Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Flux pinning characteristics in cylindrical ingot niobium used in
  superconducting radio frequency cavity fabrication   We present the results of from DC magnetization and penetration depth
measurements of cylindrical bulk large-grain (LG) and fine-grain (FG) niobium
samples used for the fabrication of superconducting radio frequency (SRF)
cavities. The surface treatment consisted of electropolishing and low
temperature baking as they are typically applied to SRF cavities. The
magnetization data were fitted using a modified critical state model. The
critical current density Jc and pinning force Fp are calculated from the
magnetization data and their temperature dependence and field dependence are
presented. The LG samples have lower critical current density and pinning force
density compared to FG samples which implies a lower flux trapping efficiency.
This effect may explain the lower values of residual resistance often observed
in LG cavities than FG cavities.

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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-alg
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The categories of this paper are: math
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The categories of this paper are: bayes-an
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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: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: eess