Measurement of keV-neutron capture cross-sections and capture γ-ray spectra of 56Fe and 57Fe

The neutron capture cross-sections and the capture gamma-ray spectra of Fe-56 and Fe-57 have been measured in the neutron energy range from 10 to 90 keV. Pulsed key-neutrons were produced from the Li-7(p,n)Be-7 reaction by bombarding a lithium target with a 1.5-ns bunched proton beam from a 3 MV Pelletron accelerator. The incident neutron spectrum on the capture sample was measured using a time-of-flight method with a Li-6-glass detector. The capture gamma-rays emitted from an iron or standard gold sample were detected with a large anti-Compton Nal(Tl) spectrometer. The capture yield of the iron or gold sample was obtained by applying a pulse-height weighting technique to the corresponding capture gamma-ray pulse-height spectrum. The capture cross-sections of Fe-56,Fe-57 were derived with errors less than 5% using the standard capture cross-sections of Au-197. The capture gamma-ray spectra were obtained by unfolding the observed capture gamma-ray pulse-height spectra. The present results for the capture cross-sections were compared with the previous measurements and the evaluated values of ENDF/B-VII.0 and JENDL-3.3. The Maxwellian-averaged capture cross-sections of Fe-56 and Fe-57 at 30 key are derived as 12.22 +/- 2.06 mb and 44.48 +/- 7.56 mb, respectively. (C) 2009 Elsevier B.V. All rights reserved.