Atmospheric Dependence of the Stopping Cosmic Ray Muon Rate at Ground Level

TL;DR

This study measures how atmospheric pressure, height, and temperature influence the ground-level rate of stopping cosmic ray muons, revealing strong anti-correlations with pressure and atmospheric height.

Contribution

It provides new quantitative analysis of atmospheric effects on stopping muon rates using linear regression, highlighting stronger correlations than for total charged particle rates.

Findings

Strong anti-correlation between pressure and muon rate (-3.0 ± 0.5)

Anti-correlation between atmospheric height and muon rate (-4.1 ± 0.5)

Pressure and height effects are more pronounced for stopping muons than for total charged particles

Abstract

The rate of low energy (< 150 MeV) cosmic ray muons was measured at ground level as a function of several atmospheric parameters. Stopped muons were detected in a plastic scintillator block and correlations were determined using a linear regression model. A strong anti-correlation between fractional changes in the ground-level pressure and stopping muon rate of -3.0 +- 0.5 was found, and also a -4.1 +- 0.5 anti-correlation with the fractional change in atmospheric height at 10 kPa pressure. A weak positive correlation with the 10 kPa temperature was also found, but it was shown not to be statistically significant in our data set. The same analysis was applied to the total rate of all charged cosmic ray particles detected with the same apparatus, and good agreement with previous work was seen. The pressure and height correlation parameters for stopping muons are larger than for the total rate of all charged particles by factors of about 1.6 and 3.7, respectively.