Determination of the Pa-233(n, f) reaction cross section from 0.5 to 10 MeV neutron energy using the transfer reaction Th-232(He-3, p)Pa-234

摘要

The fission probability distributions of Pa-232,Pa-233,Pa- 234 and (231) Th have been measured up to an excitation energy of 15 MeV, using the transfer reactions Th-232(He-3, t)Pa-232, Th-232(He-3, d)Pa-233 Th-232(He-3, p)Pa-234 and Th-232(He-3, He-4)(231) Th. From these measurements, the neutron induced fission cross sections of Pa-231, Pa-233 and Th-230 have been determined from the product of the fission probabilities of Pa-232, Pa-233 and Th-231 respectively with the calculated compound nucleus formation cross sections in the Pa-231 +n, Pa-233+n and Th-230 +n reactions. The validity of the applied method has been successfully tested with the existing neutron induced fission cross sections of Th-230 and Pa-231. Special emphasis is put on the Pa-233(n, f) reaction which is of importance for thorium fueled nuclear reactors. Based on a statistical model analysis of the neutron induced fission cross section as a function of neutron energy, it has been possible to determine the barrier parameters of the Pa-234 fissioning nucleus. Cross sections for the compound nucleus inelastic scatttering (233)pa(n, n') and radiative capture Pa-233(n, y) reactions have also been calculated and compared with recent evaluations. (C) 2004 Elsevier B.V. All rights reserved.