FERMILAB-SLIDES-18-043-PPD Electric Field Effect s s on th e e Muon Anomalou s s Precession n ๐ - 2 Frequency i n n the Fermila b b Muo n 2 Experiment Wanwei Wu Department of Physics and Astronomy University of Mississippi (on behalf of the Muon ๐ -2 Collaboration) APS April Meeting, Columbus, OH Session X08, Tuesday, April 17, 2018 This document was prepared by [Muon g-2 Collaboration] using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359
Introduction g -2 โ ): A particle with spin has a magnetic moment ( ๐ โ ) aligned with its spin ( ๐ โ = ๐ ๐ โ ๐ 2๐ ๐ Dirac, 1928 Dirac Theory predicts that ๐ = 2. However, experiments showed that ๐ โ 2. /01 Anomalous Magnetic Dipole Moment: ๐ = 1 . Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 2
Introduction g -2: Standard Model (SM) QED : Dirac term Vacuum polarization Schwinger term EW : Hadron : 567 + ๐ 2 34 = ๐ 2 69 + ๐ 2 :;< = 116591828(50)ร10 0FF ๐ 2 Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 3
Introduction g -2: New Physics (Beyond the SM) ๐ 2 represents a sum New Physics over all physics, it is proportional to: sensitive to a wide range of potential new physics. SM: 116591828(50)ร10 0FF ~3.3๐ BNL ๐ -2: 116592080(63) HIH ร10 0FF Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 4
Fermilab Muon g-2 Experiment Big Picture! Spin rotation of a muon in a magnetic field โข Spin precession frequency โข Cyclotron rotation frequency Muon anomalous precession frequency: Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 5
Fermilab Muon g-2 Experiment Big Picture! Weak focusing muon storage ringโ Electrostatic quadrupoles provide vertical focusing Super conducting coil +27.2 kV -27.2 kV -27.2 kV +27.2 kV Super conducting coil Super conducting coil Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 6
Fermilab Muon g-2 Experiment Big Picture! Electrostatic focusing โข Cyclotron rotation frequency โข Spin precession frequency Muon anomalous precession frequency: Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 7
Fermilab Muon g-2 Experiment Big Picture! โ M ๐ถ = 0 , the second term vanishes. Assuming ๐พ - By choosing ๐ฟ = 29.3 , the third term vanishes. The corresponding - momentum (3.904 GeV/c)/radius (711.2 cm) is then called โmagicโ momentum/radius. ๐ ๐ ; = ๐ 3 โ ๐ R = ๐ 2 ๐ ๐ถ We measure ๐ ; by using the decay positron signals and measure ๐ถ - 12 T U by observing the Larmor frequency of stationary protons ( ๐ S = โ ) with NMR probes. For our final analysis, we can solve for ๐ 2 and rewrite it as (using - ๐ W = ๐ W ๐โ/4๐ W ) : ๐ S ๐ 2 ๐ 2 = ๐ ; ๐ W ๐ S ๐ W ๐ W 2 Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 8
Electric Field Electrostatic Quadrupole System if electrostatic quadrupole (ESQ) plates misaligned ESQ plates introduce E-field multipoles closed-orbit distortion muon loss โ M ๐ถ ) corrections shifts in E-field and pitch ( ๐พ โฆโฆ Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 9
Electric Field OPERA-3D: 3-Dimension Map Electric Potential at the end of plates (zone map) V=27.2kV, from Downstream theta=0ยฐ Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 10
Electric Field Correction Fast Rotation Analysis - Muons are injected into the storage ring as a bunchโradial distribution - Muons at inner equilibrium radii will go steadily ahead of those at outer equilibrium radii -> debunching - Modulation of decay positron count (fast rotation signals) can be used to study the debunching - Fast rotation analysis: use a model of the time evolution of the bunch structure to obtain the momentum (radial) distribution of decayed muons Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 11
Fast Rotation Analysis ๐ ๐ ๐๐ฃ๐จ๐ฃ๐ง๐ฃ๐ด๐๐ฎ๐ฃ๐ฉ๐จ ๐๐๐ฎ๐ข๐ฉ๐ Two bin sets: โฆโฆ Radial bins (i) (Lx=90 mm) Time bins (j) (i.e., 50 bins w/width=1.8mm) (positron count histogram) Note: The geometry factors ๐พ [\ are known functions of ring geometry and the apparent time structure of the injected bunch (injection zero time and beam revolution time). Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 12
Fast Rotation Analysis Toy MCโInjection Pulse & Signals Counts/[ns] counts Time [ns] Time [ฮผs] Signals seen by Detector Injection Pulse Counts/[ns] Counts/[ns] Bunch overlap Time [ฮผs] Time [ฮผs] Signals seen by Detector ( early time ) Signals seen by Detector ( late time ) Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 13
Fast Rotation Analysis Toy MCโ ๐ ๐ and ๐ผ ๐ซ Fit the arrival time of bunches by number of turns to find out the injection zero time and beam revolution time ๐ข ๐๐๐๐ = ๐๐ R + ๐ข s Arrival time of bunch by turns Arrival time of bunch [us] counts/1[ns] Time [ฮผs] Number of turns Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 14
Fast Rotation Analysis Toy MCโRadial Distribution Apply the ๐ 1 minimization analysis and solve for the radial (momentum) bin contents: With this distribution, we are able to evaluate the electric field corrections to g-2. (๐ฆ W = ๐ wW;x โ ๐ s , ๐ s is the โmagicโ radius; ) Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 15
Fast Rotation Analysis Toy MCโCheck the Results counts Time [ฮผs] Red: Original Data Blue: Fast Rotation Results counts counts Early time Late time Time [ฮผs] Time [ฮผs] Time [ฮผs] Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 16
Conclusion (๐ฆ W = ๐ wW;x โ ๐ s , ๐ s is the โmagicโ radius; ) ยง The electric field plays a very important role in the Fermilab Muon g-2 Experiment in many ways, i.e., muon orbits, muon losses, E-field correction. ยง The electric field has a significant effect on the muon anomalous precession frequency: - We need to align the electrostatic quadrupole plates very carefully; - We need to know the 3D electric field map; - We need to know the muon momentum/radius distribution through the so-called fast rotation analysis. ยง The Experiment is running and it will be a great time to study muon anomaly including its electric field corrections. โThank You! Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 17
Backup Backup Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 18
Measurement of ๐ ๐ in History Backup Goals: Accuracy: 0.14 ppm Deviation: โฅ 5๐ Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 19
Backup Big Picture! Straw Trackers Kicker Modules Pions with p = 3.11 GeV/c are collected from target and Central sent to beamline Orbit Storage Ring Calorimeters: *24 around the ring Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 20
Backup Big Picture! For our final analysis, we can solve for ๐ 2 and rewrite it as (using - ๐ W = ๐ W ๐โ/4๐ W ) : ๐ S ๐ 2 ๐ 2 = ๐ ; ๐ W ๐ S ๐ W ๐ W 2 About 1.5ร10 FF Statistical Error Run duration 17 ยฑ 5 months (100 ppb) decay positron ๐ 2 Systematic Error fixed probes, Trolley calibration, (140 ppb) on ๐ S (70 ppb) trolley measurements of B , etc. 20 ppb Lost Muons < 30 ppb CBO Systematic Error on ๐ ; (70 ppb) โ M ๐ถ โ 0 ) 30 ppb E and Pitch ( ๐พ Others Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 21
Backup Polarized Muon Beam ยง Muon is produced polarized : in-flight decay, both โforwardโ and โbackwardโ muons are highly polarized Pion decay modes: -- http://pdg.lbl.gov/2014/listings/rpp2014-list-pi-plus-minus.pdf Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 22
Backup Beam Resonances March 22 Lost Muons Quad scan for beam resonance studyโLost Muons Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 23
Backup Decay Positron Signal BNL gโ2 PRD 2006 Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 24
Backup Fast Rotation Analysis counts Decay positron energy histogram Energy Cut to select the decay positron signal Energy [MeV] counts counts Decay positron time histogram (after energy cut) Time [ฮผs] Time [ฮผs] If we can functionalize the Real situations: a lot of backgrounds, backgrounds, we can remove them in i.e., muon lifetime, g-2 frequency, fast rotation analysis, i.e., ๐ and ๐ ; CBO, Muon losses โฆ. Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 25
Backup Fast Rotation Analysis Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 26
Backup Fast Rotation Analysis Example (bunch # 0): Radius distribution Peak at 711.5 cm Tuesday, 4/17/2018 Wanwei Wu / APS April Meeting 27
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