Observation of Seasonal Variations with the MINOS Far Detector

TL;DR

This study reports the detection of seasonal fluctuations in underground muon rates at the MINOS detector, closely linked to atmospheric temperature changes, confirming theoretical predictions with high precision.

Contribution

It provides the first detailed measurement of the correlation between muon rate variations and atmospheric temperature at the MINOS site.

Findings

Muon rate fluctuates by about 4% seasonally.

Muon rate variation is highly correlated with atmospheric temperature.

Measured temperature coefficient is 0.87, close to the expected 0.91.

Abstract

An observation of seasonal variations in underground muon rate, $R_{\mu}$, has been performed at Soudan, MN, by the MINOS Far Detector. The four percent fluctuation seen over three years was highly correlated to the temperature variations of the upper atmosphere. The coefficient relating variations in temperature to variations in muon rate was found to be: $\alpha_T = (T/R_{\mu})(\partial R_{\mu}/ \partial T) = 0.87 \pm 0.03$, which is near the expectation of 0.91.