Abstract: According to the invention, a magnetic field gradiometer detector for detecting a material of interest positioned in a detecting region outside the detector includes a transmitter for generating an output signal at a selected frequency, a receiver for detecting the signal, a probe, and a switch coupling the receiver and transmitter with the probe that alternately connects and disconnects the receiver and transmitter to the probe, switching between transmitting and receiving. The probe includes tuning elements and a gradiometer coil array. The gradiometer coil array includes a first surface coil and a second surface coil wound in an opposite sense, the probe having a first side and an opposite second side, with the first and second surface coils configured asymmetrically such that the probe projects a magnetic field in the outside detecting region adjacent to the first side while being self-shielded on the second side.

Abstract: A magnetic resonance detection apparatus is provided that is not susceptible to acoustic ringing, and a method is provided for eliminating or canceling acoustic ringing from a detected magnetic resonance signal. Specifically, a composite pulse is utilized that allows for both efficient reduction of acoustic ringing signals and the detection of true NQR signals. The composite pulse can be used in any of the common NQR pulse sequences currently utilized simply via substitution of the original single pulses with the composite pulse. Furthermore, although a preferred application involves the spin-1 nucleus 14N and NQR, the composite pulse will be useful for the NQR of other nuclei such as 35Cl and 39K and in NMR applications and involving half-integer quadrupolar nuclei and spin-½ nuclei. In addition, coil ringdown and piezoelectric ringing are also substantially reduced.

Abstract: An NQR apparatus for irradiating a sample with an RF magnetic field and for determining the presence of a target material by detecting an NQR signal includes a transmitter for generating an output signal at a selected frequency, a receiver for detecting the NQR signal, a probe, and a switch coupling the receiver and the transmitter with the probe for alternately connecting and disconnecting the receiver and the transmitter to the probe, thereby switching the NQR apparatus between a transmitting mode and a receiving mode. The probe consists of a resonant circuit that includes a coil array. The coil array includes a first figure-8 coil and a partially overlapping, second figure-8 coil for generating an RF magnetic field in a detecting region outside the probe.

Abstract: A magnetic resonance detection apparatus is provided that is not susceptible to acoustic ringing, and a method is provided for eliminating or canceling acoustic ringing from a detected magnetic resonance signal. Specifically, a composite pulse is utilized that allows for both efficient reduction of acoustic ringing signals and the detection of true NQR signals. The composite pulse can be used in any of the common NQR pulse sequences currently utilized simply via substitution of the original single pulses with the composite pulse. Furthermore, although a preferred application involves the spin-1 nucleus 14N and NQR, the composite pulse will be useful for the NQR of other nuclei such as 35CI and 39K and in NMR applications and involving half-integer quadrupolar nuclei and spin- 1/2 nuclei. In addition, coil ringdown and piezoelectric ringing are also substantially reduced.