[en] It was shown that the k_0-method using the recently developed extended Hogdahl formalism for non-1/ν nuclides and neutron temperatures from thermocouple readings can give k_0-NAA results for Eu and Lu accurate to about 1 %. The necessary Q_0 and k_0 values for "1"5"1Eu(n,γ)"1"5"2Eu, "1"5"1Eu(n,γ)"1"5"2"mEu and "1"7"6Lu(n,γ)"1"7"7Lu were measured by reactor irradiation of certified standards and gamma-ray counting. The present measurements of k_0-values did not confirm the previously published values; they were higher by 6 % for "1"5"2Eu and by 16 % for "1"5"2"mEu. (author)

[en] In neutron activation analysis the sample to be analysed is counted with the same detection efficiency as the standard or else a correction factor is determined to correct for the difference. The components contributing to the uncertainty of the detection efficiency correction factor were identified and evaluated by using "1""2Ta gamma-rays for typical NAA samples counted 1 and 100 mm from the detector. Uncertainties as high as 20 % were found due to coincidence summing and gamma attenuation. It was shown how to incorporate these components into the NAA uncertainty budget. (author)