Resolution Limiting Factors in Low-Energy Cascade Zenith Angle Reconstruction with the IceCube Upgrade

TL;DR

This paper investigates the factors that limit the accuracy of zenith angle reconstruction for low-energy neutrino events in the IceCube Upgrade, aiming to approach the intrinsic resolution limits for hadronic showers.

Contribution

It identifies and analyzes key physical and instrumental factors affecting zenith angle resolution, providing insights to optimize event reconstruction in low-energy neutrino detection.

Findings

Transverse hadronic shower spread impacts angular resolution

Photon scattering in ice degrades zenith angle accuracy

Instrumental resolutions and noise set practical limits

Abstract

The IceCube Neutrino Observatory includes low energy extensions such as the existing DeepCore subarray and the upcoming IceCube Upgrade, which will consist of seven new strings of photosensors with denser instrumentation than the existing array. The setup will allow for the study of neutrino oscillations with greater sensitivity compared to the existing instrumentation, improve neutrino mass ordering studies, and test for the unitarity of the PMNS mixing matrix with high precision. A critical component in these low-energy physics analyses is the accurate reconstruction of event information, particularly the zenith angle of incoming neutrinos. In this study, we discuss the processes that limit the zenith resolution, which include the transverse spread of the hadronic shower, in-ice photon scattering, module resolutions, and module noise. By considering approximations to these processes, we aim to approach the intrinsic zenith resolution limits for purely hadronic events.