Juggler Documentation

Table of Contents

• Project Juggler
  • Overview
    • Components
    • Internal Units
    • Running Juggler
• Outline of tracking and vertexing
  • The ACTS way of tracking
    • Source Links and Measurements
    • Proto tracks
    • Initial Track parameters and Seeding
  • Vertexing

Project Juggler

Concurrent event processor for NP experiments, based on the Gaudi framework.

Dependencies:

• v5.x requires Gaudi v36+, ACTS v15.1+, DD4hep 1.17+, NPdet v1.0+ and eicd v1.1+
• v4.x requires Gaudi v36+, ACTS v13+, DD4hep 1.17+, NPdet v1.0+ and eicd v1.1+
• v3.6 requires Gaudi v36+, ACTS v13+, DD4hep 1.17+, NPdet v1.0.0 and eicd v0.9.0
• v3.5 requires Gaudi v36+, ACTS v13+, DD4hep 1.17+, NPdet v0.9.0, eicd v0.8.0
• v3.4 requires Gaudi v36+, ACTS v8.2+, DD4hep 1.17+, NPdet v0.9.0, eicd v0.8.0
• v3.0 requires Gaudi v35+, ACTS v8.1+, DD4hep 1.17+, NPdet v0.7.0 eicd v0.5.0
• v2.0 requires Gaudi v35+, ACTS v8.1+, DD4hep 1.17+ and eicd v0.2.0
• v1.8 requires Gaudi v33-34, ACTS 8.1+, DD4hep 1.16.1+ and eicd v0.2.0
• v1.5 requires Gaudi v33-34, ACTS 8.1 and DD4hep 1.16.1

Overview

Components

• Juggler Base
• Digitization Algorithms
• Hit Reconstruction Algorithms
• Tracking Algorithms
• PID Algorithms

Internal Units

The juggler internal units are (GeV, mm, ns, and radians).

Running Juggler

Here is an example for topside

./scripts/run_topside.py -i inputevents.hepmc -o output_events.root -n 10
../where_ever/../juggler/build/run gaudirun.py options/example_reconstruction.py

Outline of tracking and vertexing

The ACTS way of tracking

First, the geometry has to be constructed. Assuming this is already done, we describe the data processing.

Source Links and Measurements

Tracker Hit  +  Geometry --> Measurement
Hit CellID   +  Surface  --> Source Link

A SourceLinker is an algorithm that looks up the surface and maps it to the hit's cellID. Naturally the same algorithm outputs measurements which are also mapped to the hit and contain the position and sensor size information (via covariance matrix).

Proto tracks

Both track finding and fitting will use the information contained in the source links and measurements. Track finding produces proto tracks or groupings of hits. Each proto track is simply a std::vector<int> storing the index of the hits associated with a track seed.

Initial Track parameters and Seeding

A Kalman filter needs a starting point and those are the Initial Track Parameters. These can be determined many different ways. Conceptually the process of determining these parameters begins with track seeding.

Vertexing

WIP