Multichannel SQUID magnetometry using double relaxation oscillation SQUIDs

Michiel J. van Duuren; Y.H. Lee; Derk Jan Adelerhof; J. Kawai; H. Kado; Jaap Flokstra; Horst Rogalla

doi:10.1109/77.488279

Multichannel SQUID magnetometry using double relaxation oscillation SQUIDs

Michiel J. van Duuren, Y.H. Lee, Derk Jan Adelerhof, J. Kawai, H. Kado, Jaap Flokstra, Horst Rogalla

Faculty of Science and Technology

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Abstract

A highly sensitive first-order gradiometer based on double relaxation oscillation SQUID's (DROS's) for multichannel use is presented. The white flux noise level of the bare DROS's is 4.5 μΦ0/√Hz (&epsi;=275 h). With wire-wound first-order gradiometers, having a baseline of 40 mm, the white magnetic field noise equals 4 fT/√Hz. As a result of the high flux-to-voltage transfer of the DROS's of about 1 mV/Φ0, this low noise level could be obtained with simple room-temperature flux locked loop electronics based on direct voltage readout. The relaxation frequency of the present DROS's is approximately 1 GHz. No degradation of the DROS characteristics caused by interference between relaxation oscillations in two adjacent channels has been observed, although the gradiometers are spaced by less than 1 mm. This shows that DROS's can be used in multichannel SQUID magnetometers.

Original language	English
Pages (from-to)	38-44
Number of pages	7
Journal	IEEE transactions on applied superconductivity
Volume	6
Issue number	1
DOIs	https://doi.org/10.1109/77.488279
Publication status	Published - 1996

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title = "Multichannel SQUID magnetometry using double relaxation oscillation SQUIDs",

abstract = "A highly sensitive first-order gradiometer based on double relaxation oscillation SQUID's (DROS's) for multichannel use is presented. The white flux noise level of the bare DROS's is 4.5 μΦ0/√Hz (&epsi;=275 h). With wire-wound first-order gradiometers, having a baseline of 40 mm, the white magnetic field noise equals 4 fT/√Hz. As a result of the high flux-to-voltage transfer of the DROS's of about 1 mV/Φ0, this low noise level could be obtained with simple room-temperature flux locked loop electronics based on direct voltage readout. The relaxation frequency of the present DROS's is approximately 1 GHz. No degradation of the DROS characteristics caused by interference between relaxation oscillations in two adjacent channels has been observed, although the gradiometers are spaced by less than 1 mm. This shows that DROS's can be used in multichannel SQUID magnetometers.",

author = "{van Duuren}, {Michiel J.} and Y.H. Lee and Adelerhof, {Derk Jan} and J. Kawai and H. Kado and Jaap Flokstra and Horst Rogalla",

year = "1996",

doi = "10.1109/77.488279",

language = "English",

volume = "6",

pages = "38--44",

journal = "IEEE transactions on applied superconductivity",

issn = "1051-8223",

publisher = "IEEE",

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TY - JOUR

T1 - Multichannel SQUID magnetometry using double relaxation oscillation SQUIDs

AU - van Duuren, Michiel J.

AU - Lee, Y.H.

AU - Adelerhof, Derk Jan

AU - Kawai, J.

AU - Kado, H.

AU - Flokstra, Jaap

AU - Rogalla, Horst

PY - 1996

Y1 - 1996

N2 - A highly sensitive first-order gradiometer based on double relaxation oscillation SQUID's (DROS's) for multichannel use is presented. The white flux noise level of the bare DROS's is 4.5 μΦ0/√Hz (&epsi;=275 h). With wire-wound first-order gradiometers, having a baseline of 40 mm, the white magnetic field noise equals 4 fT/√Hz. As a result of the high flux-to-voltage transfer of the DROS's of about 1 mV/Φ0, this low noise level could be obtained with simple room-temperature flux locked loop electronics based on direct voltage readout. The relaxation frequency of the present DROS's is approximately 1 GHz. No degradation of the DROS characteristics caused by interference between relaxation oscillations in two adjacent channels has been observed, although the gradiometers are spaced by less than 1 mm. This shows that DROS's can be used in multichannel SQUID magnetometers.

AB - A highly sensitive first-order gradiometer based on double relaxation oscillation SQUID's (DROS's) for multichannel use is presented. The white flux noise level of the bare DROS's is 4.5 μΦ0/√Hz (&epsi;=275 h). With wire-wound first-order gradiometers, having a baseline of 40 mm, the white magnetic field noise equals 4 fT/√Hz. As a result of the high flux-to-voltage transfer of the DROS's of about 1 mV/Φ0, this low noise level could be obtained with simple room-temperature flux locked loop electronics based on direct voltage readout. The relaxation frequency of the present DROS's is approximately 1 GHz. No degradation of the DROS characteristics caused by interference between relaxation oscillations in two adjacent channels has been observed, although the gradiometers are spaced by less than 1 mm. This shows that DROS's can be used in multichannel SQUID magnetometers.

U2 - 10.1109/77.488279

DO - 10.1109/77.488279

M3 - Article

SN - 1051-8223

VL - 6

SP - 38

EP - 44

JO - IEEE transactions on applied superconductivity

JF - IEEE transactions on applied superconductivity

IS - 1

ER -

Multichannel SQUID magnetometry using double relaxation oscillation SQUIDs

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