To generate  collisions at a given energy and write result to stdout so
that they can be an input to the primary file to Epics. (file name should
start with +).  Also you can generate a kind of trace files to visualize
particle tracks at each collision.  (Use geomview).

If you use an interaction model other than dpmjet, 
you may directly go to the section of how to prepare the
param file.  For dpmjet, you have to read the next section.

1)  preparation of files for dpmjet.
The standard files for dpmjet are organized so that the
maximum lab energy is 4x10^14 eV. This is not enough for
,say, generating collisions at LHC energies.  Therefore, 
we have to prepare appropriated files at such a high 
energy.

We distingush  projectile and target for the collision.
Collision generation is performed at the rest system of
the target and the resultant particle information is
obtained in the original system.  (Say, CMS where
the target is moving).  

Modify dpmjet.inp as follows:
A) nucleon or nucleus case
* projectile / target
*...+....1....+....2....+....3....
PROJPAR        2          1         give mass # and charge
TARPAR         14         7           //
*
* energy of interaction
*...+....1....+....2....+....3....+.
ENERGY       21480.                 give lab energy/n  in GeV.

B)  hadron (pi, K) case
  
*...+....1....+....2....+....3....                                ...7....
PROJPAR                                                               PION+  
TARPAR         14         7          

(for Kaon,  give KAON+ etc).    hadron cannot be a target.

2) Read param file and give parameters.
    px,py,pz is momentum / n in GeV.
The energy in dpmjet.inp may be known as equivalent lab. energy /n.
when you run the program.  Then, give ( that value +epsilon) in
dpmjet.inp

3) ./make.csh to compile
4) ./Gencol...  < param > +somefile


