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arXiv · 2303.14101

Compton-Getting effect due to terrestrial orbital motion observed on cosmic ray flow from Mexico-city Neutron Monitor

Carlos Navia·Marcel de Oliveira·Andre Nepomuceno
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Abstract

We look for a diurnal anisotropy in the cosmic ray flow, using the Mexico-City Neutron Monitor (NM) detector, due to the Earth's orbital motion and predicted by Compton-Getting (C-G) in 1935, as a first-order relativistic effect. The Mexico-City NM's geographic latitude is not very high ($19.33^{\circ}$N), and it has a high cutoff geomagnetic rigidity (8.2 GV) and mountain altitude (2274 m asl) favoring the observation of the C-G effect. Furthermore, during the solar cycle minima, the galactic cosmic ray flux is maxima, and the solar magnetic field gets weakened, with a dipolar pattern. Its influence on cosmic rays reaching Earth is the smallest. Analysis of the combined counting rate during two solar minima, 2008 and 2019, from Mexico-city NM's data yields the C-G effect with an amplitude variation of (0.043$\pm$ 0.019)\%, and phase of (6.15$\pm$ 1.71) LT. The expected amplitude variation is 0.044\%, and the phase of 6.00 LT.

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Carlos Navia, Marcel de Oliveira, Andre Nepomuceno. 2023-03-12. Compton-Getting effect due to terrestrial orbital motion observed on cosmic ray flow from Mexico-city Neutron Monitor. https://arxiv.org/abs/2303.14101

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