The code
PHG4mRICHDetector.cc  PHG4mRICHSteppingAction.cc  PHG4mRICHSubsystem.cc
PHG4mRICHDetector.h   PHG4mRICHSteppingAction.h   PHG4mRICHSubsystem.h

PHG4mRICHDetector.* contains the detector description.

It bleongs in the dir "coresoftware/simulation/g4simulation/g4detectors/"
and must be compiled together to produce "libg4detectors.so"

mRICH has a macro "G4_mRICH.C" that sets up mRICH.
The mRICH is called by the overall setup macro "G4Setup_EICDetector.C"
The setup macro gets called by the main maco "Fun4All_G4_EICDetector.C"
The main macro has flags that allows enabling and disabling any detector