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
_
++
_
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