The bulk density of a soil or core sample is defined as the mass of any particles divided by the total volume they occupy- including the volume of the particles and any void volumes. The bulk density of a core depends greatly on its mineral composition and degree of compaction.
A 137-Caesium gamma source emits photons with energies of 0.662 MeV towards the core. These photons pass through the core and are then detected on the other side. The number of photons that reach the detector without interacting with the core material can be used to determine its density.
The bulk density data can be used to give an indication of depositional history and for the calculation of acoustic impedance and the construction of synthetic seismograms.
For more information about the ore density sensor see the Geotek website: Gamma Density – Geotek Ltd.