GEM leads in developing advanced quantum magnetometer technologies, including the Overhauser, optically pumped Potassium (K-Mag) and Proton Precession magnetometers. The company is recognized as the successful commercial developer of both the Overhauser and Potassium magnetometer / gradiometer. Moreover, its Proton Precession magnetometer / gradiometer is the latest technology system in its class.
Quantum magnetometers take advantage of the spin of subatomic particles (nuclei and unpaired valence electrons). Through a process of polarization, particles are caused to precess in the earth’s ambient magnetic field. The resulting frequency of precession can be translated directly into magnetic field units. Quantum results are scalar (total field intensity) as opposed to vector (i.e. from fluxgate geophysical instruments or GEM’s Suspended dIdD technology).
The spin of nuclei and unpaired valence electrons is associated with the magnetic moment and is characteristic for each particular particle. Coupling of each particle’s magnetic moment with the applied field is quantized or limited to a discrete set of values as determined by quantum mechanical rules.
In the ambient magnetic field, there are 2I + 1 orientations for electrons and for nuclei (i.e. protons and Helium 3). For each of these, I = ½. There are therefore, only 2 orientations allowed (parallel and anti-parallel to magnetic field). Since the populations of each of the orientations are different, an assembly of magnetic moments will produce a tiny net macroscopic magnetization that is aligned with the magnetic field.
Macroscopic nuclear or electron spin magnetization is static. If elementary magnetic moments are forced out of alignment with the direction of the ambient magnetic field, the corresponding particles precess (i.e. rotate) around the field in a plane of precession perpendicular to the field direction. They precess with an associated angular frequency, called the Larmor frequency which is in general proportional to the magnetic field value.
However, in weak magnetic fields, such as the Earth’s, the signals of all scalar magnetometers are just too weak for simple measurement of Larmor frequency. They must be boosted in intensity or “polarized” to ensure sufficient sensitivity of measurement. Due to the distribution of local magnetic fields, all particles in the sensor precess with naturally different frequencies and lose synchronism over time. The signal associated with the precession decays exponentially and the characteristic time of decay is called “transversal” relaxation time T2.
Similarly, if we apply a magnetic field to an assembly of spins, it takes time to establish macroscopic magnetization. The increase is again exponential with the time constant, T1, called “longitudinal” relaxation time. The intensity of magnetization is proportional to the strength of the applied magnetic field.
The strength of the magnetization and therefore, of the detectable precession signal, depends on the difference in populations of the two orientations of magnetic moments.
Increasing that difference is called polarization and can be achieved in three ways in quantum magnetometers:
- Application of strong auxiliary magnetic field (actually flux density) to polarize nuclear, usually protons.
- Transfer of natural polarization of auxiliary electrons to protons (Overhauser effect).
- Optical manipulation or “pumping” of electrons by elevating them to a higher state selectively.
Note: In practice, T2 is very short in solid samples. All quantum magnetometers therefore use liquid or gaseous sensors. In liquids and gases T1 and T2 assume values between a fraction of a second to several seconds. An exception is Helium 3, which has a T2 value of several hours or even days.
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FAQs
Quantum magnetometers are based on the spin of subatomic particles: • Nuclei – usually protons or the Helium 3 isotope. • Unpaired valence electrons. The spin of nuclei and unpaired valence electrons is associated with the. magnetic moment and is characteristic for each particular particle.
What is the most precise magnetometer? ›
Nuclear Magnetic Resonance is the most precise technology to measure magnetic fields, and the PT2026 is the most precise NMR magnetometer on the market.
What can a magnetometer be used for? ›
A magnetometer is a passive instrument that measures changes in the Earth's magnetic field. In ocean exploration, it can be used to survey cultural heritage sites such as ship and aircraft wrecks and to characterize geological features on the seafloor.
What is a magnetometer on my phone? ›
How it Works. Smartphones come equipped with a magnetometer so that your phone can sense its orientation in space, and use basic apps like the Compass App to determine your location with respect to Magnetic North (or South!). The way this is done is through an internal chip that contains a 3-axis magnetometer.
What weapons does a magnetometer detect? ›
Local aberrations in the magnetic field produced by ferromagnetic objects, such as guns and knives, can be detected by extremely sensitive magnetometers.
What is the general purpose of a magnetometer? ›
magnetometer,, instrument for measuring the strength and sometimes the direction of magnetic fields, including those on or near the Earth and in space. Magnetometers are also used to calibrate electromagnets and permanent magnets and to determine the magnetization of materials.
What will set off a magnetometer? ›
The magnetometer can only detect ferrous (iron or steel) objects.
What does a magnetometer pick up? ›
Magnetometers can be used as metal detectors: they can detect only magnetic (ferrous) metals, but can detect such metals at a much greater distance than conventional metal detectors, which rely on conductivity.
Why does the secret service use magnetometers? ›
Everyone who comes through the White House must pass through a metal detector, or magnetometer. This special machine alerts the Secret Service to any potential weapons that are being brought into the complex.
What is the purpose of the magnetometer on the iPhone? ›
The magnetometer measures the strength of the magnetic field surrounding the device. In the absence of any strong local fields, these measurements will be of the ambient magnetic field of the Earth, allowing the device to determine its “heading” with respect to the geomagnetic North Pole and act as a digital compass.
The magnetometer sensor measures the magnetic field for all three physical axes (x, y, z) in μT (micro Tesla). This specification defines two new interfaces: Magnetometer that reports calibrated magnetic field values, and. UncalibratedMagnetometer that reports uncalibrated magnetic field values.
How to check magnetometer in Android? ›
On several Android phones, including Samsung phones, you can enter *#0*# in the phone dialer and it will call up a hardware test menu. From there, select Sensor and you will see the magnetic sensor output as well as other sensor data. Press the back button several times to get out.
What does magnetic quantum do? ›
What does the Magnetic Quantum Number Determine? The magnetic quantum number primarily determines the number of orbitals and the orientation of orbitals in a given sub-shell. Consequently, it is dependent on the orbital angular momentum quantum number, also known as the azimuthal quantum number.
How does a quantum compass work? ›
A quantum compass contains clouds of atoms frozen using lasers. By measuring the movement of these frozen particles over precise periods of time the motion of the device can be calculated.
What is the difference between a magnetometer and a metal detector? ›
The term "metal detector" (MD) generally refers to some type of electromagnetic induction instrument, although traditional magnetometers are often used to find buried metal. The disadvantage of magnetometers is that they can be used only for locating ferrous metals.
Is A magnetometer the same as a compass? ›
Magnetometers can work in several ways. The simplest, the magnetic compass, also simply known as a magnetometer, tracks the orientation of a magnetic needle within the Earth's magnetic field, in the same way as a traditional compass.
