Recent advancements of the NEWS-G experiment (2004.12795v1)

Abstract: NEWS-G (New Experiments With Spheres-Gas) is an experiment aiming to shine a light on the dark matter conundrum with a novel gaseous detector, the spherical proportional counter. It uses light gases, such as hydrogen, helium, and neon, as targets to expand dark matter searches to the sub-GeV/c$^{2}$ mass region. NEWS-G produced its first results with a 60 cm in diameter detector installed at LSM (France), excluding at 90% C.L. cross-sections above $4.4\cdot{10}^{37}$ cm$^{2}$ for dark matter candidates of 0.5 GeV/c$^{2}$ mass. Currently, a 140 cm in diameter detector is being built at LSM and a commissioning run is underway, prior to its installation at SNOLAB (Canada) at the end of the year. Presented here are developments incorporated in this new detector: a) sensor technologies using resistive materials and multi-anode read-out that allow high gain and high pressure operation; b) gas purification techniques to remove contaminants (H${2}$O, O${2}$); c) reduction of ${}^{210}$Pb induced background through copper electroforming methods; d) utilisation of UV-lasers for detector calibration, detector response monitoring and estimation of gas related fundamental properties. This next phase of NEWS-G will allow searches for low mass dark matter with unprecedented sensitivity.