MuscRat.jl

A Muon Simulation for Cosmic Ray Analysis Tasks

The MuscRat project is designed to analyze the flux of cosmic rays in detectors. It was originally designed to generate only muons, though some results of the PARMA code (Sato 2015) have been included to help generate realistic distributions of µ±, γ, and e± from cosmic ray air showers. This code runs in Julia 1.x (tested for 1.7 and up).

Analytic geometry allows MuscRat to compute the flux through muon detectors of simple, regular shape. Shapes implemented are:

• a sphere (Sphere)
• a cylinder (Cylinder) with axis along any cartesian axis (1, 2, or 3), including the specific cases of:
  • a vertical cylinder (Vcylinder)
  • a horizontal cylinder (Hcylinder)
• a rectangular prism (Box) oriented square to the cartesian axes

Particles are generated:

• The combined µ± flux is generated by a CRMuonGenerator from one of the two analytic formulas found in Su et al (2021): those of Reyna 2006 or Chatzidakis et al. 2015. At the moment, these are only sea-level values.
• The flux for particles at elevation 1675 meters (Boulder, Colorado) as computed by PARMA (Sato 2015). This uses a ParmaGenerator(p::Particle) where p is one of MuscRat.Gamma, MuscRat.Electron, MuscRat.Positron, MuscRat.µplus, or MuscRat.µminus. The PARMA calculations were run outside of MuscRat and the results stored in data/parma_electron.txt and similar.
• The generator returned by CRMuonGenerator or ParmaGenerator is used like this

using Unitful, MuscRat
Nparticles = 1000000
g = ParmaGenerator(MuscRat.µplus)
# or
g = CRMuonGenerator(100, 100; Pmin=0.1u"GeV/c", Pmax=1000.0u"GeV/c")
p, cosθ = generate(g, Nparticles)
# p is an array of the momenta (units of GeV/c)
# cosθ is the corresponding array of cosine of the zenith angle

References

• Su, N., et al., (2021). "A Comparison of Muon Flux Models at Sea Level for Muon Imaging and Low Background Experiments." Frontiers in Energy Research, 9. doi:10.3389/fenrg.2021.750159
• Reyna, D. (2006). "A Simple Parameterization of the Cosmic-Ray Muon Momentum Spectra at the Surface as a Function of Zenith Angle" arXiv:hep-ph/0604145
• Chatzidakis, S., Chrysikopoulou, S., Tsoukalas, L. H. (2015). "Developing a cosmic ray muon sampling capability for muon tomography and monitoring applications." Nuclear Instruments and Methods in Physics Research, Section A, 804 33. doi:10.1016/j.nima.2015.09.033
• Sato, T., (2015). "Analytical Model for Estimating Terrestrial Cosmic Ray Fluxes Nearly Anytime and Anywhere in the World: Extension of PARMA/EXPACS." PLOS ONE, 10 e0144679. doi:10.1371/journal.pone.0144679