Measurement of Activation Cross Sections Producing Short-Lived Nuclei with Pulsed Neutron Beam

Abstract

Activation cross sections for the (n, n′) reaction were measured by means of the activation method at the neutron energies of 3.1 and 2.54 MeV by using a pulsed neutron beam. Target nuclei were 79Br, 90Zr, 197Au, and 207Pb, whose half‐lives were between 0.8 and 8 s. The cross section for the 90Zr (n, n′) 90mZr reaction was obtained for the first time in this energy range. The d‐D neutrons were generated by bombarding a deuterated titanium target with a 350‐keV d+ beam at the 80‐degree beam line of the Fusion Neutronics Source at the Japan Atomic Energy Research Institute. In order to obtain reliable activation cross sections, careful attention was paid to correct the efficiency for a volume source, and the self‐absorption of gamma rays in an irradiated sample. The systematics of the (n, n′) reaction at the neutron energy of 3.1 MeV, which could be predicted within an accuracy of 50%, was proposed on the basis of our data.