@@ -121,16 +121,19 @@ npsim --runType run --enableG4GPS \
This will run geant4 using the General Particle Source (GPS) tool.
The output will be a root file containing the generated events and GEM tracker hits.
Look at [gps.mac](https://eicweb.phy.anl.gov/EIC/tutorials/ip6_tutorial_1/-/blob/master/gps.mac).
See the [GPS Documentation](http://www.fe.infn.it/u/paterno/Geant4_tutorial/slides_further/GPS/GPS.pdf) for more information.
Refer to the [GPS Documentation](http://www.fe.infn.it/u/paterno/Geant4_tutorial/slides_further/GPS/GPS.pdf) for more setup possibilities.
## Using detector description in analysis
### Preface: data model
First, the data model used by `npsim is described here
https://eic.phy.anl.gov/eicd/
First, the geant4 output data model used by `npsim` is [described in a single yaml file](https://eicweb.phy.anl.gov/EIC/NPDet/-/blob/master/src/dd4pod/dd4hep.yaml).
Note that this is purposefully factorized from the larger EIC data model, `eicd`, which is used
fmt::print(" \"layer\" index is {}.\n",layer_index);
```
See [BitFieldCoder documentation](https://dd4hep.web.cern.ch/dd4hep/reference/classdd4hep_1_1DDSegmentation_1_1BitFieldCoder.html) documentation for more details.
For more information, see the [BitFieldCoder documentation](https://dd4hep.web.cern.ch/dd4hep/reference/classdd4hep_1_1DDSegmentation_1_1BitFieldCoder.html).