Thermal neutron cross-section and resonance integral for 164Dy(n,γ) 165Dy reaction

Abstract

The thermal neutron cross-section ( σ 0) and the resonance integral ( I 0) of the reaction 164Dy(n,γ) 165Dy were measured by the activation method, using 55Mn(n,γ) 55Mn monitor reaction as a single comparator. The diluted MnO 2 and Dy 2O 3 powder samples within and without a cylindrical Cd shield case were irradiated in an isotropic neutron field obtained from the 241Am–Be neutron sources, moderated with paraffin wax. The γ-ray spectra from the irradiated samples were measured by high-resolution γ-ray spectrometry with a calibrated n-type Ge detector. The necessary correction factors for γ-ray attenuation, thermal neutron and resonance neutron self-shielding effects and epithermal neutron spectrum shape factor (α) were taken into account in the determinations. The thermal neutron cross-section for 164Dy(n,γ) 165Dy reaction studied has been determined to be 2672±104 b at 0.025 eV. This result has been obtained relative to the reference thermal neutron cross-section value of 13.3±0.1 b for the 55Mn(n,γ) 56Mn reaction. For the thermal neutron cross-section, most of the experimental data and evaluated one in ENDF/B-VI, in general, are in good agreement with the present result. The resonance integral has also been measured relative to the reference value of 14.0±0.3 b for the 55Mn(n,γ) 56Mn monitor reaction using a 1/ E 1+ α epithermal neutron spectrum of the 241Am–Be neutron source. By defining Cd cut-off energy 0.55 eV, the resonance integral obtained was 527±89 b. The existing experimental and evaluated data for the resonance integral are distributed from 335 to 820 b. The present resonance integral value agrees with some previously reported values, 520 b by Holden, 505 b by Simonits et al. and 575±100 b by Heft, within the limits of error.