• Miley, Harry S.
• Aalseth, Craig E.
• Day, Anthony R.
• Farmer, Orville T.
• Seifert, Allen
• Warren, Glen A.
• Mcintyre, Justin I.
• Miller, Erin A.
• Fast, Jim E.
• Hoppe, Eric W.
• Hossbach, Todd W.
• Litke, Kevin E.

Abstract

Ultra-pure materials are needed for the construction of the next generation of ultra-low level radiation detectors. These detectors are used for environmental research as well as rare nuclear decay experiments, e.g. probing the effective mass and character of the neutrino. Unfortunately, radioactive isotopes are found in most construction materials, either primordial isotopes, activation/spallation products from cosmic-ray exposure, or surface deposition of dust or radon progeny. Copper is an ideal candidate material for these applications. High-purity copper is commercially available and, when even greater radiopurity is needed, additional electrochemical purification can be combined with the final construction step, resulting in “electroformed” copper of extreme purity. Copper also offers desirable thermal, mechanical, and electrical properties. To bridge the gap between commercially-available high purity copper and the most stringent requirements of next-generation low-background experiments, a method of additional chemical purification is being developed based on well-known copper electrochemistry. This method is complemented with the co-development of surface cleaning techniques and more sensitive assay for both surface and bulk contamination. Developments in the electroplating of copper, surface cleaning, assay of U and Th in the bulk copper, and residual surface contamination will be discussed relative to goals of less than 1 microBq/kg Th.

Topics

• Deposition
• impedance spectroscopy
• surface
• experiment
• laser emission spectroscopy
• copper
• activation