What is in LArSoft


LArSoft provides tools to carry out simulation, reconstruction and analysis of LArTPC data. Consider for instance, an event generation, detector simulation, reconstruction workflow as shown in the following figure:

Each piece will be described in more detail.

Event Generation

Event generationTypically run as at least three separate phases:

  • “Beam” simulation
  • Event generation
  • Detector simulation and response




Beam Simulation

  • Generates neutrino flux hitting the detector
  • Simulated sources can include accelerator, sun, astrophysical sources, KDAR sources, etc. (so not strictly from accelerator beams)

The beam simulation is external to LArSoft

There are multiple event generators available that  are integrated into LArSoft in different ways.

  • Genie:  GENIEGen module
  • Single particles:  SingleGen module
  • Cosmic ray generators:  CORSIKA, CRY

Geant4 simulation

Geant4 simulation

  • Particle propagation simulation
  • Models energy depositions in the detector
  • The only simulation currently integrated with LArSoft




Combine flux and geometry with neutrino physics usually with GENIE, which can be embedded in the offline framework.

Detector simulation

Detector simulation

A separate workflow in itself

Bulk properties include reinteractions, decays, energy loss and transport. Particles to be dealt with range from 100 GeV to 25MeV. Emphasis is on the sub-5GeV range. Particles include all species of hadrons, charged leptons and ions.


Basic particle physics combined with specific detector geometries.

  • Majority are Geant4 based
  • Generally these simulations are embedded into the experiment’s offline framework
  • LArSoft uses art


ReconstructionThree major paradigms, each with its own variants, modules, workflows

  • 2D clustering and view matching
  • Image processing / deep learning techniques
  • 3D imaging



For more information, please see Erica Snider’s Introduction to LArSoft – source material.

For information about simulations in general, please consult Robert Hatcher’s Simulation Tools in Neutrino Experiments.