Dear FLUKA developers,

For the sake of my ZDC studies, I am very interested in obtaining the description of the spectators in HI collisions provided by DPMJET + FLUKA. My goal would be to generate Heavy Ion collisions and then propagate to the ZDC all the spectator neutrons ( discarding spectator protons and fragments, since the magnets in the LHC would wipe most of them off ) in our Geant4 simulations.

In order to do this, I can imagine two different solutions:

  1. Use DPMJET within FLUKA, setting up a simulation in collider mode w/ HI and trying to dump all the produced particles outcoming from the collision point (e.g. using a small cylinder built around it as a dump surface). Then feed the output to our Geant4 simulation.
  2. Use DPMJET + FLUKA libraries as a standalone generator - to produce output files to be fed to our Geant4 simulation (or directly embedding the generator into the simulation).

From a practical point of view, 2) would be preferable, but I fear I have not enough experience w/ FORTRAN to establish the bundle. May I ask you if you know whether such a DPMJET+FLUKA package exists already? I found something on the web done for EIC, from ~ 10 years ago, but it was w/an old DPMJET version. I successfully compiled it vs the latest FLUKA release, but I did not manage to run it successfully (all the examples were crashing w/ a core dump).
If this kind of package does not exist and trying to build it would be too time expensive, may I ask you if solution 1) sounds reasonable to you?

Thanks in advance for your help,
Best regards,

ciao @rlongo
personally I’m not aware of an operational Geant4 interface with DPMJET.
For solution 1, I suggest to produce a dump file before the TAS entrance position, scoring particle info at a vacuum region boundary by means of the BXDRAW entry of the src/user/mgdraw.f routine, to be customized (removing irrelevant unformatted printout) and activated by the USERDUMP card. I understand that you are going to consider only neutrons that can make it through the beam mechanical aperture up to the TAN.
Morever, in addition to the DPMJET source term corresponding to nuclear inelastic collisions, you should take a look also at ElectroMagnetic DIssociation products (i.e. neutrons), which you can also obtain by means of the SPECSOUR card you would already use for the above (better as an independent process in a separate simulation, to be properly weighted according to the respective cross section, rather than as a competing process in the same simulation).
Best, Francesco