Range Of Magnetic Intensities Research Articles

Effects of the anomalous magnetic moments of the quarks on the neutral pion properties within a SU(2) Nambu–Jona Lasinio model

The properties of the neutral pion in quark matter under the influence of an external magnetic field are studied. The effects of the anomalous magnetic moments (AMM) of the quarks at finite density is considered. The inclusion of the AMM into the NJL model gives rise to additional magnetic effects. In particular the Dirac sea produce new divergences in the vacuum contributions, which depend explicitly on the magnetic field. An improper treatment of these contributions is the source of unphysical results, as emphasized in recent investigations. The pion polarization function is evaluated in the random phase approximation using analytic regularization and a subtraction scheme to deal with such divergencies. This procedure is combined with the standard three momentum cutoff, and reduces to it for vanishing magnetic intensity. The pion mass and coupling constant are evaluated for a wide range of magnetic intensity and baryonic density.

Flight Calibration of the Van Allen Probe Magnetometers

Abstract The twin Van Allen Probes each carry a triaxial fluxgate magnetometer. Their orbits transverse a large of range of magnetic intensity. A procedure is described that calibrates the magnetometer in the spinning-spacecraft frame and in the presence of a persistent gradient of the magnetic field. This is done by extending a model based on a constant background magnetic field to a model with a changing magnetic field during intervals used for calibration. Model parameters derived from short intervals are obtained by direct calculation, and uncertainties are propagated throughout the analysis. A daily ensemble analysis of interval-derived parameters and uncertainties is then made to correct for sensor bias and misalignment. The whole analysis is iterated to convergence in a few steps based on the estimated uncertainties associated with the model parameters.

Interpretation of high resolution aeromagnetic data of Kaoje and its environ, western part of the Zuru Schist belt, Nigeria: implication for Fe–Mn occurrence

This study presents an appraisal of mineralization potential and the geologic record of Kaoje and environs using high-resolution aeromagnetic data. The data were analyzed using the fast Fourier transform technique for reduction-to-equator (RTE), analytic signal (AS), total horizontal derivative (THDR), tilt derivative (TDR), spectral analysis and Euler deconvolution at varying spectral indices. The reduced to equator residual magnetic intensity range from -73.4 to 205.6 nT and are associated with contrasting lithology of the Sedimentary and Basement Complex rocks. The anomalies and analytic signal amplitude unfold and update the extension of Zuru Schist to the southern region of Kaoje, elongated banded gneiss within the schist body, pegmatite intrusion through the migmatite and NNW-SSE trending schist hosted manganite and sandstone-hosted goethite. Estimated depth to shallow and deeper magnetic sources ranged from 0 to 59 m and 225–415 m respectively, and the corresponding Euler solutions revealed perfect clustering along notable geologic features and minerals. The iron mineralization are revealed as sourced from the magmatic bodies that lie beneath the sedimentary rocks and a corresponding sphere geologic model within northwest and southwest of Kaoje at a depth range of 0–225 m. The structural trends suggested the tectonic events in the area and indicate an imprint of Zungeru-Anka transcurrent fault that serves as a conduit for iron mineralizing fluid to Kaoje.

Analysis of aeromagnetic anomalies and structural lineaments for mineral and hydrocarbon exploration in Ikom and its environs southeastern Nigeria

The purpose of this study is to analyze the aeromagnetic data of Ikom and its environs in Cross-River State, Nigeria in order to delineate the structural lineaments according to their spatial and directional attributes as well as define the depth to magnetic causative bodies. This was achieved with the aid of an acquired, digitized and processed aeromagnetic intensity contour map covering Ikom and its adjacent areas. The aeromagnetic data was subjected to diverse data enhancement and transformation routines. Regional-residual analysis was implemented on the total magnetic intensity map (contour interval = 20 nT) to generate a residual magnetic intensity contour map. Results show that the area is characterized by a very complex pattern of magnetic intensities of both long and short wave-lengths. Sequel to the regional-residual anomaly separation, azimuth orientation of the lineament structures delimited on the maps portray NS and NE-SW as the principal trends with E-W and NW-SE as the minor trends. Two depth sources were obtained by employing the commonly known Peter's half-slope method. Depth range for the deeper causative sources is 0.83 km–3.5 km with a magnetic intensity range of −30 nT to −220 nT while the superficial sources had a range of 0.2 km–0.75 km and a magnetic intensity that vary from −10 nT to 20 nT. The deeper magnetic sources are attributed to the underlying pre-Cambrian basement complex rocks and intra basement structures such as fractures and faults whereas the superficial sources are due to basement intrusives as well as ore-bearing veins present in the overlying Cretaceous rocks. The shallow basement depth and prevalence of intrusives and linear structures are indications of an area of good mineral prospects but unfavorable for hydrocarbon formation.

Magnetic-Ionic-Liquid-Functionalized Photonic Crystal Fiber for Magnetic Field Detection

A compact optical fiber magnetic field sensor based on a magnetic-ionic-liquid-functionalized photonic crystal fiber (PCF) has been proposed and experimentally demonstrated. The magnetic field sensor was fabricated by splicing an index-guiding PCF having one magnetic-ionic-liquid-infiltrated (MIL-infiltrated) air hole in the innermost layer infiltrated with conventional single-mode fibers. The transmission spectral magnetic response of the proposed sensor have been measured and theoretically analyzed. Owing to the effective interaction between the MIL and transmission light as well as the controllable attenuation property of MIL, the magnetic field sensitivity reaches up to −0.01991 dB/Oe for a relatively linear magnetic intensity range of 0 to 440 Oe.

Modification of the masses of the lightest neutral mesons in a hadronic medium under an external magnetic field

The effective masses of the neutral mesons in a hadronic medium and under an external magnetic field are evaluated as functions of the baryonic density and the field intensity. For this purpose the meson polarization is evaluated in the one loop approximation using a Quantum Hadrodynamics model which includes pions, sigma, omega, and rho mesons. The propagators of the baryons include the full effect of the coupling to the magnetic field through their charges and their anomalous magnetic moments. Within the range of magnetic intensities considered here $10^{17}$ G $< B < 10^{19}$ G, the dependence on B is moderate for the pion and the longitudinal component of the omega meson, and negligible for the remaining mesons.

Intensity-based magnetic field measurement employing tilted long-period fiber gratings

An intensity-interrogated fiber magnetic field sensor based on magnetic fluid (MF) and tilted long-period fiber grating (TLPFG) has been proposed. The sensor is constructed by a TLPFG immersed in the MF. The TLPFGs supported the coupling between the LP01 core mode and the forward-propagating cladding modes with different azimuthal order l = 0, 1, 2,…, which shows different spectral response behaviors with normal long-period fiber gratings. The experimental results and theoretical analysis show that resonance wavelengths of TLPFG present different characteristics by tuning the applied magnetic field intensity. The transmission loss of the TLPFG increases for some dips, while they reduce for the others with the increment of the applied magnetic field intensity. Taking advantage of the optical power difference for various wavelength regions, a magnetic field intensity sensitivity of 0.05 dB Oe−1 could be achieved for a magnetic intensity range from 75 Oe to 300 Oe. Due to its low cost and compactness, the proposed sensor is expected to find potential applications in the field of magnetic field measurement and photonic devices.

Loss-Based Magnetic Field Sensor Employing Hollow Core Fiber and Magnetic Fluid

An inline optical fiber magnetic field sensor based on hollow core fiber (HCF) wall integrated with magnetic fluid tuned by magnetic field was proposed by sandwiching a length of HCF between two single mode fibers with offset joints. Intermodal interference is present in the HCF wall, mode propagation, as well as mode field distribution within the HCF wall have been simulated, and the contrast ratio of the interference fringes in response to the variation of the applied magnetic field has been theoretically analyzed and experimentally observed. The maximum sensing sensitivity of -0.02173 dB/Oe within the linear magnetic intensity range from 150 to 300 Oe has been achieved.

Magnetic-field sensor based on core-offset tapered optical fiber and magnetic fluid

A magnetic field sensor based on an asymmetrical fiber modal Mach–Zehnder interferometer (MMZI) is achieved by cascading tapered fiber with the core-offset structure. The MMZI is sealed by the magnetic fluid and its spectral dependence on magnetic field has been investigated. The results show that the transmission variations of the two dips are about 8 dB and 10 dB for a magnetic intensity range from 0 Oe to 400 Oe, respectively. The highest magnetic sensitivity reaches 0.03407 dB Oe−1. The proposed sensor based on the intensity demodulation is cost-effective and robust; therefore, the device is beneficial to the magnetic field sensing applications and other magneto-optical tunable photonics devices.

English

&nbsp; Ground magnetic survey of eastern part of Ilesa town in Osun State, Southwest Nigeria was performed. Total field magnetic data was recorded using high resolution proton precision geometric magnetometer which implores total components of the ground magnetic anomaly data running through fifteen traverses. This research focused on delineation of faults in this part of the highly mineralized Ilesa schist belt. The field data was qualitatively and quantitatively interpreted and the results gave values for the total component measurements of ground magnetic anomaly that varied between a minimum negative peak value of about -330 gammas and a maximum positive peak value of about 80 gammas. Depth to the basement rock was estimated using Peters half slope method which gave a maximum depth to basement of about 160 m. Information on wide range of magnetic intensities over the different rock types in this area were obtained from the interpretations. The results generated were used to delineate rock boundaries, major and minor faults in this area. &nbsp; Key words:&nbsp;Magnetic intensities, residual ground magnetic, geomagnetic sections, Ilesa east.

Directional orientation of birds by the magnetic field under different light conditions.

This paper reviews the directional orientation of birds with the help of the geomagnetic field under various light conditions. Two fundamentally different types of response can be distinguished. (i) Compass orientation controlled by the inclination compass that allows birds to locate courses of different origin. This is restricted to a narrow functional window around the total intensity of the local geomagnetic field and requires light from the short-wavelength part of the spectrum. The compass is based on radical-pair processes in the right eye; magnetite-based receptors in the beak are not involved. Compass orientation is observed under 'white' and low-level monochromatic light from ultraviolet (UV) to about 565 nm green light. (ii) 'Fixed direction' responses occur under artificial light conditions such as more intense monochromatic light, when 590 nm yellow light is added to short-wavelength light, and in total darkness. The manifestation of these responses depends on the ambient light regime and is 'fixed' in the sense of not showing the normal change between spring and autumn; their biological significance is unclear. In contrast to compass orientation, fixed-direction responses are polar magnetic responses and occur within a wide range of magnetic intensities. They are disrupted by local anaesthesia of the upper beak, which indicates that the respective magnetic information is mediated by iron-based receptors located there. The influence of light conditions on the two types of response suggests complex interactions between magnetoreceptors in the right eye, those in the upper beak and the visual system.

Magnetoresistance of CuxCo1‐xFe2O4 Ferrites

Magnetoresistance measurements (Δ/R) were carried out on CuxCo1‐xFe2O4 samples with x=1, 0.75, 0.50, 0.25 and cobalt ferrite in the range of magnetic intensity (H) from 1.0 to 4.5 kG. Linear plots were obtained between log (Δ/R) and log H for all compositions except that of cobalt ferrite. The values of n at x=0.5 do not agree with the results of some authors. The discrepancy may be attributed to the value of magnetic field intensity at which such measurements were carried out. The similarity of features of n and μD with composition leads us to believe that the magnetoresistance may arise from the scattering of conduction electrons by localized electrons involving the s‐d exchange interaction.