The use of simulation for the optimisation of the signal-to-noise ratio in cyclic activation analysis

Abstract

It is always useful to predict the result of an experiment without having to carry it out. In cyclic activation analysis where the signal-to-noise ratio for the detection of short-lived nuclides in a given matrix is particularly sensitive to the value of the timing parameters, determination of the best conditions for the detection of a nuclide of interest, without resort to preliminary experiments, is most helpful. Simulation and optimisation of a gamma-ray spectrum is derived for a sample irradiated in cyclic mode. The simulation includes consideration of photopeak, Compton continuum, single and double escape peaks and bremsstrahlung. The simulation output forms the input to the signal-to-noise ratio optimisation routine. Consequently the sensitivities, and detection limits for the isotopes of interest can be deduced from the optimised spectrum. Interference from other gamma-lines is identified, if applicable. In addition, a graphical output of the simulated spectrum and a listing of the optimised activation parameters, detection limits and sensitivites are produced. The programme has been extended to include simulation of conventionally neutron activated samples. Examples for standard reference materials are given as illustrations, together with measured spectra.