac

Execute ExGflasha in 'interactive mode' with visualization

 % ./ExGflasha
   ....
  Idle> type your commands
  ....
  Idle> exit

The GFLASH activated via:

/GFlash/flag 1

Histograms

ExGflasha produces several histograms: The histograms defined in ExGflashHistoManager class

Content of these histo:

h0 : energy deposit per event
h1 : the number of hits per event
h2 : the energy per hit ( in MeV )
p0 : longitudinal energy profile
p1 : radial energy profile
p2 : cumulated longitudinal energy profile
p3 : cumulated radial energy profile

To define the output file name with histograms, use the UI command :

/analysis/setFileName name

Macros

The macros to run in batch mode:

test.mac - default macro for example testing, it show how to use different application commands: redefine the histograms and profiles, change the geometry and material, etc
csi.mac - like test.mac but produce profiles in CsI Material
testLong.mac - make the runs with more statistics using default geometry and histograms setting, the material is G4_PbWO4
csiLong.mac - show how to run testLong.mac with different material (CsI)

Each macro executes two runs with fast simulation flag ON (the output file name is set to gflash01.root ) and OFF (the output file name is set to gflash00.root )

In addition, the ROOT macros cmpL.C, cmpR.C and cmpE.C file are provided, which can be used to draw superimposed full and fast histograms for radial and lateral profiles and also the normalized total energy deposition in calorimeter.

See also Category "parameterisations/gflash" documentation.