Design and Calibration of a Deep Ocean Nuclear Probe for Sediment Water Content

摘要

A laboratory model of a nuclear moisture meter was constructed and calibrated. The meter which is composed of an AmBe neutron source and a Cd-covered LiI detector, measures epithermal neutrons. Samples of varying composition and moisture content were assembled and used to determine the accuracy of the meter. The atom-percent-water in any sample was found to vary linearly with epithermal count rate, a result expected and predicted theoretically. These measurements were sediment-independent. The moisture content was determined from the atom-percent-water by using porosity. The moisture content was sediment-dependent, as expected. The moisture content can be determined over a range of about 20 to 350%. If no information is known about the sediment, the maximum error in moisture content is about 32%; the average error is about 16%. If information is available concerning the sediment (as from a core sample or a gamma density probe), the maximum error in moisture content is about 23%; the average error is about 9%. (Author)