Temperature effect of muons detected underground by scintillation detectors

The A.I. Kuzmin Cosmic Ray Spectrograph in Yakutsk contains a 24-NM-64 neutron monitor and a system of underground MT and SMT muon detectors for recording muons at levels of 0, 7, 20, and 40 m of water equivalent. The temperature effect of muons observed with MT telescopes on gas-discharge counters has been analyzed in the previous work [Yanchukovsky, 2023]. Here we calculate the temperature effect of muons recorded by SMT telescopes. Distributions of the density of temperature coefficients for muons recorded on the surface and at different depths underground were found from SMT telescope data for the period from January 2016 to December 2018, using data on the altitude profile of the atmosphere temperature over Yakutsk for the same period. In the analysis of multidimensional data, we applied the methods of regression on principal components. When constructing a system of linear equations in the space of principal components, we employed the method of projections to latent structures (PLS2). The obtained results were compared with the results of theoretical calculations. The found distributions of the density of temperature coefficients allow us to correctly take into account the temperature effect in data from SMT muon telescopes.