Testing diffusion of cosmic rays in the heliosphere with p/He data from AMS. (arXiv:1811.08909v1 [astro-ph.HE])

Testing diffusion of cosmic rays in the heliosphere with p/He data from AMS. (arXiv:1811.08909v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tomassetti_N/0/1/0/all/0/1">Nicola Tomassetti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barao_F/0/1/0/all/0/1">Fernando Bar&#xe3;o</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bertucci_B/0/1/0/all/0/1">Bruna Bertucci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fiandrini_E/0/1/0/all/0/1">Emanuele Fiandrini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Figueiredo_J/0/1/0/all/0/1">Jos&#xe9; Figueiredo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barreira_J/0/1/0/all/0/1">Jo&#xe3;o Barreira</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Orcinha_M/0/1/0/all/0/1">Miguel Orcinha</a>

After six years of continuous observations in space, the Alpha Magnetic
Spectrometer experiment has released new data on the temporal evolution of the
proton and helium fluxes in cosmic rays. These data revealed that the ratio
between proton and helium fluxes at the same value of rigidity $R=p/Z$
(momentum/charge ratio) is not constant at $Rlesssim$ 3 GV. In particular, the
ratio is found to decrease steadily during the descending phase of Solar Cycle
24 toward the next minimum. We show that such a behavior is a remarkable
signature of the $betatimeslambda(R)$ dependence in the diffusion of cosmic
rays in heliosphere, where $beta$ is their adimensional speed and $lambda(R)$
is their mean free path, a universal function of rigidity for all nuclei. This
dependence is responsible for distinctive charge/mass dependent effects in the
time-dependent modulation of low-rigidity particles.

After six years of continuous observations in space, the Alpha Magnetic
Spectrometer experiment has released new data on the temporal evolution of the
proton and helium fluxes in cosmic rays. These data revealed that the ratio
between proton and helium fluxes at the same value of rigidity $R=p/Z$
(momentum/charge ratio) is not constant at $Rlesssim$ 3 GV. In particular, the
ratio is found to decrease steadily during the descending phase of Solar Cycle
24 toward the next minimum. We show that such a behavior is a remarkable
signature of the $betatimeslambda(R)$ dependence in the diffusion of cosmic
rays in heliosphere, where $beta$ is their adimensional speed and $lambda(R)$
is their mean free path, a universal function of rigidity for all nuclei. This
dependence is responsible for distinctive charge/mass dependent effects in the
time-dependent modulation of low-rigidity particles.

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