Gamma Resonances near Threshold for the Production of Thermal Photoneutrons

Abstract: We have determined the positions of the (gamma,n) resonances and upper limits for the integrated cross sections for the (gamma,n) reactions, using data for the inverse process (n,gamma). With the aid of these data we have estimated the number of low-energy neutrons which can be generated by the irradiation of a target with a gamma-ray beam. Among the reactions producing thermal neutrons via (gamma,n) reaction we mention 185Re(gamma,n)184Re with an upper limit of the integrated cross section of 2.4 b-eV, and 178Hf(gamma,n)177Hf with an upper limit of the integrated cross section of 0.9 b-eV.