On the Interaction of Galactic Cosmic Rays with Heliospheric Shocks During Forbush Decreases. (arXiv:2002.09454v1 [physics.space-ph])
<a href="http://arxiv.org/find/physics/1/au:+Kirin_A/0/1/0/all/0/1">Anamarija Kirin</a>, <a href="http://arxiv.org/find/physics/1/au:+Vrsnak_B/0/1/0/all/0/1">Bojan Vršnak</a>, <a href="http://arxiv.org/find/physics/1/au:+Dumbovic_M/0/1/0/all/0/1">Mateja Dumbović</a>, <a href="http://arxiv.org/find/physics/1/au:+Heber_B/0/1/0/all/0/1">Bernd Heber</a>
Forbush decreases (FDs) are depletions in the galactic cosmic ray (GCR) count
rate that last typically for about a week and can be caused by coronal mass
ejections (CMEs) or corotating interacting regions (CIRs). Fast CMEs that drive
shocks cause large FDs that often show a two-step decrease where the first step
is attributed to the shock/sheath region, while the second step is attributed
to the closed magnetic structure. Since the difference in size of shock and
sheath region is significant, and since there are observed effects that can be
related to shocks and not necessarily to the sheath region we expect that the
physical mechanisms governing the interaction with GCRs in these two regions
are different. We therefore aim to analyse interaction of GCRs with
heliospheric shocks only. We approximate the shock by a structure where the
magnetic field linearly changes with position within this structure. We assume
protons of different energy, different pitch angle and different incoming
direction. We also vary the shock parameters such as the magnetic field
strength and orientation, as well as the shock thickness. The results
demonstrate that protons with higher energies are less likely to be reflected.
Also, thicker shocks and shocks with stronger field reflect protons more
efficiently.
Forbush decreases (FDs) are depletions in the galactic cosmic ray (GCR) count
rate that last typically for about a week and can be caused by coronal mass
ejections (CMEs) or corotating interacting regions (CIRs). Fast CMEs that drive
shocks cause large FDs that often show a two-step decrease where the first step
is attributed to the shock/sheath region, while the second step is attributed
to the closed magnetic structure. Since the difference in size of shock and
sheath region is significant, and since there are observed effects that can be
related to shocks and not necessarily to the sheath region we expect that the
physical mechanisms governing the interaction with GCRs in these two regions
are different. We therefore aim to analyse interaction of GCRs with
heliospheric shocks only. We approximate the shock by a structure where the
magnetic field linearly changes with position within this structure. We assume
protons of different energy, different pitch angle and different incoming
direction. We also vary the shock parameters such as the magnetic field
strength and orientation, as well as the shock thickness. The results
demonstrate that protons with higher energies are less likely to be reflected.
Also, thicker shocks and shocks with stronger field reflect protons more
efficiently.
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