Statistical Significance of Non-Reproducibility of Cross Sections in Dissipative Reactions

Two independent excitation function measurements have been performed in the reaction system of ¹⁹F+⁹³Nb using two target foils of the same nominal thickness. We measured the dissipative reaction products at incident energies of 102 through 108 MeV with a step of 250 keV. The variance of energy autocorrelation functions of the reaction products was found to be three times of that originated from the randomized counting rates. By analysing the probability distributions of the deviations in the measured cross sections, we found that about 20% of all the deviations exceeds three standard deviations. This indicates that the non-reproducibility of the cross sections in the two independent measurements is of a statistical significance but not originated from randomized fluctuation of counting rates.