Abstract
Abstract. 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 RC; 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, δB, 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.
Highlights
With momentum p and charge q, interacting with the Earth’s magnetic field B, the concept of the cutoff rigidity RC, where the rigidity R is defined as R = p/q = rL · B, with rL representing the Larmor radius, is used as a measure for the ability of a particle to penetrate the magnetic field at a certain location
In order to investigate the correlation between the geomagnetic field structure and the cutoff rigidity, the magnitude of the magnetic field |B| as well as the measure δB, defined below, representing the field geometry will be compared with computations of the cutoff rigidity
Our previous investigations showed the formula to be a too rough approximation, and suggested the cutoff rigidity to be related to the geometry of the magnetic field
Summary
With momentum p and charge q, interacting with the Earth’s magnetic field B, the concept of the cutoff rigidity RC, where the rigidity R is defined as R = p/q = rL · B, with rL representing the Larmor radius, is used as a measure for the ability of a particle to penetrate the magnetic field at a certain location. On the basis of the investigations by Pilchowski et al (2010) and Fichtner et al (2012) the influence of the magnetic field geometry and its magnitude on the computed vertical cutoff rigidity is investigated in the following in more detail. In order to investigate the correlation between the geomagnetic field structure and the cutoff rigidity, the magnitude of the magnetic field |B| as well as the measure δB, defined below, representing the field geometry will be compared with computations of the cutoff rigidity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
