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Effect of low-frequency ambient magnetic fields on the control unit and RF head of a commercial SQUID magnetometerThe control unit and RF head of the SHE model 330XRFSQUID system are shown to be sensitive to ambient ac magnetic fields below 1 HZ, which cause the appearance of false signals corresponding to a magnetometer signal of 0.000001 phi(0) per gauss of field applied. The control unit shows a sensitivity that is linear with frequency, suggesting that the signal is generated by Faraday induction. In contrast, the RF head response is independent of frequency and shows a strong second-harmonic coversion. This response may be due to the magnetic field sensitivity of the ferrite core inductor in the tuned amplifier of the RF head. These signals induced by ambient fields are a potential source of error in Stanford's Relativity Gyroscope experiment, which uses SQUID's on board a rolling satellite as part of the gyroscope readout system. The extent of the magnetic field sensitivity in these components necessitates the use of additional magnetic shielding aboard the satellite.
Document ID
19840066091
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Marcus, C. M. (Stanford University Stanford, CA, United States)
Date Acquired
August 12, 2013
Publication Date
September 1, 1984
Publication Information
Publication: Review of Scientific Instruments
Volume: 55
ISSN: 0034-6748
Subject Category
INSTRUMENTATION AND PHOTOGRAPHY
Funding Number(s)
CONTRACT_GRANT: NAS8-34619
Distribution Limits
Public
Copyright
Other