Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Frequency-domain calculation of Smith-Purcell radiation for metallic and
  dielectric gratings   The intensity of Smith-Purcell radiation from metallic and dielectric
gratings (silicon, silica) is compared in a frequency-domain simulation. The
numerical model is discussed and verified with the Frank-Tamm formula for
Cherenkov radiation. For 30 keV electrons, rectangular dielectric gratings are
less efficient than their metallic counterpart, by an order of magnitude for
silicon, and two orders of magnitude for silica. For all gratings studied,
radiation intensity oscillates with grating tooth height due to electromagnetic
resonances in the grating. 3D and 2D numerical models are compared.

31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: nlin
1
The categories of this paper are: cs