Modification of a FIT rock magnetometer using non-cryogenic magnetic field sensors and their potential for high-sensitivity measurements
Year: 2026
Type: article
Abstract: We present options on how to modify a F.I.T. Messtechnik GmbH SQUID rotation magnetometer (FIT) for measurement of rock samples, using modern magnetic field sensors which are all of non-cryogenic nature. These include three types of fluxgate magnetometers by Stefan Mayer Instruments, and a novel atomic pumping magnetometer from QuSpin Inc. All sensors may be interchanged easily with the original SQUID sensor and between them. We installed these sensors and determined their sensitivity and measurement precision when used in the FIT magnetometer system, without any other modifications. The sensors tested have a wide range of cost, between about $90 and $10,000, and noise levels vary accordingly from about 10 − 3 Am − 1 for the most economic down to 2•10 − 7 Am − 1 (0.7•10 − 12 Am 2 ) for the most expensive. These noise levels depend on the operation parameters like integration time of the lock-in amplifier, the distance of the sensor from the rotating sample, or gain settings. All fluxgate sensors cover large intensity ranges up to > 10 3 Am − 1 , but the atomic pumping magnetometer QZFM Gen.2 can only be used at low intensities, < 6 to 75•10 − 3 Am − 1 depending on the gain setting. Moving the sensor 8 centimeters away from the sample extends the range of the magnetization intensity that could be measured up to 3.6 Am − 1 ; this is easy to do and only requires a re-calibration of the system under such a changed condition. Measuring in the close position five times at 5 s integration time remanent magnetization of a sample of 9.4•10 − 6 Am − 1 intensity provided a mean direction with an confidence angle α 95 = 4.1°, demonstrating that a very high sensitivity of the FIT maybe achieved installing the QZFM sensor, e.g., suitable for measuring low intensity rocks like stalagmites. Another good choice is the Stefan Mayer Instruments FL1-100 sensor with a noise level of > 5 •10 − 6 Am − 1 , which allows measuring many sediments and igneous rocks up to magnetizations of 1000 Am − 1 . Even the most economic fluxgate sensor would be well suitable for measuring lava flow samples, as it has a noise level of 0.4–1 •10 − 3 Am − 1 .
Source: Earth Planets and Space
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $1,640
OpenAlex ID: W7204127228