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

The fission cross-sections of the ²³²Th(n,f)¹³⁴Te and ²³²Th(n,f)¹³⁴I reactions induced by neutrons around 14 MeV 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,2 n)^89(m+g)Zr to ⁹³Nb(n,2 n)^92mNb reactions. The experimentally determined ²³²Th(n,f)¹³⁴Te reaction cross-sections are 9.57±0.47 mb at E_n=14.1±0.3 MeV, 10.0±0.5 mb at E_n=14.5±0.3 MeV and 10.7±0.6 mb at E_n=14.7±0.3 MeV, 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 (~5.7×10⁻³ mb) refered to the Minimal Detectable Activity (MDA) with the gamma measurements. - Highlights: • By NAA method, D-T neutrons were used to bombard ²³²Th sample. • This work mainly focused on the fission fragments with mass number A=134. • Fission cross-section data were deduced for ²³²Th (n,f)¹³⁴Te and ²³²Th(n,f)¹³⁴I.