Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Covariant Formulation of the Transition Radiation Energy Spectrum of an
  Electron Beam at a Normal Angle of Incidence onto a Round Metallic Screen
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ