Neutron capture cross sections on 63Cu and 186W were measured by fast neutron activation method at neutron energies from 1 to 2 MeV. Monoenergetic fast neutrons were produced
by 3H(p,n)3He reaction. Neutron energy spread by target thickness, which was assumed to be the main factor of neutron energy spread,
was estimated to be 1.5% at neutron energy of 2.077 MeV. Neutron capture cross sections on 63Cu and 186W were calculated by reference comparison method on those of 197Au(n,γ). Not only statistical errors of gamma-counts from samples but also systematic errors in the counting efficiency for
HP Ge detector and the uncertainty of areal density of samples were considered in calculating neutron capture cross section.
Estimated neutron capture cross sections on 63Cu and 186W were also compared with ENDF-6 data.