Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of circularly polarized photons for a linear collider
  polarized positron source   Various methods of obtaining longitudinally polarized positrons for future
linear colliders are reviewed. Special attention is paid to the schemes using
circularly polarized high-energy photons for positron production. Most
effectively such photons are obtained from electrons passing through a helical
undulator or colliding with a circularly polarized laser wave. Spectrum and
polarization of radiation emitted during helical motion of electrons are
considered in detail. A new simple presentation of known formulas is used to
account for the influence of the wave intensity, of the electron-beam angular
divergence, of the collimation of radiation, and of the lateral and temporal
profiles of the laser bunch on the radiation properties.

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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
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The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat