Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Polarized positron production at MeV electron accelerators   The Polarized Electrons for Polarized Positrons (PEPPo) experiment has
demonstrated the efficient transfer of polarization from electrons to positrons
produced by the bremsstrahlung radiation of a polarized electron beam in a
high-$Z$ target. Positron polarization up to 82\% has been measured for an
initial electron beam momentum of 8.19 MeV/$c$, limited only by the electron
beam polarization. Combined with the high intensity and high polarization
performances of polarized electron sources, this technique extends efficient
polarized positron capabilities from GeV to MeV electron accelerators. This
presentation reviews the PEPPo proof-of-principle experiment and addresses the
perspectives for future applications.

17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas