New Experiments With Spheres-Gas (NEWS-G) is a direct dark matter detection experiment using Spherical Proportional Counters (SPCs) with light noble gases to search for low-mass Weakly Interacting Massive Particles (WIMPs). We report the results from the first physics run taken at the Laboratoire Souterrain de Modane (LSM) with SEDINE, a 60 cm diameter prototype SPC operated with a mixture of $mathrm{Ne}+mathrm{CH}_{4}$ (0.7 %) at 3.1 bars for a total exposure of $9.7;mathrm{kgcdot days}$. New constraints are set on the spin-independent WIMP-nucleon scattering cross-section in the sub-$mathrm{GeV/c^2}$ mass region. We exclude cross-sections above $4.4 times mathrm{10^{-37};cm^2}$ at 90 % confidence level (C.L.) for a 0.5 $mathrm{GeV/c^2}$ WIMP. The competitive results obtained with SEDINE are promising for the next phase of the NEWS-G experiment: a 140 cm diameter SPC to be installed at SNOLAB by summer 2018.
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