Speaker
Description
Rare-event search experiments, for example those looking for dark matter and neutrinoless double beta decay, require increasingly sensitive detectors. A critical aspect of this is the reduction of backgrounds from detector materials, especially those in contact with the sensitive volume. High-grade copper is an attractive construction choice, due to its commercial availability and lack of long-lived radioisotopes. Despite this, copper can still represent a dominant background, with impurities from the ore, implanted during manufacture or from cosmogenic activation. Underground additive-free electroforming provides a method to produce ultra-pure copper parts with orders of magnitude reduction in background. This contribution will describe a copper electrodeposition facility constructed at Boulby, the UK’s deep underground laboratory, and show first results of electroformed copper which is critical for several future experiments. One such experiment DarkSPHERE, a large diameter spherical proportional counter, will be presented along with the near-term plan to electroform a 30cm spherical proportional counter as the first step towards its construction.