Internship Report from the year 2013 in the subject Geography / Earth Science - Miscellaneous, grade: 2,3, RWTH Aachen University (Lehrstuhl für Geologie, Geochemie und Lagerstنtten des Erdِls und der Kohle), course: Petrophysics Practical Course, language: English, abstract: The MSCL-experiment encloses the stepwise measurement of three different parameters: Gamma density, P-wave-velocity (compressional wave travel time) and magnetic susceptibility. Each is measured by different sensors. A photo of the apparatus is shown in figure 1. The four core samples G1, a black stone, coarse-grained and compacted with small mica particles and bigger white quartz inclusions, could be a gabbro and G2 a greenish sandstone with small particles and lesser compaction, each unsaturated and saturated with water are halved and ""transported on a stepper motor-driven tracking system"" to the sensors. If the rock sample is heterogeneous and the halves dont accord in their mineral composition, you will have now a potential error source. The samples are laid on the tracking system. A motor pushes them first to a laser, where the length is measured, than to the gamma source and then to the P-wavevelocity- sensor. Here you have a second potential error source: When the P-wavevelocity- sensor presses the samples down for measuring, they were lift on the other side. To avoid the lifting the rock samples have to be pressed and so the measurements are not really accurate. [...]