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Elise Novitski Harvard University Lepton Moments 21 July 2014

Correlated cyclotron and spin measurements to make an improved measurement of the electron magnetic moment. Elise Novitski Harvard University Lepton Moments 21 July 2014. Correlated cyclotron and spin measurements to make an improved measurement of the electron magnetic moment.

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Elise Novitski Harvard University Lepton Moments 21 July 2014

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  1. Correlated cyclotron and spin measurements to make an improved measurement of the electron magnetic moment Elise Novitski Harvard University Lepton Moments 21 July 2014

  2. Correlated cyclotron and spin measurements to make an improved measurement of the electron magnetic moment Elise Novitski Harvard University Lepton Moments 21 July 2014 Shannon FogwellHoogerheide

  3. Acknowledgements • Prof. Gerald Gabrielse PhD Students: • Ronald Alexander (new student) • Maryrose Barrios (new student) • Elise Novitski (PhD in progress…) • Joshua Dorr (PhD, Sept. 2013) • Shannon FogwellHoogerheide (PhD, May 2013)

  4. Standard Model Triumph • Most Precisely Measured Property of an Elementary Particle • Tests the Most Precise Prediction of the Standard Model Experiment: Standard Model: • Testing the CPT Symmetry built into the Standard Model Electron: Positron: D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008) R. Boucjendira, P. Cladé, S. Guellati-Khélifa, F. Nez, and F. Biraben, Phys. Rev. Lett. 106, 080801 (2011) T. Aoyama, M. Hayakawa, T. Kinoshita, and M. Nio, Phys. Rev. Lett. 109, 111808 (2012)

  5. Fine Structure Constant • Most Precise determination of α D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008) R. Boucjendira, P. Cladé, S. Guellati-Khélifa, F. Nez, and F. Biraben, Phys. Rev. Lett. 106, 080801 (2011) T. Aoyama, M. Hayakawa, T. Kinoshita, and M. Nio, Phys. Rev. Lett. 109, 111808 (2012)

  6. Fine Structure Constant • Most Precise determination of α We want to improve the experimental precision! D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008) R. Boucjendira, P. Cladé, S. Guellati-Khélifa, F. Nez, and F. Biraben, Phys. Rev. Lett. 106, 080801 (2011) T. Aoyama, M. Hayakawa, T. Kinoshita, and M. Nio, Phys. Rev. Lett. 109, 111808 (2012)

  7. Ingredients of a g/2 measurement • Measure cyclotron frequency • Measure anomaly frequency • Measure axial frequency (less precision needed) • Calculate special relativistic shift ( ) • CalculateDw/w from measured cavity mode couplings D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  8. Ingredients of a g/2 measurement • Measure cyclotron frequency • Measure anomaly frequency • Measure axial frequency (less precision needed) • Calculate special relativistic shift ( ) • CalculateDw/w from measured cavity mode couplings D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  9. Ingredients of a g/2 measurement • Measure cyclotron frequency • Measure anomaly frequency • Measure axial frequency (less precision needed) • Calculate special relativistic shift ( ) • CalculateDw/w from measured cavity mode couplings D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  10. Uncertainties in the 2008 measurement g/2 = 1.001 159 652 180 73 (28) [0.28 ppt] Uncertainties for g in parts-per-trillion. Leading uncertainty is lineshape model uncertainty– limits precision to which it is possible to split our anomaly and cyclotron lines D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  11. Spin and cyclotron detection • Magnetic bottle creates z-dependent B field, which adds another term to axial Hamiltonian • Modifies axial frequency to depend on spin and cyclotron states: L. S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986)

  12. Coupling to axial motion broadens cyclotron and anomaly lines L. S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986) B. D’Ursoet al., Phys. Rev. Lett. 94, 113002 (2005) D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  13. New Technique: Correlated Measurement 2008 Protocol New Protocol Apply cyclotron and anomaly drives simultaneously Generate 2-D correlated lineshape, extract g/2 • Cyclotron attempts followed by anomaly attempts • Combine data, adjust for field drift, fit both lines to extract g/2 anomaly detuning cyclotron detuning

  14. Advantages of the correlated measurement protocol • Eliminates magnetic field drifts between a given anomaly and cyclotron data point • In low-axial-damping limit, system stays in single axial state during a measurement, creating discrete peaks • Combined with cooling to axial ground state, each point is a full g-2 measurement anomaly frequency detuning cyclotron frequency detuning L. S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986) B. D’Urso, Ph.D. thesis, Harvard University (2003)

  15. Technical challenges of the correlated measurement protocol • Need to be in low axial damping limit to take full advantage, so must develop a method of decoupling particle from amplifier • Lower transition success rate, so statistics could be an issue • Both cyclotron and anomaly drive attempts must be successful to get an excitation • Much narrower lines, and must still know B-field well enough to drive transitions L. S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986) B. D’Urso, Ph.D. thesis, Harvard University (2003)

  16. Axial decoupling and the discrete lineshape limit • A technical challenge: decoupling particle from amplifier to prevent reheating of axial motion • A consequence of decoupling: reaching the discrete-lineshape limit in one or both lines, where quantum nature of axial motion is evident • With cavity-assisted axial sideband cooling, goal is to reach lowest axial state L. S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986) B. D’Urso, Ph.D. Thesis, Harvard University, 2003

  17. Cavity-assisted axial sideband cooling • Decouple axial motion from amplifier • Apply a drive at to couple axial and cyclotron motions • Cooling limit: • Cooling rate: • Interaction with the resonant microwave cavity mode structure: a challenge that can be converted into an advantage L. S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986)

  18. Trap as a resonant microwave cavity TE111 27.4 GHz Power coupling efficiency: L. S. Brown, G. Gabrielse, K. Helmerson, and J. Tan, Phys. Rev. Lett. 51, 44-47 (1985) L. S. Brown and G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986) J. Tan and G. Gabrielse, Phys. Rev. A 48, 3105-3122 (1993) D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  19. Strong cyclotron damping modes: cause short lifetime and cavity shift, so must be avoided Cooling modes: enable axial-cyclotron sideband cooling Cavity mode structure of the 2008 trap was not conducive to cavity-assisted axial sideband cooling Trap dimensions Measurements done in this range Cyclotron frequency (GHz) Trap radius/height ratio • Frequencies good for avoiding cyclotron modes were 30 linewidths away from good cooling modes • Cooling was attempted but axial ground state was never reached D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008) D. Hanneke, Ph.D. thesis, Harvard University (2007)

  20. Strong cyclotron damping modes: cause short lifetime and cavity shift, so must be avoided Cooling modes: enable axial-cyclotron sideband cooling Cavity mode structure of the new trap will enable cavity-assisted axial sideband cooling • Can drive directly on good cooling mode • Axial ground state should be achievable S. FogwellHoogerheide, Ph.D. Thesis, Harvard University, 2013 New trap dimensions Cyclotron frequency (GHz) New g-2 measurements will be done here Trap radius/height ratio

  21. Additional techniques for improving cyclotron and anomaly frequency measurements • Narrower lines • Smaller magnetic bottle • Lower axial state via cavity-assisted axial sideband cooling • Cleaner lineshapes for finer linesplitting • Reduce vibrational noise (improved support structure to maintain alignment) • Improve magnet stability (changes to cryogen spaces and magnet design) D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  22. Another frontier: better statistics • Rate-limiting step: wait for cyclotron decay after anomaly transition attempt (or correlated transition attempt) • To speed this step, sweep down with adiabatic fast passage or π-pulse Uncertainties for gin parts-per-trillion. D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev Lett. 100, 120801 (2008)

  23. Status and outlook Improvements that have already been implemented Remaining basic preparation New techniques in development Develop method for detuning particle from amplifier Demonstrate cavity-assisted axial sideband cooling and correlated measurement protocol • New apparatus with positrons, improved stability, smaller magnetic bottle, etc • Transfer positrons from loading trap into precision trap to prepare for positron measurement • Characterize apparatus (cavity mode structure, systematic checks, etc) New measurements of positron and electron g-2 at greater precision than the 2008 electron measurement

  24. theory measurement → determination of electron mass Bound electron g-value and Electron mass Larmorprecession frequency of the bound electron: Ion cyclotron frequency: B me=0,000 548 579 909 067 (14)(9)(2) u (stat)(syst)(theo) [S. Sturm et al., Nature 506, 467-470 (2014)] δme/me=3∙10-11 Wolfgang Quint, GSI/Heidelberg

  25. theory measurement → determination of electron mass Bound electron g-value and Electron mass Larmorprecession frequency of the bound electron: Ion cyclotron frequency: B me=0,000 548 579 909 067 (14)(9)(2) u (stat)(syst)(theo) [S. Sturm et al., Nature 506, 467-470 (2014)] δme/me=3∙10-11 Wolfgang Quint, GSI/Heidelberg

  26. theory measurement → determination of electron mass Bound electron g-value and Electron mass Larmorprecession frequency of the bound electron: Ion cyclotron frequency: B POSTER: WOLFGANG QUINTWEDNESDAY AFTERNOON me=0,000 548 579 909 067 (14)(9)(2) u (stat)(syst)(theo) [S. Sturm et al., Nature 506, 467-470 (2014)] δme/me=3∙10-11 Wolfgang Quint, GSI/Heidelberg

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