Genetic algorithms used in model finding and fitting for neutron reflection experiments

A fitting procedure based on genetic algorithms is described. This procedure is used to find scattering length density profiles that correspond to measured neutron reflectivity data. It gives parameters of a model that fits the data, without any a priori knowledge about the sample. It can give different parameter sets of a model, that yield equally good fits to the data, which stresses the nonuniqueness of the solutions.