Abstract: Quantum information processing device includes resonator incorporating material containing physical systems, each of physical systems having at least four energy states, transition between two energy states of at least four energy states, and transition energy between at least two energy states of at least four energy states, at least four energy states being non-degenerate when magnetic field fails to be applied to physical systems, transition resonating in resonator mode that is in common between physical systems, each of at least four energy states representing a quantum bit, transition energy being shifted when magnetic field is applied to physical systems, and magnetic-field application unit configured to apply magnetic field having direction and intensity to material, to eliminate linear transition energy shift between two energy states included in physical systems, each of two energy states included in physical systems being with excluding two energy states resonating in resonator mode.

Abstract: The device enables strains of at least one surface (1) of a sample (2) to be measured versus temperature. Strains in a direction perpendicular to a predetermined plane, for example the plane of the surface (1), are measured by composite images. Strains in said plane are measured by image correlation. The measurements by image correlation and by composite images use a common visible light detection camera (3). The sample (2) is arranged in an enclosure (6) transparent at least locally to visible light (L). At least one infrared emitter (9) enables an infrared light to be created in a spectral band for a large part not detected by the camera (3).

Abstract: The present invention relates to a method and system in which multi-coherent resonances of a microwave in which the alkali-metal atoms in the ground state are driven simultaneously by a microwave hyperfine frequency ?H and a Zeeman frequency ?Z. The driving influences on the atom can include magnetic fields or by optically pumping light modulated by a Zeeman frequency ?Z or a microwave hyperfine frequency ?H or by combinations of their harmonics or subharmonics. Multi-coherent resonances permit simultaneous measurement or control of the ambient magnetic field and measurement or control of a hyperfine resonance frequency of alkali-metal atoms. In one embodiment, the hyperfine frequency for a controlled magnetic field can serve as an atomic clock frequency.

Abstract: A magnetic resonance force microscope (MRFM) generator for producing an RF magnetic field uniformly over the whole of a sample. A cantilever with magnetic probe tip is self-excited. Under this condition, spins in the sample are controlled to produce a magnetic resonance force. A frequency demodulator measures the resonant frequency of the cantilever from the output detection signal from a cantilever displacement-measuring instrument based on the magnetic resonance force.

Abstract: A magnetic resonance imaging system (10) includes a transmit coil (22) and one or more receive coils (32). The transmit coil includes one or more circuit segments (44, 44, 80, 90) including a light-sensitive metal-insulator-semiconductor capacitor (50) which is connected by an optic fiber to one of a plurality of variable light sources (68). In the set-up mode, the transmit coil transmits RF pulses into an examination region (14). A plurality of the receive coils are disposed around the imaging region. The tuning processor (60) analyzes the received RF fields from around the imaging region and determines adjustments to the amount of light transmitted to each light-sensitive capacitor to shim or tune the transmit coil to optimize RF field homogeneity. Further, the receive coils (32) include a light-sensitive capacitor whose illumination is changed during RF transmission to detune the receive coil.

Abstract: This apparatus for producing a hyperpolarized noble gas includes: a hyperpolarized noble gas generating cell in which a noble gas is subjected to an optical pumping in the presence of an alkali metal so as to generate a hyperpolarized noble gas; and a very fine capillary tube having an inside diameter of 0.1 to 1.25 mm which is positioned downstream from the hyperpolarized noble gas generating cell. This nuclear magnetic resonance spectrometer includes the above apparatus for producing a hyperpolarized noble gas and a nuclear magnetic resonance measuring instrument. This magnetic resonance imager includes the above apparatus for producing a hyperpolarized noble gas and a magnetic resonance image measuring instrument.

Abstract: A magnetic resonance (MR) system and method for generating information about an object is provided. The MR system comprises at least one MR detector configured to sense a plurality of signals within a shielded environment and a digitizing circuit configured for digitizing the analog signals to generate digital signals. The MR detector, digitizing circuit is located within a shielded environment. The system further comprises a first transmission element configured for transmitting the plurality of digital signals to a plurality of electronic devices.

Abstract: A radio-frequency tunable atomic magnetometer for detection of nuclear quadrupole resonance (NQR) from room temperature solids, including detection of nitrogen-containing explosives placed external to a sensor unit. A potassium radio-frequency magnetometer with sensitivity of 0.24 fT/Hz1/2 operating at 423 kHz is provided. The magnetometer detected a 14N NQR signal from room temperature ammonium nitrate (NH4NO3) in the zero-applied field limit. Results demonstrate first time detection of NQR with an atomic magnetometer, providing that a cryogen-free atomic magnetometer, with intrinsically frequency-independent sensitivity and easy tuning capabilities, can be an attractive new tool for detecting magnetic resonance signals in the kHz to MHz range.

Abstract: A cell in one example comprises an alkali metal and a coating of parylene on an interior surface of the cell. In one implementation, the alkali metal may be an optically pumped gaseous phase of an alkali metal. The parylene coating minimizes interaction of the excited state of the alkali metal, increases lifetime of the excited state, and minimizes interaction of nuclear spin states with the cell walls.

Abstract: A method comprises the steps of providing a nuclear magnetic resonance cell with first, second, and third nuclear moment gases and at least one optically pumpable substance; obtaining first, second, and third measured precession frequencies that correspond to the first, second, and third nuclear moment gases, wherein the first, second, and third measured precession frequencies are altered from corresponding first, second, and third Larmor precession frequencies by a rotational rate and corresponding first, second, and third local magnetic fields; and determining the rotational rate with compensation for the first, second, and third local magnetic fields through employment of the first, second, and third measured precession frequencies.

Abstract: Methods and systems for spatially resolved spin resonance detection in a sample of material are disclosed. Also disclosed are methods and systems for spatially resolved impedance measurements in a sample of material. The disclosed methods and samples can be used in screening of plurality of biological, chemical and material samples.

Abstract: Methods and systems for spatially resolved spin resonance detection in a sample of material are disclosed. Also disclosed are methods and systems for spatially resolved impedance measurements in a sample of material. The disclosed methods and samples can be used in screening of plurality of biological, chemical and material samples.

Abstract: Methods and systems for spatially resolved spin resonance detection in a sample of material are disclosed. Also disclosed are methods and systems for spatially resolved impedance measurements in a sample of material. The disclosed methods and samples can be used in screening of plurality of biological, chemical and material samples.

Abstract: An NMR gyroscope in one example comprises a support structure affixed within an enclosure, an NMR cell affixed to the support structure, a plurality of permanent magnets disposed about the NMR cell to produce a magnetic field within the cell, and a field coil disposed proximate the cell to produce a modulated magnetic field transverse to the magnetic field produced by the permanent magnets.

Abstract: A ferromagnetic lens in the presence of a DC magnetic field and a smaller AC magnetic field creates a localized minimum of the magnitude of the magnetic field vector of the combined magnetic field in a volume defined in free space away from the lens referred to as the focus volume. The localized minimum can be nonzero, and can create conditions for spin resonance in the focus volume. The focus volume defined in free space away from the lens can be very small, providing excellent resolution for magnetic resonance imaging, for example.

Abstract: Methods and systems for spatially resolved spin resonance detection in a sample of material are disclosed. Also disclosed are methods and systems for spatially resolved impedance measurements in a sample of material. The disclosed methods and samples can be used in screening of plurality of biological, chemical and material samples.

Abstract: The present invention provides a high sensitivity atomic magnetometer and methods of measuring low intensity magnetic fields that relate to the use of an alkali metal vapor and a buffer gas; increasing the magnetic polarization of the alkali metal vapor thereby increasing the sensitivity of the alkali metal vapor to a low intensity magnetic field; probing the magnetic polarization of the alkali metal vapor, the probing means providing an output from the alkali metal vapor, the output including characteristics related to the low intensity magnetic field; and measuring means that receives the output, determines the characteristics of the low intensity magnetic field, and provides a representation of the low intensity magnetic field. In addition, the invention relates to a magnetometer and methods that provide a representation of a first magnetic field originating within a sample volume. The sample volume may be part or all of a subject, such as a human subject.

Abstract: A novel spin resonance microscope is disclosed, the microscope design comprising an integrated evanescent wave probe and scanning tunneling microscope tip. The probe and tip may be either the same structure, or they may be separate structures. The integrated design allows for coherent excitation of precessing electron spin states in the sample such that spin resonance may be detected because the tunneling current is modulated by the spin resonance. Spin resonance may be affected by either adjacent nuclei, or by adjacent electrons. The present apparatus requires significantly reduced power inputs, such that the dead time of the system is short, and relaxation phenomena may be evaluated without swamping the instrument's electronics.

Abstract: An apparatus and method for remote NMR/MRI spectroscopy having an encoding coil with a sample chamber, a supply of signal carriers, preferably hyperpolarized xenon and a detector allowing the spatial and temporal separation of signal preparation and signal detection steps. This separation allows the physical conditions and methods of the encoding and detection steps to be optimized independently. The encoding of the carrier molecules may take place in a high or a low magnetic field and conventional NMR pulse sequences can be split between encoding and detection steps. In one embodiment, the detector is a high magnetic field NMR apparatus. In another embodiment, the detector is a superconducting quantum interference device. A further embodiment uses optical detection of Rb—Xe spin exchange. Another embodiment uses an optical magnetometer using non-linear Faraday rotation. Concentration of the signal carriers in the detector can greatly improve the signal to noise ratio.

Abstract: The present invention provides a high sensitivity atomic magnetometer and methods of measuring low intensity magnetic fields that relate to the use of an alkali metal vapor and a buffer gas; increasing the magnetic polarization of the alkali metal vapor thereby increasing the sensitivity of the alkali metal vapor to a low intensity magnetic field; probing the magnetic polarization of the alkali metal vapor, the probing means providing an output from the alkali metal vapor, the output including characteristics related to the low intensity magnetic field; and measuring means that receives the output, determines the characteristics of the low intensity magnetic field, and provides a representation of the low intensity magnetic field. In addition, the invention relates to a magnetometer and methods that provide a representation of a first magnetic field originating within a sample volume. The sample volume may be part or all of a subject, such as a human subject.

Abstract: Methods for spatially resolved spin resonance detection in a sample of material, with a resolution as small as 0.5 ? m –1 mm. In one embodiment, a coupler having at least one pair of degenerate orthogonal modes provides an evanescent input signal along one coupler axis to the sample, to which a magnetic field is applied, and senses a spin interaction signal along another coupler axis. In another embodiment, an evanescent input signal is applied to the sample along one of two identical transmission line resonators, and a difference of the two resonator signals provides a spin interaction signal. In another embodiment, a polarized laser beam provides an evanescent input signal to the sample, and the spin interaction signal is sensed according to a second beam polarization direction. Certain ferromagnetic or ferrimagnetic molecules, such as YIG, can be used to tag selected chemical and biological molecules, using spatially resolved spin resonance detection for interrogation.

Abstract: The present invention provides a method and system to simultaneously use the microwave and Zeeman end resonances associated with the same sublevel of maximum (or minimum) azimuthal quantum number m to lock both the atomic clock frequency and the magnetic field to definite values. This eliminates the concern about the field dependence of the end-resonance frequency. In an embodiment of the system of the present invention, alkali metal vapor is pumped with circularly-polarized D1 laser light that is intensity-modulated at appropriate resonance frequencies, thereby providing coherent population trapping (CPT) resonances. In another embodiment, pumping with constant-intensity circularly-polarized D1 laser light enhances magnetic resonances that are excited by alternating magnetic fields oscillating at appropriate resonance frequencies.

Abstract: Methods and systems for spatially resolved spin resonance detection in a sample of material are disclosed. Also disclosed are methods and systems for spatially resolved impedance measurements in a sample of material. The disclosed methods and samples can be used in screening of plurality of biological, chemical and material samples.

Abstract: A detector of near-infrared light includes a light receiving device having a perovskite-type composite oxide expressed by a general formula of La1−xPrxCrO3 (where 0<x<1) and magnetization measuring means for measuring an increase in magnetization in the composite oxide of the light receiving device when the light receiving device is irradiated with near-infrared light at room temperature.

Abstract: The present invention provides a high sensitivity atomic magnetometer and methods of measuring low intensity magnetic fields that relate to the use of an alkali metal vapor and a buffer gas; increasing the magnetic polarization of the alkali metal vapor thereby increasing the sensitivity of the alkali metal vapor to a low intensity magnetic field; probing the magnetic polarization of the alkali metal vapor, the probing means providing an output from the alkali metal vapor, the output including characteristics related to the low intensity magnetic field; and measuring means that receives the output, determines the characteristics of the low intensity magnetic field, and provides a representation of the low intensity magnetic field. In addition, the invention relates to a magnetometer and methods that provide a representation of a first magnetic field originating within a sample volume. The sample volume may be part or all of a subject, such as a human subject.

Abstract: An device for use with an MR imaging system emits radio-frequency signals within a first range when acquiring data. A resonant circuit within the device includes a plurality of electrical components. An opto-electronic component within the device electrically communicates with the resonant circuit. The opto-electronic component is controlled to operate in a plurality of modes. The electrical components are not sensitive to the radio-frequency signals within the first range when the opto-electronic component is operating in one of the modes.

Abstract: Magnetic resonance force microscopy (MRFM) is a technology capable of detecting the magnetic resonance of a small number of spins and, potentially, a single spin of an electron or nucleus. Most methods use soft cantilevers with microscopic dimensions (microns) which have been developed for atomic force microscopy. Cantilevers have been both a solution and problem of high sensitivity force detection. They are difficult to fabricate and it is difficult to achieve the right sensitivity and stiffness with them. The proposed invention eliminates the cantilever and replaces it with small, magnetically sensitive objects called birdies, which are manipulated above a sample using electromagnetic field control. The basic principles of the cantilever-free MRFM are the same as those of traditional, cantilever-based systems. Motion of the birdie induced by magnetic resonance is monitored using optical interferometry.

Abstract: A vectorial magnetometer (1), measures the components of a magnetic field in three directions (Oxyz) using a scalar magnetometer (2). The field is periodically modulated in each of the directions by generators (Gx, Gy, Gz) which have a specific frequency for each direction and that power coils (Ex, Ey, Ez). Synchronous demodulation of the of the output signal of the scalar magnetometer (2) for each of the three frequencies permits the relative continuous component of each axis to be found. The vectorial magnetometer (1) is characterised in that it has means (Dx D′x, Dy D′y, Dz D′z) that can carry out a double demodulation for phase and quadrature for each of the frequencies and processing means (70) that use the continuous component modules for phase and quadrature to calculate a transfer function of the scalar magnetometer at the frequency in question, and to apply this function to the correction of the components.

Abstract: Methods for spatially resolve spin resonance detection in a sample of material, with a resolution as small as 0.5 &mgr;m-1 mm. In one embodiment, a coupler having at least one pair of degenerate orthogonal modes provides an evanescent input signal along one coupler axis to the sample, to which a magnetic field is applied, and senses a spin interaction signal along another coupler axis. In another embodiment, an evanescent input signal is applied to the sample along one of two identical transmission line resonators, and a difference of the two resonator signals provides a spin interaction signal. In another embodiment, a polarized laser beam provides an evanescent input signal to the sample, and the spin interaction signal is sensed according to a second beam polarization direction. Certain ferromagnetic or ferrimagnetic molecules, such as YIG, can be used to tag selected chemical and biological molecules, using spatially resolved spin resonance detection for interrogation.

Abstract: A diode laser-pumped magnetometer includes a diode laser that emits a polarized pumping laser beam with resonant optical radiation; and a K-cell through which a magnetic field is manifested from an independent source, the K-cell containing atoms with a dipole experiencing a torque due to the magnetic field. The atoms are excited by the resonant optical radiation of the pumping laser beam and periodically emitting a response radiation as they return to ground state such that the response radiation includes photons that indicate one unit of angular momentum indicative of the torque due to the magnetic field. Finally, a photodetector serves as a means for measuring the response radiation of the K-cell to indicate thereby a measure of the magnetic field in the K-cell from the independent magnetic source.

Abstract: A magnetic resonance imaging apparatus generates an MR signal from an object by applying a gradient field pulse generated by a gradient field coil and a high-frequency magnetic field pulse generated by a high-frequency coil to the object in a static field, and reconstructs an image on the basis of the MR signal. The gradient field coil is housed in a sealed vessel. The internal air in the sealed vessel is exhausted by the pump to prevent noise. By controlling the operation of the pump using a control circuit, noise in imaging operation can be reduced more effectively.

Abstract: Methods for obtaining a signal from optically pumped magnetometers are described in which a broadband self-oscillation magnetometer (31, 37) is coupled to an absorption cell (32, 40) in such a way that the self-oscillating magnetometer has the function of a voltage-controlled oscillator.

Abstract: A method of imaging a spatial distribution of a noble gas by nuclear magnetic resonance spectrometry includes detecting a spatial distribution of at least one noble gas by NMR spectrometry and generating a representation of said spatial distribution of the noble gas. The noble gas is selected from noble gas isotopes having nuclear spin, preferably Xenon-129 and/or Helium-3. The noble gas is at least thermally or equilibrium polarized and is preferably hyperpolarized, most preferably hyperpolarized by optical (laser) pumping in the presence of an alkali metal or by metastability exchange. The generation of the representation of the noble gas spatial distribution includes at least one dimension, preferably 2 or 3 dimensions of the spatial distribution. The noble gas may be imaged according to the invention in chemical or biological systems, preferably in a human or animal subject or organ system or tissue thereof.

Abstract: A single-mode semiconductor laser for optical pumping in H.sup.e and .sup.4 He and high-sensitivity magnetometers based upon these systems. A distributed Bragg reflection (DBR) or distributed feedback (DFB) single mode, preferably InGaAs laser diode (1) which obviates the need for optomechanical arrangements and their inherent instabilities as required by the prior art laser pumped magnetometers. By constructing a DBR or DFB region (28) within the laser diode structure, the laser is forced to operate within a single-mode at a wavelength that is jointly determined by the gain of the laser medium and feedback from the Bragg grating. This wavelength is controllable in one of three ways: (1) temperature control (13) of the laser diode junction and grating, (2) injection current control (12) within the gain region, (3) current control (11) of the Bragg grating region or any combination of the three.

Abstract: A coupled radio frequency field and light polarization magnetometer. The polarization direction P and the direction of the radio frequency field B.sub.1 are kept parallel to one another and perpendicular to the field B.sub.0 which is to be measured. The polarizer is connected to the coil, which produces B.sub.1, and the assembly is rotated by a piezoelectric motor.

Abstract: Resonance magnetometer with optical pumping using a monolithic laser. The laser (30) includes a single element (32) (crystal or fiber) whose length is modulated to provide both a wavelength and amplitude control.

Abstract: Resonance magnetometer with optical pumping using a monolithic laser. The laser (30) includes a single element (32) (crystal or fiber) ensuring whose length is modulated to provide both a wavelength and amplitude control.

Abstract: A linear ion trap for frequency standard applications is provided with a plurality of trapping rods equally spaced and applied quadrupole rf voltages for radial confinement of atomic ions and biased level pins at each end for axial confinement of the ions. The trapping rods are divided into two linear ion trap regions by a gap in each rod in a common radial plane to provide dc discontinuity, thus dc isolating one region from the other. A first region for ion-loading and preparation/fluorescence is biased with a dc voltage to transport ions into a second region for resonance/frequency comparison with a local oscillator derived frequency while the second region is held at zero voltage. The dc bias voltage of the regions is reversed for transporting the ions back into the first region for fluorescence/measurement. The dual mode cycle is repeated continuously for comparison and feedback control of the local oscillator derived frequency.

Abstract: Optical pumping magnetometer with controlled polarization.This magnetometer comprises a linear polarizer (16), whose orientation is controlled (42,44) in such a way that the detection signal is at a maximum, no matter what the orientation of the field to be measured.Application to the construction of isotropic magnetometers.

Abstract: A magnetometer for precise measurement of weak magnetic fields involves a system which injects a plurality of light beams into a gas containing cell. An optical multiplexer receives the light beams emitted by a source and successively supplies a plurality of light beams which traverse a corresponding number of polarizers. The beams are subsequently injected into the cell 10 in the plurality of different directions in order to optically pump the gas. A detection device detects an electrical resonance signal and supplies a plurality of signals corresponding to the optical pumping beams.

Abstract: A magnetometer having three trirectangular trihedron windings (20x, 20y, 20z) which are put into service successively by a multiplexer (50). The means frequency (F.sub.m) of the three measurement signals is independent of the orientation of the weak magnetic field which is to be measured.

Abstract: A gas cell, preferably in the shape of a hemi-sphere, forms a transparent enclosure for helium or an alkali metal vapour. A coil forms an A.C. magnetic field H.sub.1 in the enclosure, the magnetic field having multi-directional field lines. A lamp or lamps, comprising either helium or alkali metal vapour, direct circularly polarized resonance radiation at the enclosure such that the radiation rays travelling through the enclosure are multi-directional. A photodetector or photodetectors detect the radiation rays after they have passed through the gas cell. The multi-directionality of the radiation rays and the A.C. magnetic field H.sub.1 ensures that the magnetometer will not possess dead-zones.

Abstract: An improved optical pumping magnetometer with sequential polarization for measurement of weak magnetic fields involves a device which sequentially modifies the polarization either in the direction of the polarization or from clockwise to counterclockwise circular polarization. As a result of the sequential modification of the polarization, the magnetometer for measurement of the weak magnetic fields has excellent isotropy while still retaining a simple construction and a small overall dimension to the device by using only a single cell.

Abstract: A gradient magnetic field coil for generating a gradient magnetic field comprises at least one pair of conductive thin plates placed on a surface of a cylinder and rod conductors for supplying an electric current to at least one pair of conductive thin plates. In case of defining a body center of the cylinder to be an origin, defining a central axis of the cylinder to be a z axis, defining an axis included in the plane, intersecting at the origin and being vertical to the z axis to be an x axis and defining an axis intersecting at the origin and being vertical to the x axis and the z axis to be a y axis, at least one pair of conductive thin plates have a symmetrical shape with respect to an x-y plane and a y-z plane, and the conductive thin plates, each facing to each other, are placed in a symmetrical position with respect to an x-z plane and have a symmetrical shape with respect to an x-z plane.

Abstract: A magnetometer is desclosed in which a gas cell containing atomic vapor is pulse pumped at one of the transitions of the gas in the cell. After the pulse has passed through the gas cell, thereby causing alignment of all the individual atomic moments along the propagation direction of the pulse, a probe beam reads out the Larmor precession frequency of the freely precessing atoms in terms of the frequency of the amplitude modulation of the probe beam caused by the free precession within the gas cell. The system is suitable for laboratory measurements of the absolute value of a magnetic field and for packaging in an expendable battery powered water-born buoy becuase of the low power consumption of the subject system.

Abstract: A magnetometer having an enclosed cell containing He.sup.3 therein for receiving light from a light source, a light source for directing light to the enclosed cell along a predetermined path, a single pick-up coil containing therein the light source and the enclosed cell, a solenoid containing the pick-up coil therein and a data collection system coupled to the pick-up coil. The light source is a source of circularly polarized light and can comprise a He.sup.4 cell and an optical system and a circular polarizer disposed serially between He.sup.4 cell and enclosed cell containing He.sup.3. The predetermined path of the light source, the enclosed cell and the pick-up coil are disposed along the axis of the solenoid. The light source can also be a laser.

Abstract: A system for the optical pumping of a cell of atomic or molecular gases comprises at least one optical cavity comprising at least one cell of atomic or molecular gases, one optical pumping wave being coupled to the optical cavity.

Abstract: A radiation source (12) for optical magnetometers (10) which use helium isotopes as the resonance element (30) includes an electronically pumped semiconductor laser (12) which produces a single narrow line of radiation which is frequency stabilized to the center frequency of the helium resonance line to be optically pumped. The frequency stabilization is accomplished using electronic feedback (34, 40, 42, 44) to control a current sources (20) thus eliminating the need for mechanical frequency tuning.

Abstract: In a magnetic field measuring device, conveyed by a carrier vehicle and released from this vehicle in order to be put into action, the excitation means and the measuring means of a nuclear magnetic resonance helium magnetometer are separated. These measuring means are fixed to a body which includes devices for the transmission and exploitation of the measurements given by the measuring means, and this set is released after the exzcitation is completed while the excitation means remain fixed in the carrier vehicle. This makes it possible to fabricate smaller and lighter magnetic localizing buoys.

Abstract: A scalar magnetometer with vector capabilities includes a cell containing .sup.3 He gas at a pressure between 0.05 Torr and 100 Toor. The cell is energized by an oscillator which partially ionizes the .sup.3 He gas. Metastable atoms are polarized and consequently ground state atoms are polarized with a radiation source. A pair of Helmholtz coils provides a small uniform magnetic field which initiates a precession of the polarized .sup.e He atoms by forcing their misalignment with the magnetic field to be measured. The angular velocity of the precession is proportional to the strength of the field. A voltage is induced in a plurality of coils that are mounted on the axes of the cell. The induced voltage provides vector information for identifying the angular position of the cell relative to the magnetic field being measured.