We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g-2 Experiment for the positive muon magnetic anomaly a_{μ}≡(g_{μ}-2)/2. The anomaly is determined from the ...precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ω_{a} between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ωover ˜_{p}^{'} in a spherical water sample at 34.7 °C. The ratio ω_{a}/ωover ˜_{p}^{'}, together with known fundamental constants, determines a_{μ}(FNAL)=116 592 040(54)×10^{-11} (0.46 ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both μ^{+} and μ^{-}, the new experimental average of a_{μ}(Exp)=116 592 061(41)×10^{-11} (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.
We present a new measurement of the positive muon magnetic anomaly, a_{μ}≡(g_{μ}-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times ...the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, ωover ˜_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From the ratio ω_{a}/ωover ˜_{p}^{'}, together with precisely determined external parameters, we determine a_{μ}=116 592 057(25)×10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{μ}(FNAL)=116 592 055(24)×10^{-11} (0.20 ppm). The new experimental world average is a_{μ}(exp)=116 592 059(22)×10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision.
The Muon g − 2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency ωam to an uncertainty of 434 parts per billion (ppb), statistical, and ...56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment's muon storage ring, the precession frequency measurement determines a muon magnetic anomaly of aμ ( FNAL ) = 116 592 040 ( 54 ) × 10−11 (0.46 ppm). This article describes the multiple techniques employed in the reconstruction, analysis, and fitting of the data to measure the precession frequency. It also presents the averaging of the results from the 11 separate determinations of ωam, and the systematic uncertainties on the result.
► Structural properties of magnetite nanoparticles in polyvinyl-alcohol thin films are investigated. ► Magnetic properties were studied by static magnetometry techniques, especially near the Verwey ...transition. ► The data obtained are discussed on the basis of complex temperature behavior of magnetic anisotropy. ► The EPR spectra and static magnetization data demonstrated clear anomalies in the interval 130–200K.
Magnetic and structural properties of magnetite nanoparticles stabilized in polyvinyl-alcohol thin films are investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) and static magnetometry techniques. The nanoparticles have well-defined crystallinity, and are superparamagnetic at room temperature. Their size distribution is characterized by the distinct log-normal law (with average diameters near 5–7nm) and slight maximum near 70–80nm. The EPR spectra and static magnetization data demonstrated pronounced anomalies in the interval between 130K (corresponding to Verwey transition) and 200K. The experimental data obtained can be understood on the basis of the half-metallic electronic structure, complex temperature behavior of the magnetic anisotropy, along with effects of “weak magnetic-electron” sublattice of the magnetite.
In this study, we developed a method for the production of androsta-9(11)-diene-3,17-dione (Δ
9(11)
-AD), which is a combination of phytosterol side-chain microbial oxidation with simultaneous ...9α‑hydroxylation and subsequent chemical regio-selective dehydration of 9α-hydroxy-3,17-diketo-intermediate without isolation and purification. Phytosterol was converted into 9α-hydroxyandrost-4-ene-3,17-dione (9-OH-AD) with the use of the wild-type
Mycobacterium
sp. VKM Ac-1817D strain. The product was extracted from the culture medium with the use of an organic solvent and dehydrated in the extract with mineral acid. The resulting Δ
9(11)
-AD was purified with the selective crystallization method. Minor products were isolated and identified. It has been shown that this strain is capable of sterol transformation with the formation of methyl ester of 9α-hydroxypregn-4-ene-3-one-20-carboxylic acid. Our approach makes it possible to simplify the flow chart for production of the target compound. It not only eliminates 9-OH-AD loss but also minimizes the amount of production waste.
This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 dataset of the Fermilab Muong−2Experiment. Two corrections to the measured muon precession ...frequencyωamare associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through the radial electric field components created by the ESQ system. The correction depends on the stored momentum distribution and the tunes of the ring, which has relatively weak vertical focusing. Vertical betatron motions imply that the muons do not orbit the ring in a plane exactly orthogonal to the vertical magnetic field direction. A correction is necessary to account for an average pitch angle associated with their trajectories. A third small correction is necessary, because muons that escape the ring during the storage time are slightly biased in initial spin phase compared to the parent distribution. Finally, because two high-voltage resistors in the ESQ network had longer than designedRCtime constants, the vertical and horizontal centroids and envelopes of the stored muon beam drifted slightly, but coherently, during each storage ring fill. This led to the discovery of an important phase-acceptance relationship that requires a correction. The sum of the corrections toωamis0.50±0.09ppm; the uncertainty is small compared to the 0.43 ppm statistical precision ofωam.
This paper considers the basic concepts of constructing an advanced direct laser writing nanolithographic system dedicated to a high-resolution synthesis of large-sized planar elements of diffractive ...optics and nanophotonics. The issues of the rational implementation of optical, mechanical and electronic units of the system are solved together with considering the functional structure for a precise computer control of the mentioned units. The proposed design of the opto-mechanical unit aims to reduce significantly the distortions of fabrication of the optical elements due to the use of a new symmetrical two-channel construction and a differential laser interferometer for the radial positioning of a focused laser beam. A complex of issues on constructing a long-working distance superresolving focusing system are also considered alongside. The complex modernization of the nanolithographic system software and hardware complex based on system-on-chip (SoC) using hybrid processors (FPGA+ARM) is considered, which will make the system more universal and portable to various IT platforms.
The international PEN collaboration aims to obtain the branching ratio for the pion electronic decay π+→e+νe(γ), aka πe2, to a relative precision of 5×10−4 or better. The PEN apparatus comprises a ...number of detection systems, all contributing vital information to the PEN event reconstruction. This paper discusses the design, performance, and Monte Carlo simulation of the mini time projection chamber (mTPC) used for pion, muon, and positron beam particle tracking. We also review the use of the extracted trajectory coordinates in the analysis, in particular in constructing observables critical for discriminating background processes, and in maximizing the fiducial volume of the target in which decay event vertices can be accepted for branching ratio extraction without introducing bias.
A Tracker Prototype Based on Cathode Straw Tubes Baranov, V. A.; Bosak, N. A.; Botay, L. E. ...
Instruments and experimental techniques (New York),
09/2018, Letnik:
61, Številka:
5
Journal Article
Recenzirano
A prototype of a 2D detector based on specially designed straw tubes with cathode data readout has been developed and tested. This detector exhibits comparable accuracies in measuring radial and ...longitudinal coordinates. Its rate capability is similar to the capabilities of traditional detectors whose tubes are smaller by half in diameter.
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