Determination of the absolute intensity of the 1205 keV γ-ray emission from 91Y.

ABSTRACT

A radiochemically pure solution of 91Y was produced by the thermal neutron fission of 235U followed by successive chemical separations to remove fission product impurities. The gamma emission rate of the 91Y 1205 keV gamma was measured using multiple high purity germanium gamma spectrometers previously calibrated for counting efficiency using a certificated mixed nuclide gamma standard. The activity concentration of the 91Y was subsequently standardised by liquid scintillation counting. From the combination the activity concentration and gamma emission intensity, the absolute intensity of the 1205 keV gamma emission was derived as 0.2297(39)%. This data agrees within the quoted uncertainties with the absolute intensity of 0.26(4)% published in nuclear data sheets A=91 (Baglin, 2013), but reduces the uncertainty by an order of magnitude.