Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Creation of ensembles of nitrogen-vacancy centers in diamond by neutron
  and electron irradiation   We created dense ensembles of negatively charged nitrogen-vacancy (NV-)
centers in diamond by neutron and electron irradiation for applications in
hybrid quantum systems and magnetometry. We characterize fluorescence
intensity, optical and coherence properties of the resulting defects by
confocal microscopy, UV/Vis and FTIR spectroscopy, optically detected magnetic
resonance and small angle X-ray scattering. We find the highest densities of
NV- at neutron fluences on the order of 10^17 cm^-2 and electron doses of 10^18
cm^-2, with spin resonance linewidths of 6 MHz. Lower electron energies
increase the ratio of centers in the desired negative charge state to those in
the neutral one. Annealing at 900 {\deg}C during the irradiation reduces the
spin resonance linewidth. Electron irradiation furthermore results in
substantially higher optical transparency compared to neutron irradiation.

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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: physics
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The categories of this paper are: nlin
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The categories of this paper are: hep-lat
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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: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: eess