Expand vertex file reader to parse particle type and momenta

[gipert]

This would make remage support a wide range of external event generators through RMGVertexFromFile. The implementation would need to be a bit more complex than what it is right now, since the input file structure is "jagged". I guess a lot of this is already implemented in RMGGrabmayrGCReader.

Actually, "vertex" in RMGVertexFromFile was originally intended to refer only to vertex position. We should maybe implement all of this as an additional generator.

[tdixon97]

I dont think the table necessarily needs to be jagged, we just need to include the evtid (and time?).

I think the option to read kinematics as a table like:

xpos,ypos,zpos, px,py,pz, particle, time, evtid (all as Arrays)

would be useful and only a relatively small modification of the current code. It might be nice to read LH5 not h5 files however.

[gipert]

Yes, I meant that the number of particles originating at the vertex is not fixed.

[tdixon97]

Started prototyping a vertex generator here: pyvertexgen.
It should be easy to write to a HDF5 file and start testing this.

[ManuelHu]

yes, but you will need to write it in geant4's ugly HDF5 ntuple format (are there even docs for it?). An LH5 reader would be very hard to add to the geant4 "analysis framework".

[tdixon97]

I don't know much about it, maybe we can write a simple converter like is done for the output?

[tdixon97]

I had a look and I am not sure how to create the Geant4 Ntuple inputs. Maybe we should go for something like the RMGGrabmayrGCReader as @gipert suggested and forget the geant4 input format.

[gipert]

• we want to use LH5
• no support for positions and momenta in the same table
• positions is simple flat table (x, y, z)
• momenta is still a flat table. Columns: evtid, g4_pid, px, py, pz