Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Redesigning the Jefferson Lab Hall A Beam Line for High Precision Parity
  Experiments   The Continuous Electron Beam Accelerator Facility (CEBAF) was built with a
thermionic electron source and the three original experimental hall lines
reflected this. A few years after beam delivery began a parity violation
experiment was approved and two polarimeters were installed in the Hall A beam
line without consultation with the accelerator physics group. The beam raster
system was placed after the new Compton polarimeter, before one accelerator
quadrupole and four quadrupoles in the new Moller polarimeter. It was very
difficult to meet experimental requirements on envelope functions and raster
shape with this arrangement so a member of the accelerator physics group had a
sixth quadrupole installed downstream of the Moller polarimeter. All of the
parity experiments in Hall A have been run with this still-unsatisfactory
configuration. The MOLLER experiment is predicated on achieving a 2% error on a
32 ppb asymmetry. Beam line changes are required to meet the systematic error
budget. This paper documents the existing beam line, an interim change which
can be accomplished during a annual maintenance down, and the final
configuration for MOLLER and subsequent experiments.

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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
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The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: econ
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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