scholarly journals Measurement of the anomalous precession frequency of the muon in the Fermilab Muon g−2 Experiment

2021 ◽  
Vol 103 (7) ◽  
Author(s):  
T. Albahri ◽  
A. Anastasi ◽  
A. Anisenkov ◽  
K. Badgley ◽  
S. Baeßler ◽  
...  
Keyword(s):  
Precession Frequency

scholarly journals Circular Rydberg states of helium atoms or helium-like ions in a high-frequency laser field

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 11-17
Author(s):  
Nikolay Kryukov ◽  
Eugene Oks
Keyword(s):  
High Frequency ◽  
Laser Field ◽  
Nuclear Charge ◽  
Rydberg States ◽  
Orbital Plane ◽  
Precession Frequency ◽  
Nonmonotonic Dependence ◽  
Absolute Value ◽  
Rydberg Electron ◽  
Frequency Laser

Abstract In the literature, there were studies of Rydberg states of hydrogenic atoms/ions in a high-frequency laser field. It was shown that the motion of the Rydberg electron is analogous to the motion of a satellite around an oblate planet (for a linearly polarized laser field) or around a (fictitious) prolate planet (for a circularly polarized laser field): it exhibits two kinds of precession – one of them is the precession within the orbital plane and another one is the precession of the orbital plane. In this study, we study a helium atom or a helium-like ion with one of the two electrons in a Rydberg state, the system being under a high-frequency laser field. For obtaining analytical results, we use the generalized method of the effective potentials. We find two primary effects of the high-frequency laser field on circular Rydberg states. The first effect is the precession of the orbital plane of the Rydberg electron. We calculate analytically the precession frequency and show that it differs from the case of a hydrogenic atom/ion. In the radiation spectrum, this precession would manifest as satellites separated from the spectral line at the Kepler frequency by multiples of the precession frequency. The second effect is a shift of the energy of the Rydberg electron, also calculated analytically. We find that the absolute value of the shift increases monotonically as the unperturbed binding energy of the Rydberg electron increases. We also find that the shift has a nonmonotonic dependence on the nuclear charge Z: as Z increases, the absolute value of the shift first increases, then reaches a maximum, and then decreases. The nonmonotonic dependence of the laser field-caused energy shift on the nuclear charge is a counterintuitive result.

Precession frequency and fast switching dependence on the in-plane and out-of-plane dual spin-torque polarizers

2012 ◽  
Vol 100 (14) ◽  
pp. 142409 ◽  
Author(s):  
Hong Zhang ◽  
Zhiwei Hou ◽  
Jianwei Zhang ◽  
Zongzhi Zhang ◽  
Yaowen Liu
Keyword(s):  
Precession Frequency ◽  
Spin Torque ◽  
Fast Switching ◽  
Out Of Plane

scholarly journals Tidal disruption event discs around supermassive black holes: disc warp and inclination evolution

2019 ◽  
Vol 487 (4) ◽  
pp. 4965-4984 ◽  
Author(s):  
J J Zanazzi ◽  
Dong Lai
Keyword(s):  
Black Hole ◽  
Equatorial Plane ◽  
Accretion Rate ◽  
Accretion Disc ◽  
Precession Frequency ◽  
Tidal Disruption ◽  
Eigenmode Analysis ◽  
Accretion Rates ◽  
Rigid Disc ◽  
Disruption Event

ABSTRACT After the tidal disruption event (TDE) of a star around a supermassive black hole (SMBH), the bound stellar debris rapidly forms an accretion disc. If the accretion disc is not aligned with the spinning SMBH’s equatorial plane, the disc will be driven into Lense–Thirring precession around the SMBH’s spin axis, possibly affecting the TDE’s light curve. We carry out an eigenmode analysis of such a disc to understand how the disc’s warp structure, precession, and inclination evolution are influenced by the disc’s and SMBH’s properties. We find an oscillatory warp may develop as a result of strong non-Keplarian motion near the SMBH. The global disc precession frequency matches the Lense–Thirring precession frequency of a rigid disc around a spinning black hole within a factor of a few when the disc’s accretion rate is high, but deviates significantly at low accretion rates. Viscosity aligns the disc with the SMBH’s equatorial plane over time-scales of days to years, depending on the disc’s accretion rate, viscosity, and SMBH’s mass. We also examine the effect of fallback material on the warp evolution of TDE discs, and find that the fallback torque aligns the TDE disc with the SMBH’s equatorial plane in a few to tens of days for the parameter space investigated. Our results place constraints on models of TDE emission which rely on the changing disc orientation with respect to the line of sight to explain observations.

scholarly journals Effect of Be-disk evolution on the global one-armed oscillations

2010 ◽  
Vol 6 (S272) ◽  
pp. 416-417
Author(s):  
Finny Oktariani ◽  
Atsuo T. Okazaki
Keyword(s):  
Density Distribution ◽  
Power Law ◽  
Oscillation Frequency ◽  
Precession Frequency ◽  
Be Stars ◽  
Disk Formation ◽  
Innermost Part ◽  
Formation Stage ◽  
Oscillation Modes ◽  
Disk Evolution

AbstractWe consider the effect of density distribution evolution on the global one-armed oscillation modes in disks around Be stars. Previous studies of global oscillations in Be disks assumed a power-law density distribution of the disk. However, observational results show that some Be stars exhibit evidence of formation and dissipation of the equatorial disk. This causes the disk density distribution can be far from a power-law form. Performing calculations for several times in the disk formation and dissipation stages, we find one-armed modes confined to the inner part of the disk in both stages. In the disk formation stage, the oscillation frequency stays approximately constant after the disk is fully developed. In the dissipation stage of the Be disk, the local precession frequency is, in general, higher than in the disk formation stage. Thus, we expect that V/R periods become shorter as the innermost part of the disk starts to accrete.

Dry-Friction Whip and Whirl Predictions for a Rotor-Stator Model With Rubbing Contact at Two Locations

2011 ◽  
Author(s):  
Dara W. Childs ◽  
Dhruv Kumar
Keyword(s):  
Analytical Solutions ◽  
Dry Friction ◽  
Supported Housing ◽  
Precession Frequency ◽  
Rigid Rotor ◽  
Clearance Ratio ◽  
Running Speed ◽  
Nonlinear Simulation ◽  
Friction Forces ◽  
Nonlinear Connections

The present work investigates the phenomena of whip and whirl for a rigid rotor contacting at two bearing locations. The idea originated with a paper by Clark et al. in 2009 on an anemometer undergoing dry friction whip and whirl. The anemometer rotor was supported by two Teflon® bushings within an elastically supported housing. The dry-friction forces arose at the bushings. Prior models for dry friction whirl and whip have considered rub at one non-support location. The present analytical model consists of a rigid rotor connected to a rigid stator at two rubbing contact locations. Analytical solutions are developed for the following normal reaction forces at the contact locations: (1) In phase, and (2) 180 degrees out of phase. Analytical solutions are only possible for the same RCl (Radius to Clearance ratio) at the two rub locations and define regions where dry-friction whirl is possible plus indication possible boundaries between whirl and whip. These solutions are similar to Black’s in 1968. A flexible-rotor/flexible-stator model with nonlinear connections at the bearings was developed to more correctly establish the range of possible solutions. The nonlinear connections at the rub surface are modeled using Hunt and Crossley’s 1975 contact model with coulomb friction. Dry friction simulations are performed for the following rotor center of gravity (C.G.) configurations: (1) Centered, (2) 3/4 contact-span location and (3) Overhang location outside the contacts. Results from the in-phase analytical solutions and the nonlinear simulations agree to some extent with the rotor mass centered and at 3/4 location in that whirl-to-whip transitions occur near the pinned rotor-stator bounce frequency. For the overhung mass case, the nonlinear simulation predicts whip at different frequencies for the two contact locations. Neither analytical solution modes predicts this outcome. No out-of-phase solutions could be obtained via time-transient simulations. Dry-friction whirling is normally characterized as supersynchronous precession with a precession frequency equal to running speed times RCl. Simulation predictions for models with different RCl mimic whirling. Simulation predictions show increasing backward precessional (BP) frequency with increasing rotor speeds. However, individual contact velocities show slipping at all conditions. Slipping is greater at one location than the other, netting a “whirl-like” motion. For the overhung model with different RCl ratios, apart from whipping at different frequency the two contacts also whirl at different frequencies corresponding to the RCl at the respective contacts. Simulations predict a different running speed for the “jump up” in precession frequency associated with a transition from whirl-to-whip with increasing running speed than for the jump-down in precession frequency for whirl-to-whip in a speed-decreasing mode.

scholarly journals Acceleration of the precession frequency for optically-oriented electron spins in ferromagnetic/semiconductor hybrids

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
F. C. D. Moraes ◽  
S. Ullah ◽  
M. A. G. Balanta ◽  
F. Iikawa ◽  
Y. A. Danilov ◽  
...  
Keyword(s):  
Ferromagnetic Semiconductor ◽  
Precession Frequency ◽  
Electron Spins
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