Techniques: The Bremen Magnetics Lab is specialized in measuring weakly magnetic materials such as sediments and minerals. We cover all relevant established paleo- and rock magnetic methods:
Vector measurement of natural remanence and artificial remanences (IRM, ARM, GRM, VRM) of single samples (cubes, cykinders) and u-channels; magnetic hysteresis, susceptibility and anisotropy; thermomagnetics at low (4-400K) and high (270-800K) temperatures and fields up to 7T; FORC analyses and REM analytics of magnetic extracts.
Pneumatic sample changer of the fully automated Bremen 2G Superconducting Rock Magnetometer
System: The remanent magnetization of rock and sediment samples determined by this magnetometer provides the basis for numerous scientific investigations. Measurements of natural and synthetic magnetizations may be performed on up to 1.5 m long so called u-channels or discrete samples (cubic and inch samples) as well. When used for discrete samples the Bremen magnetometer is used in an in-house developed automated mode which allows for the autonomous exchange of samples. This provides a measurement capacity for almost 100 samples per 24 hours.
System: With the MPMS-XL7 we determine the temperature-dependent magnetic properties of sample material in peak dc fields of ±7 Tesla in temperatures ranging from 1.9 to 400 K. The instrument measures magnetic hysteresis loops, remanent magnetizations as well as the frequency-dependent magnetic susceptibility. The sample size may be 5 mm in diameter and 9 mm in length to the maximum. The use of the optional oven with a maximum temperature of 800 K reduces the sample size to a length of 5 mm and a diameter of 1.6 mm. The device is equipped with the EverCool Option for re-liquefying Helium gas. This allows for an almost permanent operation of the system.
Alternating Gradient Magnetometer PMC MicroMag 2900 Team:Thomas Frederichs Room: University of Bremen, GEO Building, Room 4050
System: The Micromag 2900 performs measurements of magnetic hysteresis and of remanent magnetization (curves of acquisition and demagnetization curves) at ambient temperature in magnetic peak fields of 1.4 T. Samples may consist of powders or rock fragments with a weight of about 10 mg. The measurements are used for the magnetic characterization of samples and allow for semi-quantitative estimations of concentration, mineralogy and magnetic grain size (domain state). Furthermore, it is possible to perform First Order Reversal Curves (FORC).
Horizontal Magnetic Translation Balance Team: Adrian Höfken Room: University of Bremen, GEO Building, Room 4170
System: The Horizontal Magnetic Translation Balance is used for temperature dependent measurements of magnetic properties between room temperature and 970 K in fields up to 150 mT. An optional cooling vessel may be used to extend the temperature range down to 80 K. For the measurements dried powder samples with a mass of few 10 mg are used. The actively, feedback controlled measurement system uses a modern data acquisition system and reaches accuracies sufficient for measurements of weak magnetic marine sediments. The temperature paths may be adapted to fit the individual sample material and targeted questions.
Bremen Horizontal Magnetic Balance
Agico Susceptometer KappaBridge KLY-2 Team:Thomas Frederichs, Liane Brück Room: University of Bremen, GEO Building, Room 4220 System: The KappaBridge KLY-2 is used in order to determine the magnetic susceptibility at ambient temperature either as a bulk measurement or as the anisotropy of magnetic susceptibility. The latter is achieved by the measurement of magnetic susceptibility in 15 different orientations. While bulk susceptibility is mainly a measure for the concentration of magnetominerals, the anisotropy provides information about the orientation of the magnetic particles within a matrix due to the presence of bottom water currents or flow textures.
KappaBridge KLY-2
Bartington Susceptometer MS2 Team:Thomas Frederichs, Liane Brück System: The MS2 may be used in combination with different sensor types according to the respective needs. A so called bulk sensor MS2B allows the determination of the magnetic susceptibility of discrete samples with a volume of up to about 10 ccm. Susceptibility can be measured at two different frequencies of the exciting magnetic field.
From the resulting different numbers for this frequency-dependent magnetic susceptibility we are able to make assumptions about the magnetic domain status and thus magnetic grain size. Furthermore the MS2 may be equipped with different coil sensors MS2C of various diameters which are used for the measurement of whole or split sediment cores. Different spot (or surface) sensors MS22E/F are used for the high-resolution susceptibility measurement of split cores. Beyond in-door operation the instrument may be used in battery mode for field surveys in combination with different sensor types. MS2 Manual John Dearing - Environmental Magnetic Susceptibility
