Time dependent solar modulation of cosmic rays from solar minimum to solar maximum. (arXiv:1904.03747v1 [astro-ph.HE])

Time dependent solar modulation of cosmic rays from solar minimum to solar maximum. (arXiv:1904.03747v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wang_B/0/1/0/all/0/1">Bing-Bing Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bi_X/0/1/0/all/0/1">Xiao-Jun Bi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fang_K/0/1/0/all/0/1">Kung Fang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lin_S/0/1/0/all/0/1">Su-Jie Lin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yin_P/0/1/0/all/0/1">Peng-Fei Yin</a>

We study the time-dependent modulation effect and derive the local
interstellar spectra (LIS) for the cosmic ray (CR) proton, helium, boron and
carbon. A two-dimensional modulation model including the variation of the
interplanetary environment with time is adopted to describe modulation process.
The propagation equation of CRs in the heliosphere is numerically solved by the
package Solarprop. We derive the LIS by fitting the latest results of several
experiments, including Voyager 1, PAMELA, BESS-POLARII and ACE, during low
solar activity periods. We further study the modulation in the polarity
reversal periods with the PAMELA proton data. We find that the rigidity
dependence of the diffusion coefficient is critical to explain the modulation
effect during reversal periods. Our results also indicate a power law relation
between the diffusion coefficient and the magnitude of the heliospheric
magnetic field (HMF) at the Earth.

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