Measurement of cross sections for thermal neutron capture and the (n, 2n) reaction of231Pa

Abstract

The cross sections of both thermal neutron capture and the (n, 2n) reaction for231Pa target have been determined by using gamma-ray and alpha-ray spectrometric methods following irradiation with neutrons possessing purely thermalized and fission-type reactor spectrum, respectively. Prior to the irradiation, a pre-chemical purification was applied to ensure the accurate determination of the target nuclide,231Pa. For the sake of alpha-spectrometric determination of the daughter230U, decayed out from parent230Pa, the chemical purification of uranium was also applied to the alpha-source preparation from the reactor-irradiated231Pa. The activity ratio of230U to232U was converted to an initial formation ratio of230Pa to232U and followed by an evaluation of cross section. The cross section value for the231Pa (n,γ)232Pa reaction process was estimated to be 186±13 barn for purely thermal neutrons. The231Pa(n, 2n)230Pa cross section value is 4.12±0.32 mbarn for fission type neutrons.