Improvement in the precision of the paleomagnetic intensity determination experiment

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(1) A new measurement system for paleointensity experimentsBased on the idea proposed by Kono et al. (J.Geomag. Geoelectr., 43,429,1991) , a new system was constructedby Natsuhara Giken Co. This system consists of (1) electric furnace with temperature control device, (2) sample rotation-translation unit, (3) fluxgate sensor with amplifier, (4) position detection unit, (5) coil for application of constant magnetic field, (6) three-layr magnetic shield, and (7) a PC to control all of these parts.(2) Software development for the new measurement systemTo control the system completely from a PC,a software package was developed including (1) motor control angle detection, (2) sliding control and position detection, (3) fluxgate signal amplification and AD conversion, (4) signal processing by FFT and calculation of magnetization, (5) temperature control, (6) magnetic field control, and (7) analysis of measurement results.(3) Experiments of paleointensity determinationUsing the newly developed instrument and the software, thermal demagnetization and Thellier's paleointensity experiments were carried out for basaltic samples from Iceland. The data analysis of experimentatl results are now in progress.