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

EDM Spin EDM Spin

_

+

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, www.intensityfrontier.orgConvenors 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)

2sin f

f CP

md e

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 paramagneticmolecules (YbF, ThO)

Quark EDM

Quark Chromo-EDM4 Fermion, 3 Gluon

Electron EDM, Electron-Quark

Physics beyond the Standard Model:

SUSY, etc.

Sector Exp Limit(e-cm)

Method StandardModel

Electron 9 x 10-29 ThO in a beam 10-38

Neutron 3 x 10-26 UCN in a bottle 10-31

199Hg 3 x 10-29 Hg atoms in a cell 10-33

M. Ramsey-Musolf (2009)

1S0

Ds Rg Cn Uut Fl Uup Lv Uus Uuo

1S0

Schiff moment of 225Ra, Dobaczewski, Engel, PRL (2005)Schiff moment of 199Hg, Dobaczewski, Engel et al., PRC (2010)

Isoscalar Isovector

Skyrme SIII 300 4000

Skyrme SkM* 300 2000

Skyrme SLy4 700 8000

Enhancement Factor: EDM (225Ra) / EDM (199Hg)

• Closely spaced parity doublet – Haxton & Henley, PRL (1983)

• Large Schiff moment due to octupole deformation – Auerbach, Flambaum & Spevak, PRL (1996)

• Relativistic atomic structure (225Ra / 199Hg ~ 3) – Dzuba, Flambaum, Ginges, Kozlov, PRA (2002)

EDM of 225Ra enhanced and more reliably calculated

- = (| - | )/2 a b

+ = (| + | )/2a b55 keV

|a |b

Parity doublet

0 0

0 0

ˆ ˆ_ . .z i i PT

i i

S HSchiff moment c c

E E

“[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, arXiv1407.1064 (2014)

• Efficient use of the rare 225Ra atoms

• High electric field (> 100 kV/cm)

• Long coherence time (~ 100 s)

• Negligible “v x E” systematic effect

EDM measurement on 225Ra in a trap

Transversecooling

Oven:225Ra

Zeeman Slower Magneto-optical

Trap (MOT)

Optical dipoletrap (ODT)

EDMmeasurement

225Ra:I = ½

t1/2 = 15 d

225Ra:I = ½

t1/2 = 15 dCollaboration of Argonne, Kentucky, Michigan State

Statistical uncertainty

100 kV/cm 10%100 s 106

100 d

Long-term goal: dd = 3 x 10-28 e cm

Argonne National Lab 8

Apparatus

Emax = 75 kV/cmE-field spatial variation < 1%/mm

B ~ 10 mGaussB-field spatial variation < 0.1%/cmB-field temporal variation < 0.01% (50sec)

2 2B dE

2 2B dE

EDM (d) Measurement

Radium EDM Data

dRa-225 = (-0.5 ± 2.5stat ± 0.2syst) × 10-22 e-cm

|dRa-225| < 5.0 × 10-22 e-cm (95% confidence)

Oct. 2014 Dec. 2014

• First EDM measurement on octupole deformed nuclei;

• First EDM measurement using cold atoms.

Outlook

• 2015 - 2016

• Longer trap lifetime;

• Implement STIRAP – more efficient way to detect spin;

• 2016 - 2018, blue upgrade – more efficient trap;

• Five-year goal (before FRIB): 10-26 e cm;

• 2020 and beyond (at FRIB): 3 x 10-28 e cm;

• Far future: search for EDM in diatomic molecules

• Effective E field is enhanced by a factor of 103;

• Reach the Standard Model value of 10-30 e cm.

Absorption Detection of Spin State

483 nm

1S0

1P1

Photons scattering events2-3 photons per atom

Signal-to-noise RatioFor 100 atoms, SNR ~ 0.2

mF = -1/2 +1/2

F = 1/2

F = 1/2

F = 3/2

STIRAP (stimulated Raman adiabatic passage)

483 nm

1429 nm

1S0

1P1

3D1

Stimulated, Adiabatic processNo fluorescence

mF = -1/2 +1/2

F = 1/2

F = 1/2

F = 3/2

Absorption Detection on a Cycling Transition

483 nm

1S0

1P1

3D1

Photons scattering events2-3 photons per atom100-1000 photons per atom

Signal-to-noise RatioFor 100 atoms, SNR ~ 0.2For 100 atoms, SNR ~ 10

mF = -1/2 +1/2

F = 1/2

F = 1/2

F = 3/2mF = +3/2

1d

E SNR

7p 1P1

Trap

, 714

nm

7s2 1S0

7p 3P1420 ns

6 ns

6d 3D1

Pump #1

7p 1P1

Slo

w &

Tra

p, 7

14 n

m

7s2 1S0

7p 3P1420 ns

6 ns

6d 3D1

Pump #1

6d 1D2

430 ms

6d 3D2

Improve trapping efficiency with a blue

upgrade

Scheme• 1st slowing laser: 483 nm (strong)• 2nd slowing laser: 714 nm• 3 repumpers: 1428 nm, 1488 nm, 2.75 mm• 171Yb as co-magnetometer * 225Ra and 171Yb trapped, < 50 mm apartBenefits• 100 times more atoms in the trap• Improved control on systematic uncertainties

7p 1P1

Trap

, 714

nm

7s2 1S0

7p 3P1420 ns

6 ns

6d 3D1

Pump #1

7p 1P1

Slo

w &

Tra

p, 7

14 n

m

7s2 1S0

7p 3P1420 ns

6 ns

6d 3D1

Pump #1

6d 1D2

430 ms

6d 3D2

Slo

w, 4

83 n

m

Pump #2

Pum

p #3

KVI barium trapS. De et al. PRA (2009)

Improve trapping efficiency with a blue

upgrade

Atom Velocity

Atom

Flu

x 60m/s

310 m/s

18

225Ra Yields

229Th7.3 kyr

225Ra15 d

225Ac10 d

Fr, Rn,…~4 hr

b

233U159 kyr

a

aa

Presently available• National Isotope Development Center, ORNL

• Decay daughters of 229Th 225Ra: 108 /s

Projected• FRIB (B. Sherrill, MSU)

• Beam dump recovery with a 238U beam 6 x 109 /s• Dedicated running with a 232Th beam 5 x 1010 /s

• ISOL@FRIB (I.C. Gomes and J. Nolen, Argonne)• Deuterons on thorium target, 1 mA x 400 MeV = 400 kW 1013 /s

• MSU K1200 (R. Ronningen and J. Nolen, Argonne)• Deuterons on thorium target, 10 uA x 400 MeV = 4 kW 1011 /s

KevinBailey

PeterMueller

TomO’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 KorschMichigan State: Jaideep SinghNorthwestern: Matt Dietrich

MichaelBishof

RichardParker

MukutKalita

RoyHolt

Z.-T.Lu

Optical Dipole Trap

20

1

4H dE E • Fiber laser: l = 1550 nm, Power = 40 Watts

• Focused to 100 mm trap depth 400 mK

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 ~ 10-1 s-1 ; Raman scat. rate ~ 10-12 s-1

• Vector light shift ~ mHz• Parity mixing induced shift negligible• Conclusion: possible to reach 10-30 e cm for 199Hg

Trap Lifetimes

Magneto-Optical Trap (MOT)in the first trap chamber

Optical Dipole Trap (ODT)in the EDM chamber

Sideview

Head-onview

ODT 0.04 mm

MOT & ODT

Systematics

• Systematic effects much smaller than Statistical error for now• No corrections needed

Systematic Effect ΔdRa-225 (e-cm)

Imperfect E-field reversal 1 × 10-23

Blue laser frequency correlations < 10-25

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

E2 Systematic

3 mCi Run (October) 6 mCi Run (December)

dE-squared syst ≤ 0.2× 10-22 e-cm dE-squared syst ≤ 0.05× 10-22 e-cm

Actual Near Term Goal

N: # atoms detected 150 300

E: Effective E-field (kV/cm) 45 75

𝜏 : Precession Time (s) 2 20

Td: Dead time (s) 48 48

T: Total time (s) 2 × 86,400 5 × 86,400

γatom: Photons per atom 2.5 1,000

γlaser: Photons per laser pulse 106 4×108

EDM sens. (e-cm) 3×10-22 4×10-25

d = What the stat. sensitivity of our experiment could be!

T. Chupp and M. Ramsey-Musolf, arXiv.1407.1064

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, 093001 (2007)

R.H. Parker et al., PRC 86, 065503 (2012)

N.D. Scielzo et al., PRA Rapid 73, 010501 (2006)

R.H. Parker et al., submitted

EDM (d) Measurement

2 2B dE

2 2B dE