Reduction of radioactive backgrounds in electroformed copper for ultra-sensitive radiation detectors

Abstract Ultra-pure construction materials are required for the next generation of neutrino physics, dark matter and environmental science applications. These new efforts require materials with purity levels at or below 1 uBq/kg 232Th and 238U. Yet radiometric analysis lacks sensitivity below ~10 uB...

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Bibliographic Details
Published in:Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2014-11, Vol.764, p.116-121
Main Authors: Hoppe, E.W., Aalseth, C.E., Farmer, O.T., Hossbach, T.W., Liezers, M., Miley, H.S., Overman, N.R., Reeves, J.H.
Format: Article
Language:English
Subjects:
COPPER
ELECTRODEPOSITION
electroforming
ICP-MS
low background
NUCLEAR FUEL CYCLE AND FUEL MATERIALS
THORIUM
URANIUM
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Summary:Abstract Ultra-pure construction materials are required for the next generation of neutrino physics, dark matter and environmental science applications. These new efforts require materials with purity levels at or below 1 uBq/kg 232Th and 238U. Yet radiometric analysis lacks sensitivity below ~10 uBq/kg for the U and Th decay chains. This limits both the selection of clean materials and the validation of purification processes. Copper is an important high-purity material for low-background experiments due to the ease with which it can be purified by electrochemical methods. Electroplating for purification into near-final shapes, known as electroforming, is one such method. Continued refinement of the copper electroforming process is underway, for the first time guided by an ICP-MS based assay method that can measure 232Th and 238U near the desired purity levels. An assay of electroformed copper at 10 uBq/kg for 232Th has been achieved and is described. The implications of electroformed copper at or better than this purity on next-generation low-background experiments are discussed.
ISSN:0168-9002
1872-9576
DOI:10.1016/j.nima.2014.06.082