Events kinematics generation - CMKIN

  The CMS detector simulation package follows the principle that the interface between the physics generators and GEANT kinematics goes via intermediate files which have a well defined format: column-wise ntuples [8]   in HEPEVT   standard structure. There are the following benefits:
files can be read in any system with CERN library installed
in GUKINE only one interface code (HEPEVT KINE) is needed
events can be analysed with PAW, independent of GEANT
The source code of this package is in KINE module.

The HEPEVT standard is explained in reference [9]. The event structure is in the common block /HEPEVT/ shown below containing information on

      PARAMETER (NMXHEP=2000)
      COMMON/HEPEVT/NEVHEP,NHEP,ISTHEP(NMXHEP),IDHEP(NMXHEP),
     &JMOHEP(2,NMXHEP),JDAHEP(2,NMXHEP),PHEP(5,NMXHEP),VHEP(4,NMXHEP)

particle status (ISTHEP), particle identifiers (IDHEP), mother-daughter interrelations (JMOHEP, JDAHEP), particle 4-momenta (PHEP) and vertices (VHEP).

Conversion routine to HEPEVT is available in PYTHIA. The STDHEP package [11] is used to interface other physics generators internal event structure with HEPEVT. See note below in section 1.4.4 concerning HEPEVT and LUHEPC routine.

Presently the generators available in the CMKIN framework are PYTHIA, ISAJET and HERWIG.    

The content of the HEPEVT common can be optionally saved with the simulated event (to VERT structure user words) to be used in later analyses. This option is activated by setting the last parameter of the KINE card to 1. See section 10.2.5 of the Reference Manual for how to retrieve this information by the routine UTFKINE.