Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nuclear Physics Experiments with Ion Storage Rings   In the last two decades a number of nuclear structure and astrophysics
experiments were performed at heavy-ion storage rings employing unique
experimental conditions offered by such machines. Furthermore, building on the
experience gained at the two facilities presently in operation, several new
storage ring projects were launched worldwide. This contribution is intended to
provide a brief review of the fast growing field of nuclear structure and
astrophysics research at storage rings.

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The categories of this paper are: hep-th
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: cond-mat
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th