Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Polarisation and Polarimetry at HERA   Longitudinal polarisation of the lepton beam is a key ingredient to the
success of the world's unique e\pmp ring collider HERA. This article aims at
providing a brief introduction to the physics motivation for deep-inelastic
scattering of polarised electrons or positrons off protons, the basic
mechanisms to establish lepton polarisation in the high-energy storage ring and
to describe briefly the three different polarimeters, which measured both the
transverse and the longitudinal polarisation.

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The categories of this paper are: cs
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The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: astro-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
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The categories of this paper are: dg-ga