Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Waiting time distribution of solar energetic particle events modeled
  with a non-stationary Poisson process   We present a study of the waiting time distributions (WTDs) of solar
energetic particle (SEP) events observed with the spacecraft $WIND$ and $GOES$.
Both the WTDs of solar electron events (SEEs) and solar proton events (SPEs)
display a power-law tail $\sim \Delta t^{-\gamma}$. The SEEs display a broken
power-law WTD. The power-law index is $\gamma_{1} =$ 0.99 for the short waiting
times ($<$70 hours) and $\gamma_{2} =$ 1.92 for large waiting times ($>$100
hours). The break of the WTD of SEEs is probably due to the modulation of the
corotating interaction regions (CIRs). The power-law index $\gamma \sim$ 1.82
is derived for the WTD of SPEs that is consistent with the WTD of type II radio
bursts, indicating a close relationship between the shock wave and the
production of energetic protons. The WTDs of SEP events can be modeled with a
non-stationary Poisson process which was proposed to understand the waiting
time statistics of solar flares (Wheatland 2000; Aschwanden $\&$ McTiernan
2010). We generalize the method and find that, if the SEP event rate $\lambda =
1/\Delta t$ varies as the time distribution of event rate $f(\lambda) = A
\lambda^{-\alpha}exp(-\beta \lambda)$, the time-dependent Poisson distribution
can produce a power-law tail WTD $\sim \Delta t^{\alpha - 3}$, where $0 \leq
\alpha < 2$.

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The categories of this paper are: q-bio
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The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: math
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat