Measurement of excitation function for ⁶³Cu(n,p)⁶³Ni by radiochemical method

The ⁶³Cu(n,p)⁶³Ni reaction that occurs when copper is irradiated with fast neutron beams can be used for estimating fast neutron dose. The measurement of the radiation released in this reaction requires measurement of the excitation function of the reaction, and the data reported so far have errors and large differences between experiments. In order to obtain details of the excitation function, the authors performed an irradiation experiment of fast neutrons against copper samples. Experiment procedures were as follows; deuterons or protons are accelerated using a Dynamitron accelerator, a deuterium/tritium-occluded cadmium foil is irradiated with the accelerated particles, and the cupper sample is irradiated with generated fast neutrons. Copper arrangement is of two types: arrangement where copper plates are placed around a neutron source and arrangement such that a hollow copper sphere becomes a neutron source. The authors evaluated the validity of the experimental value based on the experimental data of the obtained reaction cross section of ⁶³Cu(n,p)⁶³Ni, and obtained the detailed excitation function of ⁶³Cu(n,p)⁶³Ni reaction in the energy range of E_n < 6 MeV and E_n ∼ 14 MeV. The obtained experimental results do not differ greatly from the excitation functions based on the statistical models of JENDL-3.3 and ENDF/B-VI, in the energy region that greatly influences the estimation of the fast neutron dose emitted from the atomic bomb. It was found that the validation of fast neutron dose based on ⁶³Cu(n,p)⁶³Ni reaction in DS02 using ENDF/B-VI is reasonable. (A.O.)