Abstract: A nuclear magnetic resonance sensing apparatus including a magnet for inducing a static magnetic field in materials to be analyzed, the magnetic field having uniform field strength around, being substantially rotationally symmetric and perpendicular to a longitudinal axis of the magnet. The apparatus includes means for generating a radio frequency magnetic field in the materials to be analyzed. The radio frequency magnetic field is substantially rotationally symmetric about the longitudinal axis and is parallel to the longitudinal axis within a sensitive volume containing the materials to be analyzed. The apparatus includes means for receiving a nuclear magnetic resonance signal from the sensitive volume. In a preferred embodiment, the means for generating and means for receiving include an antenna coil wound so that turns of the coil lie in planes perpendicular to the longitudinal axis of the magnet.

Abstract: In a method for the acquisition and evaluation of data obtained in a nuclear magnetic resonance tomography apparatus, only data for a constant sub-region of an overall dataset, that was obtained from a preceding measurement, are updated by new measured data in subsequent successive measurements (keyhole method). In order to sharply reproduce measurement subjects in the visual display which move from measurement to measurement while only slightly lengthening the registration time in comparison to a standard keyhole measurement sequence, data for difficult sub-regions of the overall dataset are additionally updated from measurement to measurement, and these sub-regions are varied in a predetermined sequence from measurement to measurement.

Abstract: An MR imaging method using NMR phenomenon and including the following steps: emitting a first group of RF pulses including a first inversion RF pulse, and excitation RF pulses emitted to excite a plurality of slices in a predetermined order; emitting slice-selecting gradient field pulses; emitting phase-encoding gradient field pulses; collecting a first group of echo signals; emitting a second group of RF pulses including a second inversion RF pulse having substantially the same frequency band as the first inversion RF pulse, and second excitation RF pulses emitted to excite the plurality of slices in a reverse order; emitting slice-selecting gradient field pulses; emitting phase-encoding gradient field pulses; collecting a second group of echo signals; repeating this pulse sequence while varying the phase-encoding gradient field pulses; adding two data corresponding to each slice, which data are included, respectively, in a first group of data and in a second group of data, thereby forming a new group of dat

Abstract: In a magnetic resonance tomography pulse sequence, a slice perpendicular to the spatial direction of an inhomogeneity in the static field is first excited. The nuclear spins are re-phased and spin echo signals are readout under a gradient in a second direction. A phase-encoding gradient is activated between the excitation and the readout of the nuclear spins. A predetermined inhomogeneity in the static magnetic field is permanently present and acts during the overall pulse sequence as a permanent magnetic field gradient. With this pulse sequence, an inhomogeneity in two spatial directions can be allowed, which simplifies the construction of a magnet considerably and improves the access to the subject under examination.

Abstract: For use in a downhole oil well logging tool which is enclosed in a sonde and suspended on an armored logging cable, a means for measuring the macroscopic thermal neutron capture cross section of the borehole fluid is set forth. In the preferred embodiment, a neutron source adjacent to a neutron detector is positioned in a sonde. The entire surrounding region in the well borehole is used as a sample chamber. Fast neutrons from the source after collision with fluid nuclei impinge on the detector which provides an output signal which is indicative of neutron flux. The count rate is most significantly dependent on the thermal neutron capture cross section of the borehole fluid. An additional detector can likewise be spaced farther from the neutron source and provide an alternate count rate. Through the use of two detectors, minor perturbations induced by changes in the environment outside the borehole can be compensated. The neutron capture cross section can be determined for the borehole fluid.