Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurements of the ionization efficiency of protons in methane   The amount of energy released by a nuclear recoil ionizing the atoms of the
active volume of detection appears "quenched" compared to an electron of the
same kinetic energy. This different behavior in ionization between electrons
and nuclei is described by the Ionization Quenching Factor (IQF) and it plays a
crucial role in direct dark matter searches. For low kinetic energies (below
$50~\mathrm{keV}$), IQF measurements deviate significantly from theoretical
predictions and simulations. We report measurements of the IQF for protons with
kinetic energies in between $2~\mathrm{keV}$ and $13~\mathrm{keV}$ in
$100~\mathrm{mbar}$ of methane. We used the Comimac facility in order to
produce the motion of nuclei and electrons of controlled kinetic energy in the
active volume, and a NEWS-G SPC to measure the deposited energy. The Comimac
electrons are used as reference to calibrate the detector with 7 energy points.
A detailed study of systematic effects led to the final results well fitted by
$\mathrm{IQF}~(E_K)= E_K^\alpha~/~(\beta + E_K^\alpha)$ with
$\alpha=0.69\pm0.08$ and $\beta = 1.31\pm0.17$. In agreement with some previous
works in other gas mixtures, we measured less ionization energy than predicted
from SRIM simulations, the difference reaching $33\%$ at $2~\mathrm{keV}$

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The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-lat