Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrahigh-density spin-polarized H and D observed via magnetization
  quantum beats   We measure nuclear and electron spin-polarized H and D densities of at least
10$^{19}\, cm^{-3}$ with $\sim$10 ns lifetimes, from the photodissociation of
HBr and DI with circularly-polarized UV light pulses. This density is $\sim$6
orders of magnitude higher than that produced by conventional
continuous-production methods, and, surprisingly, at least 100 times higher
than expected densities for this photodissociation method. We observe the
hyperfine quantum beating of the H and D magnetization with a pick-up coil,
i.e., the respective 0.7 and 3 ns periodic transfer of polarization from the
electrons to the nuclei and back. The $\rm{10^{19}\,cm^{-3}}$ spin-polarized H
and D density is sufficient for laser-driven ion acceleration of spin polarized
electrons, protons, or deuterons, the preparation of nuclear-spin-polarized
molecules, and for the demonstration of spin-polarized D-T or D-$\rm{{^3He}}$
laser fusion, for which a reactivity enhancement of $\rm{\sim50\%}$ is
expected.

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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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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: bayes-an
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The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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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: cond-mat
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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph