Measurements of the values of alpha on 239Pu resonances

Alpha, equal to the ratio of the radiative-capture cross section of a neutron to the fission cross section, is one of the basic constants necessary for the optimization of reactors. In this paper the method of multiplicity spectroscopy was used to perform absolute measurements of alpha for plutonium 239 for allowed resonances in the neutron energy range 7-200 eV. Two different detectors and correspondingly two different methods for separating the fission multiplicity spectra from the total measured multiplicity spectra were used. Measurements were performed on the 26-meter path of the LUE-60 Fakel linear accelerator. Boron 10, cadmium, and cadmium oxides filters were used to absorb recycling neutrons. A full description of the data acquisition system and spectrometer and a comprehensive analysis of the measurements, their accuracy, and their implications are given