[Paper Review] Probing the Cosmic Ray "Knee" and Very High Energy Prompt Muon and Neutrino fluxes via Underground Muons

Raj Gandhi, Sukanta Panda|arXiv (Cornell University)|Dec 14, 2005

Astrophysics and Cosmic Phenomena5 citations

TL;DR

This paper proposes using large underground muon detectors as pair-meters to probe very high energy muons (1–1000 TeV), corresponding to surface muons of 2–5000 TeV and primary cosmic rays of 20 TeV–50,000 TeV. The study demonstrates the observational feasibility of such muons, enabling improved understanding of prompt high-energy neutrino fluxes and the origin of the cosmic ray 'knee' in the spectrum.

ABSTRACT

We calculate event rate and demonstrate the observational feasibility of very high energy muons (1 TeV-1000 TeV) in a large mass underground detector operating as a pair-meter. This energy range corresponds to surface muon energies of $\\sim$(2 TeV - 5000 TeV) and primary cosmic ray energies of $\\sim$ (20 TeV - 5 $\ imes 10^4$ TeV). Such measurements would significantly assist in an improved understanding of the prompt contribution to $\ u_e, \ u_{\\mu}$ and $\\mu$ fluxes in present and futute ultra-high energy neutrino detectors. In addition, they would shed light on the origin of the observed 'knee' in the cosmic ray spectrum.

Motivation & Objective

• To assess the feasibility of detecting very high energy muons (1–1000 TeV) in large underground detectors.
• To link underground muon measurements to the prompt contributions in high-energy neutrino fluxes (νₑ, νμ, ντ).
• To investigate the origin of the cosmic ray spectrum 'knee' at ~10^15–10^16 eV using muon data.
• To support future ultra-high energy neutrino detectors by constraining prompt neutrino backgrounds.

Proposed method

• Modeling muon event rates in large underground detectors operating as pair-meters.
• Calculating muon energy spectra from primary cosmic rays via atmospheric cascade processes.
• Estimating muon fluxes at underground depths for energies from 1 TeV to 1000 TeV.
• Relating underground muon rates to surface muon and primary cosmic ray energies using energy loss and propagation models.
• Using detector mass and muon energy thresholds to determine pair-meter sensitivity.
• Applying theoretical frameworks for prompt neutrino production to infer flux contributions from muon data.

Experimental results

Research questions

• RQ1 Can very high energy muons (1–1000 TeV) be observed in large underground detectors with sufficient sensitivity?
• RQ2 What is the contribution of prompt processes to the high-energy neutrino fluxes (νₑ, νμ, ντ) in the 1–1000 TeV range?
• RQ3 How do muon measurements constrain the origin of the cosmic ray spectrum 'knee' at ~10^15–10^16 eV?
• RQ4 To what extent can underground muon data improve background modeling for future ultra-high energy neutrino detectors?

Key findings

• The study demonstrates the observational feasibility of detecting very high energy muons in the 1–1000 TeV range using large underground detectors.
• Muons in this energy range correspond to surface muons of 2–5000 TeV and primary cosmic rays of 20 TeV to 5×10⁴ TeV.
• Such measurements can significantly improve constraints on prompt neutrino fluxes in ultra-high energy neutrino detectors.
• The method provides a pathway to probe the origin of the cosmic ray 'knee' through muon-based indirect measurements.
• The pair-meter technique enables sensitive detection of muons in the very high energy regime, enhancing neutrino background characterization.
• The results support the use of underground muon detectors as complementary tools for high-energy astrophysics and cosmic ray studies.