How to get  Geant volume ID of the CTB (any other detectors)?

- go to an empty directory
- select you star enviromnet (stardev/new/pro)
- run:
staf -w 0
detp geometry year2001
make geometry
gprint volume

How to input generator ntuples with events into gstar?

All types of  input files are read in the same maner:

make gstar
user/input u file_name

The file type will be identified by its extension, in the ntuple case:

user/input u evgen.1.nt

Where to find information about hits produced in the particular detector?

Any system XXXX produces hits XXXH. System name is taken as the first 4
letters of its geo module. Detectors are defined in HITS operators.

Is it nessesary to modify g2tmain.g and g2rmain.g to run st_geant_maker?

No. g2t/g2r mains are test version (used in staf only) st_geant_maker
does not use them