Ultralow temperature NMR detection using dc SQUIDs

Nuclear magnetic resonance (NMR) experiments at ultralow temperatures place high demands on superconducting quantum interference device (SQUID) amplifiers. We have developed a suitable direct-coupled readout SQUID electronics system, which utilizes additional positive feedback (APF), and have achiev...

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Bibliographic Details
Published inApplied superconductivity Vol. 6; no. 10; pp. 751 - 757
Main Authors Thomasson, S.L., Gould, C.M.
Format Journal Article
LanguageEnglish
Published Elsevier Ltd 1999
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Summary:Nuclear magnetic resonance (NMR) experiments at ultralow temperatures place high demands on superconducting quantum interference device (SQUID) amplifiers. We have developed a suitable direct-coupled readout SQUID electronics system, which utilizes additional positive feedback (APF), and have achieved a system bandwidth of 5 MHz, maximum slew rate of 1.3×10 7 Φ 0/s at 14 kHz and a white noise level of 3.4 μΦ 0/ Hz . We have also investigated improving the signal-to-noise ratio by using a low noise series array of dc SQUIDs and by placing the SQUID amplifier closer to the ultralow temperature experiment. We will discuss how we have configured our SQUID amplifiers for operation at T≪1 K.
ISSN:0964-1807
1879-1530
DOI:10.1016/S0964-1807(99)00038-1