Influence of the terrestrial magnetic field geometry on the cutoff rigidity of cosmic ray particles
Studies of the propagation of charged energetic particles in the Earth's magnetic field go back to Carl Størmer. In the end, his investigations finally lead to the definition of the so-called cutoff rigidity <i>R</i><sub>C</sub>; that is, the minimum momentum per char...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2013-10-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/31/1637/2013/angeo-31-1637-2013.pdf |
| Summary: | Studies of the propagation of charged energetic particles in the Earth's
magnetic field go back to Carl Størmer. In the end, his investigations
finally lead to the definition of the so-called cutoff rigidity
<i>R</i><sub>C</sub>; that is, the minimum momentum per charge a particle must have in
order to reach a certain geographical location. Employing Monte Carlo
simulations with the PLANETOCOSMICS code we investigate the correlation
between the geomagnetic field structure and the cutoff rigidity. We show that
the geometry of the magnetic field has a considerable influence on the
resulting cutoff rigidity distribution. Furthermore, we will present a simple
geometry-based parameter, δ<i>B</i>, which is able to reflect the
location-dependent cutoff rigidity. We show that this correlation is also
visible in the temporal evolution of the Earth's magnetic field, at least
over the last 100 yr. Using latitude scans with neutron monitors,
changes of the relative counting rates at different positions are calculated,
showing small variations for, e.g., Kiel and Moscow, while large ones occur
at Mexico City as well as on the British Virgin Islands. |
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| ISSN: | 0992-7689 1432-0576 |