Searches for and Characterization of Astrophysical Neutrinos using Starting Track Events in IceCube

TL;DR

This paper presents a method to identify astrophysical neutrinos in IceCube by focusing on starting events, reducing atmospheric background, and enabling new measurements and alerts for astrophysical sources.

Contribution

The paper introduces a novel starting event selection technique that lowers background contamination, improving sensitivity to astrophysical neutrinos in IceCube data.

Findings

Reduced atmospheric muon background in neutrino detection.

Lowered energy threshold for astrophysical neutrino identification.

Demonstrated potential for real-time alerts and source searches.

Abstract

The IceCube Neutrino Observatory is a cubic kilometer-sized detector designed to detect neutrinos of astrophysical origin. However, muons created by cosmic rays interacting in the atmosphere pose a significant background for these astrophysical neutrinos particularly in the southern equatorial sky. Identifying neutrino events that start in the detector allows us to reduce the atmospheric muon component while retaining a high rate of starting neutrino events. The method presented today also rejects atmospheric neutrinos if they are accompanied by muons from the same cosmic ray shower, lowering the 50$\%$ purity threshold for astrophysical-to-atmospheric neutrinos from 100 TeV to ~10 TeV at declinations less than -25{\deg}. We use 10$\%$ (burn sample) of 9.5 years IceCube data to demonstrate the status of this dataset. We outline a planned measurement of the diffuse neutrino flux inclusive of theoretical and detector systematic uncertainties. In addition, we discuss searches for neutrino point sources and diffuse galactic plane neutrino emission in the Southern sky and plans to release high astrophysical-purity real-time alerts to the multi-messenger community.