Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab
Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab
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DOI：
10.1103/physrevaccelbeams.24.044002
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发表时间：
2021-04-27
影响因子：
1.7
通讯作者：
Wu, W.
中科院分区：
文献类型：
--
作者：
Albahri, T.;Anastasi, A.;Wu, W.
本文介绍了费米实验室μ g - 2实验运行1数据集的束流动力学系统修正及其不确定度。由于在储存环中使用静电四极（ESQ）垂直聚焦，对测量的μ子进动频率ω（m）（a）的两个校正与众所周知的效应有关。平均垂直取向的运动磁场被横向穿过ESQ系统产生的径向电场分量的相对论μ子感觉到。这种修正取决于储存的动量分布和环的调谐，环具有相对较弱的垂直聚焦。垂直的电子感应加速器运动意味着μ子并不在一个与垂直磁场方向完全正交的平面内绕环运行。校正是必要的，以考虑与它们的轨迹相关联的平均俯仰角。第三个小的修正是必要的，因为在存储时间期间逃离环的μ子与母分布相比在初始自旋阶段略有偏置。最后，由于ESQ网络中的两个高压电阻器的RC时间常数比设计的要长，所以在每次填充储存环期间，储存的μ子束的垂直和水平质心和包络线会发生轻微的漂移，但是是一致的。这导致了一个重要的相位-接受关系的发现，需要修正。对omega（m）（a）的校正总和为0.50 +/- 0.09 ppm;与omega（m）（a）的0.43 ppm统计精度相比，不确定度较小。
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 omega(m)(a) 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(m)(a) is 0.50 +/- 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of omega(m)(a).