Improvements to the control portion of the moisture from a material, in particular for the study of the soils

摘要

1,125,017. Measurement of moisture content. ELECTRICITE DE FRANCE. July 29, 1966 [July 30, 1965], No. 34283/66. Heading G1A. [Also in Division G6] The moisture content of a material, e.g. soil, is measured by means of a detector of neutrons transmitted through the material from a source of fast neutrons, thermal neutrons due to scattering in the material being prevented from being detected. The fast neutron source which may be e.g. a mixture of americium and beryllium, and should not emit high energy y-radiation, is mounted at the end of a rod 3, which can be let down into a bore hole 2, within a guide tube 6. The tube 6 is attached by portion 7, to a member 10 which can swivel with respect to seating 12. The casing 8 holds two sets of detectors each including a fast neutron detector DN and a gama detector DG. The latter is included to detect gamma radiation, from a source 5, e.g. of Cs 137, in order to measure the mass per unit volume of the soil, at the same time as the moisture content is measured by the neutron detector. The casing 8 is swivellable about the part 10 so that a suitable or preferred position of measurement can be obtained. By pivoting one or both detector casings 21, 22 to the casing 8, e.g. by pivot 25, irregularities in the ground surface are able to be dealt with. The gamma and neutron detector outputs are fed to respective pre-amplifiers which are mounted in the casing 8 at locations 17 and 18. The measurement taken is an average of the two detector outputs. From the measurements of moisture content per unit volume, and weight (or density) per unit volume, the ratio of these quantities, moisture content to weight, can be calculated. The fast neutron detector comprises a conventional boron fluoride type tube (33) Fig. 3 (not shown), responsive to thermal neutrons, located at the centre of a paraffin moderator (34) which has a filter jacket of indium and cadmium foils (35, 36). The filter eliminates thermal neutrons and the fast neutrons passing through are reduced to thermal energy by the moderator for detection by the tube (33).