Neutron beam methods in the analysis of reference materials

Facilities have been established at numerous research reactors for chemical analysis using neutron beams. Neutron depth profiling (NDP) is used to measure the depth distribution of those elements that undergo (n, p) or (n, α) reactions with thermal neutrons. Prompt gamma activation analysis (PGAA) employs the gamma radiation emitted when a neutron is captured. The combination of PGAA and instrumental neutron activation analysis (INAA) can be used to determine non-destructively over 30 elements in a single sample. The characterization of reference materials is aided by the practical non-dependence of PGAA, like NAA, on the nature of the sample matrix. New opportunities have opened recently with the development of cold neutron beams and neutron optical devices. (author)