# Event Display using Druid

## Introduction

• 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.

### Shortcut

• 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.

## Usage

• 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.