Application of a dc SQUID to RF amplification: NQR
Abstract
Superconducting QUantum Interference Devices (SQUIDs) have been used for more than a decade for the detection of magnetic resonance. Until recently, these devices had mostly been confined to operation in the audiofrequency range, so that experiments have been restricted to measurements of resonance at low frequencies, or of changes in the static susceptibility of a sample induced by RF irradiation at the resonant frequency. However, the recent extension of the operating range of low noise dc SQUIDs to radiofrequencies (RF) allows one to detect magnetic resonance directly at frequencies up to several hundred megahertz. The properties of dc SQUIDs as tuned RF amplifers are summarized. The development of a SQUID system for the detection of pulsed nuclear quadrupole resonance (NQR) at about 30 MHz and is described and then, a novel technique for observing magnetic resonances in the absence of any externally applied RF fields is also described.
- Publication:
-
Presented at the 3rd International Conference on Superconducting Quantum Devices
- Pub Date:
- May 1985
- Bibcode:
- 1985sqd..conf.....H
- Keywords:
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- Amplification;
- Interferometers;
- Magnetic Resonance;
- Nuclear Quadrupole Resonance;
- Pulsed Radiation;
- Radio Frequencies;
- Squid (Detectors);
- Direct Current;
- Frequencies;
- Low Noise;
- Instrumentation and Photography