Atomic Parity Violation
in a single trapped radium ion
Oscar O. Versolato
TRIμP, University of Groningen, Kernfysisch Versneller Instituut
The Netherlands
TCP 2010 Saariselkä, April 12th, 2010
Talk Outline

Motivation for atomic parity violation (APV) exp’s

The case for radium 
Measurement principle; light shifts

First experimental results

Spin‐off project: optical clock
April 12th, 2010
TCP 2010
Low‐energy tests of the Standard Model
The Standard Model (SM) of particle physics is incomplete 
searches for physics “beyond the SM” at two, complementary, fronts:
High energy collider experiments: Direct observation of new particles
LHC @ CERN
April 12th, 2010
Low energy searches: indirect, but with high precision
TRIP @ KVI
TCP 2010
TRIμP: Trapped Radioactive Isotopes: micro‐laboratories for fundamental Physics
Testing fundamental symmetries

Atomic parity violation (APV) in Ra+

T‐Violation
 EDM in radium/deuteron
 T‐violating correlation coefficient in 21Na beta‐decay

Lorentz & CPT invariance in beta‐decay
April 12th, 2010
TCP 2010
Atomic parity violation (APV)
Weak interaction (violates parity):
q

Mediated by Z0 bosons, mass ≈ 91 GeV, short‐ranged

Atomic states acquire tiny admixture of opposite‐parity states

Strength grows faster than Z 3 (Bouchiat (1974))

q
V
Z0
e
A
e
Nucleus also has a weak charge QW; all quarks add coherently
QW = –N+(1–4 sin2θW)Z + rad. corr. + “new physics”
A sense of scale:
Qw(Cs) ≈ ‐73.9
Qw(Ra) ≈ ‐131.4
Best limit on the mass of Z’ from APV
April 12th, 2010
TCP 2010
Atomic parity violation (APV)
Key in the acceptance of the Standard Model, GSW theory
 Neutral currents  proof in neutrino scattering experiments and APV
 First APV SM test by Bouchiat & Bouchiat (1982‐3) on 133Cs
 State‐of‐the‐art APV result on 133Cs by Wieman (1999)
 Other elements: 209Bi (Oxford), 208Pb and 205Tl (Oxford, Seattle), Dy, Yb
(Berkeley), and molecules
QW = –N+(1–4 sin2θW)Z + rad. corr. + “new physics”
 Probe of neutron distribution and search for anapole moment
April 12th, 2010
TCP 2010
Experiments on the Weinberg angle
High energy (near the Z0‐pole)
1.
SLD @ SLAC (Stanford)
2.
LEP @ CERN (Geneva)
5
4
3
Cesium atom
5
Radium ion
Radium ion
Derevianko (2009)
≈ 3 %
Derevianko
2009
2
5
1
Time Medium energy
3.
E158 @ SLAC (Stanford)
•
Qw(e) of the electron
4.
NuTeV @ Fermilab (Chicago)
•
neutrino scattering
5.
Qweak @ J‐Lab (Virginia)
•
Qw(p) of the proton
Low energy: atomic parity violation (APV)
Cesium atoms: 6S1/2–7S1/2 transition 
Experiment: 0.35%, Boulder, (ENS Paris)

Theory: 0.3%, Derevianko et al.
Barium ion: 6S1/2–5D3/2 transition
 Experiment: UW Seattle
 Theory: %‐level
Francium atoms: 7S1/2– 8S1/2 transition

Experiments: Legnaro (coll.), TRIUMF (coll.) 
Theory: %‐level
Radium ion: 7S1/2–6D3/2 transition
 Experiment: KVI Groningen
 Theory: %‐level
April 12th, 2010
TCP 2010
APV and Physics beyond the SM
On par with high‐energy exp’s
q
q
V
QW = –N+(1–4 sin2θW)Z + rad. corr. + “new physics”
Z0
e
Extra Z’ boson in SO(10) GUTs:
 M Z2 
 QW  2 N  Z  ae '   vd '    2 
 MZ' 
Bounds on MZ’ from cesium APV
(84% confidence level, ξ= 52°Derevianko 2009)
Mz’> 1.3 TeV/c2
Bounds on MZ’ from radium APV
Mz’> 5 TeV/c2
April 12th, 2010
A
e
Londen en Rosner (1986)
Marciano en Rosner (1990)
Altarelli et al. (1991)
Compare
Tevatron MZ’> 0.82 TeV/c2
Compare
Sensitivity full LHC MZ’ ~4.5 TeV/c2
TCP 2010
Complementarity:
SUSY and E6 Z’ meet APV
•SUSY loop corrections correlated shift in QW(p) and QW(e) Qweak @ J‐Lab (Virginia)
The role of atomic parity violation:
SLAC (Stanford)
M.J. Ramsey‐Musolf and S. Su (2007)
• APV is (almost) insensitive to SUSY loops (Cancellation of neutron and proton effects)
• APV is very sensitive to additional Z’ bosons
→ Use APV to tell these two apart models
April 12th, 2010
TCP 2010
Complementarity:
Weak coupling constants
QW  2 C1u 2 Z  N   C1d Z  2 N 
C1u   12  43 sin 2  W
 3 C1u  C1d Z  N   C1u  C1d Z  N 
C1d  12  23 sin 2  W
APV probes “orthogonal” set
Young et al. PRL 2007
April 12th, 2010
TCP 2010
Talk Outline

Motivation for atomic parity violation (APV) exp’s

The case for radium 
Measurement principle; light shifts

First experimental results

Spin‐off project: optical clock
April 12th, 2010
TCP 2010
The case for radium
Bouchiat & Bouchiat (1974) : “faster than Z3”
General advantages of Ra+ vs. Cs, Ba+
Z3Kr
APV size
• Heavy: APV signal increases faster than Z3
• Semiconductor laser diodes only
• Different isotopes available at TRImP
Ra+
Courtesy of L.W. Wansbeek
Ba+(Cs)
+
Ca
Isotope
The radium ion experiment
210‐214
Ra
I
1/2
Sr
Z3
+
Halflife 1/2
Possible production
2.74(6) min
206Pb + 12C  21XRa + n
Z (atomic number)
223Ra
• Parity‐violation induced lightshifts 3/2+ E. N. Fortson (PRL 1993)
11.43(5) d
p + 232Th  223Ra + AX + an + bp
224Ra
0+
3.6319(23)d
• Single ion experiment: 225Ra
Long coherence times and tractable systematics
1/2+
14.9(2) d
p + 232Th  224Ra + AX + an + bp
229Th  225Ra + 
226Ra
0+
1600(7) y
Commercially available
227Ra
3/2+
42.2(5) min
p + 232Th  227Ra + AX + an +bp
So far, limited experimental knowledge of Ra+ (nothing on D‐states)
April 12th, 2010
TCP 2010
APV in Ra+
7P3/2
7P1/2
6D5/2
6D3/2 + ε nP3/2
Ra+
E2
q
q
V
Z0 Weak interaction
E1APV
e
7S1/2 + ε nP1/2
A
e
Measurement of interference term E2 x E1APV
E 1APV  k Q W
Infer weak charge
Measure
Calculate atomic wavefunctions
April 12th, 2010
TCP 2010
APV calculations
E 1APV  k Q W
Infer weak charge
Measure
Calculate atomic wavefunctions
Calculations:
kRa
= 46.4(1.4) ∙ 10‐11 iea0 /N
kCs
= 0.8906(26) ∙ 10‐11 iea0 /N
L.W. Wansbeek et al. (2008) S‐S
Cs
A. Derevianko et al. (2009)
0.9
Key points:
• APV amplitude 50 x larger! (much faster than Z3)
• Need to improve on calculations (need sub‐1%)
April 12th, 2010
S‐D
Ba+
2.2
Fr
14.2
Ra+
46.4
TCP 2010
Talk Outline

Motivation for atomic parity violation (APV) exp’s

The case for radium

Measurement principle; light shifts

First experimental results

Spin‐off project: optical clock
April 12th, 2010
TCP 2010
7P3/2
7P1/2
APV lightshift
6D5/2
6D3/2 + ε nP3/2
E2
•
AC Stark shift
2
2
∆ωAC Stark = |E1 + E2| ≈ |E2| + 2<(E1 E2)
•
7S1/2 + ε nP1/2
Effective magnetic field
Polar vector, and like Beff
APV observable σ . Beff
~ E
~2 + E
~ ×E
~ 2)
~ 1 · ∇)
~ 1 × (∇
2<(E1 E2) ∝ 2(E
•
E1APV
pseudoscalar
Example of fields: Two standing waves

E1  ixˆ cos(kz )

E 2  zˆ sin( kx)
x̂
ẑ
ŷ
E.N. Fortson
April 12th, 2010
|E2|2 purely scalar
TCP 2010
Atomic parity violation in Ra+
Interference of E2/E1APV
7P3/2
7P1/2
6D5/2
6D3/2 + ε nP3/2
E2
E1APV
mf=1/2
B0
|E2|2
E2 . E1APV
7S1/2 + ε nP1/2
mf=‐1/2
Measurement with RF spectroscopy + electron shelving method
~ 10 Hz
x̂
ẑ
ŷ
April 12th, 2010
TCP 2010
Sensitivity of the Ra+ experiment
S1/2‐D3/2 wavelength [nm]
Lifetime D3/2 state [sec]
EAPV [10‐11 iea0]
Quench rate D3/2 due to coupling [Hz]
Ba+
2051
81
2.1
0.08
Ra+
828
0.3
46.4
1.6
S‐S
S‐D
Cs
Ba+
0.9
2.2
Fr
Ra+
14.2
46.4
N. E. Fortson,
Phys. Rev. Lett. 70, (1993)
Statistical sensitivity in one day
0.5 %
0.1 %
Ra+ superior for a competitive APV experiment
5 fold improvement over Cs result is feasible! April 12th, 2010
TCP 2010
Talk Outline

Motivation for atomic parity violation (APV) exp’s

The case for radium 
Measurement principle; light shifts

First experimental results

Spin‐off project: optical clock
April 12th, 2010
TCP 2010
Experimental setup: production
12C target
206Pb beam
206Pb + 12C ARa
+ (218‐A) n
Produced 210‐214Ra
TRIμP separator
Thermal ionizer
To RFQ (Paul trap)
April 12th, 2010
TCP 2010
Experimental setup: trapping & lasers
7P3/2
7P1/2
708 nm
468 nm
1079 nm
6D5/2
6D3/2
7S1/2
Radiofrequency Quadrupole (RFQ)
April 12th, 2010
Simplified level scheme of Ra+
TCP 2010
Measurements, Fall 2009
• Excited‐state laser spectroscopy on trapped short‐lived ions
• 62D3/2 hyperfine structure in 213Ra+
• Isotope shift of – 62D3/2 ‐72P1/2 and
– 62D3/2 ‐72P3/2 transitions in 212, 213, 214Ra+
• Lifetime of the 62D5/2 state
O.O. Versolato et al. arXiv:1003.5580
April 12th, 2010
7P3/2
7P1/2
708 nm
468 nm
1079 nm
6D5/2
6D3/2
7S1/2
TCP 2010
Fluorescence signal at 468 nm [a.u.]
62D3/2 hyperfine structure in 213Ra+
F=1‐F’=0
F=2
F=1
F’=1
F’=0
F=1‐F’=1
F=2‐F’=1
468 nm
F=1
F=0
7P3/2
7P1/2
1079 nm
6D5/2
6D3/2
F=2
F=1
7S1/2
- 277.8000 THz
Experiment1
1054(9) MHz
1.
2.
3.
Theory2
1082 MHz
Theory3
1086 MHz
O.O. Versolato et al. arXiv:1003.5580
R. Pal et al., Phys. Rev. A 79 (2009)
L.W. Wansbeek et al., Phys. Rev. A 78 (2008)
April 12th, 2010
Probe of atomic wave functions at origin
TCP 2010
62D3/2 ‐72P1/2 isotope shift
Fluorescence signal at 468 nm [a.u.]
212Ra+
214Ra+
212Ra+
7P3/2
7P1/2
1079 nm
6D5/2
6D3/2
468 nm
7S1/2
IS
7P3/2
7P1/2
214Ra+
1079 nm ‐ IS
6D5/2
6D3/2
468 nm
- 277.8040 THz
Probe of atomic theory & size and shape of the nucleus
April 12th, 2010
7S1/2
Similar for 212Ra+ – 213Ra+ isotope shift
TCP 2010
62D3/2 ‐72P3/2 isotope shift via
optical shelving
7P
3/2
7P1/2
Fluorescence signal at 468 nm [a.u.]
708 nm
468 nm
6D5/2
6D3/2
1079 nm
7S1/2
- 423.4310 THz
April 12th, 2010
TCP 2010
7P3/2
7P1/2
708 nm
64
212Ra+
468 nm
Confirms long coherence time!
60
6D5/2
6D3/2
1079 nm
7S1/2
56
Fluorescence signal at 468 nm [a.u.]
Lifetime of the 62D5/2 state
0
0.2
0.4
0.6
0.8
Time since beam off [sec]
Experiment1 Lower limit!
Theory2
Theory3
232(4) ms
297(4) ms
303(4) ms
1.
2.
3.
O.O. Versolato et al. arXiv:1003.5580
B. K. Sahoo et al., Phys. Rev. A 76, 040504(R) (2007)
R. Pal et al., Phys. Rev. A 79, 062505 (2009)
April 12th, 2010
Probe of E2 matrix element
TCP 2010
First experimental results, summary
• Excited‐state laser spectroscopy on trapped short‐lived ions
• Measured: – 62D3/2 hyperfine structure in 213Ra+
– Isotope shifts of 62D3/2 ‐72P1/2 and 62D3/2 ‐72P3/2 transitions in 212, 213, 214Ra+
– Lifetime (lower bound) of 62D5/2 state
• Crucial steps towards APV experiments, constraining theory
• Next steps:
– laser cooling of few ions in UHV
– more isotopes
April 12th, 2010
TCP 2010
Outlook
• New beamline connecting new Paul traps in UHV
finished in experimental hall
• Commissioning phase starts next week
• Next step: laser cooling of trapped Ra+
• Towards single ion cooling in UHV and 5‐fold improvement of cesium APV exp’t.
First beamtime starts next week!
E1APV theory is currently accurate to about 3 %, expecting to go to 1 % soon
Khriplovich:
April 12th, 2010
E 1APV7(SN1 / 2) HW 7 P
k1(/ 2N ) Q W ( N )
QW ( N )
E1APV



R
E1' APV
E 1' APV7(SN
) 'W 7k P(1N
Q 'W ( N ' )
1 / 2' H
/ 2 ' )Q ' W ( N ' )
TCP 2010
Talk Outline

Motivation for atomic parity violation (APV) exp’s

The case for radium 
Measurement principle; light shifts

First experimental results

Spin‐off project: optical clock
April 12th, 2010
TCP 2010
+
Ra
optical clock
7P3/2
7P1/2
7S1/2‐6D3/2 E2 transition:
• Narrow (Δν ~ 1 Hz)
• Optical regime (4 x 1014 Hz) 468 nm
High‐quality clock based on off‐the‐
shelf available semiconductor lasers
F’=2
F’=1
7P1/2
F=3
F=0
F=2
F=1
April 12th, 2010
I=3/2
F=1
F=2
828 nm CLOCK
7S1/2
I=0
1079 nm
6D5/2
6D3/2
828 nm CLOCK
7S1/2
• Absence of electric quadrupole shift in 223Ra (I=3/2)
6D3/2
• Long lived (~ 11 days); no need for cyclotron
• Ra+: Sensitive candidate for search of time‐variation of fine‐structure constant a (Flambaum (2000)) ‐‐ (aZ)2
TCP 2010
Ra+ optical clock, performance
O.O. Versolato et al. (in preparation)
Competitive performance, easy lasers
April 12th, 2010
TCP 2010
The crew & acknowledgements 
Experiment
•
•
•
•
•

Theory
•
•
•
•

Joost van den Berg Gouri Giri
Oscar Versolato Lorenz Willmann
Klaus Jungmann
Lotje Wansbeek
Bijaya Sahoo
Lex Dieperink
Rob Timmermans
International collaborators
• B. P. Das (India)
• N. E. Fortson (USA)
April 12th, 2010

Funding
•
•
•
•
FOM open competition
NWO Toptalent grant
NWO Veni fellowship
ITSLEIF
TCP 2010
Systematics
•
Deviation from the ideal beam geometry can induce spin-dependent shifts
that can mimic a PNC shift, but are caused by chirality in the fields rather
than by a parity-violating interaction.
•
Each of these shifts due to imperfections in the beams depends on three
small parameters.
•
Largest of these shifts:
 spur  10 4 sin  sin  sin  Bea0 E1 / h

: spatial phase error from E1 antinode

: misalignment between E1 and E2
B : misalignment between B and E2
•
Dc-electric fields vanish inside trap  no dc Stark mixing
April 12th, 2010
TCP 2010
Experimental requirements
Some requirements for a sub 1% PNC measurement in Ba+:
Sets of three misalignment parameters (polarization, beam directions, spatial phases) have to be <10‐9. Specifically: spatial phase <10‐3  ion has to be stable with respect to standing wave to ~ 5 Å
Polarizations <10‐3
2m laser linewidth ~10 kHz, due to frequency dependence of the lightshift. Laser intensity stability of ~10‐4.
Calibration of E1 field to sub 1% ‐ Use off‐resonant shifts in the D‐state and matrix elements.
Magnetic field stability of ~0.1G. On paper, could be done to 0.1%. April 12th, 2010
TCP 2010
Theoretical status Calculation of E1APV in Ra+ using relativistic coupled‐cluster (CC) theory1:
E1APV = 46.4(1.4) ∙ 10‐11 iea0 (−Qw/N)





1.
2.
3.
Accuracy (3 %) estimated from calculated vs. experimental The Delaware2 group (2009) find 45.9 ∙ 10‐11 iea0 (−Qw/N)
Dzuba et al.3 (2001) find 45.9 ∙ 10‐11 iea0 (−Qw/N) Achieved in Cs: 0.3 %
For a SM test, we need sub‐1 % accuracy!
L.W. Wansbeek et al., Phys. Rev. A 78, 050501(R) (2008).
R. Pal et al., Phys. Rev. A 79, 062505 (2009).
Dzuba et al., Phys Rev. A 63, 062101 (2001).
April 12th, 2010
TCP 2010
Improving the accuracy
Work to be done on the theory side

Improvement of CC theory 
Inclusion of small corrections
•
•

Vacuum polarization + other QED corrections
Nuclear structure effects
Study of different isotopes
Experimental input is needed!

Last and only spectroscopic data is from Ebbe Rasmussen (1934) 
ISOLDE @ CERN (1980s)
•
•
•

Isotope shifts of the 7S1/2 – 7P1/2 line
Hyperfine structure of this line
Lifetimes Isotope shift of the of the 7P1/2 – 6D3/2 line for 212‐214Ra+ measured @ KVI!
With new experimental input: sub‐1% is a realistic goal!
April 12th, 2010
TCP 2010
The Boulder 133Cs experiment
from Gwinner (2009)
April 12th, 2010
TCP 2010
An alternative: a ratio measurement?

The idea is1
Taking the ratio of two measurements of E1APV for two isotopes N and N’
will cancel the atomic uncertainty.
E 1APV ( N )  k ( N )Q W ( N )
E 1APV ( N )
k ( N ) QW ( N )
QW ( N )


E 1' APV ( N ' ) k ( N ' )Q ' W ( N ' ) Q ' W ( N ' )



1.
A value for the ratio is equally informative on the Weinberg angle
Best case scenario:  N  N '  N  10
For radium a wide range of isotopes is available!
V. A. Dzuba, V. V. Flambaum, and I. B. Khriplovich, Z. Phys. D, 1, 243 (1985) April 12th, 2010
TCP 2010
The relevant isotopes of radium
Recently produced
on‐line
Spectroscopy!
{
Available off‐line for EDM experiment
Comercially available
April 12th, 2010
Lifetime
Spin
209
4.6(2) s
5/2
211
13(2) s
1/2
212
13.0(2) s
213
2.74(6) m
214
2.46(3) s
221
28.2 s
5/2
223
11.43(5) d
3/2
224
3.6319(23) d
1/2
 225
 226
14.9(2) d
227
42.2(5) m
3/2
229
4.0(2) m
5/2
ΔN ≈ 10!
1/2
1600 y
TCP 2010
The uncertainty in a ratio measurement


Atomic uncertainty cancels: small nuclear uncertainty remains
Two major contributions
•
•
Neutron skin Nuclear radius
Nuclear radius

Proton radius of radium has never been measured

Ratio between isotopes  sensitive to radial differences

These can be extracted from isotope shifts

Recent measurements at the KVI!

Resulting uncertainty ~ 0.1 %
April 12th, 2010
TCP 2010
Neutron skin
neutrons
Neutron skin 
R(neutron) – R(proton)

Hard to measure

Weak charge mainly sensitive to
neutron distribution
protons
214Ra+
Alex Brown (MSU)
Resulting uncertainty ~ 0.1 %
April 12th, 2010
TCP 2010
Meet the radium ion
April 12th, 2010
TCP 2010
64
7P3/2
7P1/2
708 nm
60
212Ra+
468 nm
56
Fluorescence signal at 468 nm [a.u.]
Lifetime of the 62D5/2 state
0
0.2
0.4
0.6
0.8
6D5/2
6D3/2
1079 nm
7S1/2
Time since beam off [sec]
Experiment1 Lower limit!
Theory2
Theory3
232(4) ms
297(4) ms
303(4) ms
1.
2.
3.
O.O. Versolato et al., in preparation
B. K. Sahoo et al., Phys. Rev. A 76, 040504(R) (2007).
R. Pal et al., Phys. Rev. A 79, 062505 (2009).
April 12th, 2010
Probe of E2 matrix element
TCP 2010
62D3/2 ‐72P3/2 isotope shift via
optical shelving
Fluorescence signal at 468 nm [a.u.]
F=2
F=1
F=1
F=0
7P3/2
7P1/2
708 nm
6D5/2
6D3/2
F=2
F=1
F=1
F=0
F=2‐F’=1
7S1/2
F=1‐F’=1
- 423.4310 THz
April 12th, 2010
TCP 2010
Atomic parity violation in Ra+
Interference of E2/E1APV
Ra+
7P3/2
7P1/2
Interference produces differential light shift of ground state m‐levels:
6D5/2
6D3/2
Repump
λ = 1.08 μm
Cooling &
detection
Off-resonant
laser
E2
λ =468 nm
λ = 828 nm
diff pnc
m=+1/2
APV
E1
0
0
0  diff
7S1/2 (+ εn n P1/2)
m=-1/2
Measurement with RF spectroscopy + electron shelving method
April 12th, 2010
TCP 2010
The scaling of the APV effect

The Bouchiat & Bouchiat (1974) “faster than Z3‐law” says:
nS1/ 2 H W nP1/ 2  K r Z 3
where Kr is a relativistic factor
Z3Kr
Ra+
Courtesy of L.W. Wansbeek
Ba+(Cs)
+
Ca
QW ~ Z
S1/2 ~ Z1/2
P1/2 ~ Z3/2
April 12th, 2010
+
Sr
Z3
Z (atomic number)
TCP 2010