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Measurement of the anomalous spin precession frequency $\omega_a$ in the Muon g - 2 experiment at Fermilab
The muon magnetic anomaly aµ = (gµ - 2)/2 is a low-energy observable,which can be both measured and computed to high precision, making ita sensitive test of the Standard Model (SM). In April 2021, the E989 Collaborationat Fermilab National Accelerator Laboratory (FNAL) published the first resultbased on the first year of data taking (Run-1), and in August 2023 a new resultwas published based on two more years of data taking (Run-2 and Run-3). Thenew result was in agreement with the first one and with the previous experimentat Brookhaven National Laboratory (BNL), and the combination of these resultsbrought the uncertainty on the experimental measurement of aµ to the unprecedentedvalue of 0.19 parts per million (ppm). This paper will present details aboutthe improvements and upgrades since the 2021 result, and it will describe the finalstatistical and systematic sources of uncertainty on .a in the 2023 result.
Measuring the anomalous precession frequency ω a for the Muon g-2 Experiment
Abstract not provided.
The Run 1 spin on the µ+ precession frequency analysis
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Muon Precession Lessons Learned
Slides presented at a Muon g-2 (E989) collaboration meeting in Liverpool, UK, on July 25, 2023.
Analysis of the muon’s spin anomalous precession frequency
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Measuring the muon precession frequency in the E989 Fermilab g-2 experiment
Since more than 50 years the electron and muon anomalies, $a_e$ and $a_\mu$, defined in terms of the gyromagnetic factor $g_i$ for particle $i$ as $a_i=(g_i-2)/2$, have provided a deep insight into the quantum structure of elementary particles.They have been, and continue to be, a milestone for the development of the Standard Model of Particle Physics against which all new theories have to be compared.For almost 20 years, the experimental value of $a_\mu$ has shown a tantalizing discrepancy of more than $3 \sigma$ from the theoretical prediction making it mandatory for experimentalists to improve the current result, dominated by the E821 experiment at BNL\cite{BNL}. The Muon $g-2$ E989 experiment at Fermilab will use the same storage ring technique used at BNL, and previously in the CERN-III experiment, with the goal of decreasing by a factor of 4 the current error on $a_\mu$, which will allow for a finer comparison with the theoretical prediction. E989 started collecting data in winter 2018 accumulating, in the period April-July 2018 (Run1) almost twice the statistics of the previous experiment (before application of data quality cuts). In this document, the experiment will be briefly described, underlying the improvements which will allow to reduce the systematic error, and some preliminary result will be shown.
The Impact of Classical and General Relativistic Obliquity Precessions on the Habitability of Circumstellar Neutron Stars’ Planets
Recently, it has been shown that rocky planets orbiting neutron stars can be habitable under plausible circumstances. If a distant, point-like source of visible light, such as a Sun-like main-sequence star or the gravitationally-lensed accretion disk of a supermassive black hole is present, possible temporal variations Δε{sub p}(t) of the planet’s axial tilt ε {sub p} to the ecliptic plane should be included in the overall habitability budget since the obliquity determines the insolation at a given latitude on a body’ s surface. I point out that, for rather generic initial spin–orbit initial configurations, general relativistic and classical spin variations induced by the post-Newtonian de Sitter and Lense–Thirring components of the field of the host neutron star and by its pull to the planetary oblateness J{sub 2}{sup p} may induce huge and very fast variations of ε {sub p} that would likely have an impact on the habitability of such worlds. In particular, for a planet’s distance of, say, 0.005 au from a 1.4 M {sub ⊙} neutron star corresponding to an orbital period P {sub b} = 0.109 day, obliquity shifts Δε {sub p} as large as ε{sub p}{sup max}−ε{sub p}{sup min}≃50{sup ∘}--100{sup ∘} over characteristic timescales as short as 10 days (J{sub 2}{sup p}) to 3 Myr (Lense–Thirring) may occur for arbitrary orientations of the orbital and spin angular momenta L, S {sub ns}, S {sub p} of the planet-neutron star system. In view of this feature of their spins, I dub such hypothetical planets as “nethotrons.”.
Precession rates for an artificial satellite.
Long period component and secular component of satellite motion evaluated, using lagrange planetary equation
Decay rates of a passive precession damper and bounds.
Bounds for decay times of pendulum damper vibrating in plane containing spin axis of space vehicle
A viscous ring damper for a freely precessing satellite.
Viscous ring damper for removing wobble motion of spin-stabilized satellite analyzed by studying energy dissipation
The precession and nutation of deformable bodies. II - The form of distorted configurations
Derivation of explicit equations governing deformations of self-gravitating viscous bodies in external force field for application to physical librations of moon
The precession and nutation of deformable bodies IV - Deformation of self-gravitating elastic solids
Equivalent equations which govern deformations of self-gravitating elastic bodies of nonuniform internal temperature
The effect of daily /24 hour/ precession of the geomagnetic dipole on the creation of Sq-variations
Daily procession of geomagnetic dipole effect on ionospheric Sq variations
The effects of viscous friction on the precession and nutation of celestial bodies.
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Formulas for precession
Literal expressions for the precessional motion of the mean equator referred to an arbitrary epoch are constructed. Their numerical representations, based on numerical values recommended at the working meeting of the International Astronomical Union Commission held in Washington in September 1974, are obtained. In constructing the equations of motion, the second-order secular perturbation and the secular perturbation due to the long-periodic terms in the motions of the moon and the sun are taken into account. These perturbations contribute more to the motion of the mean equator than does the term due to the secular perturbation of the orbital eccentricity of the sun.
Material science and solid state physics studies with positive muon spin precession
The hyperfine field on the muon, B sub hf, at interstitial sites in dilute Fe(Al) alloys was measured for four different concentrations of Al and as a function of temperature by the muon spin rotation method. The magnitude of B sub hf, which is negative, decreases at rates ranging from 0.09 + or - 0.03% per at.% Al at 200 K to an asymptotic limit of 0.35 + or - far above 440 K. This behavior shows that sites near the Al impurity are weakly repulsive to the muon, with an interaction potential of 13 + or - 3 meV. In order to fit the temperature dependence of the hyperfine field, it is necessary to hypothesize the existence of a small concentration of unidentified defects, possibly dislocations, which are attractive to the muon. Although the Al impurity acts as a non-magnetic hole in the Fe lattice, the observed decrease in B sub hf is only 35% of the decrease in the bulk magnetization. It is concluded that B sub hf is determined mainly by the enhanced screening of conduction electrons in Fe and Fe(Al). Since the influence of the Al impurity on the neighboring Fe monents is very small, most of the change in B sub hf is therefore attributed to the increase in conduction electron polarization of the Al impurity.