We propose to evaluate transmission, fluorescence, and backscattering techniques of x-rays or gamma-rays to determine defects in high-z coatings on low-z substrates. The proposal includes x-ray spectral analysis, followed by experimental measurements on actual samples, to determine optimum design parameters and the minimum size of defect that can be detected. Under favorable experimental results, both the parameters and the operating concept for an optimum instrument can be defined at the end of phase i, for the eventual fabrication of a prototype in phase ii we propose to evaluate transmission, fluorescence, and backscattering techniques of x-rays or gamma-rays to determine defects in high-z coatings on low-z substrates. The proposal includes x-ray spectral analysis, followed by experimental measurements on actual samples, to determine optimum design parameters and the minimum size of defect that can be detected. Under favorable experimental results, both the parameters and the operating concept for an optimum instrument can be defined at the end of Phase I, for the eventual fabrication of a prototype in Phase II
