Cosmic Ray Spectrum and Composition from PeV to EeV from the IceCube Neutrino Observatory

TL;DR

This paper presents measurements of the cosmic ray energy spectrum and composition from PeV to EeV energies using the IceCube Neutrino Observatory, combining surface and deep detector data with machine learning techniques.

Contribution

It introduces a novel method to simultaneously determine the all-particle spectrum and elemental composition of cosmic rays in the PeV to EeV range.

Findings

All-particle energy spectrum measured across PeV to EeV energies.

Elemental group spectra extracted using combined surface and in-ice data.

Machine learning approach improves composition resolution.

Abstract

The IceCube Neutrino Observatory at the South Pole is a multi-component detector capable of measuring the cosmic ray energy spectrum and composition from PeV to EeV, the energy region typically thought to cover the transition from galactic to extragalactic sources of cosmic rays. The IceTop array at the surface is sensitive to the electromagnetic part of the air shower while the deep in-ice array detects the high-energy (TeV) muonic component of air showers. IceTop's reconstructed shower size parameter, S$_{125}$, is unfolded into a high statistics all-particle energy spectrum. Furthermore, for air showers that pass through both arrays, the in-ice reconstructed muon energy loss information is combined with S$_{125}$ in a machine learning algorithm to simultaneously extract both the all-particle energy spectrum and individual spectra for elemental groups. The all-particle spectra as well as spectra for individual elemental groups are presented.