Search Results

You are looking at 1 - 2 of 2 items for :

  • Author or Editor: T. Day x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All Modify Search
Journal of Radioanalytical and Nuclear Chemistry
Authors: E. Hoppe, A. Seifert, C. Aalseth, A. Day, O. Farmer, T. Hossbach, J. McIntyre, H. Miley, J. Smart, and G. Warren

Abstract  

Spectrometers for the lowest-level radiometric measurements require materials of extreme radiopurity. Measurements of rare nuclear decays, e.g., neutrinoless double-beta decay, can require construction and shielding materials with bulk radiopurity reaching one micro-Becquerel per kilogram or less. When such extreme material purity is achieved, surface contamination, particularly solid daughters in the natural radon decay chains, can become the limiting background. High-purity copper is an important material for ultra-low-background spectrometers and thus is the focus of this work. A method for removing surface contamination at very low levels without attacking the bulk material is described. An assay method using a low-background proportional counter made of the material under examination is employed, and the preliminary result of achievable surface contamination levels is presented.

Restricted access

Abstract  

The search for neutrinoless double beta decay in 76Ge has driven the need for ultra-low background Ge detectors shielded by electroformed copper of ultra-high radiopurity (<0.1 μBq/kg). Although electrodeposition processes are almost sophisticated enough to produce copper of this purity, to date there are no methods sensitive enough to assay it. Inductively coupled plasma mass spectrometry (ICP/MS) can detect thorium and uranium at femtogram levels, however, this assay is hindered by high copper concentrations in the sample. Electrodeposition of copper samples removes copper from the solution while selectively concentrating thorium and uranium contaminants to be assayed by ICP/MS. Spiking 232Th and 238U into the plating bath simulates low purity copper and allows for the calculation of the electrochemical rejection rate of thorium and uranium in the electroplating system. This rejection value will help to model plating bath chemistry.

Restricted access