Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Construction and Expected Performance of the Hadron Blind Detector for
  the PHENIX Experiment at RHIC   A new Hadron Blind Detector (HBD) for electron identification in high density
hadron environment has been installed in the PHENIX detector at RHIC in the
fall of 2006. The HBD will identify low momentum electron-positron pairs to
reduce the combinatorial background in the $e^{+}e^{-}$ mass spectrum, mainly
in the low-mass region below 1 GeV/c$^{2}$. The HBD is a windowless
proximity-focusing Cherenkov detector with a radiator length of 50 cm, a CsI
photocathode and three layers of Gas Electron Multipliers (GEM). The HBD uses
pure CF$_{4}$ as a radiator and a detector gas. Construction details and the
expected performance of the detector are described.

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The categories of this paper are: acc-phys
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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: q-bio
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph