General

  The CMS simulation system includes the following phases:  

  CMKIN -- standard CMS physics generation package
  CMGEO -- creates GEANT geometry RZ-file from titles 
  CMSIM -- the CMS GEANT simulation including detector and infra
            structure in the experimental hall (low-beta quads etc)
  CMRAW -- CMS raw data simulation, performs event pile-up and hits
            digitisation
  CMREC -- the CMS event reconstruction
  CMANA -- the CMS event analysis

Each program phase can be run independently provided the output file from the previous phase is available. The data flow diagram is presented in Fig.1.1. It uses GEANT and support from the CERN library. It has the following features:

• The geometry, materials, rotation matrices, magnetic field etc. constants are stored on Zebra tz title files. These files are maintained by CVS and they reside on the titl module.
• All communication among modules is done with GEANT ZEBRA structures.

The result of this is an RZ-file which is used for simulation (CMSIM/CMRAW) or reconstruction (CMREC). CMSIM fills the KINE structure, does TRAcKing, and makes HITs. CMRAW performs pile-up of events from a given number of bunches and makes Digitisations. The structures are output using the FZ packages for later analysis (in CMREC) or in combinations with trigger events for simulation of pile-up effects. The following sections give specific details concerning the different parts of this system (CMGEO, CMSIM and CMREC).

  
Figure 1.1: The CMS simulation program and data flow diagram.

The detailed program flow charts are presented in the Reference Manual.