Precision measurement of relative <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e5861" altimg="si78.svg"><mml:mi>γ</mml:mi></mml:math>-ray intensities from the decay of 61Cu

A discrepancy, well outside reported uncertainties, has been observed between the accepted and measured values of intensity ratio two strongest γ rays following 61Cu β+ decay. This discrepancy significant impact since natNi(d,x)61Cu reaction historically one only a few IAEA recommendations for use as deuteron flux monitor considerable number published cross sections in to that beam section may depend on choice either first or second ray those calculations. To determine magnitude this error most precisely, over hundred separate measurements 283 keV 656 γ-ray emission were collected from seven experiments variety detectors detection geometries. weighted average all these indicates an value listed Nuclear Data Sheets 11% primary second-highest 61Cu, potentially introducing production measurements, using nickel activation current monitor, dose rates when is used nuclear medicine. General agreement with ten other ratios suggests probable secondary (656 keV) emission, which accordingly should be updated 10.8% 9.69%.