HOW TO USE PEP-N GEANT SIMULATION
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The PEP-N detector is simulated using GEANT3. In order to
start using the simulation you need to have a simple idea of
how geant works.

There are some standard routines that the user can modify to
simulate the experiment. The more important are:
1) GUKINE:   defines the kinematics of the reactions to be
	     simulated. Notice that once you have generated
	     the reaction and stored it, geant will simulate
	     all the physics processes automatically (eg.
	     scattering, decay, generation of secondary
             particles,...).
2) UGEOM:    defines the materials to be used and the geometry
	     of the detectors.
3) GUSTEP:   called at each step of the propagation of the
	     particle. Can be used to follow the propagation
             the particles.

The simulation can be used in two ways:
1) BATCH MODE:
   Generates N events and fills the n-tuple.
   You need to compile using "make" in the appropriate directory.
   To run the executable you are asked from the program to set
   some cards. Here is one example:

	KINE 3 .35     ! reaction kind 3 (6 pions) with electron
		       ! energy of .35GeV
	TRIG 1000      ! production of 1000 events
	STOP	       ! end of cards

2) INTERACTIVE MODE:
   plots of the detector can be printed out as well as the particle
   propagation and the reactions inside the detectors.
   To use the simulation interactively you should write into the
   "Makefile" the line:
	PROGRAM = Interactive
   before compiling.
   To run the executable give just the card:
	STOP
   After that you can use the geant commands. For example you can
   use "cards3.kumac":

        NEXT				! clear screen
	DCUT PEP2 2 0. 7. 10. .06 .06	! cutted view of the apparatus
					! (PEP2) along axis 2 (y)
	KINE 3 .35			! reac. kind 3 (as before)
	TRIG				! start new event
	DXYZ				! draw tracks

For more information refer to GEANT manual:
http://wwwinfo.cern.ch/asdoc/geant_html3/geantall.html  (HTML version)

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M.Negrini 14/02/01 - negrini@fe.infn.it