Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New mechanism of X-ray radiation from a relativistic charged particle in
  a dielectric random medium   We have considered X-ray radiation of a relativistic charged particle moving
in a system consisting of microspheres distributed randomly in a dielectric
material. A new mechanism based on the diffusional scattering of pseudophotons
is suggested. The result leads to a stronger dependence of radiation intensity
on the particle energy, than that predicted by the traditional transition
radiation theory,and explains a recent experiment on such a system of randomly
distributed superconducting granules.

35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci