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Philip Harris

*. * (mainly neutron) for the EDM collaboration. Electric-Dipole Moment Searches. Philip Harris. Overview. 1. nEDM “Classic”. New limit: |d n | < 3.0 x 10 -26 e.cm Discovery of new systematic effect. 2. CryoEDM. Under development: 100x improved sensitivity.

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Philip Harris

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  1. * *(mainly neutron)for the EDM collaboration Electric-Dipole Moment Searches Philip Harris

  2. Overview 1. nEDM “Classic” • New limit: |dn| < 3.0 x 10-26 e.cm • Discovery of new systematic effect 2. CryoEDM Under development: 100x improved sensitivity 3. Other EDM experiments

  3. dn = dns Electric Dipole Moments • Separation between+,- charge centres • EDMs are • P odd • T odd • Complementary approachto study of CPv + E

  4. CP violation & the neutron EDM • SM EDM predictions very small • Beyond SM predictions typ. 106 greater • EDMs are excellent probe of BSM CPv • Tight constraints on SUSY etc • Strong CP Problem: s < 2 x 10-10 rads (axions? Zavattini et al., PRL 96,110406 (2006))

  5. g squark quark electric dipole moments: q q gaugino scale of SUSY breaking: naturally ~200 GeV CP phase from soft breaking naturally O(1) du< 2  1025 n and Hg experiments give: ~ 10-100 times less! dd< 5  1026 L2 2 Implications for SUSY naturally ~ a/p mq dq~ (loop factor)sinCP du,d~ 31024e.cm naturally “SUSY CP problem” L> 2 TeV?CP< 10-2 ?

  6. Constraints on SUSY parameters MSUSY = 500 GeV tan b = 3 Pospelov & Ritz, hep-ph/0504231

  7. SUSY, cont’d Lebedev et al., hep-ph/0402023

  8. Now CryoEDM History Factor 10 every 8 years on average

  9. Measurement principle Use (Ramsey) NMR on ultracold neutrons in B,E fields () – () = – 4 E d/ h assuming B unchanged when E is reversed. B0 B0 B0 E E <Sz> = + h/2 h(0) h() h() <Sz> = - h/2 Energy resolution of our detector: <10-21 eV

  10. Approx scale 1 m High voltage lead Magnetic field coil B E /analysing foil Apparatus Magnetic shielding Storage cell S N Magnet & polarizing foil Ultracold neutrons (UCN) UCN detector

  11. Apparatus HV feedthru Neutron storage chamber B-field coils

  12. Electric Field + - nEDM measurement • Keep track of neutron resonant frequency • Look for n freq changes correlated with changes in E

  13. Mercury co-magnetometer Compensates B drift...

  14. nEDM measurement Raw neutron frequency 29.9295 Corrected frequency 29.9290 29.9285 29.9280 -10 D B = 10 T Precession frequency (Hz) 29.9275 29.9270 29.9265 29.9260 0 5 10 15 20 25 Run duration (hours)

  15. Stat. limit now 1.51 x 10-26 e.cm Neutron EDM results (binned)

  16. What’s going on here, for example? Neutron EDM results (individual runs)

  17. and, from Special Relativity, extra motion-induced field Conspiracy theory Two effects:

  18. Bnet Br Bnet Bv Bv Bv Bnet Br Bnet Geometric Phase J. Pendlebury et al., PRA 70 032102 (2004) P. Harris, J. Pendlebury, PRA 73 014101 (2006) ... so particle sees additional rotating field Bottle (top view) Frequency shift  E Looks like an EDM, but scales with dB/dz

  19. Geometric Phase How to measure it • Consider • Should have value 1 • R is shifted by magnetic field gradients • Plot EDM vs measured R-1:

  20. Geometric Phase Magnetic field down

  21. Geometric Phase Magnetic field up

  22. The answer? B up B down Results EDM R-1 0 Nearly...

  23. Results Small dipole/quadrupole fields can pull lines apart & add GP shifts EDM B up R-1 0 B down

  24. Results Small dipole/quadrupole fields can pull lines apart & add GP shifts EDM B up R-1 0 Measure and apply correction ...difficult! B down

  25. Error budget (10-26e.cm)

  26. Final Result New limit: |dn| < 3.0 x 10-26 e.cm (90% CL) (prev. limit 6.3 x 10-26 e.cm, PRL 82, 904 (1999)) Preprint hep-ex/0602020 www.neutronedm.org

  27. Dispersion curve for free neutrons Landau-Feynman dispersion curve for 4He excitations ln = 8.9 Å; E = 1.03 meV 2. CryoEDM 100-fold improvement in sensitivity! R. Golub and J.M. Pendlebury Phys. Lett. 53A (1975), Phys. Lett. 62A (1977) More neutrons Higher E field Better polarisation Longer coherence time

  28. CryoEDM overview Neutron beam input Cryogenic Ramsey chamber Transfer section

  29. CryoEDM Turns on October 2006

  30. 3. Other EDM experiments: PSI • spallation target • D2O moderator • currently testing apparatus from ILL

  31. Other nEDM experiments: Mainz • Testing UCN source at TRIGA, Mainz for later installation at FRM, Munich

  32. Other nEDM experiments: USA • SNS at ORNL LANL-led testing underway not yet funded

  33. Electron EDM: Berkeley State analyser laser Down beam E field B field State preparation laser Up beam • Use unpaired e-in paramagnetic atom • Pairs of Tl beams in opposite E fields • Na beams as comagnetometer Final result: de<1.6 x 10-27 e.cm (systematics limited)

  34. Electron EDM measurements (This slide mainly from DeMille, PANIC ’05)

  35. Molecule interferometer PMT Pulsed supersonic YbF beam source detection laser Yb target B E skimmer Ar+SF6 pulsed YAG laser Imperial College Electron EDM experiment state recombiner state splitter pump laser J.J.Hudson, B.E. Sauer, M.R. Tarbutt, & E.A. Hinds, PRL. 89, 023003 (2002).

  36. The interference fringes Data being taken now. Systematics being studied. Current status: Expected 2010: de = _ ± 5 x 10-28 e.cm de = _ ± 5 x 10-29 e.cm Fluorescence signal EDM given by fringe shift with reversal of E or B Magnetic field (nT)

  37. 199Hg EDM • Optically pumped 199Hg atoms precess in B, E fields, modulating absorption signal • Dual cells remove effect of drifts in B • Result: d(199Hg) < 2.1 x 10-28 e cm • Provides good limit on CPv effects in nuclear forces, inc. qQCD

  38. ... and more! • Muon EDM: from g-2 (7E-19; proposal at JPARC for ~10-24) • Deuterium EDM: similarprinciple (may reach ~10-29 e.cm) • Tau weak dipole moment – look for CP-odd observables in diff. x-sec at Z res.(6E-18 e.cm from LEP data) Sensitivity to physics BSM depends on source of CPv

  39. Conclusions • New nEDM limit, 3.0 x 10-26 e.cm • Tightens the constraints on beyond-SM CPv • Systematics understood as never before • CryoEDM coming soon – 100x more sensitive • Several new measurements starting up • Watch this space!

  40. spare slides

  41. Cryogenic Ramsey chamber HV electrode Superfluid He n storage cells

  42. “Spin up” neutron... 1. Apply /2 spin flip pulse... 2. Free precession... 3. Second /2 spin flip pulse. 4. Ramsey method of Separated Oscillating Fields

  43. Ramsey resonance • “2-slit” interference pattern • Phase gives freq offset from resonance

  44. Four-layer mu-metal shield High voltage lead Quartz insulating cylinder Coil for 10 mG magnetic field Upper electrode Main storage cell Hg u.v. lamp PMT to detect Hg u.v. light Vacuum wall Mercury prepolarising cell RF coil to flip spins Hg u.v. lamp Magnet S N UCN guide changeover UCN polarising foil Ultracold neutrons (UCN) UCN detector nEDM apparatus

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