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A SQUID based AC susceptometer for the investigation of large samples
A Pasquarelli1, C Del Gratta, S Della Penna
1Istituto di Elettronica dello Stato Solido, CNR, Roma, Italy.
Physics in Medicine and Biology
|November 1, 1996
Abstract:
We developed a SQUID based susceptometer with a large available magnetized volume for the investigation of large objects. The magnetizing field is generated by a pair of Helmoltz coils. To achieve a high signal-to-noise ratio, the susceptometer is operated in a lock-in mode with an AC magnetizing field. A negative feedback control allows the rejection of the applied field with a relative residual of 1 x 10(-7). The apparatus was tested with substances of known magnetic susceptibility. The overall sensitivity, stated in terms of the magnetic moment, is better than 7 x 10(-11) A m2 for small samples.