Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two different origins of the Q-slope problem in superconducting niobium
  film cavities for a heavy ion accelerator at CERN   Superconducting niobium film cavities deposited on copper substrates (Nb/Cu)
have suffered from strong field-dependent surface resistance, often referred to
as the Q-slope problem, since their invention. We argue that the Q-slope may
not be an intrinsic problem, but rather originates from a combination of
factors which can be revealed in appropriate environmental conditions. In this
study, extrinsic effects were carefully minimized in a series of experiments on
a seamless cavity. The origin of the Q-slope in low frequency cavities is
traced back to two contributions with different temperature and magnetic field
dependences. The first component of Q-slope, affecting the residual resistance,
is caused by trapped magnetic flux which is normally suppressed by a magnetic
shield for bulk niobium cavities. The second, temperature dependent component
of Q-slope, is similar to the medium-field Q-slope which is well known in bulk
niobium cavities. These results are compared with theoretical models and
possible future studies are proposed.

18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga