Searching for light-dark matter with Spherical Proportional Counters

The precise particle nature of dark matter, which makes up most of the matter in the universe, remains elusive and is one of the leading open questions in physics. The NEWS-G collaboration is searching for light dark matter candidates with a novel gaseous detector concept, the spherical proportional counter. Access to the mass range from 0.05 to 10 GeV is enabled by the combination of low energy threshold, light gaseous targets (H, He, Ne), and highly radio-pure detector construction. Initial NEWS-G results obtained with SEDINE, a 60 cm in diameter spherical proportional counter operating at LSM (France), excluded for the first time WIMP-like dark matter candidates down to masses of 0.5 GeV. The collaboration currently operates a 140 cm in diameter spherical proportional counter, SNOGLOBE, constructed at LSM using 4N copper with 500 um electroplated inner layer, which is currently collecting data in SNOLAB (Canada). This seminar will discuss recent NEWS-G results and the developments in spherical proportional counter instrumentation and detector understanding that contributed to the first results with SNOGLOBE from its commissioning data. The next stage of the experiment, using detectors constructed from ultra-pure electroformed copper directly in the underground laboratory where they will be operated will be presented, with the construction of a 30 cm in diameter detector commencing this year in the Boulby underground laboratory, and the plans to construct a larger scale detector, DarkSPHERE - with both detectors having the potential to break new ground in the dark matter puzzle.