Determination of k0 and Q0 for 113In(n,gamma)114In reaction with covariance analysis

Abstract

The use of k0 method for quantitative reactor Neutron Activation Analysis (NAA) is a well-known technique for determining multi-element concentrations in different materials. In order to achieve good results, there is a continuing need for improving the accuracy of k0 and Q0 parameters for several neutron capture reactions. 113In(n, )114In reaction can be considered particularly interesting because k0 and Q0 discrepancies appear in the literature. This fact motivated the present work which is focused on the measurement of k0 and Q0 values for this reaction with the purpose of improving the existing data catalogues. The irradiations were performed near the core of the IEA-R1 4.5 MW swimming-pool nuclear research reactor of the Nuclear and Energy Research Institute (IPEN-CNEN/SP), in São Paulo, Brazil. The distribution of epithermal neutron flux in the IEA-R1 is close to zero at the chosen irradiation position, which favors to obtain Q0 accurately. Two irradiations were carried out in sequence using two sets of samples: the first with a cadmium cover around the samples and the second without. The activity measurements were carried out in an HPGe gamma-ray spectrometer. Standard sources of 152Eu, 133Ba, 60Co and 137Cs supplied by the IAEA were used in order to obtain the HPGe gamma-ray peak efficiency as a function of the energy. The covariance matrix methodology was applied to all uncertainties involved. The final values for k0 and Q0 were compared with the literature.