Search for a Electric Dipole Moment in...
Transcript of Search for a Electric Dipole Moment in...
Search for aElectric Dipole Moment
in Ra-225
Peter Mueller
Argonne National Laboratory
2
Argonne Cold Atom TrappersArgonne Cold Atom Trappers
Z.-T. Lu, P. Mueller, I. Sulai, K. Bailey, M. Kalita, S.M. Hu, W. Williams, W. Jiang,
T.P. O’Connor, J. Singh, R. Parker, M. Dietrich, R. Holt
Argonne Natl Lab, Univ. of Chicago, Univ. of Kentucky
Electric Dipole Moment (EDM) Violates Both P and T
+
-
+
-
-
+
T P
EDM Spin EDM Spin EDM Spin
A permanent EDM violates both time-reversal symmetry and parity
Neutron
Diamagnetic Atoms (Hg, Ra)
Paramagnetic Atoms (Tl)Molecules (PbO,YbF)
Quark EDM
Quark Chromo-EDM
Electron EDM
Physics beyond the Standard Model:
SUSY, String…
The Seattle EDM Measurement
Courtesy of Michael Romalis
2 215 Hz
B dEf
h
µ+
+= ≈
2 215 Hz
B dEf
h
µ−
−= ≈
0.6 nHzf f+ −− <
The best limit on atomic EDM
EDM (199Hg) < 3 x 10-29 e-cmGriffith et al., Phys Rev Lett (2009)
E
E
199Hg stable, high Z, J = 0, I = ½, high vapor pressure
+e
-e
UnitEDM
Schiff moment of 225Ra, Dobaczewski, Engel (2005)
Schiff moment of 199Hg, Ban, Dobaczewski, Engel, Shukla (2010)
Skyrme Model Isoscalar Isovector Isotensor
SIII 300 4000 700
SkM* 300 2000 500
SLy4 700 8000 1000
Enhancement Factor: EDM ( 225Ra) / EDM (199Hg)
• Closely spaced parity doublet – Haxton & Henley (1983)
• Large intrinsic Schiff moment due to octupole deformation
– Auerbach, Flambaum & Spevak (1996)
• Relativistic atomic structure (225Ra / 199Hg ~ 3)
– Dzuba, Flambaum, Ginges, Kozlov (2002)
EDM of 225Ra enhanced
Ψ− = (|α⟩ − |β⟩)/√2
Ψ+ = (|α⟩ + |β⟩)/√255 keV
|αααα⟩⟩⟩⟩ |ββββ⟩⟩⟩⟩
Parity doublet
225Ra:I = ½
t1/2 = 15 d
225Ra:I = ½
t1/2 = 15 d
ψ ψ ψ ψψ ψ
≠
≡ = +−∑ 0 0
0 0
0 0
ˆ ˆˆ . .
z i i PT
z
i i
S HS S c c
E E
ψ ψ ψ ψψ ψ
≠
≡ = +−∑ 0 0
0 0
0 0
ˆ ˆˆ . .
z i i PT
z
i i
S HS S c c
E E
225Ra Source
229Th
7.3 kyr
225Ra
15 d
225Ac
10 d
Fr, Rn…
~ 4 hr
β
• ~10 mCi (or 300 ng) 225Ra sources from Oak Ridge Nat’l Lab
• Test source: ~100 µCi (or 100 µg) 226Ra (1600 yr)
233U
159 kyrα
αα
Future Rare Isotope Facility
Yield for 225Ra ~ 1010 - 1012 s-1
Future Rare Isotope Facility
Yield for 225Ra ~ 1010 - 1012 s-1
Stern man
Geiger counter
Special thanks to our health physicists P. Niquette, L. Sprouse, A. Garcia.
Radium oven
Experiment seems feasible with modest(~ 10 mCi) 225Ra sources.
EDM measurement on 225Ra
Transverse
cooling
Oven:225Ra
Zeeman
SlowerMagneto-optical
Trap (MOT)
Optical dipole
trap (ODT)EDM
measurement
Why trap 225Ra atoms
• Large enhancement:
EDM (Ra) / EDM (Hg) ~ 102 – 103
• Efficient use of the rare 225Ra atoms
• High electric field (> 100 kV/cm)
• Long coherence times (~ 100 s)
• Negligible “v x E” systematic effect
7s2 1S0
7p 3P0°
7p 3P1°
7p 3P2°
6d 3D1
6d 3D2
6d 3D3
6d 1D2
7p 1P1°
420 ns
0.4 ms
6 ns
0.7 ms1
70
1e-1
5e-4
2e-6
5e-2
2e-2
2e-3
7e-10
4e-5
6e-4
5e-2
2e-2
Radium Atom Energy Level DiagramV. Dzuba, V. Flambaum et al., PRA 61 (2000)
* Without repump, 1.7 × 104 cycles.
* With repump at 1428 nm, 1.7 × 107 cycles.
• Linewidth ~ 400 kHz
• Cooling 7 µK, 14 mm/s
• B gradient ~ 1 G / cm
483
nm
6 µs
0-4 -3 -2 -1 0 1 2 3 4
Ra
fluor
esce
nce
sign
al
Probe frequency shift (MHz)
Laser-Trapping of 225Ra and 226Ra Atoms
1S0
3P1
Laser-cooling
3D1
1P1 Repump
100x Ra atomic beam
Ra atom trap!
• Key 225Ra frequencies, lifetimes measuredScielzo et al. PRA (2006)
• 225Ra laser cooled and trapped!Guest et al. PRL (2007)
1P1
3D1
3/2
3/2 -> 3/2
3/2 -> 1/2
1/2 -> 3/2
1/2 -> 1/2
3/2
1/2
1/2
6999.83 cm-1
F540(4) MHz
4196(2) MHz
7031(2) MHz
ISOLDE: 4195(4) MHz*
*Ahmad et al., Phys. Lett. 133B, 47 (1983)
Ra-226 Ra-225
226Ra and 225RaHyperfine constants and isotope shift on 3D1 - 1P1
Guest et al. PRL (2007)
Radium Atom Repump Dynamics
1429nm Repumping
to 1P1
3P1
3P0
3D11.5 E3
9.9 E1
Laser-cooling
2000
cm-1
0
N(ν)
Blackbody spectrum@ 298K
(kBT/hc) = 210cm-1)
Bij ρ(ν ij ,T ) =Aij
eE /kBT −1, Bji = gi
g j
Bij
2.2 E2
7.4 E1
3.4 E1
3.4 E1
298 K thermaltransition rates
0.6 ms
1S0
1P1
482nm
EDM Beamline
B-Field: Shields, Coils, Magnetometers --- Done
µ-shields: Shielding factor = 3 x 104
Design Goal
B = 10 mG
Stability: < 1 ppm in 100 sec
Uniformity: < 1% / cm
B field < 0.1% / cm, ~ 0.3 ppm / 100s Rb cell magnetometer: Budker design
Rb Magnetometry
Shields
Rb
Coil
Rb
B
Ra-225
Rel. B-Field Stabilityx10-7
3
4
100 s ( 3 nG / 10 mG )
5
6
EDM Science Chamber
Standing wave ODT
Shuttle
ODT
HV Electrodes
E-Field: 100 kV / cm -- Done.• 20 kV over 2mm vacuum gap• < 50 pA leakage currents observed• ~10-10 Torr UHV in 2 m glass tube
1 cm
EDM Beamline
Optical Dipole Trap
20
1
4H dE Eα= − = −% • Fiber laser: λ = 1550 nm, Power = 40 Watts
• Focused to 100 µm � trap depth 400 µK
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
• Conclusion: possible to reach 10-30 e cm for 199Hg
Atom Transfer Steps
(A)
MOTStanding WaveHolding ODT10W 1550 nm
Travelling WaveBus ODT 50W1550 nm
(B)
(C) (D)
714 nmLaser Cooling Polarize and
Measure
483 nm Probe
Mirror
“iEDM” Beamline
Translation stageiEDM Chamber
ODT Transport
50 cm
~ 30,000226Ra atoms
• > 50 cm transport
with moving lens
• “lossless” motion
• atom lifetime limited
by vacuum ~ 10 s
Overlap of Crossed ODTs
Imaging Beam, 714 nm
Optical LatticeHolding ODT
Bus ODT, 1550 nm
5 mm
Compression and Handoff with 1D MOT
Imaging
B Field
Imaging
Compression
(A) (B)
(C)
> 60% efficiency
DC MOT EDM
-> AC MOT!
Atom Imaging
Detector
CCD
1.2 m
With Atoms…
Without Atoms…
And Again…
In case you didn’t catch that…
~700 226Ra Atoms
1.4% Absorption
Precession MeasurementP
opul
atio
n of
m=
-1/2
Time (s)
225Ra
Next Steps
• 225Ra transfer, pumping and precession
• Shadow imaging of 225Ra
• Installation of EDM science chamber
(shields, coils, electrodes)
• Measurement of EDM to follow
EDM measurement on 225Ra
Transversecooling
Oven:225Ra
Zeeman Slower Magneto-optical
trap
Opticaldipole trap
EDMmeasurement
Statistical uncertainty:
100 kV/cm
10 s 10410%
10 days
δδδδd = 3 ×××× 10-26 e cm
Best experimental limit: d(199Hg) < 3 × 10-29 e cm
Ra / Hg Enhancement factor ~ 102 -103
100 s 106
100 days
δδδδd = 3 ×××× 10-28 e cm
6He
νe
6Li+
β - θ
T
+
-
EDM Spin
+
-
EDM Spin
He
He
Ra
Kr,Ar
www.phy.anl.gov/mep/atta/google atom trap
Weak Interaction Studies: ββββ−−−−νννν Angular Correlations
6He
6Li
t1/2=0.808 sec
100%β
0+
1+
Qβ=3.510 MeV
-1.0
-0.5
0.0
0.5
1.0
Cor
rela
tion
Coe
f. a
1.00.80.60.40.20.0
T
A
V
S
-50
-40
-30
-20
-10
0
10
20
a(ex
p) -
a(S
M)
x
10-3
1.00.80.60.40.20.0
Fermi fraction
6He n
21Na
32Ar
38mK
21Na
Atom Trap Ion Trap
ββν
β
ββνβ θθ
E
mb
E
paEN ++∝ )cos(1),(
Beta-Decay Study with Laser Trapped 6He
Recoil time-of-flight spectrum
• ∼1x109 6He/s production yield• trapping rate ∼2x103 6He/s• ∼0.1% statistics in ∼4 weeks beam time
Atom trap properties• Highly selective capture• No RF fields or space charge• Low temperature sample (mK)• Tight spatial confinement (< 100µm)
250 300 350 400 450
a = -1/3
Cou
nts
Time of Flight, ns
a = +1/3
Optical DipoleTrap (ODT)
Beta-Decay Study with Laser Trapped 6He
Project funded through Mueller’s DOE Early Career Grant (July 2011 – June 2016)
Collaboration with University of Washington/CENPA
And Michigan State University
Phase I: coincidence detection in MOT - 2012/13
• Aim to measure a with <0.5%
• Use UWash/CENPA tandem to produce 6Hevia 7Li(d,3He)6He @ 18 MeV, 5pmA
• Target & transfer line installed
• ~1x109 6He/s transferred
• MOT apparatus installed at CENPA, 4He trapped
• Electrode structure & detector systemunder design
Phase II: 6He transfer into ODT - 2014/15
• Aim to measure a with ~0.1%
• Develop ODT transfer techniques
• Design “high precision” detector system
Beyond 2015
• Explore applicability to other noble-gasisotopes, e.g. 32Ar, 18,19Ne
• Explore higher intensity sources for 6He
MOT chamber
Electrode &DetectorAssembly
Fundamental Physics
At the Intensity Frontier
Nov. 30th – Dec. 2nd 2011
Working group
Nucleons, Nuclei & Atoms
www.intensityfrontier.org