Home > Research > Publications & Outputs > Beam dynamics corrections to the Run-1 measurem...

Electronic data

  • 2104.03240v1

    Accepted author manuscript, 5.89 MB, PDF document

    Available under license: CC BY: Creative Commons Attribution 4.0 International License

Links

Text available via DOI:

View graph of relations

Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published
  • Muon g-2
Close
Article number044002
<mark>Journal publication date</mark>27/04/2021
<mark>Journal</mark>Physical Review Accelerators and Beams
Issue number4
Volume24
Number of pages34
Publication StatusPublished
<mark>Original language</mark>English

Abstract

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 $\omega_a^m$ 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 $\omega_a^m$ is 0.50 $\pm$ 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of $\omega_a^m$.