Noise characterization of highly sensitive SQUID magnetometer systems in unshielded environments

Chwala, A.; Kingman, John; Stolz, R.; Schmelz, M.; Zakosarenko, V.; Linzen, S.; Bauer, Frank; Starkloff, M.; Meyer, Matthias; Meyer, H.‐G.

doi:10.1088/0953-2048/26/3/035017

Cited by 29 publications

(23 citation statements)

References 11 publications

(21 reference statements)

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“…Many signals (or sources of noise, depending on your perspective) can be seen in this data collected with the ARMIT sensors. Below 10 Hz we see 1/f noise generally attributed to rotational changes in coupling to the earth's magnetic field (Chwala et al, 2013). The 3 & 5 Hz peaks in B field data are "seismic" in origin from crew movement near the sensor.…”

Section: Discussionmentioning

confidence: 91%

Joint sensing of B and dB/dt responses

Macnae

Kratzer

2013

ASEG Extended Abstracts

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Section: Discussionmentioning

confidence: 91%

Joint sensing of B and dB/dt responses

Macnae

Kratzer

2013

ASEG Extended Abstracts

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“…It should be noted that the latest LTS SQUID system [14] features 2 sets of SQUID triplets; Table 1 only lists parameters for the low sensitivity SQUIDs which are intended for TEM measurements. The additional triplet of high sensitive SQUIDs (< 2 fT/ √ Hz) is designed for the use in geophysical methods with weak signals (LOTEM, CSAMT) or even passive (MT, AMT).…”

Section: System Setupmentioning

confidence: 99%

“…in the field. These measurements should be carried out in a rural area with two identical systems; the intrinsic noise can in this case be calculated by correlation techniques [14]. The same method cannot be used in the shielded room, because the signals at both cryostat locations are very different due to field gradients in the shielded room.…”

Section: Performance In the Laboratory And In The Fieldmentioning

confidence: 99%

SQUID Systems for Geophysical Time Domain Electromagnetics (TEM) at IPHT Jena

Chwala

Stolz

Schmelz

et al. 2015

IEICE Trans. Electron.

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SUMMARY Forty years after the first application of Superconducting Quantum Interference Devices (SQUIDs) [1], [2] for geophysical purposes, they have recently become a valued tool for mineral exploration. One of the most common applications is time domain (or transient) electromagnetics (TEM), an active method, where the inductive response from the ground to a changing current (mostly rectangular) in a loop on the surface is measured. After the current in the transmitter coil is switched, eddy currents are excited in the ground, which decay in a manner dependent on the conductivity of the underlying geologic structure. The resulting secondary magnetic field at the surface is measured during the off-time by a receiver coil (induced voltage) or by a magnetometer (e.g. SQUID or fluxgate). The recorded transient signal quality is improved by stacking positive and negative decays.Alternatively, the TEM results can be inverted and give the electric conductivity of the ground over depth. Since SQUIDs measure the magnetic field with high sensitivity and a constant frequency transfer function, they show a superior performance compared to conventional induction coils, especially in the presence of strong conductors.As the primary field, and especially its slew rate, are quite large, SQUID systems need to have a large slew rate and dynamic range. Any flux jump would make the use of standard stacking algorithms impossible.IPHT and Supracon are developing and producing SQUID systems based on low temperature superconductors (LTS, in our case niobium), which are now state-of-the-art. Due to the large demand, we are additionally supplying systems with high temperature superconductors (HTS, in our case YBCO). While the low temperature SQUID systems have a better performance (noise and slew rate), the high temperature SQUID systems are easier to handle in the field.The superior performance of SQUIDs compared to induction coils is the most important factor for the detection of good conductors at large depth or ore bodies underneath conductive overburden.

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“…Here A eff = /B being the effective area of the SQUID magnetometer [1]. Modern SQUID magnetometer systems already exhibit magnetic field noise level down to 1 fT/Hz 1/2 [2]. They are used e.g.…”

Section: Introductionmentioning

confidence: 99%

“…According to [3], beside the cooling-issue today's biggest challenge for bringing ULF MRI into clinical practice is the enhancement of the signal-to-noise-ratio (SNR), which determines the imaging time t ∝ 1/(SNR) 2 . In order to increase the SNR ∝ B p /B S , one needs to lower the SQUID system noise B S = S B 1/2 and to increase the strength of the pre-polarizing field B p .…”

Section: Introductionmentioning

confidence: 99%

Thin-Film-Based Ultralow Noise SQUID Magnetometer

Schmelz

Zakosarenko

Chwala

et al. 2016

IEEE Trans. Appl. Supercond.

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Abstract-We report on the development of an ultralow noise thin-film based SQUID magnetometer. A niobium thin-film pickup coil is connected to the input coil of a SQUID current sensor. The low capacitance of the used sub-micrometer crosstype Josephson junctions enable superior noise performance of the device. Application scenarios e.g. in geophysics and ultra-low field magnetic resonance imaging are discussed.

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Noise characterization of highly sensitive SQUID magnetometer systems in unshielded environments

Cited by 29 publications

References 11 publications

Joint sensing of B and dB/dt responses

Joint sensing of B and dB/dt responses

SQUID Systems for Geophysical Time Domain Electromagnetics (TEM) at IPHT Jena

Thin-Film-Based Ultralow Noise SQUID Magnetometer

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