Data reduction and uncertainty propagation of time-of-flight spectra with AGS

Results of neutron time-of-flight measurements are commonly used to parameterize neutron induced reaction cross sections in the resonance region based on the R-matrix reaction theory. Reaction yields or transmission as well as their covariance information are derived starting from measured counting spectra. They are then used in a least squares adjustment for obtaining model parameters. In this paper, a compact formalism is presented to propagate both the correlated and uncorrelated uncertainty components. Full information on the origin of each correlated component of the covariance matrix is maintained. This is particularly important in order to avoid a bias on the model parameters through a phenomenon known as Peelle's Pertinent Puzzle (PPP). This compact formalism was implemented into the data reduction code AGS (Analysis of Geel Spectra).