Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Storage Ring Cross Section Measurements for Electron Impact Single and
  Double Ionization of Fe^13+ and Single Ionization of Fe^16+ and Fe^17+   We report measurements of electron impact ionization (EII) for Fe^13+,
Fe^16+, and Fe^17+ over collision energies from below threshold to above 3000
eV. The ions were recirculated using an ion storage ring. Data were collected
after a sufficiently long time that essentially all the ions had relaxed
radiatively to their ground state before data were collected. For single
ionization of $\fethirteen$ we find that previous single pass experiments are
more than 40% larger than our results. Compared to our work, the theoretical
cross section recommended by Arnaud & Raymond (1992) is more than 30% larger,
while that of Dere (2007) is about 20% greater. Much of the discrepancy with
Dere (2007) is due to the theory overestimating the contribution of
excitation-autoionization via n=2 excitations. Double ionization of Fe^13+ is
dominated by direct ionization of an inner shell electron accompanied by
autoionization of a second electron. Our results for single ionization of
Fe^16+ and Fe^17+ agree with theoretical calculations to within the
experimental uncertainties.

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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci