Remote analysis of surfaces by neutron-gamma-ray inelastic scattering technique

Abstract

Reversing the procedure of a number of years' work in the determination of the cross sections for production of γ rays by 14-Mev neutrons interacting in pure elements, we have been studying the feasibility of applying our techniques to the remote chemical analysis of unknown materials. We have measured the spectra of γ rays produced by neutrons in a large sandpile containing various known percentages of the elements O, Mg, Al, Si, and Fe. A general statement can be made that a 5 per cent abundance of any of these elements can be quantitatively determined to a precision of better than 10 per cent. The method, using fast gating and timing circuits to select only the γ rays originating unambiguously from the neutron inelastic scattering process, appears so promising that a miniature, pulsed accelerator is now being tested and packaged. Applications to the analysis of the lunar surface, planetary atmospheres, and the earth's crust and mantle are discussed.