Measurement Of Fission Cross Sections For ²³²Th（n,f）X Reaction Induced By Neutrons Around 14MeV

Fission reaction of 232 Th induced by neutrons around 14 MeV was studied using activation technique, and cross sections of fission fragments 89Rb、130Sb、134Te、138Xe、141Ba were measured as well. The experiment was performed using K-400 Intense Neutron Generator and HPGe-γ spectrometer with low background at the Institute of Nuclear Physics and Chemistry, C hina Academy of Engineering Physics. The fast neutrons were produced via T(d,n)4He reaction, and neutron flux was monitored on line by concomitant α particles, and neutron energies were measured by the method of cross-section ratio of 90Zr(n, 2n)89Zr reaction to 93Nb(n, 2n)92mNb reaction. Experiment sample is ThO2 of 99.5% purity and monitor is Al of 99.99% purity. Three samples were irradiated by neutrons at 0o、45o、90o directions.The present work tried to study the short half- life(several minutes) products from the fission reaction in which 89 Rb,130Sb,134 Te,134I,138 Xe,138Cs,141 Ba were existed apparently. A relative measurement method was used to calculate fission cross sections, and cross sections of 232Th(n,f)89Rb、232Th(n,f) 130Sb、232Th(n,f) 134Te、232Th(n,f) 138Xe、232Th(n,f) 141 Ba at neutron energies of 14.1±0.3,14.5±0.3,14.7±0.3 MeV were obtained respectively. In these analyses, correc tions from neutron- flux instability, precursor-nuclides β- decay, sample self-absorption, sample sizes, cascade-coincidence effects and efficiency-distance dependency were considered.