A new data treatment scheme for integrated intensities in neutron Compton scattering

Abstract

A new data reduction scheme is presented for time-of-flight data collected in neutronCompton scattering experiments with the aim of obtaining the scattering intensities. Themethod proposed is a single number approach as it makes use of the count rates detectedin the individual time-of-flight channels. The most convenient seems to be thevariant of the method where time-of-flight channels are chosen corresponding tocenters of recoil peaks of individual masses. With such a choice of time-of-flightchannels, the method presented is more robust against unwanted background signalsand noise than the method widely used in NCS studies based on fitting entiretime-of-flight band shapes in the framework of the convolution approximation.Moreover, it should perform better than the model-free Dorner method as itdoes not require the numerical integration of the signal, which is also sensitiveto baseline and noise. As an example of the performance of the new method,polyethylene data are treated and compared to results obtained previously usingconventional data reduction and the model-free method proposed by Dorner. Itis shown that all three data reduction schemes lead to the same results for thescattering intensities of protons in polyethylene, thus strengthening the conclusionabout the anomalous scattering cross-section of protons in this substance. In thefuture the new data reduction scheme can be used to treat the data from otherexperiments where the conventional NCS data treatment and/or Dorner method faildue to noise and/or unwanted background signals present in the time-of-flightspectra.