Advances in sensor development and demonstration of superconducting gradiometers for mobile operation

Clem, T.R.; Froelich, M.C.; Ovenvay, D.J.; Purpura, J.W.; Wiegert, R. F.; Koch, R. H.; Lathrop, D. K.; Rozen, J. R.; Eraker, J. H.; Schmidt, J. M.

doi:10.1109/77.622056

Cited by 20 publications

(9 citation statements)

References 16 publications

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“…The second term is the stripline µΦ 0 /Hz 1/2 up to 10 µΦ 0 /Hz 1/2 . Therefore, th eld gradient resolution is 36 fT/m⋅Hz 1/2 up to 7 omparable to the results given in [7] in statio That corresponds to a field resolution in one oop of 1.45 fT/Hz 1/2 up to 2.9 fT/Hz 1/2 . First m n an uniform field showed a balance in the ran p to 10 3 /m.…”

Section: Squid Fabrication and Layoutsupporting

confidence: 80%

LTS SQUID sensor with a new configuration

Stolz¹,

Fritzsch²,

Meyer³

1999

Supercond. Sci. Technol.

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We have developed highly sensitive SQUID-based magnetometers and gradiometers, fabricated in a standard Nb/AlOX/Nb technology. The SQUID itself is designed as a current sensor having an input coil and a feedback coil. The number of turns of the input coil can be adjusted to ensure optimal coupling to the pickup loops with an inductance in the range from 5 nH to 300 nH. Several types of planar pickup loop configurations have been realized. The magnetometer has a pickup loop with a size of 1 cm × 1 cm. With a typical white noise level better than 4 µ0 Hz-1/2 and an effective area of 2.6 mm2 a field resolution of 3.2 fT Hz-1/2 results for the magnetometer. Two loops connected in series with an area of 2 cm × 2 cm each and a baseline of 4 cm were used in the gradiometer. We measured a 7.5 mm2 effective area for each loop and a field gradient resolution of 36 fT m-1 Hz-1/2 corresponding to a field resolution in the loop of 1.6 fT Hz-1/2.

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Section: Squid Fabrication and Layoutsupporting

confidence: 80%

LTS SQUID sensor with a new configuration

Stolz¹,

Fritzsch²,

Meyer³

1999

Supercond. Sci. Technol.

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“…The average moment for five typical UXO are also shown. These are nominal moments culled from various sources (Clem et al, 1997;Billings, 2004). Magnetic moments from UXO vary depending on the ordnance type and its orientation relative to the Earth's field (Altshuler, 1996;Billings et al, 2002).…”

Section: Single Targetsmentioning

confidence: 99%

“…A detection threshold of 1.5 nT with a background field of 50,000 nT at 65u inclination was used. Moments for the UXO types were derived from Clem (1997) and Billings (2004). The ''x'' indicates altitudes where the minimum density is too sparse to be considered a cluster.…”

Section: Multiple Targetsmentioning

confidence: 99%

Magnetic Response of Clustered UXO Targets

Gamey

2008

Journal of Environmental & Engineering Geophysics

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The objective of many recent UXO surveys has been described as ''wide-area assessment'' with the purpose of obtaining better definition of a known problem area. The targets of interest are clusters of ordnance, fragments and debris which are all indicators of greater contamination, higher risk of UXO hazard and higher remediation or construction costs. This is a different problem from the detection and discrimination of individual anomalies.This paper provides a definition of a ''cluster'' based on the amount of overlap between individual dipole signatures. In total field surveys, magnetic anomalies overlap significantly and show an increased amplitude response once the individual sources are spaced closer than 0.5 times the sensor height. When this condition is extended over a large area, such as the center of a target site, the result can be comparable to a horizontal sheet of dipoles.The equations to simulate a horizontal sheet are derived, and from these the relative density of targets may be calculated from the measured data by assuming a nominal target moment. Two field tests support both the qualitative and quantitative predictions.Extending this concept to field practice, we examine some of the implications for standard operational procedures. For example, if we accept that QA/QC metrics should represent the targets of interest, then we should require wide-area assessment surveys to create impractically large grids of surface frag. Likewise, for detection of clusters the concepts of detection probability and search radius based on single items are irrelevant. Discrimination techniques that rely on dipole fitting will be extremely inaccurate. Instead, QA parameters and models suitable for horizontal sheets will have to be derived.

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“…Some low-temperature experiments, such as flux expulsion experiments of superconductors [1,2], not only require magnetic sensors capable of operating at liquid helium temperature (4.2 K), but also require a sensor with a high dynamic range of several tens of Gauss, a high magnetic field resolution of more than 0.1 milligauss (mG), and good linearity. Superconducting quantum interference devices (SQUIDs) [3,4] are often used to measure weak magnetic fields at low temperature. However, the high price, complex operation, easy damage and small dynamic range limit the applications of SQUIDs in some fields.…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Properties of the Magnetic Sensor with Amorphous Wire

Umemori

Ueki

et al. 2020

Sensors

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We found that a magnetic sensor made of a coil wound around a 5 f0.1 mm (Fe0.06Co0.94)72.5Si2.5B15 (FeCoSiB) amorphous wire could operate in a wide temperature range from room temperature to liquid helium temperature (4.2 K). The low-temperature sensing element of the sensor was connected to the room-temperature driving circuit by only one coaxial cable with a diameter of 1 mm. The one-cable design of the magnetic sensor reduced the heat transferring through the cable to the liquid helium. To develop a magnetic sensing system capable of operating at liquid helium temperature, we evaluated the low-temperature properties of the FeCoSiB magnetic sensor.

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Advances in sensor development and demonstration of superconducting gradiometers for mobile operation

Cited by 20 publications

References 16 publications

LTS SQUID sensor with a new configuration

LTS SQUID sensor with a new configuration

Magnetic Response of Clustered UXO Targets

Low-Temperature Properties of the Magnetic Sensor with Amorphous Wire

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