Measurement of thermal neutron cross section and resonance integral for the Er-170(n,gamma)Er-171 reaction by using a gold monitor

Abstract

The thermal neutron cross section (sigma(0)) and the resonance integral (I-0) of the reaction Er-170(n,gamma)Er-171 were measured by an activation method using a reaction Au-197(n,gamma)Au-198 as a single comparator. The high-purity natural erbium (Er-nat), and gold (Au-197) foils with and without Cd cover with the thickness of 0.5 mm were irradiated in a neutron field of the Pohang neutron facility. The induced activities in the activated foils were measured with a well calibrated coaxial HPGe detector. The thermal neutron cross section for the Er-170(n,gamma)Er-171 reaction has been determined to be sigma(0) = 7.80 +/- 0.35 barn, relative to the reference value of 98.65 +/- 0.09 barn for the Au-197(n,gamma)Au-198 reaction. By assuming the cadmium cutoff energy of 0.55 eV, the resonance integral for the Er-170(n,gamma)Er-171 reaction is I-0 = 40.4 +/- 2.8 barn, which is determined relative to the reference value of 1550 +/- 28 barn for the Au-197(n,gamma)Au-198 reaction. In order to improve the accuracy of the experimental results the epithermal neutron spectrum shape factor (alpha) was determined, and the necessary corrections for the counting loss caused by gamma-ray attenuation (F-g), the thermal neutron shelf-shielding (G(th)), the resonance neutron self-shielding (G(epi)) effects, the gamma-ray coincidence summing effect, as well as neutron flux fluctuation. The present results are compared with the reference data and discussed. (C) 2013 Elsevier B.V. All rights reserved.