Measurement of muon flux variations with scintillators in Mexico City and their correlation to solar activity

Abstract

In this work we report the variations of the atmospheric muons flux in Mexico City. The measurements were performed from September to December 2023 at the Institute of Nuclear Sciences of UNAM, located at coordinates 19.32°N 99.18°W with an altitude of 2274 meters above sea level and a cutoff rigidity of 8.24 GV. The experimental setup consists of a pair of scintillators, with dimensions of 50cm x 1m. To compensate for fluctuations in air pressure, we calculate the barometric coefficient using data, which is determined to be -0.21%/mb. The observed muon flux corresponds to 98.3 ± 2.6 m−2 s−1 sr−1 and is consistent with other measurements at the same location. We have identified three variations in the pressure-corrected muon flux that exhibit a pattern similar to those observed by a neutron cosmic ray detector at UNAM. Through an extensive analysis of the publicly available geomagnetic data, we have correlated these variations with a phenomenon known as a Forbush decrease.