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The thermal neutron cross section ( σ 0 ) and the resonance integral ( I 0 ) of the reaction 170 Er(n, γ) 171 Er were measured by an activation method using a reaction 197 Au(n, γ) 198 Au as a single comparator. The high-purity natural erbium ( nat Er) and gold ( 197 Au) 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 170 Er(n, γ) 171 Er reaction has been determined to be σ 0 = 7.80 ± 0.35 barn, relative to the reference value of 98.65 ± 0.09 barn for the 197 Au(n, γ) 198 Au reaction. By assuming the cadmium cut-off energy of 0.55 eV, the resonance integral for the 170 Er(n, γ) 171 Er reaction is I 0 = 40.4 ± 2.8 barn, which is determined relative to the reference value of 1550 ± 28 barn for the 197 Au(n, γ) 198 Au reaction. In order to improve the accuracy of the experimental results the epithermal neutron spectrum shape factor ( α ) was determined, and the necessary corrections for the counting loss caused by γ-ray attenuation ( F g ), the thermal neutron shelf-shielding ( G th ), the resonance neutron self-shielding ( G epi ) effects, the γ-ray coincidence summing effect, as well as neutron flux fluctuation. The present results are compared with the reference data and discussed. |
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