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Fennel

Fennel Logo

Cherenkov light yield simulation for particles and cascades

Python 3.8+ License

Fennel is a Python package for simulating Cherenkov light production from particles. It calculates light emissions from both cascades (electromagnetic and hadronic) and tracks using the Aachen parametrization.

Features

✨ Comprehensive Physics Coverage

  • Tracks: Muon light yield with energy loss mechanisms (ionization, bremsstrahlung, pair production)
  • EM Cascades: Electron, positron, and photon-initiated showers
  • Hadron Cascades: Pion, kaon, proton, and neutron-initiated showers with EM fraction and muon production

🚀 High Performance

  • NumPy-based calculations for CPU efficiency
  • Optional JAX backend for GPU acceleration
  • Optimized parametrizations from GEANT4 simulations

🎯 User-Friendly API

  • Simple, intuitive interface
  • Comprehensive type hints for IDE support
  • Detailed NumPy-style documentation
  • Flexible configuration via YAML or dictionaries

📊 Wavelength-Dependent Yields

  • Customizable wavelength grids
  • Angular distributions
  • Longitudinal shower profiles

Quick Example

from fennel import Fennel

# Initialize
f = Fennel()

# Calculate muon track yields
wavelengths, photons = f.track_yields(
    energy=100.0,  # 100 GeV muon
    particle=13,    # PDG code for muon
    wavelength=400  # 400 nm
)

# Calculate EM cascade yields
wavelengths, total_photons, profile, angles = f.em_yields(
    energy=100.0,   # 100 GeV
    particle=11     # electron
)

# Calculate hadron cascade yields  
results = f.hadron_yields(
    energy=100.0,   # 100 GeV
    particle=2212   # proton
)

Installation

pip install fennel_seed

For JAX GPU acceleration: 

pip install fennel_seed[jax]

For development: 

git clone https://github.com/MeighenBergerS/fennel.git
cd fennel
pip install -e .[dev]

Key Concepts

Tracks vs Cascades

  • Tracks: Charged particles (primarily muons) that travel long distances while emitting Cherenkov light continuously
  • EM Cascades: Electromagnetic showers from electrons, positrons, or photons that develop through pair production and bremsstrahlung
  • Hadron Cascades: Hadronic showers from pions, kaons, protons, or neutrons with both electromagnetic and purely hadronic components

Parametrization

Fennel uses the Aachen parametrization based on detailed GEANT4 simulations. The parametrization includes:

  • Energy-dependent track lengths and shower profiles
  • Angular distributions of Cherenkov photons
  • Wavelength-dependent yields
  • EM fraction in hadronic showers
  • Muon production in hadronic interactions

Documentation Structure

Citation

If you use Fennel in your research, please cite:

@software{fennel2024,
  author = {Meighen-Berger, Stephan},
  title = {Fennel: Cherenkov Light Yield Simulation},
  year = {2024},
  url = {https://github.com/MeighenBergerS/fennel},
  version = {1.3.4}
}

The package includes distributions developed in multiple studies - see Citation for complete references.

License

Fennel is released under the MIT License. See LICENSE.txt for details.

Support

Acknowledgments

Developed by Stephan Meighen-Berger based on the Aachen parametrization for Cherenkov light production.