Precision Measurement of the Relative Gamma-Ray Intensities Following the Decay of <sup>61</sup>Cu
ORAL
Abstract
A discrepancy, well outside reported uncertainties, has been observed between the accepted and measured intensity ratios of the two strongest gamma rays following 61Cu β decay. This discrepancy has significant impact since the natNi(d,x)61Cu reaction has historically been one of the few IAEA recommendations for use as a deuteron flux monitor. A considerable number of published cross sections measured in ratio to that beam monitor cross section may depend on the choice of using either the first or second strongest gamma ray in those calculations. To determine the magnitude of this error most precisely, over a hundred separate measurements of the 283 keV to 656 keV gamma-ray emission ratio were collected from seven experiments and a variety of detectors and detection geometries. A weighted average of these ratios indicates an 11% error in the value listed in the Nuclear Data Sheets, most probably in the second-highest intensity gamma ray, 656 keV. This has potentially introduced an 11% error in 61Cu production cross section measurements, cross sections using nickel activation as a deuteron beam current monitor, and/or in dose rates when 61Cu is used in nuclear medicine.
*This work was performed under the auspices the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344 and Lawrence Berkeley National Laboratory under Contract No. DE-AC02-05CH11231. This research is supported by the U.S. Department of Energy Isotope Program, managed by the Office of Science for Nuclear Physics.
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Publication: D. L. Bleuel, L. A. Bernstein, R. A. Marsh, J. T. Morrell, B. Rusnak, A. S. Voyles, "Precision measurement of relative gamma-ray intensities from the decay of Cu-61," Appl. Radiat. Isot., 170, 109625 (2021). DOI: 10.1016/j.apradiso.2021.109625
Presenters
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Darren L Bleuel
- Lawrence Livermore Natl Lab