Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fermilab 4.3-MeV Electron Cooler   The Recycler Electron Cooler (REC) was the first cooler working at a
relativistic energy (gamma = 9.5). It was successfully developed in 1995-2004
and was in operation at Fermilab in 2005-2011, providing cooling of antiprotons
in the Recycler ring. After introducing the physics of electron cooling and the
REC system, this paper describes measurements carried out to tune the electron
beam and optimize its cooling properties. In particular, we discuss the cooling
strategy adopted for maximizing the collider integrated luminosity.

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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-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: nlin
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn