Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nitrogen Contamination Causes High Field Q-Slope (HFQS) in Buffered
  Chemical Polished SRF Cavities   Buffered Chemical Polishing (BCP) was the most conventional polishing method
for superconducting radio frequency (SRF) Niobium (Nb) cavity surface
preparation before the discovery of Electropolishing (EP), which is superior to
BCP in high gradient performance. The High Field Q-slope (HFQS) is perfectly
eliminated by taking the low temperature bake (LTB) post EP, which guarantees
high gradient performance in EP'ed cavities. The mechanism of the HFQS is well
understood for EP'ed cavities. On the other hand, there is no common consensus
on the HFQS with BCP, since even BCP with LTB does not always resolve the HFQS.
BCP is much easier to apply and still an important preparation technology for
very complicated SRF structures like low beta cavities. Therefore, overcoming
the issue of HFQS with BCP is highly beneficial to the SRF community. This
paper mines a large number of available data sets on BCP'ed cavity performance
with fine grain, large grain, and even single crystal niobium materials under
different experimental settings. We found that all existing explanations for
HFQS with BCP are inconsistent with some experimental results, and propounded
nitrogen contamination as a new model. We checked that nitrogen contamination
agrees with all existing data and nicely explains unresolved phenomena.
Combining these evidence, we deduce that nitrogen contamination is the cause of
HFQS in BCP.

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The categories of this paper are: mtrl-th
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The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
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The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int