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

75803-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 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 will be constructed and outfitted with plating baths that are made from very pure plastics that use high purity chemicals purified even further by the repeated dissolution/re-precipitation of copper salts. Ultra-pure copper, collected on the cathodes of one bath, will be used as anodes in a second bath, progressively increasing the purity of the final product. One hundred kilograms of copper metal will be produced for testing. 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.