Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Imaging Hybrid Photon Detectors with Minimized Dead Area and Protection
  Against Positive Ion Feedback   Imaging Hybrid Photon Detectors (HPD) have been developed for integration in
large area Cherenkov detectors for high energy physics and astrophysics. The
presented designs - developed particularly for the experiments MAGIC, LHCb and
AQUA-RICH - comprise very good imaging properties, protection against positive
ion feedback and(or) minimum dead area. The underlying innovations are
discussed in some detail.

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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: eess