RA07
Current Status of the University of Oklahoma
e-EDM Search.
John Moore-Furneaux*, Neil Shafer-Ray
Columbus OH, 6/23/2011
*J.E. Furneaux
INTRODUCTION
Molecular Spectroscopy and the e-EDM
Recent combination of Microwave Spectra (Hannover) and Optical Spectra
(Oklahoma) has allowed us to characterize the ground state of PbF.
More Details: Theory: RA05 Experiment: RA06, RA08, RA09, FD01
INTRODUCTION
Take a closer look at the ground
X1 ( J  1/ 2,  )
states of 208Pb19F
INTRODUCTION
A MAGNETIC FIELD LIFTS ALL DEGENERACIES
J=1/2, +, F=1
M= 1
M=0
M = -1
J=1/2, +, F=0
M=0
INTRODUCTION
IN AN APPLIED ELECTRIC FIELD, 1 DEGENERACY
REMAINS.
M=1, M = -1
J=1/2, +, F=1
M=0
M=0
J=1/2, +, F=0
INTRODUCTION
Time reversal (or CP) Symmetry leads to a ±M degeneracy of any
system that is not broken by an electric field along the quantization
axis.
The existence of an electron electric dipole moment would break this
symmetry.
To search for an e-EDM we will look for DU=U+M –U-M in
a strong E field.
(Hoogeveen 1990)
Std. Mod.
(Arnowitt 2001)
Super Sym.
INTRODUCTION
Since its proposal in 1950 by Purcell and Ramsey**, many have
hunted for the e-EDM with the most recent limit of 10-27 e-cm
reported this year by the Hinds* group at Imperial College
found by probing the YbF molecule.
**Phys. Rev. 78, 807, 1950.
*Nature 473, 493–496, 2011.
This Talk
1) The PbF molecule vs other systems.
2) Outline of our measurement strategy.
3) pc-REMPI spectroscopy of the X1 A transition
4) Demonstration of laser frequency and polarization control
needed for a ~10-27 e-cm measurement.
5) The dream: A beam line measurement of the e-EDM.
Comparison of PbF to other e-EDM sensitive molecules
internal field
molecule (GV/cm)
Radiativeapproximate
g-factor
magnitude lifetime polarization field
(ms)
(kV/cm)
g
*
g
*
10+
g
- can be polarized by
207PbF
PbF is about a *factor
of
PbF
is
a
“g-2”
e-EDM
system.
e
Theg-2
ground-state of
*
- as small as 0.26kV/cm,
3
times
less
sensitive
than
a
field
“g-2” impliesPbF
g factor
of ~0.04
207
g-2
is
sensitive
to-an e-EDM 0.2-1.0
*
ePbF
HgF or ThO
requires ~5kV/cm
“g” implies g factor
of ~1 0.1**
g
*
6
and 2 less than WC.
g
?
*
0.2-1.0
g-2
*
1.0*
0.001-0.1***
1.0*
g-2
*
~0.0001*
g-2
100.*
*
~0.0001*
-60#
g-2
WC
~0.001#
+Hudson,
PRL 89 23003, 2002
*Meyer, Bohn, PRA 78, 010502R 2008
**DeMille, PRA 61 052507, 2000
***Prepint, Learnhardt, 2010
#http://www-personal.umich.edu/~aehardt/research/WC.html
Measurement Strategy
PbF+ + e-
5.0
A NEW TYPE OF
1+1+1 REMPI developed for
the PbF e-EDM effort.
476.Nm ,76 MHz
6ps 800 mW
4.0
3.0
D-state (lifetime ~150 ps)
D 2S1/2
pc-REMPI
energy (eV)
2.0
A-state (lifetime ~4usec)
1.0
A2P1/2
X2P1/2
0.0
-1.0
436 nm CW 10MHz
-2.0
X state
-3.0
3.0
5.0
7.0
R(Bohr)
Sivakumar et al, Mol Phys, 108, (972) 2010.
1290
1285
229
1280
227
1275
225
1270
223
1265
Ground hyperfine states resolved!
221
1260
0
2
4
frequency offset (GHz)
6
mass (u)
photoelectron - photoion delay (ns)
Measurement Strategy
Signal (counts)
Measurement Strategy
Frequency (GHz)
Entire e-EDM measurement occurs while our CW excitation laser is locked to
the Qfe(1/2) F=1 DF=0 transition at 436.7 nm or 444.1 nm.
Measurement Strategy
Salient Features:
1) No atomic Reference needed (We can lock anywhere!)
2) Inexpensive (No Frequency Comb Needed)
3) Reference and diode laser continuously locked (Very tight lock)
Saturated absorption spectroscopy of Te2 about
1GHz from the bandhead
of the X1  A transition of PbF
Frequency range: 674,611,022 + 60 - 360 MHz
N2 pressure range: 1140 – 1240 torr
Time period: 48 hours.
Stability: ~2MHz / 48hours
PBS
volts
Laser
250
-250
A
B
C
EOAM
D
E
0 t(ms) 2
ED
EC
e-
EE
l/4
l/2
EB EA
PbF
Ei
fif
Ef
PbF+
  ( pEDM Eeff / )  (time of flight)
 0.2mrad /1027 e cm
Incoherent
superposition
of M=1 and
M=-1 states
1  1
2
1 ei  1 ei
2
e   PbF signal
A+B cos 2 (  fif )
PBS
volts
Laser
A
250
B
-250
0
counts
faux e-EDM labview signal
A C E
B D
EOAM
C
D
l/4
l/2
E
t(ms)
2
ED
EC
e-
EE
EB
EA
PbF
Ei
fif
synchronization time(2ms)
Ef PbF+
e- - PbF+
correlation time(ns)
  ( pEDM Eeff / )  (time of flight)
 0.2mrad /1027 e cm
1  1
1 ei  1 ei
2
e   PbF signal
A+B cos 2 (  fif )
2
Incoherent superposition
of M=1 and M=-1 states
PBS
synchronization time(2 ms)
data collection electronics
photodetector
faux e-EDM
PbF+
faux
pulse
generator
voltage to
frequency
converter
photodetector signal
A+Bcos 2 ( faux  fif )
Total of 200 reversals in 4 hrs
Status of the OU e-EDM experiment
(1)We have demonstrated complete hyperfine state resolution
with an ultrasensitive continuous resonance enhanced
multi-photon ionization scheme.
(2)We have created rotating linear light with sufficient phase
and frequency stability to measure an e-EDM at the
<10-27e cm level.
(3) We have tested our data collection system by creating a
faux e-EDM signal.
GUIDED e-EDM EXPERIMENT
100,0000
Coherence time (msec)
10,0000
1000
100
10
1
0.1
0.01
0.001
0.0001
2/17/05
7/2/06
11/14/07
3/28/09
8/10/10
?
?
The Proposed PbF Beam Line Experiment
FEATURES:
50 ms coherence time, 100kHz data collection rate.
At 10-27 e cm, the (PbF) phase rotation is 3 mrad.
~ 10
26
e  cm / sec
Graduate Students
Student
Where They Are Now
Sivakumar Poopalasingam, 2009
Post Doc, Delaware State
C.P. McRaven, 2010
Post Doc, Brookhaven National Laboratory
Milinda Rupasinghe (2011)
Graduate Student
Tao Yang
Graduate Student
James Coker
Graduate Student
Haoquan Fan
Graduate Student
Jeffery Gillean
Undergraduate
Senior Collaborators
Senior PI
Where They Are
Greg Hall
Brookhaven National Laboratory
Trevor Sears
Brookhaven National Laboratory,
Stony Brook
John Furneaux
OU
Jens-Uwe Grabow
Gottfried-Wilhelm-Leibniz-Universität,
Hannover
Richard Mawhorter
Pomona College
Neil Shafer-Ray
OU
Funding Agencies
DOE
DOE-FG02-07ER46361
NSF
NSF-PHY-0602490, 0855431
University of Oklahoma
Board of Regents Exploration Grant
A GUIDED e-EDM EXPERIMENT
Potential Minimum in
U = USTARK + mg guides the beam.
After ~2 meters, the PbF beam
stops diverging!
E
-3000
volts
+3000
volts
The Proposed PbF Beam Line Experiment
FEATURES:
5 s coherence time, 100kHz data collection rate.
At 10-27 e cm, the (PbF) phase rotation is 300 mrad.
~ 10
28
e  cm / sec
Measurement Strategy
476.nm
76 MHz
6ps
800 mW
multichannel scalar
MCP
PbF+
436 nm
cw
10MHz
e-
MCP
Expected Spectra of the Q[1/2] Transition in an E Field (95% Uniformity)
E 0.2 kV cm f 674588.GHz
E 4. kV cm f 674588.GHz
6
6
5
5
4
4
3
3
2
2
1
1
0
1.0
0.5
0.0
0.5
1.0
1.5
2.0
0
1.0
E 7.9 kV cm f 674588.GHz
6
X1 ( J  1/ 2, e, F  1,| M | 1)  A( J  1/ 2, f , F  1,| M | 1)
5
0.0
0.5
1.0
1.5
2.0
E 11.6 kV cm f 674588.GHz
6
5
X1 ( J  1/ 2, e, F  1,| M | 1)  A( J  1/ 2, f , F  1, M  0)
4
4
X1 ( J  1/ 2, e, F  1,| M | 0)  3A( J  1/ 2, f , F  1,| M | 1)
3
2
2
1
1
0
1.0
0.5
0.5
0.0
0.5
1.0
1.5
2.0
0
1.0
0.5
0.0
0.5
1.0
1.5
2.0