ANALYSIS OF GAMMA-RAY CONTINUUM SPECTRA TO DETERMINE THE CHEMICAL-COMPOSITION

Neutron induced gamma-ray spectra from various geological samples were analyzed to evaluate the usefulness of continuum spectra in deriving the chemical composition information. A fast Fourier transform techniq ue has been used to estimate the signal content of selected energy ban ds of the continuum spectra Monte Carlo calculations have been perform ed using the major gamma-ray energy sources (due to Fe, Ca, Si and Al) to generate the corresponding detected gamma-ray spectra The experime ntal spectra are compared to the simulated spectra to check the consis tency of the signal distribution between the peak and the continuum. T he continuum above and below a chosen gamma-ray line is calculated to find what fraction of the lower energy continuum is due to that line. The accuracy of the relative elemental concentrations determined by th is method is confirmed through comparison with laboratory elemental an alysis of the samples. It is found that using the continuum could grea tly increase the sensitivity and precision of the measurement of eleme ntal concentrations determined from gamma-ray spectra of thick target sources, for spectra having peaks of poor statistical significance. Ho wever, for thin target sources or spectra with very good statistics in their peaks, this method may not be very advantageous.