Cosmic Ray Flux Correlation between McMurdo and Jang Bogo Neutron Monitor
Issued Date
2024-09-27
Resource Type
eISSN
18248039
Scopus ID
2-s2.0-85212301470
Journal Title
Proceedings of Science
Volume
444
Rights Holder(s)
SCOPUS
Bibliographic Citation
Proceedings of Science Vol.444 (2024)
Suggested Citation
Kittiya A., Nuntiyakul W., Seripienlert A., Sáiz A., Ruffolo D., Evenson P., Sonsrettee W., Oh S. Cosmic Ray Flux Correlation between McMurdo and Jang Bogo Neutron Monitor. Proceedings of Science Vol.444 (2024). Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/102509
Title
Cosmic Ray Flux Correlation between McMurdo and Jang Bogo Neutron Monitor
Corresponding Author(s)
Other Contributor(s)
Abstract
Neutron monitors are large ground-based detectors responding to primary cosmic rays by measuring atmospheric secondary particles, primarily neutrons. A charged cosmic ray striking the atmosphere from a specific sky direction with a specific rigidity (momentum per unit charge) was necessarily moving from a well-defined direction in space, called the asymptotic direction. McMurdo and Jang Bogo Antarctic stations have similar geomagnetic latitudes but slightly different longitudes. From December 17, 2015, to January 9, 2017, six of the eighteen neutron monitor units from McMurdo were transferred to Jang Bogo (with full transfer to Jang Bogo completed in December 2017). Count rate data are recorded in ten-second intervals, but in this work, we average to one-minute Cosmic Ray Flux Correlation between McMurdo and Jang Bogo Neutron Monitor intervals with cleaned and pressure-corrected data. Autocorrelation functions are well fit as the sum of three components: an exponential function peaking at zero lag, a linear function, and a sinusoid with a period of one day, centered at zero lag (ϕ = 0). The cross-correlation of the average over-counter tubes for the two stations does not show the exponential term. Adjusting the phase (ϕ) for the best-fit yields a time lag (τ) of 167 minutes. By calculating cosmic ray trajectories in Earth’s magnetic field throughout the time interval analyzed in this work, we determine the weighted-average difference in asymptotic longitudes to be 41.8°± 1.97°, corresponding to a time lag of 167.2 ± 7.86 minutes. This is in close agreement with the observed lag in the sinusoidal component of the cross-correlation. In summary, this analysis can distinguish between temporal and directional variations.