987 research outputs found
Spatial gradients of GCR protons in the inner heliosphere derived from Ulysses COSPIN/KET and PAMELA measurements
During the transition from solar cycle 23 to 24 from 2006 to 2009, the Sun
was in an unusual solar minimum with very low activity over a long period.
These exceptional conditions included a very low interplanetary magnetic field
(IMF) strength and a high tilt angle, which both play an important role in the
modulation of galactic cosmic rays (GCR) in the heliosphere. Thus, the radial
and latitudinal gradients of GCRs are very much expected to depend not only on
the solar magnetic epoch, but also on the overall modulation level. We
determine the non-local radial and the latitudinal gradients of protons in the
rigidity range from ~0.45 to 2 GV. This was accomplished by using data from the
satellite-borne experiment Payload for Antimatter Matter Exploration and
Light-nuclei Astrophysics (PAMELA) at Earth and the Kiel Electron Telescope
(KET) onboard Ulysses on its highly inclined Keplerian orbit around the Sun
with the aphelion at Jupiter's orbit. In comparison to the previous A>0 solar
magnetic epoch, we find that the absolute value of the latitudinal gradient is
lower at higher and higher at lower rigidities. This energy dependence is
therefore a crucial test for models that describe the cosmic ray transport in
the inner heliosphere
The sandwich in the middle: using collective effects for stronger optomechanical coupling
Peer ReviewedPostprint (updated version
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