Gas and copper purity investigations for NEWS-G

Abstract

Abstract In the search for low mass dark matter particles the NEWS-G collaboration utilises the spherical proportional counter, a novel detector concept. Currently, the next stage of the experiment, NEWS-G@SNOLAB, is under preparation. The choice and processing of construction materials and gases are of paramount importance for the minimisation of experimental backgrounds. The effect of impurities on detector performance, both regarding the gas and construction materials, is presented and the efforts undertaken to maximise the sensitivity of the experiment are discussed. In particular, the method of electroplating a cladding-type ultra-pure copper layer on the inner surface of the detector is detailed and preliminary results are presented.