Optimisation of Data Collection and Processing for Efficient Strain Scanning

Abstract

A constraint to the academic and industrial exploitation of neutron strain scanning is its cost in relation to that of alternative techniques. Generally, a large proportion of the resource cost is that for beam-time. The efficient utilisation of beam-time can be enhanced by optimising data collection and processing. The selection of three principal related factors — detector range, angular step size and the counting time — determines the data quality and uncertainties in defining the Bragg peak parameters required to determine strain. Theoretical and numerical analysis of computed and experimental data are used to establish a general set of well-founded, semi-empirical but theoretically-based, practical “rules of thumb” to be used when making strain measurements to a specified statistical uncertainty. The “rules” apply mostly to constant wavelength techniques where the angular position and other profile parameters of a single symmetrical Bragg peak are required but have relevance for fixed angle time-of-flight methods.