Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Experiments with Parametric X-Ray Radiation (PXR) from Non-Relativistic
  Electrons   Interaction of non-relativistic electrons with single crystal target may
produce coherent x-rays. That is the result of interference between two known
x-ray generation mechanisms having orientational behavior, namely parametric
x-rays and coherent {\it Bremsstrahlung}. Experiments aimed to PXR research
were performed with 50-100 keV electrons and its distinctive features were
observed. Requirements to the experimental set-up, detector instrumental
response, and targets as well as experiment geometry are discussed in detail.
Series of PXR spectra in various conditions were recorded and their distinctive
features were observed. Tuning of radiation frequency with crystal-target
rotation was observed for the first time for low energy electrons. Dependence
of the x-ray frequency on the beam energy was detected. Soft PXR peak with
energy below 1 keV was observed for the first time. Possible applications of
PXR for structure analysis and crystallography are discussed. These results are
obtained in the framework of ISTC project {#}B626

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The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph