Gamma-ray spectrum from Cd induced by fast neutrons in indoor experiments

Abstract Spectrum of gamma-rays from nuclear reactions with fast neutrons on cadmium measured by the time-of-flight method is analyzed. Impact of neutrons re-scattered on the experimental facilities and surroundings down to thermal energies is considered for indoor experiments. New unfolding procedure is proposed and used for determination from experimental amplitude spectrum of the gamma spectrum induced by fast neutrons only. The flux of the thermal neutrons is estimated by MCNP code. Spectrum of gamma ray from Cd induced by fast neutrons is corrected and its systematical uncertainties are estimated. The re-calculated gamma-spectrum is smaller than previous one and in the energy range ∼ 3.5÷6.5 MeV the differences between these spectra can reach ∼ 30%. Two wide peaks are observed as before in exponentially dropping yield for gamma-ray energies near neutron separation energy (∼ 4.5÷10 MeV) but with lesser intensities.