Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct measurement of neutrons induced in lead by cosmic muons at a
  shallow underground site   Neutron production in lead by cosmic muons has been studied with a Gadolinium
doped liquid scintillator detector. The detector was installed next to the
Muon-Induced Neutron Indirect Detection EXperiment (MINIDEX), permanently
located in the T\"ubingen shallow underground laboratory where the mean muon
energy is approximately 7 GeV. The MINIDEX plastic scintillators were used to
tag muons; the neutrons were detected through neutron capture and
neutron-induced nuclear recoil signals in the liquid scintillator detector.
Results on the rates of observed neutron captures and nuclear recoils are
presented and compared to predictions from GEANT4-9.6 and GEANT4-10.3. The
predicted rates are significantly too low for both versions of GEANT4. For
neutron capture events, the observation exceeds the predictions by factors of $
1.65\,\pm\,0.02\,\textrm{(stat.)}\,\pm\,0.07\,\textrm{(syst.)} $ and $
2.58\,\pm\,0.03\,\textrm{(stat.)}\,\pm\,0.11\,\textrm{(syst.)} $ for GEANT4-9.6
and GEANT4-10.3, respectively. For neutron nuclear recoil events, which require
neutron energies above approximately 5 MeV, the factors are even larger, $
2.22\,\pm\,0.05\,\textrm{(stat.)}\,\pm\,0.25\,\textrm{(syst.)} $ and $
3.76\,\pm\,0.09\,\textrm{(stat.)}\,\pm\,0.41\,\textrm{(syst.)} $, respectively.
Also presented is the first statistically significant measurement of the
spectrum of neutrons induced by cosmic muons in lead between 5 and 40 MeV. It
was obtained by unfolding the nuclear recoil spectrum. The observed neutron
spectrum is harder than predicted by GEANT4. An investigation of the
distribution of the time difference between muon tags and nuclear recoil
signals confirms the validity of the unfolding procedure and shows that GEANT4
cannot properly describe the time distribution of nuclear recoil events. In
general, the description of the data is worse for GEANT4-10.3 than for
GEANT4-9.6.

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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: math-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th