Event Display using Druid

Estimated reading time: 2 minutes


  • Druid is used to visualize event information and detector geometry.
  • We can better understand event and reconstruction algorithm performance.
  • With the gdml file, detector geometry could be visualized to simulation level.

Event Display

  • Firstly, you need to download the file named with *.slcio and add it to the directory geometryfile in the Druid.
  • Secondly, using command “Druid *.slcio”, the following window will display:
  • From left side, finding the “Eve,Files,Options” three buttons, and choosing “Options”.
  • Showing different event by operating “Event Navigation”.
  • For more interesting event graph, setting the energy cut and other variables.
  • For more information collecting in sub-detector, clicking “Eve” and moving to left interface. You can click whatever you like.
  • When you point to one line in graph with mouse, there will show the information about the line left by particle.

Geometry Display

  • The following picture is my operation, you can follow.
  • After operation as showed above, we can get following window.


  • Command+W: change the graph to line structure
  • Command+E: change the background
  • Command+R: back to original graph

Dynamical Graph

  • Double click “Edit Object”. From left side, finding the “Eve, Files, Options” three buttons, and choosing “Eve”. You will see the following window:
  • We can see four buttons “Style Guides Clipping Extras” on a row in left, select “Extras” button and click start,you will see dynamical detector’s geometry.
  • You can turn the values showed on the left side to control the concrete display.


  • Flexible parameter managing beside the steering file

    Druid   # print the instruction for the input format
  • Separate geometry & data display

    Druid *.slcio    # display the first event in given slcio file
    Druid *.gdml(*.xml or *.root)  # display detector geometry
  • Together with other arguments:

    Druid *.slcio $EventNumber   # given event in giver slcio file
    Druid *.slcio *.gdml(*.xml)  # first event & geometry
    Druid *.slcio *.gdml(*.xml) $EventNumber
    Druid *.slcio *.gdml(*.xml) $RunNumber $EventNumber

If you have any problem, contact zhuyf@ihep.ac.cn. You have to install LCIO and ROOT before installing Druid. I had installed Druid on macbook, macos version is 10.13.1, LCIO version is v02-04-03, ROOT version is root_v5.34.36.macosx64-10.11-clang70.tar. Have a good time.