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SQUID Systems Adapted to Record Nuclear Magnetism in Low Magnetic Fields.

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Title: SQUID Systems Adapted to Record Nuclear Magnetism in Low Magnetic Fields.
Authors: Burghoff, M.1 Martin.Burghoff@ptb.de, Hartwig, S.1, Kilian, W.1, Vorwerk, A.2, Trahms, L.1
Source: IEEE Transactions on Applied Superconductivity. Jun2007 Part 1 of 3, Vol. 17 Issue 2, p846-849. 4p.
Subjects: Superconducting quantum interference devices, Superconductors, Cryoelectronics, Electronic materials, Solid state electronics, Nuclear magnetism, Magnetism, Nuclear physics, Magnetic fields
Abstract: We modified two SQUID measurement systems, originally developed and optimized for biomagnetic applications, with the aim to employ them for observing the precession of nuclear magnetism in low fields of a microtesla or less. To this end, coil systems for the polarization and for the observation of the nuclear magnetization were added to the set-up. In addition, SQUID readout electronics had to be fast enough to allow for short dead times after switching off the polarizing field. One system was a single channel gradiometer that is routinely used for measuring the relaxing magnetism of magnetic nanoparticles. The second system was a 304 SQUID system that was designed for multichannel vector-magnetocardiography and vector-mag- neto-encephalography. Both systems had in common that they operated in a magnetically shielded environment provided by multi-layer mu-metal walk-in rooms. With the single channel system we determined the natural proton NMR line width of benzene in the fast motional limit to be (112 ± 3) mHz. The accuracy of this value was improved by excluding experimentally the presence of line broadening by the inhomogeneity of the residual environmental field in the magnetically shielded room. To this end, the transversal relaxation of hyperpolarized 129Xe gas was measured demonstrating that the spectrometer has a spectral resolution of about 6 mHz for 1H. By using a 304 SQUID vector magnetometer system the precession of 1H in multiple distilled water samples was recorded. From the spatially resolved data of the multi-SQUID system, positions and moments of the multiple samples were estimated. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:We modified two SQUID measurement systems, originally developed and optimized for biomagnetic applications, with the aim to employ them for observing the precession of nuclear magnetism in low fields of a microtesla or less. To this end, coil systems for the polarization and for the observation of the nuclear magnetization were added to the set-up. In addition, SQUID readout electronics had to be fast enough to allow for short dead times after switching off the polarizing field. One system was a single channel gradiometer that is routinely used for measuring the relaxing magnetism of magnetic nanoparticles. The second system was a 304 SQUID system that was designed for multichannel vector-magnetocardiography and vector-mag- neto-encephalography. Both systems had in common that they operated in a magnetically shielded environment provided by multi-layer mu-metal walk-in rooms. With the single channel system we determined the natural proton NMR line width of benzene in the fast motional limit to be (112 ± 3) mHz. The accuracy of this value was improved by excluding experimentally the presence of line broadening by the inhomogeneity of the residual environmental field in the magnetically shielded room. To this end, the transversal relaxation of hyperpolarized 129Xe gas was measured demonstrating that the spectrometer has a spectral resolution of about 6 mHz for 1H. By using a 304 SQUID vector magnetometer system the precession of 1H in multiple distilled water samples was recorded. From the spatially resolved data of the multi-SQUID system, positions and moments of the multiple samples were estimated. [ABSTRACT FROM AUTHOR]
ISSN:10518223
DOI:10.1109/TASC.2007.898203