= format of the file : beam1.dat and beam2.dat = 

 data formatted in ASCII : 


 1. The energy of the Macroparticle in GeV
 2. x position at the intersection plane (microns)
 3. y position at the intersection plane (microns)
 4. z position within the bunch in micron
 5. the angle x' i.e. the relativistic beta_x = vx/c (microradians)
 6. the angle y' i.e. the relativistic beta_y = vy/c (microradians)

''From the version 1.0.0 on, the 3 components of the polarization vector have been added, but uniquely in the case where the keyword '''bmt_precession=1''' is switched on'' : 

 7. degre of polarization in the x transverse direction 
 8. degre of polarization in the y transverse direction 
 9. degre of polarization in the longitudinal direction (along the trajectory)