Parity nonconservationParity nonconservationin the 6sin the 6s22 11SS00 – 6s5d – 6s5d 33DD11 transition transition

in Atomic Ytterbium:in Atomic Ytterbium:

status of the Berkeley experimentsstatus of the Berkeley experiments

K. Tsigutkin, J. Stalnaker, V. K. Tsigutkin, J. Stalnaker, V. Yashchuk, D. BudkerD. Budker

Department of Physics,University of Department of Physics,University of California, BerkeleyCalifornia, Berkeley

Weak interaction in AtomsWeak interaction in Atoms)(I

I22HHH 55

NSDNSI rQG WF

)θsin41( 2WW ZNQ

133133Cs Cs *,***,** 205205Tl Tl ******

QQWW --72.11(2772.11(27))

--114.2(3.114.2(3.8)8)

sinsin22WW 0.2261(10.2261(12)2)

0.220(7)0.220(7)

)2/1()1(K

;1

K

2/1

2

I

IlI

QA w

Nuclear spin independent contribution

Nuclear spin dependent termA-Anapole momentA-Neutral currentsQW-Radiative corrections

22

3/23

1

K2/1

;;1015.1

CI

ZNAgAA

-Magnetic moment in terms of nuclear magnetong-Weak coupling constant of the unpaired nucleonC2- Coupling constants for the valence nucleon

Unpaired neutron: n=-1.2; gn=-1Unpaired proton: p=3.8; gp=5

25.1);θsin1(2/ 222 Wnp CC

Unpaired Unpaired protonproton

133133Cs Cs I=7/2I=7/2

205205Tl Tl I=1/2I=1/2

AA100100 36.4(6.2)36.4(6.2) -22(30)-22(30)

2 2 100100 -5-5 -5-5

Anapole moment is much bigger for nuclei with

unpaired proton

Unpaired Unpaired neutronneutron

AA100100 2 2 100100

173173Yb Yb I=5/2I=5/2

-4.5-4.5 3.63.6*C.Wood et al, Science 1997. (Univ. of Colorado, Boulder) ** J. Guéna, M. Lintz, and M. A. Bouchiat PRA 2005 *** P. Vetter et al, PRL 1995. (Univ. of Washington, Seattle)

Khriplovich & Flambaum

Signature of the weak Signature of the weak interaction in atomsinteraction in atoms

HPNC mixes |ns1/2> and |n`p1/2> states of valence electron APNC of dipole-forbidden transition.If APC is also induced, the amplitudes interfere.

)(2 222

PNCPNCPCPCPNCPC AoAAAAAR

Interference

E-field

Stark-effect

E1 PC-amplitude E

E1-PNC interference term is odd in E

Reversing E-field change the transition rate.

Transition rate APNCAStark

PCAAPCA’PC interference

MUST:Determine APC with high precisionLimit A’PC

Atomic structure of YbAtomic structure of Yb

By observing the 6s2 1S0 – 6s6p 3P1 556 nm decay the pumping rate of the 6s2 1S0 – 6s5d 33DD11 408 nm transition is determined.

In addition, the population of 6s6p 3P0 metastable level is probed by pumping the 6s6p 3P0 - 6s7s 3S1 649 nm transition.

Yb isotopes and abundancesYb isotopes and abundances

C.J. Bowers et al, PRA 1999

Rotational invariant and Rotational invariant and geometry of the Yb geometry of the Yb

experimentexperiment BEεBε

mmq ;ε)1(A

,,1,,εE)1(A

q-qq

PNC

q-qq

Stark

i

mjmmmji

= 2.24(25)10-8 e a0/(V/cm) – Stark transition polarizability (Measured by J.Stalnaker at al, PRA 2006)

|| = 1.08(24)10-9 (QW/104) e a0/(V/cm) – Nuclear spin-independent PNC amplitude (Calculations by Porsev et al, JETP Lett 1995; B. Das, PRA 1997 )

Rotational invariant to which the PNC-Stark interference term is proportional is chosen so that E is along the excitation light axis. This suppresses the interference between M1 and Stark amplitudes emphasizing the PNC-Stark contribution.

Reversals:B – evenE – odd – odd – even

PNC effect on line shapes:PNC effect on line shapes:even isotopeseven isotopes

θcosθsinβδEθcos2

ER

θcosθsinβδ2EθsinER

θ)cos,sinθ(0,ε

(E,0,0)E

222

1

2220

PNC-Stark PNC-Stark interference interference termsterms

176Yb

ERR

RR

EE

EE

2

Rate modulation under the E-field reversal yields:

PNC effect on line shapes:PNC effect on line shapes:odd isotopesodd isotopes

θcosθsinδβE3

22

3

EβR

θcosθsinδβE3

22

3

EβR

θ)cos,sinθ(0,ε

(E,0,0)E

FF

22FF

FF

22FF

PNC-Stark PNC-Stark interference interference termsterms

171Yb

NSDJI

NSD10-12 ea0

for odd Yb isotopes

=10-9 ea0

` must be measured with 0.1% accuracy

Experimental setupExperimental setup

Yb density in the beam ~1010 cm-3

Reversible E-field up to 15 kV/cm, spatial homogeneity 99%Reversible B-field up to 100 G, homogeneity 99%

Light collection efficiency:

Interaction region: ~2% (556 nm)

Detection region: ~25%

Optical system and control Optical system and control electronicselectronics

Light powers:Ar+: 15WTi:Sapp (816 nm): 1WDoubler (408 nm): 50 mWPBC:Confocal design, 25 cm;Finesse ~4000

Locking:Pound-Drever-Hall technique

Doppler width and spectral Doppler width and spectral resolutionresolution

-60 -40 -20 0 20 400.00

0.02

0.04

0.06

0.08

0.10

0.12

173Yb (5/2-3/2)17 MHz

Inte

nsi

ty [

V]

Frequency shift [MHz]

55 MHz

176Yb

Application of the atomic beam collimator allows to reduce the Doppler broadening by a factor of 10 .

Spectral lines of closely neighboring isotopes can be clearly resolved.

Scanning over 408 nm line, observing 556 nm fluorescence at the interaction region. Observations of the 649 nm line will contribute to a factor of 10 increase in the sensitivity.

Line shapes under the B-Line shapes under the B-fieldfield

-60 -40 -20 0 20 40 600.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

173Yb (5/2-3/2)

176Yb

Inte

nsi

ty [

V]

Frequency shift [MHz]

14 MHz B=20 GUnder application of B-field line profiles demonstrate predicted shapes

Signal averaged over 100 scans

Scan rate = 1 Hz

Ready to collect data with E-field modulation

Systematic effectsSystematic effects

),,( zy dEdEEE

),,( 0BdBdBB yx

)sincos),cos(sin,0( θdθθdθeidC

kd

E-field inhomogeneityB-field inhomogeneity Distortion of

linear polarization of the light

Residual light propagation in the PBC

q-q

q-q-qq ε)1(ε1εE)1(A

ikdMi

M1~300

z

yx

dEdC

dEB

dB Required:

Non-reversing dBx, dEz << 1%

Terms having same dependence on the leading E-field reversal and same polarization angle dependence as the Stark-PNC interference term must be limited

SummarySummary

• The program of measurements needed to understand the system is complete.

• It is now possible to proceed with confidence towards a first measurement of PNC in Yb

• The challenge will then be to refine the system to achieve the fractional precision needed to observe NSD effects.