Monte Carlo simulations of neutrino and charged lepton propagation in the Earth with nuPyProp

TL;DR

nuPyProp is a Python tool that simulates neutrino and lepton propagation through the Earth, aiding in the analysis of neutrino fluxes for various detectors by providing lookup tables and modeling uncertainties.

Contribution

The paper introduces nuPyProp, a new flexible Python code for simulating neutrino and charged lepton propagation in the Earth, including stochastic and continuous energy loss models.

Findings

nuPyProp generates accurate lookup tables for neutrino and lepton exit probabilities.

The code compares favorably with other simulation packages.

Modeling uncertainties are identified and quantified.

Abstract

An accurate modeling of neutrino flux attenuation and the distribution of leptons they produce in transit through the Earth is an essential component to determine neutrino flux sensitivities of underground, sub-orbital and space-based detectors. Through neutrino oscillations over cosmic distances, astrophysical neutrino sources are expected to produce nearly equal fluxes of electron, muon and tau neutrinos. Of particular interest are tau neutrinos that interact in the Earth at modest slant depths to produce $\tau$-leptons. Some $\tau$-leptons emerge from the Earth and decay in the atmosphere to produce extensive air showers. Future balloon-borne and satellite-based optical Cherenkov neutrino telescopes will be sensitive to upward air showers from tau neutrino induced $\tau$-lepton decays. We present nuPyProp, a python code that is part of the nuSpaceSim package. nuPyProp generates look-up tables for exit probabilities and energy distributions for $\nu_\tau\to \tau$ and $\nu_\mu\to \mu$ propagation in the Earth. This flexible code runs with either stochastic or continuous electromagnetic energy losses for the lepton transit through the Earth. Current neutrino cross section models and energy loss models are included along with templates for user input of other models. Results from nuPyProp are compared with other recent simulation packages for neutrino and charged lepton propagation. Sources of modeling uncertainties are described and quantified.