Expected Muon Energy Spectra and Zenithal Distributions Deep Underwater

TL;DR

This paper calculates underwater muon energy spectra and zenith distributions, comparing prompt and conventional muon fluxes at different depths and angles, with implications for neutrino telescope observations.

Contribution

It introduces three models for prompt muon production and analyzes their impact on muon fluxes at various underwater depths and angles.

Findings

Prompt muon flux becomes comparable to conventional flux at higher energies for larger zenith angles.

Crossing energy varies significantly with depth, e.g., 300 TeV at Baikal and 8 TeV at NESTOR.

Muon flux at crossing energy is much lower at NESTOR depth compared to Baikal.

Abstract

Energy spectra and zenith angle distributions of atmospheric muons are calculated for the depths of operation of large underwater neutrino telescopes. The estimation of the prompt muon contribution is performed with three approaches to charm hadroproduction: recombination quark-parton model, quark-gluon string model, and perturbative QCD based models. Calculations show that the larger are zenith angles and water thickness above the detector, the lower is the energy at which the prompt muon flux becomes equal to conventional one (``crossing energy'') . For instance, for the depth of the Baikal Neutrino Telescope and for zenith angle of 78 degrees the crossing energy is about 300 TeV, whereas it is only 8 TeV for the NESTOR depth. Nevertheless, the muon flux of the crossing energy at NESTOR depth is in order of magnitude lower in comparison with the Baikal depth.