18 research outputs found
Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab
This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 dataset of the Fermilab Muon g-2 Experiment. Two corrections to the measured muon precession frequency Ïam are 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 designed RC time 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 to Ï_{a}^{m} is 0.50±0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of Ï_{a}^{m}
Magnetic-field measurement and analysis for the Muon g â 2 Experiment at Fermilab
The Fermi National Accelerator Laboratory (FNAL) Muon g - 2 Experiment has measured the anomalous precession frequency a_{ÎŒ}(g_{ÎŒ} - 2)/2 of the muon to a combined precision of 0.46 parts per million with data collected during its first physics run in 2018. This paper documents the measurement of the magnetic field in the muon storage ring. The magnetic field is monitored by systems and calibrated in terms of the equivalent proton spin precession frequency in a spherical water sample at 34.7C. The measured field is weighted by the muon distribution resulting in \tilde{Ï}'_{p}, the denominator in the ratio \tilde{Ï}_{a}/\tilde{Ï}'_{p} that together with known fundamental constants yields aÎŒ. The reported uncertainty on \tilde{Ï}'_{p} for the Run-1 data set is 114 ppb consisting of uncertainty contributions from frequency extraction, calibration, mapping, tracking, and averaging of 56 ppb, and contributions from fast transient fields of 99 ppb
Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20Â ppm
We present a new measurement of the positive muon magnetic anomaly, a_{ÎŒ}âĄ(g_{ÎŒ}-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, Ï[over Ë]_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, Ï_{a}. From the ratio Ï_{a}/Ï[over Ë]_{p}^{'}, together with precisely determined external parameters, we determine a_{ÎŒ}=116â592â057(25)Ă10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{ÎŒ}(FNAL)=116â592â055(24)Ă10^{-11} (0.20 ppm). The new experimental world average is a_{ÎŒ}(exp)=116â592â059(22)Ă10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision
Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab
This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 data set of the Fermilab Muon g-2 Experiment. Two corrections to the measured muon precession frequency are 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 designed RC time 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 to is 0.50 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of
Measurement of the anomalous precession frequency of the muon in the Fermilab Muon g-2 Experiment
The Muon g-2 Experiment at Fermi National Accelerator Laboratory (FNAL) has
measured the muon anomalous precession frequency 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 (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
eleven separate determinations of \omega_a, and the systematic uncertainties on
the result.Comment: 29 pages, 19 figures. Published in Physical Review
Magnetic Field Measurement and Analysis for the Muon g-2 Experiment at Fermilab
The Fermi National Accelerator Laboratory has measured the anomalous precession frequency of the muon to a combined precision of 0.46 parts per million with data collected during its first physics run in 2018. This paper documents the measurement of the magnetic field in the muon storage ring. The magnetic field is monitored by nuclear magnetic resonance systems and calibrated in terms of the equivalent proton spin precession frequency in a spherical water sample at 34.7C. The measured field is weighted by the muon distribution resulting in , the denominator in the ratio / that together with known fundamental constants yields . The reported uncertainty on for the Run-1 data set is 114 ppb consisting of uncertainty contributions from frequency extraction, calibration, mapping, tracking, and averaging of 56 ppb, and contributions from fast transient fields of 99 ppb
Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab
This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 data set of the Fermilab Muon g-2 Experiment. Two corrections to the measured muon precession frequency are 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 designed RC time 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 to is 0.50 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of
Poisoning pyridoxal 5-phosphate-dependent enzymes: a new strategy to target the malaria parasite Plasmodium falciparum
The human malaria parasite Plasmodium falciparum is able to synthesize de novo pyridoxal 5-phosphate (PLP), a crucial cofactor, during erythrocytic schizogony. However, the parasite possesses additionally a pyridoxine/pyridoxal kinase (PdxK) to activate B6 vitamers salvaged from the host. We describe a strategy whereby synthetic pyridoxyl-amino acid adducts are channelled into the parasite. Trapped upon phosphorylation by the plasmodial PdxK, these compounds block PLP-dependent enzymes and thus impair the growth of P. falciparum. The novel compound PT3, a cyclic pyridoxyl-tryptophan methyl ester, inhibited the proliferation of Plasmodium very efficiently (IC(50)-value of 14 microM) without harming human cells. The non-cyclic pyridoxyl-tryptophan methyl ester PT5 and the pyridoxyl-histidine methyl ester PHME were at least one order of magnitude less effective or completely ineffective in the case of the latter. Modeling in silico indicates that the phosphorylated forms of PT3 and PT5 fit well into the PLP-binding site of plasmodial ornithine decarboxylase (PfODC), the key enzyme of polyamine synthesis, consistent with the ability to abolish ODC activity in vitro. Furthermore, the antiplasmodial effect of PT3 is directly linked to the capability of Plasmodium to trap this pyridoxyl analog, as shown by an increased sensitivity of parasites overexpressing PfPdxK in their cytosol, as visualized by GFP fluorescence