About

Evd is a geometry and event display built using the EVE Environment¹. It loads GDML geometries and ROOT MC truth outputs from both Geant4 Validation App and Celeritas (RootStepWriter) to draw simulated events within the geometry.

Dependencies

• ROOT

Build

$ mkdir build
$ cd build
$ cmake ..
$ make

Run

$ ./evd geometry.gdml [simulation.root] [flags]

Input files and flags

• geometry.gdml: Load the gdml geometry. This is the only mandatory input.
• simulation.root: Load the simulation run. Compatible with utils/geant4-validation-app and celeritas::RootStepWriter.
• -vis [vis_level]: Set the visualization level of the gdml. Higher values = more details. Default value is 1.
• -noworld: Hide world volme.
• -e [event_id]: Event number to be displayed. If negative, all events are drawn. Default: 0.
• -s: Show step points.
• -cms: For cms2018.gdml only. Load the CMS geometry without the surrounding building and set the LHC beamline to invisible.

Interface

Keyboard / mouse commands

• Mouse left click: Rotate view.
• cmd + mouse left click: Pan view.
• Mouse/trackpad scroll or j/k: Zoom.
• w/e/r/t: Toggle between different views.
• shift/ctrl: Increase / decrease action rate. E.g. shift + j/k zooms in/out at larger steps. Valid for mouse actions as well.

Event track list

Particle tracks are shown in the event directory and named using the convention [event_id]_[track_id]_[particle_name_or_pdg]. PDG is only used if it is not mapped to a name in MCTruthViewerInterface.

Development

• To read events from different ROOT files, add a new concrete implementation of MCTruthViewerInterface and call it in EventViewer.
• TEve issue: on macOS, the x close button of the evd window causes ROOT to crash. Typing .q in the terminal or using the Quit ROOT option in the Browser menu avoids that.

Footnotes

1. M. Tadel. Overview of EVE – the event visualization environment of ROOT. 2010 J. Phys.: Conf. Ser. 219 042055. ↩