Dear rooters,

let me ask you two question on PYTHIA6 events generation:

  1. I have problems with running of p(beam)+p (fixed target) interaction with low beam momenta:
    I PYTHIA will be initialized for p on p fixed target
    I at 10.629 GeV/c lab-momentum
    I corresponding to 4.667 GeV center-of-mass energy
    Error: too low CM energy, 4.667 GeV for event generation.

I use root 4.03/02 and pythia6.319.

I read on root posts dated by 1999 (or 2000) that pythia6 has some bugs while version 5 does not… Is it still the case?

  1. Second thing is that current root make EGPythia6 interface assuming
    while in the example which builds the library this common block is called:

this make not possible to use Pythia6 (however the fix is obvious :slight_smile:. This is just FYI).

Any help on question 1) will be appreciated. Thanks, Dmitry


I’ve tried it with Pythia5 and Pythia6, with a simple Fortran program to initialize the event generator – therefore, no Root involved.

There seems to be a cut-off CMS energy of 10GeV. This has nothing to do with Root.

Perhaps you might want to use other Monte Carlo programs for your work. I don’t know the workings of Pythia but I guess it is designed for using high (relativistic) collisions, and 5GeV for protons might be in the frontier.

Thank you for your answer,
sorry for some delay in my reply - I was out of city.