= format of the file : secondaries.dat = 

 data formatted in ASCII : 


 1. energy of the particle (GeV), E1. Positive for electron, negative for positron.
 2. normalized velocity in x direction (vx/c = px/E) 
 3. normalized velocity in y direction (vy/c = py/E)
 4. normalized velocity in z direction (vz/c = pz/E)
 5. process label : 0 = Breit-Wheeler ; 1 = Bethe-Heitler ; 2 = Landau-Lifschitz
 6. a label, individuating each pair
 
Remark : the x,y,z positions (nanometers) have been suppressed from the 0.7.2-b version on.