A muon-track reconstruction exploiting stochastic losses for large-scale Cherenkov detectors

TL;DR

This paper introduces a stochastic loss-based muon-track reconstruction method for IceCube, significantly improving angular resolution by modeling the muon energy loss as stochastic showers rather than continuous loss.

Contribution

It presents a novel parametrization of muon energy loss using stochastic showers, enhancing the accuracy of muon track reconstruction in Cherenkov detectors.

Findings

Up to 20% improvement in angular resolution for through-going tracks

Up to 2 times better resolution for starting tracks

Enhanced robustness in uncertainty estimation

Abstract

IceCube is a cubic-kilometer Cherenkov telescope operating at the South Pole. The main goal of IceCube is the detection of astrophysical neutrinos and the identification of their sources. High-energy muon neutrinos are observed via the secondary muons produced in charge current interactions with nuclei in the ice. Currently, the best performing muon track directional reconstruction is based on a maximum likelihood method using the arrival time distribution of Cherenkov photons registered by the experiment's photomultipliers. A known systematic shortcoming of the prevailing method is to assume a continuous energy loss along the muon track. However at energies $>1$ TeV the light yield from muons is dominated by stochastic showers. This paper discusses a generalized ansatz where the expected arrival time distribution is parametrized by a stochastic muon energy loss pattern. This more realistic parametrization of the loss profile leads to an improvement of the muon angular resolution of up to $20\%$ for through-going tracks and up to a factor 2 for starting tracks over existing algorithms. Additionally, the procedure to estimate the directional reconstruction uncertainty has been improved to be more robust against numerical errors.