FPFDisplay

FPFDisplay is an interactive event display for the output of FPFSim based on the ROOT TEve framework. It provides a tool to visualize the FPF geometry as well as simulated events in both 3D and 2D projections.

How to build

• Source the CERN LCG software stack from cvmfs: source setup_cvmfs.sh.
• Create a new directory to contain the executables (assume the path is /path/to/build).
• Assume the path to the source code is /path/to/source.
• To compile, you need to go to the build directory cd /path/to/build.
• And then cmake -S /path/to/source -B /path/to/build.
• Finally, make.

After a successful build, the FPFDisplay executable will be available in build/.

Running

You can run the event display with the following command:

./FPFDisplay <geometry.gdml> [datafile.root]

• <geometry.gdml>
  GDML file exported from FPFSim using the /det/saveGdml macro command.

• [datafile.root] (optional)
  FPFSim output ROOT file containing saved trajectory information.

  /tracking/storeTrajectory 1
  /histo/saveTrack true
  

  If provided, FPFDisplay will overlay tracks from this file on the geometry.

Navigation

You can navigate the display in the following ways:

• You can use the mouse to rotate or zoom the geometry.
• You can use the arrow keys to pan the geometry, recentering the camera.
• If you click on a track, it will get highligthed across the views.
• You can move across events using the "Backward" and "Forward" buttons in the "Event control" tab.

Using VNC on lxplus

If running on lxplus, it is better to do it through a VNC server. An helper script lxplus_vnc_setup.sh is provided to start one according to CERN guidelines. It determines the port and the command you need to run, given your user id to avoid clashes with other people.

Follow the on-screen instructions, for example:

1. Run lxplus_vnc_setup.sh once on lxplus.
2. Then, in your local terminal, set up an SSH tunnel (port will be shown by the script):

   ssh -L <VNC_PORT>:localhost:<VNC_PORT> <username>@lxplus.cern.ch
   

3. Launch your VNC client and connect to localhost:<VNC_PORT>.
4. The VNC sever automatically disconnects as you log off.