Modeling of backscattering gamma ray sediment gages

Semi-empirical mathematical models were developed to predict the response of gamma-scattering gages. A single scatter model was used to develop an equation describing the response of a close spaced gage. Laboratory experiments and Monte Carlo simulation were conducted to determine the effects of changes in the collimation angles and the source to detector spacing on the numerical coefficients. A more general model was developed to predict the response to both sediment density and equivalent atomic number. Water with a small amount of barium chloride was used to simulate a wide range of densities and chemical compositions to obtain numerical coefficients. The response was found to be a function of source to detector distance collimation angles, photon energies registered by the detector as well as sediment density and chemical composition