scholarly journals Cross-Relaxation Effects in a Ruby L?Band (1440 Mc/s) Maser at Low Magnetic Fields

1961 ◽  
Vol 14 (3) ◽  
pp. 381 ◽  
Author(s):  
GS Bogle ◽  
FF Gardner
Keyword(s):  
Magnetic Field ◽  
Transition Probability ◽  
Cross Relaxation ◽  
Gaussian Shape ◽  
Crystal Axis ◽  
Relaxation Effects ◽  
Low Field ◽  
Field L ◽  
L Band ◽  
The Magnetic Field

The reversals of maser behaviour which occur in ruby at low fields on cooling from 80� to 4 oK are explained in terms of cross-relaxation transitions (resonant interchanges of energy between neighbouring paramagnetic ions). For an angle of 29� between the magnetic field and the crystal axis a cross-relaxation process has been demonstrated which involves groups of three ions and has a transition probability of 700� 100 per second in 0�013% ruby. The profile of the cross-relaxation resonance has a half-width of 190�30 Mcts at half-intensity, and has an approximately Gaussian shape. It should be possible to obtain useful low-field L-band maser action at 4 oK by pumping V41 with the magnetic field nearly perpendicular to the crystal axis, and also at 80 oK using a concentration ten times higher, i.e. 0�13%

Textured Beta-Sialon:Eu2+ Phosphor Deposits Fabricated by Electrophoretic Deposition (EPD) Process within a Strong Magnetic Field: Preparation Process and Photoluminescence (PL) Properties Depending on Orientation

2015 ◽  
Vol 654 ◽  
pp. 268-273
Author(s):  
Chen Ning Zhang ◽  
Tetsuo Uchikoshi ◽  
Li Hong Liu ◽  
Benjamin Dierre ◽  
Yu Jin Cho ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Electric Field ◽  
Strong Magnetic Field ◽  
Electrophoretic Deposition ◽  
Intensity Ratio ◽  
Preparation Process ◽  
Crystal Axis ◽  
Chromaticity Coordinates ◽  
The Magnetic Field

Beta-sialon:Eu2+ phosphor deposits were fabricated by electrophoretic deposition (EPD) process within a strong magnetic field (12 T). The direction of the magnetic field was adjusted to be parallel or perpendicular to that of the electric field, that is, vertical-or horizontal setup. The oriented deposits were fabricated by aligning the β-sialon:Eu2+ particles along the higher magnetic-susceptibility c-crystal axis (a, b-crystal plane). For the case of vertically-setup magnetic field, the oriented deposit aligned along the c-axis possessed higher relative deposit density than the randomly fabricated deposit, as a result, varying the intensity ratio of emission and transmitted excitation, and therefore, presenting different chromaticity coordinates; for the case of horizontally-setup magnetic field, photoluminescence (PL) intensities of the deposits oriented along c-axis were significantly improved by comparing with those of the randomly-oriented ones.

scholarly journals On the Bottom Magnetic Fields of Millisecond Pulsars

2004 ◽  
Vol 218 ◽  
pp. 47-48
Author(s):  
Chengmin Zhang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Accretion Rate ◽  
Induced Magnetic Field ◽  
Radio Observations ◽  
Millisecond Pulsars ◽  
Low Field ◽  
Field Evolution ◽  
Field Decay ◽  
The Magnetic Field

The magnetic field strengths of most millisecond pulsars (MSPs) are about 108–9 gauss. The accretion-induced magnetic field evolution scenario here concludes that field decay is related to the accreted mass, that the minimum or bottom field stops at about 108 gauss for Eddington-limited accretion, and scales with the accretion rate as M1/2. The possibility of low field (∼ 107 gauss) MSPs has been proposed for future radio observations.

Magnetic Properties and Crystal Structure of (Fe,Ni)2( P,Si) Quaternaries of Fe2P-Type

2020 ◽  
Vol 1001 ◽  
pp. 53-60
Author(s):  
Tian Yi Ren ◽  
Rui Hong Wang ◽  
Tian Liang Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Permanent Magnet ◽  
Room Temperature ◽  
Easy Axis ◽  
Magnetocrystalline Anisotropy ◽  
Hexagonal Structure ◽  
Crystal Axis ◽  
P Type ◽  
The Magnetic Field

(Fe,Ni)2(P,Si) compounds were synthesized and characterized. Ni substitution in Fe1.95-xNixP0.7Si0.3 is found to favor the formation of Fe2P-type hexagonal structure. The samples appear nearly single phase. Powder oriented in the magnetic field shows a pronounced uniaxial magnetic anisotropy with c axis as the easy axis. Magnetization measurements carried out along and perpendicular to the c crystal axis demonstrate a significant magnetic anisotropy, making these materials potential candidates for permanent magnet applications. We found that (Fe,Ni)2(P,Si) compound has no remanent magnetic field and coercivity, but it has a large magnetocrystalline anisotropy at room temperature. Therefore, doping Fe2P type compounds with a small amount of Ni and Si may be a promising way to create new materials with large magnetocrystalline anisotropy at room temperature, and thus rare-earth free permanent magnet.

scholarly journals A possible shortcut for neutron–antineutron oscillation through mirror world

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Zurab Berezhiani
Keyword(s):  
Magnetic Field ◽  
Environmental Conditions ◽  
Transition Probability ◽  
New Physics ◽  
Flight Time ◽  
Upper Limit ◽  
Nuclear Stability ◽  
The Magnetic Field

AbstractExisting bounds on the neutron-antineutron mass mixing, $$\epsilon _{n{\bar{n}}} < \mathrm{few} \times 10^{-24}$$ ϵ n n ¯ < few × 10 - 24  eV, impose a severe upper limit on $$n - {\bar{n}}$$ n - n ¯ transition probability, $$P_{n{\bar{n}}}(t) < (t/0.1 ~\mathrm{s})^2 \times 10^{-18}$$ P n n ¯ ( t ) < ( t / 0.1 s ) 2 × 10 - 18 or so, where t is the neutron flight time. Here we propose a new mechanism of $$n- {\bar{n}}$$ n - n ¯ transition which is not induced by direct mass mixing $$\epsilon _{n{\bar{n}}}$$ ϵ n n ¯ but is mediated instead by the neutron mass mixings with the hypothetical states of mirror neutron $$n'$$ n ′ and mirror antineutron $${{\overline{n}}} '$$ n ¯ ′ . The latter can be as large as $$\epsilon _{nn'}, \epsilon _{n\bar{n}'} \sim 10^{-15}$$ ϵ n n ′ , ϵ n n ¯ ′ ∼ 10 - 15  eV or so, without contradicting present experimental limits and nuclear stability bounds. The probabilities of $$n-n'$$ n - n ′ and $$n-\bar{n}'$$ n - n ¯ ′ transitions, $$P_{nn'}$$ P n n ′ and $$P_{n\bar{n}'}$$ P n n ¯ ′ , depend on environmental conditions in mirror sector, and they can be resonantly amplified by applying the magnetic field of the proper value. This opens up a possibility of $$n-{\bar{n}}$$ n - n ¯ transition with the probability $$P_{n{\bar{n}}} \simeq P_{nn'} P_{n\bar{n}'}$$ P n n ¯ ≃ P n n ′ P n n ¯ ′ which can reach the values $$\sim 10^{-8} $$ ∼ 10 - 8 or even larger. For finding this effect in real experiments, the magnetic field should not be suppressed but properly varied. These mixings can be induced by new physics at the scale of few TeV which may also originate a new low scale co-baryogenesis mechanism between ordinary and mirror sectors.

scholarly journals Human magnetic field registration capability using low-field magnetic sensors

2021 ◽  
Author(s):  
Natalija Bricina ◽  
Jurijs Dehtjars ◽  
Ksenija Jasina ◽  
Hermanis Sorokins
Keyword(s):  
Magnetic Field ◽  
Heart Rate ◽  
Data Collection ◽  
Magnetic Sensors ◽  
Low Field ◽  
Magnetic Detector ◽  
The Magnetic Field

The aim of the study was to find out whether it is possible to detect the human magnetic field without shielding using sensors. For this, an experiment "the possibility of detecting the human magnetic field using sensors" was conducted. During the experiment it was found that with the help of a low-field magnetic detector it is possible to register a person's magnetic field, which is changing if there is a change in a heart rate. During the study, a device for recording the magnetic field of a human was assembled, a methodology for obtaining data was developed, a description of the materials and equipment used was provided. In accordance with the described methods of data collection, measurements of human magnetic field with and without load were made. The data obtained during the study were processed and the results were displayed. Based on the obtained results, an analysis was carried out, conclusions were drawn and recommendations for subsequent studies were indicated. As a result, the possibility of detecting a human's magnetic field using sensors was first studied.

scholarly journals Effect of Noise on the Decoherence of a Central Electron Spin Coupled to an Antiferromagnetic Spin Bath

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
G. C. Fouokeng ◽  
M. Tchoffo ◽  
S. Moussiliou ◽  
J. C. Ngana Kuetche ◽  
Lukong Cornelius Fai ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Spin ◽  
Spin System ◽  
Transition Probability ◽  
Entangled State ◽  
Energy Splitting ◽  
Gaussian Shape ◽  
Autocorrelated Noise ◽  
Low Magnetic Field ◽  
Antiferromagnetic Spin

We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ) transitions during a two-level crossing of a central electron spin (CES) coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state) of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.

The Magnetic Field of 1H1752+08

1995 ◽  
Vol 12 (1) ◽  
pp. 66-70
Author(s):  
Lilia Ferrario ◽  
Dayal T. Wickramasinghe ◽  
Jeremy Bailey ◽  
David Buckley
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Line Intensity ◽  
White Dwarf ◽  
Field Structure ◽  
Cataclysmic Variable ◽  
Magnetic Field Structure ◽  
Low Field ◽  
The Mean ◽  
The Magnetic Field

AbstractWe present spectropolarimetric observations of the eclipsing cataclysmic variable 1H1752+08. Modelling of the line intensity and polarisation spectra of 1H1752+08 shows that the magnetic field structure of the white dwarf is off-centre and the mean photospheric field strength is about 7 MG, the lowest measured in a cataclysmic variable (CV). We argue that 1H1752+08 is most probably a low-field AM Herculis system.

scholarly journals MUON ACCELERATION USING FIXED FIELD, ALTERNATING GRADIENT (FFAG) RINGS

2005 ◽  
Vol 20 (16) ◽  
pp. 3861-3864
Author(s):  
D. J. SUMMERS
Keyword(s):  
Magnetic Field ◽  
Repetition Rate ◽  
High Field ◽  
Muon Energy ◽  
Neutrino Factory ◽  
Fixed Field ◽  
Low Field ◽  
Gain Energy ◽  
The Magnetic Field ◽  
Proof Of Principle

Given their 2.2 μs lifetime, muons must be accelerated fairly rapidly for a neutrino factory or muon collider. Muon bunches tend to be large. Progress in fixed field, alternating gradient (FFAG) lattices to meet these challenges are reviewed. FFAG magnets are naturally wide; low momentum muons move from the low field side of a gradient magnet to the high field side as they gain energy. This can be exploited to do double duty and allow a large beam admittance without unduly increasing the magnetic field volume. If the amount of RF must be reduced to optimize cost, an FFAG ring can accommodate extra orbits. I describe scaling FFAGs in which the bends in each magnet are energy independent and non-scaling FFAGs in which the bends in each magnet do vary with muon energy. In all FFAG designs the sum of the bends in groups of magnets are constant; otherwise orbits would not close. Ways of keeping the accelerating beam in phase with the RF are described. Finally, a 1 MeV proof of principle scaling FFAG has been built at KEK and began accelerating protons in June 2000 with a 1 kHz repetition rate.

Cranial surgery with an expanded compact intraoperative magnetic resonance imager

2006 ◽  
Vol 104 (4) ◽  
pp. 611-617 ◽  
Author(s):  
Michael Schulder ◽  
Sussan Salas ◽  
Michael Brimacombe ◽  
Peter Fine ◽  
Jeffrey Catrambone ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Resonance ◽  
First Generation ◽  
Additional Time ◽  
Mean Error ◽  
Low Field ◽  
Skull Base Lesions ◽  
Time Required ◽  
Navigational Tool ◽  
The Magnetic Field

✓In this article the authors report the implementation of an expanded compact intraoperative magnetic resonance (iMR) imager that is designed to overcome significant limitations of an earlier unit. The PoleStar N20 iMR imager has a stronger magnetic field than its predecessor (0.15 tesla compared with 0.12 tesla), a wider gap between magnet poles, and an ergonomically improved gantry design. The additional time needed in the operating room (OR) for use of iMR imaging and the number of sessions per patient were recorded. Stereotactic accuracy of the integrated navigational tool was assessed using a water-covered phantom. Of the 55 patients who have undergone surgery in the PoleStar N20 device, diagnoses included glioma in 13, meningioma in 12, pituitary adenoma in nine, other skull base lesions in seven, and miscellaneous other diagnoses. The extra time required for use of the system averaged 1.1 hours (range 0.5–2 hours). Imaging sessions averaged 2.3 per surgery (range one–six sessions). Measurement of stereotactic accuracy revealed that T1-weighted images were the most accurate. Thinner slices yielded measurably greater accuracy, although this was of questionable clinical significance (all sequences ≤ 4 mm had a mean error of ≤ 1.8 mm). The position of the phantom in the center compared with the periphery of the magnetic field did not affect accuracy (mean error 0.9 mm for each). The PoleStar N20 appears to make intraoperative neuroimaging with a low-field-strength magnet much more practical than it was with the first-generation device. Greater ease of positioning resulted in a decrease in added time in the OR and encouraged a larger number of imaging sessions.

Recurring magnetic field anomalies in the South Atlantic and the first palaeointensities from Saint Helena

2021 ◽  
Author(s):  
Yael Engbers ◽  
Andy Biggin ◽  
J. Michael Grappone
Keyword(s):  
Magnetic Field ◽  
South Atlantic ◽  
Lava Flows ◽  
Sufficient Time ◽  
The South ◽  
Common Assumption ◽  
Low Field ◽  
The Earth ◽  
Geocentric Axial Dipole ◽  
The Magnetic Field

&lt;p&gt;A long-lived hypothesis is that, if averaged over sufficient time (ca 10 million years), the Earth&amp;#8217;s magnetic field approximates a geocentric axial dipole (GAD). Despite this common assumption, the question of how significant the non-GAD features are in the time-averaged field is an important and unresolved one. In the present-day field, the South Atlantic Anomaly (SAA) is the biggest irregularity in the field. We know that this anomaly has not always been a part of the field, but in Engbers et al., 2020, it was shown that the magnetic field shows irregular behaviour in this region on a million-year timescale. The irregular behaviour was demonstrated through a substantially high VGP dispersion (21.9&amp;#186;) for lava flows from Saint Helena that are between 8 and 11 million years old. The island of Saint Helena is located at the margin of the present-day SAA and has declination -16.6&amp;#186;, inclination -57.5&amp;#186; relative to expected GAD values of 0.0&amp;#186;/-7.8&amp;#186; (Dec/Inc). We have now commenced the measurements of absolute palaeointensity data from this location. So far, we have performed thermal and microwave IZZI-Thellier experiments on 2 localities from Saint Helena. The site mean results show variable but generally very low field intensities, although further work is required to make these sufficiently robust. Our low field estimates suggest a field in the South Atlantic that is not only unstable, but mainly weaker than expected. This could mean that recurring reversed flux patches (RFP) are responsible for the irregularities and weaknesses in the field in this region, stretching back up to 11 million years ago.&lt;/p&gt;

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