Determination of Soil Water Content at Intermediate Spatial Scale Using Cosmic-Ray Neutrons

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0126241ZredaThis proof-of-concept project will provide data to test the feasibility of a new method for soil water determination. The method is based on thermalization of cosmic-ray neutrons by hydrogen atoms present within water molecules in soils. It has several appealing characteristics: it is noninvasive (measurements can be conducted above the ground); it measures moisture at an intermediate scale; it may be scalable by changing instrument position and/or configuration; it can be easily automated for long-tern unsupervised monitoring; and it is safe (it does not use an artificial source of neutrons). The proposed work will involve measurements and modeling of the intensity of cosmic-ray neutrons under controlled water content conditions. The specific objectives of the proposed research are: (1) to identify and quantify any trends in neutron intensity with water content and with chemistry of soil; (2) to quantify the effect of water layer placed on top of soil on the neutron intensity; and (3) to determine what the measurement volume is and whether it can be controlled by instrument position above the ground or by instrument configuration.