The NEWS-G light dark matter experiment: Results with a hydrogen-rich target

The NEWS-G direct detection experiment employs Spherical Proportional Counters (SPCs) with light atom gas mixtures to search for low-mass Dark Matter (DM). NEWS-G has already set competitive constraints on spin-independent interactions at the Laboratoire Souterrain de Modane (LSM), and is commissioning a new 140 cm diameter SPC at SNOLAB in Sudbury, Canada, with improved shielding, sensor technology, and radio-pure construction. Earlier in development, this SPC was operated at the LSM with a 135 mbar methane target gas for a limited physics campaign. This hydrogen rich target allows for sensitivity to DM particle masses of approximately 100 MeV/c². Robust calibrations of the detector response to single-electron ionizations are necessary to exploit this potential, which is done primarily with a UV laser and ³⁷Ar. These and other preliminary results will be presented, as well as an overview of the experimental setup.