Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Air Fluorescence Relevant for Cosmic-Ray Detection - Summary of the 5th
  Fluorescence Workshop, El Escorial 2007   High-energy cosmic rays with energies exceeding $10^{17}$ eV are frequently
observed by measurements of the fluorescence light induced by air showers. A
major contribution to the systematic uncertainties of the absolute energy scale
of such experiments is the insufficient knowledge of the fluorescence light
yield of electrons in air. The aim of the 5th Fluorescence Workshop was to
bring together experimental and theoretical expertise to discuss the latest
progress on the investigations of the fluorescence light yield. The results of
the workshop will be reviewed as well as the present status of knowledge in
this field. Emphasis is given to the fluorescence light yield important for air
shower observations and its dependence on atmospheric parameters, like
pressure, temperature, and humidity. The effects of the latest results on the
light observed from air showers will be discussed.

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The categories of this paper are: stat
34
The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
19
The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
37
The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol