Measurement of thermal neutron cross-sections and integrals for Hf-179(n,gamma)Hf-180m and Hf-180(n,gamma)Hf-181 reaction at the Pohang neutron facility

Abstract

The thermal-neutron cross-sections and the resonance integrals for the Hf-179(n,gamma)Hf-180m and the Hf-180(n,gamma)Hf-181 reactions have been measured by the activation method. The high purity Hf and Au metallic foils within and without a Cd shield case were irradiated in a neutron field of the Pohang neutron facility. The gamma-ray spectra from the activated foils were measured with a calibrated p-type high-purity Ge detector. In the experimental procedure, the thermal neutron cross-sections, sigma(0), and resonance integrals, I-0, for the Hf-179(n,gamma)Hf-180m and the Hf-180(n,gamma)Hf-181 reactions have been determined relative to the reference values of the Au-197(n,gamma)Au-198 reaction, with sigma(0) = 98.65 +/- 0.09 barn and I-0 = 1550 +/- 28 barn. In order to improve the accuracy of the experimental results, the interfering reactions and necessary correction factors were taken into account in the determinations. The obtained thermal neutron cross-sections and resonance integrals were sigma(0) = 0.424 +/- 0.018 barn and I-0 = 6.35 +/- 0.45 barn for the Hf-179(n,gamma)Hf-180m reaction, and sigma(0) = 12.87 +/- 0.52 barn and I-0 = 32.91 +/- 2.38 barn for the Hf-180(n,gamma)Hf-181 reaction. The present results are in good agreement with recent measurements. (C) 2007 Elsevier B.V. All rights reserved.