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.