Measurement of fission cross-section for 134Te and 134I in 232Th(n,f) reaction induced by 14 MeV neutrons

Abstract

The fission cross-sections of the 232Th(n,f)134Te and 232Th(n,f)134I reactions induced by neutrons around 14MeV were measured by the neutron activation and off-line gamma ray technique. The neutron fluence was monitored on line using the accompanying α-particles from the T(d,n)α reaction, meanwhile, neutron energies were obtained from the cross-section ratio method of 90Zr(n,2n)89(m+g)Zr to 93Nb(n,2n)92mNb reactions. The experimentally determined 232Th(n,f)134Te reaction cross-sections are 9.57±0.47mb at En=14.1±0.3MeV, 10.0±0.5mb at En=14.5±0.3MeV and 10.7±0.6mb at En=14.7±0.3MeV, respectively. Whereas, the isotope 134I of which characteristic γ-rays were detected in the γ-spectrum was concluded to be originated from 134Te decay. According to the cascade deduction formulism, the cross-section of 232Th(n,f)134I was estimated to be below a value (~5.7×10−3mb) refered to the Minimal Detectable Activity (MDA) with the gamma measurements.