Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiphoton Double Ionization of Helium at 394nm - a Fully Differential
  Experiment   We report on a kinematically complete experiment on strong field double
ionization of helium using laser pulses with a wavelength of 394\,nm and
intensities of $3.5-5.7\times10^{14}\,W/cm^2$. Our experiment reaches the most
complete level of detail which previously has only been reached for single
photon double ionization. We give an overview over the observables on many
levels of integration, starting from the ratio of double to single ionization,
the individual electron and ion momentum distributions over joint momentum and
energy distributions to fully differential cross sections showing the
correlated angular momentum distributions. Within the studied intensity range
the ratio of double to single ionization changes from $2\times 10^{-4}$ to
$1.5\times 10^{-3}$. We find the momentum distributions of the $\rm{He}^{2+}$
ions and the correlated two electron momentum distributions to vary
substantially. Only at the highest intensity both electrons are emitted to the
same direction while at the lowest intensity back-to-back emission dominates.
The joint energy distribution of the electrons shows discrete structures from
the energy quantization of the photon field which allows us to count the number
of absorbed photons and thus access the parity of the final state. We find the
energy of the individual electron to show a peak structure indicating a
quantized sharing of the overall energy absorbed from the field. The joint
angular momentum distributions of the two electrons show a highly directed
emission of both electrons along the polarization axis as well as clear
imprints of electron repulsion. They strongly change with the energy sharing
between the electrons. The aspect of selection rules in double ionization which
are also visible in the presented dataset has been subject to a preceding
publication [1].

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The categories of this paper are: stat
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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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
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ph