992 research outputs found
Magnetocardiography with a modular spin-exchange relaxation free atomic magnetometer array
We present a portable four-channel atomic magnetometer array operating in the
spin exchange relaxation-free regime. The magnetometer array has several design
features intended to maximize its suitability for biomagnetic measurement,
specifically foetal magnetocardiography, such as a compact modular design, and
fibre coupled lasers. The modular design allows the independent positioning and
orientation of each magnetometer, in principle allowing for non-planar array
geometries. Using this array in a magnetically shielded room, we acquire adult
magnetocadiograms. These measurements were taken with a 6-11 fT Hz^(-1/2)
single-channel baseline sensitivity that is consistent with the independently
measured noise level of the magnetically shielded room.Comment: 15 pages, 5 figure
Optical Magnetometer Array for Fetal Magnetocardiography
We describe an array of spin-exchange relaxation free optical magnetometers
designed for detection of fetal magnetocardiography (fMCG) signals. The
individual magnetometers are configured with a small volume with intense
optical pumping, surrounded by a large pump-free region. Spin-polarized atoms
that diffuse out of the optical pumping region precess in the ambient magnetic
field and are detected by a probe laser. Four such magnetometers, at the
corners of a 7 cm square, are configured for gradiometry by feeding back the
output of one magnetometer to a field coil to null uniform magnetic field noise
at frequencies up to 200 Hz. Using this array, we present the first
measurements of fMCG signals using an atomic magnetometer
Fabrication of Mullite Body Using Superplastic Transient Phase
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65799/1/j.1151-2916.1992.tb05542.x.pd
Anomalous rotational-alignment in N=Z nuclei and residual neutron-proton interaction
Recent experiments have demonstrated that the rotational-alignment for the
nuclei in the mass-80 region is considerably delayed as compared to the
neighboring nuclei. We investigate whether this observation can be
understood by a known component of nuclear residual interactions. It is shown
that the quadrupole-pairing interaction, which explains many of the delays
known in rare-earth nuclei, does not produce the substantial delay observed for
these nuclei. However, the residual neutron-proton interaction which is
conjectured to be relevant for nuclei is shown to be quite important in
explaining the new experimental data.Comment: 4 pages, 3 figures, final version accepted by Phys. Rev. C as a Rapid
Communicatio
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