Low magnetic susceptibility materials and applications in magnetic gradiometry

Sunderland, Andrew; Li, Ju; Blair, David; McRae, Wayne; Golden, Howard

doi:10.1088/0964-1726/18/9/095038

Cited by 6 publications

(2 citation statements)

References 27 publications

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“…First, 99.9 wt% high purity copper is used for the top and bottom plugs because of less magnetic impurity contained in the material. It was reported earlier that alloys such as Brass contain unacceptable amount of magnetic impurities 22,23 , whereas soft materials such as pure aluminum are difficult to be machined, and tend to fail in vacuum sealing. Secondly, we use the drinking straw as the material for fixing all the ultra-low-temperature parts.…”

Section: Instrument Design and Operationmentioning

confidence: 99%

Tiny adiabatic-demagnetization refrigerator for a commercial superconducting quantum interference device magnetometer

Sato

Okuyama

Kimura

2016

Review of Scientific Instruments

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A tiny adiabatic-demagnetization refrigerator (T-ADR) has been developed for a commercial superconducting quantum interference device magnetometer [Magnetic Property Measurement System (MPMS) from Quantum Design]. The whole T-ADR system is fit in a cylindrical space of diameter 8.5 mm and length 250 mm, and can be inserted into the narrow sample tube of MPMS. A sorption pump is self-contained in T-ADR, and hence no complex gas handling system is necessary. With the single crystalline GdGaO garnet (∼2 g) used as a magnetic refrigerant, the routinely achievable lowest temperature is ∼0.56 K. The lower detection limit for a magnetization anomaly is ∼1 × 10 emu, estimated from fluctuation of the measured magnetization. The background level is ∼5 × 10 emu below 2 K at H = 100 Oe, which is largely attributable to a contaminating paramagnetic signal from the magnetic refrigerant.

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Section: Instrument Design and Operationmentioning

confidence: 99%

Tiny adiabatic-demagnetization refrigerator for a commercial superconducting quantum interference device magnetometer

Sato

Okuyama

Kimura

2016

Review of Scientific Instruments

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“…Extensive work has been done in the NMR/MRI community to develop probes [4,5] and materials [6,7] whose magnetic susceptibility match to that of certain tissues so as not to distort the MRI images. Low magnetic susceptibility materials are also of interest in other areas of magnetic instrumentation [8] and for applications in standards laboratories in devices such as the watt balance [9]. The recentlylaunched Lisa Pathfinder mission,whose scientific goal is to perform the R&D needed to develop a space-based measurement system for gravitational waves, employs test masses made of a low magnetic susceptibility gold-platinum alloy in part to minimize magnetic effects [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Materials with low DC magnetic susceptibility for sensitive magnetic measurements

Khatiwada¹,

Dennis²,

Kendrick³

et al. 2015

Meas. Sci. Technol.

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Materials with very low DC magnetic susceptibility have many scientific applications. To our knowledge however, relatively little research has been conducted with the goal to produce a totally nonmagnetic material. This phrase in our case means after spatially averaging over macroscopic volumes, it possesses an average zero DC magnetic susceptibility. We report measurements of the DC magnetic susceptibility of three different types of nonmagnetic materials at room temperature: (I) solutions of paramagnetic salts and diamagnetic liquids, (II) liquid gallium-indium alloys and (III) pressed powder mixtures of tungsten and bismuth. The lowest measured magnetic susceptibility among these candidate materials is in the order of 10 −9 cgs volume susceptibility units, about two orders of magnitude smaller than distilled water. In all cases, the measured concentration dependence of the magnetic susceptibility is consistent with that expected for the weighted sum of the susceptibilities of the separate components within experimental error. These results verify the wellknown Wiedemann additivity law for the magnetic susceptibility of inert mixtures of materials and thereby realize the ability to produce materials with small but tunable magnetic susceptibility. For our particular scientific application, we are also looking for materials with the largest possible number of neutrons and protons per unit volume. The gallium-indium alloys fabricated and measured in this work possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature liquid, and the tungsten-bismuth pressed powder mixtures possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature solid. This ratio is a figure of merit for a certain class of precision experiments that search for possible exotic spin-dependent forces of Nature.

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Systematic Review of fMRI Compatible Devices: Design and Testing Criteria

et al. 2017

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Functional Magnetic Resonance Imaging (fMRI) is at present one of the most used methodologies for functional brain exploration, both in clinical and research settings. fMRI can noninvasively measure neural activity by using specific experimental paradigms. Often, these paradigms require the stimulation of the subject to perform sensorimotor tasks: in the past, the stimuli have been administered manually for investigating fundamental aspects of tactile perception and somatosensory processing. Nowadays, the use of mechatronic devices to stimulate the subject during fMRI studies is growing, also to assure reproducibility, control, and monitoring of task performances. For these reasons, researchers are interested in designing interfaces to be used inside the MRI environment during fMRI studies. For the design of every new device safety and compatibility constraints, imposed by the presence of high static magnetic field, switching magnetic gradients and radiofrequency electromagnetic pulses, must be satisfied. Moreover, it should be considered that functional imaging sequences are even more sensitive to perturbations of the magnetic field than MRI standard diagnostic sequences. Despite several existing devices for use in fMRI studies, an extensive review is still lacking. Our survey aims to introduce into the challenges imposed on the development of fMRI-compatible devices. The current state of the art of compatible devices in fMRI will be presented, pointing out the functionalities and peculiarities of various kinds of device. A particular emphasis will be placed on the tests for the evaluation of fMRI compatibility. This review will be useful both for designers of devices to be used in fMRI studies and for neuroscientists that are having to design fMRI experimental paradigm, and therefore require an overview of existing instruments, but also a knowledge of the benefits and criticism arising from their use.

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Low magnetic susceptibility materials and applications in magnetic gradiometry

Cited by 6 publications

References 27 publications

Tiny adiabatic-demagnetization refrigerator for a commercial superconducting quantum interference device magnetometer

Tiny adiabatic-demagnetization refrigerator for a commercial superconducting quantum interference device magnetometer

Materials with low DC magnetic susceptibility for sensitive magnetic measurements

Systematic Review of fMRI Compatible Devices: Design and Testing Criteria

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