In the logging of a grade characteristic of a borehole core, the core is placed in a trough which is caused to move, in step fashion, through an annular detector. For each step the detector measures a characteristic of a notional segment of the core. The measures are corrected to compensate for contributions...http://www.google.fr/patents/US4623792?utm_source=gb-gplus-shareBrevet US4623792 - Core logging
