Seasonal Modulations of the Underground Cosmic-Ray Muon Energy

TL;DR

This study analyzes seven years of data from the LVD experiment to understand how seasonal atmospheric temperature variations influence underground muon energy and the resulting cosmogenic neutron flux.

Contribution

It provides the first detailed measurement of seasonal modulations in muon energy and neutron flux at a deep underground site, highlighting energy variations as the main driver.

Findings

Muon energy modulations correlate with atmospheric temperature changes.

Mean muon energy variations significantly impact neutron flux underground.

Seasonal amplitude of muon energy changes exceeds that of muon intensity.

Abstract

The parameters of the seasonal modulations (variations) in the intensity of muons and cosmogenic neutrons generated by them at a mean muon energy of 280 GeV have been determined in the LVD (Large Volume Detector) experiment. The modulations of muons and neutrons are caused by a temperature effect, the seasonal temperature and density variations of the upper atmospheric layers. The analysis performed here leads to the conclusion that the variations in the mean energy of the muon flux are the main source of underground cosmogenic neutron variations, because the energy of muons is more sensitive to the temperature effect than their intensity. The parameters of the seasonal modulations in the mean energy of muons and the flux of cosmogenic neutrons at the LVD depth have been determined from the data obtained over seven years of LVD operation.