A Method for Electroforming Copper with Ultra-Low Levels of Radioactivity

75803S The search for rare events, such as double beta decay and dark matter, requires large masses of detectors and support materials. These extremely rare events are difficult to distinguish from other interactions caused by the radioactive decay of radionuclides contained in these materials. Therefore, if these materials could be made virtually free of radioactive contamination, the probability of successful searches would be enhanced. In this project, the radiopurity of one such material, electroformed copper, will be enhanced by using an already pure form of copper, oxygen-free high conductivity (OFHC) copper, which is electroplated in baths assembled from ultra-pure chemicals and construction materials. By performing the electroplating deep underground, cosmic-ray-induced radioactivity, which would otherwise be present in the copper, can be radically reduced. Other metals could be produced in a similar manner. In Phase I, an underground copper electroplating laboratory was constructed and outfitted with plating baths made from very pure plastics and high purity chemicals. It was shown that ultra-pure copper, collected on the cathodes of one bath, could be used as anodes in a second bath, thus progressively increasing the purity of the final product. In Phase II, techniques will be developed for testing the plating bath and the quality of the copper produced. Methods will be developed to continually clean the bath of radioactive contaminants thus prolonging the useful life of the bath. Two tons of copper will produced for use as inner shielding for ultra-low background detectors. Commercial Applications And Other Benefits as described by the awardee: The high purity material would have applicability to research projects in nuclear physics and other sciences.