Speaker
Description
The diurnal modulation in the galactic cosmic ray flux has been investigated by the three POLA-R scintillator telescopes of the Extreme Energy Events (EEE) Project, installed at Ny-Ålesund (79° N) in the Svalbard archipelago, employing a dataset collected by these detectors in the period 2019-2025. Evidence of a diurnal modulation, with an amplitude of the order of 0.1 % or less, was evidenced in the data. Amplitudes and phases (time of maxima) of the observed diurnal anisotropy in the cosmic ray flux were extracted by a harmonic fit of the averaged daily trend, using a moving average along different periods. A quantitative comparison was made with the data collected by the Barentsburg Neutron Monitor, located not far from our detectors, showing that the amplitude of the anisotropy for muons is smaller, at least by a factor 2, than for neutrons, although the trend of the phase over the last years was similar both for muons and neutrons. A survey of various aspects of the observed diurnal modulation and the main results achieved so far will be discussed in this contribution.