Measurement of moisture and hydrogen contents by intermediate neutron moderation

An intermediate neutron moderation method for measurement of moisture and/or hydrogen contents of small samples is presented. The sample is placed on the top face of a neutron howitzer, with a cadmium sheet between. Thermal neutrons resulting from intermediate neutron moderation in the sample are detected with a³He proportional counter placed on the sample, by a cadmium difference method. With a 500 mCi Am-Be neutron source, the limit of moisture detection for a 10×20×1.8 cm³ asbestos plate in 1 min count time is 0.5 wt.%. The precision of measuring the hydrogen contents of 250 ml hydrocarbons containing 112 mg H/ml is 0.9% under the same conditions.