Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: More on the Interaction Region of PEP-N   The PEP-N project consists of a small, very low-energy e- storage ring (VLER)
located in one of the interaction-straight regions of PEP-II. The small ring is
brought into collision with the low-energy (3.1 GeV) e+ beam (LER). The
center-of-mass energies from this collision are between the Phi and J/Psi
resonances. We achieve a head-on collision through the use of a central
magnetic dipole field that generates a large horizontal bending field. This
field is also the central field of the detector. The large energy range of the
VLER, in order to maximize the center-of-mass energy range, complicates the
collision point geometry. In order to maintain the beam orbits near the
collision point two techniques are used. The first is to scale the central
dipole field up and down with the energy of the VLER and the second is to use
passive shielding to decrease the integral B.dl of the dipole field seen by the
VLER. Changes in the orbit of the LER are corrected with local bending magnets.
Further details of the interaction region geometry as well as design issues
that include synchrotron radiation from the high-current positron beam are
discussed.

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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: bayes-an
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The categories of this paper are: physics
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: astro-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: math-ph