Nuclear constants for use in reactor activation analysis especially (n, γ) cross-sections and absolute gamma intensities, are known to show a rather large scatter in literature. Thermal and resonance cross-sections for the 75As (n, γ)76As reaction is determined by the method of foil activation using 55Mn (n, γ)56Mn as a reference reaction. The experimental sample with and without a cadmium cover of 1-mm wall thickness was irradiated in the isotropic neutron field of the outer irradiation sites 7 of Ghana Research Reactor-1 facility which is a miniature neutron source reactor designed by the Chinese. The irradiation channel used has a neutron spectral parameter (α) found to be (0.037 ± 0.001). The induced activity in the sample was measured by gamma ray spectrometry with a high purity germanium detector. A standard solution of Arsenic was used for the analysis. The necessary correction for gamma attenuation, thermal neutrons and resonance neutron self-shielding effects were not taken into account during the experimental analysis because they were negligible. By defining cadmium cut-off energy of 0.55 eV, the result for 75As (n, γ)76As reaction was found to be: thermal neutron cross-section σ0 = (4.28 ± 0.19) b and resonance integral I0 = (61.88 ± 1.07) b.
Source/Report: Nuclear Engineering and Design; v. 240(5); ISSN 0029-5493; ; CODEN NEDEAU; May 2010; p. 980-984; S0029-5493(10)00006-3; Available from http://dx.doi.org/10.1016/j.nucengdes.2009.12.020; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Publ. Year: 2010