The optimization of a neutron scattering water content gauge for soils or concretes

It is shown how the use of a cadmium cover over the detector in a neutron scattering water content gauge eliminates the undesired influence of the chemistry of the soil or concrete on the reading. Equations relating time of count to error in water density are derived and used to determine the optimum distance between source and detector, which was found to be 7 cm from centre to centre.