抄録
The radioactive nuclides 124Sb (T1/2=60.3 d) and 125Sb (T1/2= 2.77 yr) were produced from natural antimony by JRR-3 reactor irradiation of 283.5 h through the single and double capture processes. After cooling of 3.50 yr, the γ-ray spectrum of the antimony sample irradiated was measured by a 50 cc coaxial type Ge(Li) detector, and the photo-peak yield ratio of 125Sb (Eγ=428 keV) to 124Sb (Eγ=1.691 MeV) was obtained. By using a relation between this photo-peak yield ratio and the 124Sb(n, γ)125Sb cross section, the reactor neutron capture cross section of 60.3-day 124Sb was obtained as 17.4+2.8-2.5 b. The thermal neutron flux at the position of antimony sample irradiated was estimated as (4.92±0.38) × 1012n/cm2•s by measuring the 1.333-MeV photo-peak yield of 60Co, which was activated by reactor irradiation of cobalt impurity contained in the antimony sample.
