1. Phase Space tracks
Mixing
It is often desirable to be able to add tracks generated by the user, according
to certain kinematic parameters, to the events produced with some event generator.
This process can be characterized as "MC embedding", whereby both the underlying
event and the additional track come from Monte Carlo.
This can be done in a number of ways. There is,
however, a quick solution that does not require writing additional Geant
code and which instead uses the existing STAF/GSTAR facilities for
mixing "process" and "background" events:
gfile p event_generator_file
gfile b phasespace_track_file
gback 0 0 -1 0 0
trig
...
trig
* as many triggers as needed
where both files are pre-generated by the user. The only problem here is
that it's necessary to guarantee that the positions of the vertices of
individual events in both files should be the same. This is done by running a
short shell script, accompanied by two simple KUMAC files as listed below.
Install
Run
2. Decays --- UNDER CONSTRUCTION! ---
Mixing
One may also wish to study decays of certain particles
in the context of events coming from an event generator.
There appears to be two approaches here:
- Inhibit the decay of that type of particle in the event
generator and in GEANT. This may be desirable in case of many
decay modes for the particle (GEANT only allows 6 decay modes
whereas particles like D0 have many times more). Then, extract
those particles and decay them "by hand" into the decay channel
being studied, thus enhancing the statistics. The resulting file,
containing the decay products propagated in the GEANT detector
model, can then be merged with the original event file and
analyzed.
-
Generate the desired particles (e.g. J/psi) externally,
according to a certain parametrization of phase space,
or using a different event generator. Decay them "by hand"
into the decay channel being studied, then follow the rest
of the logic described above.
Similarly to the process described above, we prepare a file
gfile p event_generator_file
gfile b phasespace_track_file
gback 0 0 -1 0 0
trig
...
trig
* as many triggers as needed
where both files are pre-generated by the user. The only problem here is
that it's necessary to guarantee that the positions of the vertices of
individual events in both files should be the same. This is done by running a
short shell script, accompanied by two simple KUMAC files as listed below.
Install
Run
|