Sensors superconducting quantum interference

Mossbauer resonance of Zn to study the influence of the gravitational field on electromagnetic radiation. A Ga ZnO source (4.2 K) was used at a distance of 1 m from an enriched ZnO absorber (4.2 K). A red shift of the photons by about 5% of the width of the resonance line was observed. The corresponding shift with Fe as Mossbauer isotope would be only 0.01%. The result is in accordance with Einstein s equivalence principle. Further gravitational red shift experiments using the 93.3 keV Mossbauer resonance of Zn were performed later employing a superconducting quantum interference device-based displacement sensor to detect the tiny Doppler motion of the source [66, 67]. 

A number of sensitive magnetic field detection devices have been developed as biosensors giant magnetoresistive (GMR) sensors [4], piezoresistive cantilevers [5], inductive sensors [6], superconducting quantum interference devices (SQUIDs) [7, 8], anisotropic magnetoresistive (AMR) rings [9], and miniature Hall crosses [10]. 

If the JJ device is made into a superconducting loop, it becomes sensitive to very small magnetic fields. These JJs are called SQUIDs, an acronym for superconducting quantum interference device. The SQUID is the world s most sensitive magnetic sensor and has extensive applications. For instance, a SQUID was used in Chad, Africa to measure magnetic anomalies during a total solar eclipse. 

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