First results from the NEWS-G direct dark matter search experiment at the LSM

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 Ne + CH4 (0.7%) at 3.1 bars for a total exposure of 9.6 kg. days. New constraints are set on the spin-independent WIMP-nucleon scattering cross-section in the sub-GeV/c(2) mass region. We exclude cross-sections above 4.4 x 10(-37) cm(2) at 90% confidence level (C.L.) for a 0.5 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. (C) 2017 Elsevier B.V. All rights reserved.