zheng-tian lu physics division, argonne national laboratory department of physics, university of...
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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
_
++
_
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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 =
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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
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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)
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1S0
Ds Rg Cn Uut Fl Uup Lv Uus Uuo
1S0
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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)
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• 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
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Argonne National Lab 8
Apparatus
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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
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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
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• First EDM measurement on octupole deformed nuclei;
• First EDM measurement using cold atoms.
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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.
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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!
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T. Chupp and M. Ramsey-Musolf, arXiv.1407.1064
Why a more sensitive radium EDM measurement is important to science
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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
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EDM (d) Measurement
2 2B dE
2 2B dE