Annual quasiperiodicity in muon rate observed by PolarquEEEst detectors at 79°N

Since 2019, three scintillator-based cosmic ray detectors, readout by SiPM and controlled by low-cost electronics, are installed in the scientific research site in Ny Ålesund (Svalbard) at 79°N, recording muons from secondary cosmic rays. The detectors are part of the EEE Project, a joint project of Centrofermi and INFN, involving almost 100 secondary schools in Italy. After collecting nearly 5 years of data, we were able to analyse the muon rate time series and observe an evident oscillating component with a period of about one year. Applying the Lomb-Scargle periodogram technique, based on sinusoidal fit optimization, we could quantify the annual component, after verifying its independence from environmental and experimental factors.