MEASUREMENT OF SEDIMENT DENSITY BY ATTENUATION OF TRANSMITTED GAMMA RAYS

The measurement of density by observing the attenuation of transmitted gamma rays was adapted to the measurement of sediment density. A dual probe, utilizing transmission techniques, was evaluated for use in measuring the density of sediments collected from runoff of plots or small watersheds. The equipment consists of a 7-mc cesium-137 source placed in one access tube and a probe containing a NaI scintillation crystal, photomultiplier tube, and preamplifier in the second tube. The high-voltage power supply and scaler ratemeter for readout are supplied in a portable unit powered by silver-cadmium rechargeable dry cells. Cesium-137 gamma radiation is measured by employing electronic discrimination to eliminate all photons of energies below about 0.65 Mev. Sediment densities were measured in silt boxes installed on a small watershed at the North Mississippi Branch Experiment Station, Holly Springs, Mississippi, following laboratory calibration tests. The dual probe employed measured densities of sediments to within 0.01 absolute density units. The vertical resolution of the apparatus is less than 1 inch so that density measurements of thin layers and of materials at interfaces can be made. In one field test sediment weights, of the order of 8,500 pounds, computed for a solt box on the basis of dual probe density determinations varied less than 1 percent from a gravimetric determination. Changes in sediment density with time, with additional increments of sediment, and with storms were effectively measured. /Author/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 817-822
  • Serial:
    • Volume: 28
    • Issue Number: 6

Subject/Index Terms

Filing Info

  • Accession Number: 00264526
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 29 1975 12:00AM