Measurement of Fission Product Yields and the Energy Integral Fission Cross Section of Thorium-232 in a Californium-252 Fission-Neutron Spectrum

The absolute cumulative fission yield of ¹⁴⁰Ba and the relative yields of ¹³¹I, ¹³²Te, and ¹⁴¹Ce were measured for ²³²Th irradiated in a ²⁵²Cf fission spectrum of neutrons. The irradiation was performed using two ²³²Th foils in contact with a nominal 1-mg ²⁵²Cf source in a large evacuated area for 41 days. The absolute yield of ¹⁴⁰Ba was deduced from an absolute measurement of its daughter product ¹⁴⁰La using a calibrated NaI(Tl) detector. The activities of ¹³¹I, ¹³²Te, and ¹⁴¹ Ce were measured relative to the 1596-ke V gamma ray of ¹⁴⁰La using a 43-cm³ Ge(Li) detector. The fission rate for the yield measurement and the integral fission cross section were measured using mica solid-state track recorders.