FairShip is the software framework powering the SHiP (Search for Hidden Particles) experiment at CERN. It provides a complete physics simulation pipeline — from proton–target interactions through detector simulation, digitisation, track reconstruction, and analysis — all built on top of FairRoot, ROOT, and Geant4.Documentation Index
Fetch the complete documentation index at: https://mintlify.com/ShipSoft/FairShip/llms.txt
Use this file to discover all available pages before exploring further.
Introduction
Learn what FairShip is and how it fits into the SHiP experiment software stack.
Installation
Set up FairShip using pixi, CVMFS, or Docker in minutes.
Quickstart
Run your first simulation, reconstruction, and analysis chain end-to-end.
Simulation
Configure event generators, geometry, and run full Geant4 detector simulations.
Reconstruction
Digitise hits, run pattern recognition, and fit tracks with GenFit or ACTS.
Python Reference
API reference for all public Python modules shipped with FairShip.
The Simulation Pipeline
FairShip models the full SHiP experimental chain in three stages:Simulate
Generate events with Pythia6/8, EvtGen, GENIE, or a particle gun, then propagate particles through the full SHiP detector geometry using Geant4.
Reconstruct
Digitise raw MC hits and run track pattern recognition and vertex fitting to produce reconstructed physics objects.
Key Features
Multiple Event Generators
Pythia6, Pythia8, EvtGen, EventCalc, GENIE, and a configurable particle gun — all selectable at run time.
Full Geant4 Integration
Complete detector geometry including the muon shield, straw tube spectrometer, SND target, and veto systems.
HNL & Dark Photon Models
Built-in production and decay modelling for Heavy Neutral Leptons and dark photons with configurable mass and couplings.
Track Reconstruction
Pattern recognition with a Hough-transform algorithm and track fitting via GenFit, plus experimental ACTS support.
Reproducible Builds
Pixi manages the full dependency stack — ROOT, Geant4, FairRoot, GenFit — with a single
pixi run build.Analysis Toolkit
Python-based signal selection, overlap checking, histogram comparison, and an interactive event display.
FairShip is developed and maintained by the SHiP Collaboration at CERN. All Python code requires Python 3 (Python 2 is no longer supported). The
master branch is the main development branch.