Measurement of the thermal neutron capture cross section and resonance integral of Am-241

Abstract

Measurements of the thermal neutron cross section and resonance integral for the reaction 241 Am(n, γ ) 241g Am have been performed at the IEA-R1 research reactor operating at 2 MW. A 4πβ − γ coincidence system applying the tracer technique has been used for measuring the activities. Irradiations with and without cadmium cover were performed and the neutron transmission through this cover was calculated by the Monte Carlo method. High resolution γ -ray spectrometry measurements were undertaken in order to check the consistency of the results and to measure activities of the neutron fluence monitor foils. Covariance analysis has been applied to all uncertainties involved. The thermal neutron cross section for 2200 m/s neutrons and the resonance integral resulted (602 ± 9) b and (1665 ± 91) b, respectively. These results are discussed and compared with previous measurements.

Absolute measurement of sources activities in the cross-section determination—Improvement by simulation

“…The time interval between the end of irradiation and beginning of counting was approximately 60 min. This paper deals with data obtained using samples made from three out of several irradiated targets used to measure the 241 Am neutron absorption cross-section [1]. …”

“…These isotopes must be considered in reactivity calculations, requiring the respective activation cross-section to evaluate their contribution to the overall radioactivity balance. This paper concerns the source standardization of one of 241 thermal neutron capture products, the radionuclide 242g Am, whose accurate induced activity measurement is needed to determine experimentally the 241 Am neutron capture cross-section [1,2].…”

Thermal Cross Section And Resonance Integral Measurements Of57Co(n,γ)58Co Reaction

“…Targets consisting of'" 0. near the reactor core with and without Cd cover. In all the irradiations, a pair of Au-At alloy foils (0.10 % of Au), one of them covered with Cd, was used to monitor the thermal and epithermal neutron fluxes in the irradiation position through the 197 Au(n,'Y)198 Au reaction as described in Maidana et al 6) The Au activities were used to determine the neutron fluence by the Westcott formalism. 9 ,10) The irradiation time was 15 h and the interval between the irradiation and counting was greater than 15 d, in order to wait for the decay of some contaminants found in the quartz tubes.…”

Neutron transmission and capture of241Am

“…Deep geological isolation is not a favorable solution and a more sophisticated approach should be followed with incineration and/or transmutation being considered as viable options. During the last decade four new measurements [2][3][4][5] have been devoted to determine the thermal capture cross section of 241 Am. The values of these four measurements are in agreement with each other, but basically disagree with the evaluated data files, except for JEFF-3.1, which has already taken them into account.…”