Zheng-Tian Lu Physics Division, Argonne National Laboratory Department of Physics, University of Chicago Search for a Permanent Electric Dipole Moment (EDM) of Radium-225 T EDMSpinEDMSpin _ + P EDM Spin _ ++ _

More CP-Violation Mechanisms? Supersymmetry More particles  More CP-violating phases Strong CP problem CP-violating phase in Quantum Chromodynamics Matter-antimatter asymmetry Require additional CP-violation mechanism(s) CPT=

Intensity Frontier Workshop, Dec 2011, Convenors for nuclear physics: Haxton, Lu, Ramsey-Musolf “The existence of an EDM can provide the “missing link” for explaining why the universe contains more matter than antimatter.” “A nonzero EDM would constitute a truly revolutionary discovery.” -- Nuclear Science Advisory Committee (NSAC) Long Range Plan (2007) “The non-observation of EDMs to-date, thus provides tight restrictions to building theories beyond the Standard Model.” -- P5 report : The Particle Physics Roadmap (2006) Priorities according to Nima Arkani-Hamed, Institute for Advanced Study

EDM Searches in Three Sectors Nucleons (n, p) Diamagnetic atoms (Hg, Ra, Rn) Electron in paramagnetic molecules (YbF, ThO) Quark EDM Quark Chromo-EDM 4 Fermion, 3 Gluon Electron EDM, Electron-Quark Physics beyond the Standard Model: SUSY, etc. SectorExp Limit (e-cm) MethodStandard Model Electron9 x ThO in a beam Neutron3 x UCN in a bottle Hg3 x Hg atoms in a cell M. Ramsey-Musolf (2009)

1S01S0 DsRgCn Uut Fl Uup Lv UusUuo 1S01S0

Schiff moment of 225 Ra, Dobaczewski, Engel, PRL (2005) Schiff moment of 199 Hg, Dobaczewski, Engel et al., PRC (2010) IsoscalarIsovector Skyrme SIII Skyrme SkM* Skyrme SLy Enhancement Factor: EDM ( 225 Ra) / EDM ( 199 Hg) Closely spaced parity doublet – Haxton & Henley, PRL (1983) Large Schiff moment due to octupole deformation – Auerbach, Flambaum & Spevak, PRL (1996) Relativistic atomic structure ( 225 Ra / 199 Hg ~ 3) – Dzuba, Flambaum, Ginges, Kozlov, PRA (2002) EDM of 225 Ra enhanced and more reliably calculated       55 keV || || Parity doublet “[Nuclear structure] calculations in Ra are almost certainly more reliable than those in Hg.” – Engel, Ramsey-Musolf, van Kolck, Prog. Part. Nucl. Phys. (2013) Constraining parameters in a global EDM analysis. – Chupp, Ramsey-Musolf, arXiv (2014)

Efficient use of the rare 225 Ra atoms High electric field (> 100 kV/cm) Long coherence time (~ 100 s) Negligible “v x E” systematic effect EDM measurement on 225 Ra in a trap Transverse cooling Oven: 225 Ra Zeeman Slower Magneto-optical Trap (MOT) Optical dipole trap (ODT) EDM measurement 225 Ra: I = ½ t 1/2 = 15 d 225 Ra: I = ½ t 1/2 = 15 d Collaboration of Argonne, Kentucky, Michigan State Statistical uncertainty 100 kV/cm 10% 100 s d Long-term goal:  d = 3 x e cm

Apparatus Argonne National Lab8

E max = 75 kV/cm E-field spatial variation < 1%/mm B ~ 10 mGauss B-field spatial variation < 0.1%/cm B-field temporal variation < 0.01% (50sec) EDM (d) Measurement

Radium EDM Data d Ra-225 = (-0.5 ± 2.5 stat ± 0.2 syst ) × e-cm |d Ra-225 | < 5.0 × e-cm (95% confidence) d Ra-225 = (-0.5 ± 2.5 stat ± 0.2 syst ) × e-cm |d Ra-225 | < 5.0 × e-cm (95% confidence) Oct. 2014Dec. 2014

First EDM measurement on octupole deformed nuclei; First EDM measurement using cold atoms.

Outlook Longer trap lifetime; Implement STIRAP – more efficient way to detect spin; , blue upgrade – more efficient trap; Five-year goal (before FRIB): e cm; 2020 and beyond (at FRIB): 3 x e cm; Far future: search for EDM in diatomic molecules Effective E field is enhanced by a factor of 10 3 ; Reach the Standard Model value of e cm.

Absorption Detection of Spin State 483 nm 1S01S0 1P11P1 Photons scattering events 2-3 photons per atom Signal-to-noise Ratio For 100 atoms, SNR ~ 0.2 m F = -1/2 +1/2 F = 1/2 F = 3/2

STIRAP (stimulated Raman adiabatic passage) 483 nm 1429 nm 1S01S0 1P11P1 3D13D1 Stimulated, Adiabatic process No fluorescence m F = -1/2 +1/2 F = 1/2 F = 3/2

Absorption Detection on a Cycling Transition 483 nm 1S01S0 1P11P1 3D13D1 Photons scattering events 2-3 photons per atom photons per atom Signal-to-noise Ratio For 100 atoms, SNR ~ 0.2 For 100 atoms, SNR ~ 10 m F = -1/2 +1/2 F = 1/2 F = 3/2 m F = +3/2

7p 1 P 1 Trap, 714 nm 7s 2 1 S 0 7p 3 P ns 6 ns 6d 3 D 1 Pump #1 7p 1 P 1 Slow & Trap, 714 nm 7s 2 1 S 0 7p 3 P ns 6 ns 6d 3 D 1 Pump #1 6d 1 D  s 6d 3 D 2 Improve trapping efficiency with a blue upgrade

Scheme 1 st slowing laser: 483 nm (strong) 2 nd slowing laser: 714 nm 3 repumpers: 1428 nm, 1488 nm, 2.75 mm 171 Yb as co-magnetometer * 225 Ra and 171 Yb trapped, < 50 mm apart Benefits 100 times more atoms in the trap Improved control on systematic uncertainties 7p 1 P 1 Trap, 714 nm 7s 2 1 S 0 7p 3 P ns 6 ns 6d 3 D 1 Pump #1 7p 1 P 1 Slow & Trap, 714 nm 7s 2 1 S 0 7p 3 P ns 6 ns 6d 3 D 1 Pump #1 6d 1 D  s 6d 3 D 2 Slow, 483 nm Pump #2 Pump #3 KVI b arium trap S. De et al. PRA (2009) Improve trapping efficiency with a blue upgrade Atom Velocity Atom Flux 60 m/s 310 m/s

Ra Yields 229 Th 7.3 kyr 225 Ra 15 d 225 Ac 10 d Fr, Rn,… ~4 hr  233 U 159 kyr   Presently available National Isotope Development Center, ORNL Decay daughters of 229 Th 225 Ra: 10 8 /s Projected FRIB (B. Sherrill, MSU) Beam dump recovery with a 238 U beam6 x 10 9 /s Dedicated running with a 232 Th beam5 x /s (I.C. Gomes and J. Nolen, Argonne) Deuterons on thorium target, 1 mA x 400 MeV = 400 kW10 13 /s MSU K1200 (R. Ronningen and J. Nolen, Argonne) Deuterons on thorium target, 10 uA x 400 MeV = 4 kW /s

Kevin Bailey Peter Mueller Tom O’Connor Cold Atom Trappers Argonne: Kevin Bailey, Michael Bishof, John Greene, Roy Holt, Nathan Lemke, Zheng-Tian Lu, Peter Mueller, Tom O’Connor, Richard Parker Kentucky: Mukut Kalita, Wolfgang Korsch Michigan State: Jaideep Singh Northwestern: Matt Dietrich Michael Bishof Richard Parker Mukut Kalita Roy Holt Z.-T. Lu

Optical Dipole Trap Fiber laser: = 1550 nm, Power = 40 Watts Focused to 100  m  trap depth 400  K EDM in an optical dipole trap – Fortson & Romalis (1999) v x E, Berry’s phase effects suppressed Cold scattering suppressed between cold Fermionic atoms Rayleigh scat. rate ~ s -1 ; Raman scat. rate ~ s -1 Vector light shift ~  Hz Parity mixing induced shift negligible Conclusion: possible to reach e cm for 199 Hg

Trap Lifetimes Magneto-Optical Trap (MOT) in the first trap chamber Optical Dipole Trap (ODT) in the EDM chamber Sideview Head-on view ODT 0.04 mm MOT & ODT

Systematics Systematic effects much smaller than Statistical error for now No corrections needed Systematic Effect Δd Ra-225 (e-cm) Imperfect E-field reversal1 × Blue laser frequency correlations< External B-field correlations Current supply correlations E-field pulsing 1D MOT Coil Magnetization Leakage current Optical lattice power correlations E x v effects Stark interference Berry’s phase

E 2 Systematic 3 mCi Run (October)6 mCi Run (December) d E-squared syst ≤ 0.2× e-cmd E-squared syst ≤ 0.05× e-cm

ActualNear Term Goal N: # atoms detected E: Effective E-field (kV/cm)4575 : Precession Time (s)220 T d : Dead time (s)4848 T: Total time (s)2 × 86,400 5 × 86,400 γ atom : Photons per atom2.51,000 γ laser : Photons per laser pulse10 6 4×10 8 EDM sens. (e-cm)3× × What the stat. sensitivity of our experiment could be!

T. Chupp and M. Ramsey-Musolf, arXiv Why a more sensitive radium EDM measurement is important to science

Preparation of Cold Radium Atoms for EDM 2006 – Atomic transitions identified and studied; 2007 – Magneto-optical trap (MOT) of radium realized; 2010 – Optical dipole trap (ODT) of radium realized; 2011 – Atoms transferred to the measurement trap; 2012 – Spin precession of Ra-225 in ODT observed; 2014 – First measurement of EDM of Ra-225. J.R. Guest et al., PRL 98, (2007) R.H. Parker et al., PRC 86, (2012) N.D. Scielzo et al., PRA Rapid 73, (2006) R.H. Parker et al., submitted

EDM (d) Measurement