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     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                            GFLASHa Example
                            ---------------

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 G4FastSimulationManager Process
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 see also: csi.mac

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 :

   "/analysys/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.
