APV Anapole Moment in Yb (status) and Some Other Topics in Atomic Parity Violation Dmitry Budker University of California, Berkeley Nuclear Science Division, LBNL PAVI, Roma, Italia September 6, 2011 Konstantin Tsigutkin Dimitri Dounas Frazer Nathan Leefer Damon English

Outline: APV in Yb: previous results Present status 0  1 APV in 0  1 two-photon transitions 0  0 APV in 0  0 two-photon transitions APV in Dy and Xe*

APV: mixing of states of opposite nominal parity A (even parity) B (odd parity) EE Enhancement APV Enhancement: Heavy atoms (high Z) Small  E

4 Atomic Yb: energy levels and transitions PV amplitude:  e·a 0 DeMille (1995) +5d6p |M1|  μ B J.E. Stalnaker, et al, PRA 66(3), (2002) β  2·10 -8 ea 0 /(V/cm) C.J. Bowers et al, PRA 59(5), 3513 (1999); J.E. Stalnaker et al, PRA 73, (2006)

5 Electric and magnetic fields define handedness The Yb PV Experiment

6 Reversals and pseudo-reversals E-field reversal (14 ms: 70-Hz modulation) Lineshape scan ( 200 ms/point x 100 pts/lineshape = 40 s ) B-field reversal (every few minutes) Polarization angle (occasionally) E-field magnitude B-field magnitude Angle magnitude

Yb PV Amplitude: Results Accuracy is affected by HV-amplifier noise, fluctuations of stray fields, and laser drifts → improved for the next phase  =39(4) stat. (5) syst. mV/cm  |  |=(8.7±1.4)× ea 0

Near Future…  Verification of expected isotopic dependence  PV in odd isotopes: NSD APV, Anapole Moment  PV in a string of isotopes; neutron distributions, … Further Ahead (?)  Testing the Standard Model [Brown et al PHYSICAL REVIEW C 79, (2009)] Completed Work Lifetime Measurements General Spectroscopy (hyperfine shifts, isotope shifts) dc Stark Shift Measurements Stark-Induced Amplitude (β): 2 independent measurements M1 Measurement (Stark-M1 interference) ac Stark Shift Measurements Verification of APV enhancement Progress in Yb APV

9 Dr. K. Tsigutkin D. Dounas-Frazer

Next Generation Apparatus

Interaction Region Spurious asymmetry scaling: New electrode design  Better than 1% uniformity in interaction region  Apply ac/dc electric fields in y- and z-directions New magnetic field coil design  Better than 0.1% uniformity in interaction region  Hanging coils eliminate thermal contact  Apply magnetic field in x-direction  Small additional coils wrapped around electrodes

Optical System Light source  Old system: Frequency-doubled Ti:Sapph pumped by Ar +  New system: 408-nm diode laser  More power & easier to tune Frequency reference  Old system: 816-nm FP with ~200 kHz excursions  New system: 408-nm FP with freq. comb for long-term stability  Goal: Excursions < 100 kHz

The Ba 2γ experiment: Damon English

The degenerate two-photon transition selection rule Destructive interference of two quantum paths S. N. Bose

DeMille

Sheldon Lee Glashow 1979 Nobel Prize "For... contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current."

The Berkeley Experiment Animated version: YouTube: Test of Bose-Einstein statistics for photons

Results

Splitting effect Mixing Effect Phys. Rev. APhys. Rev. A 80(4), (2009)

Anapole-induced 0 → 1 → 1 transitions Modified Stark-interference technique Exploits 2-photon selection rules  J = 0 → J = 1 forbidden to all multipole orders  Suppresses SI PV-induced E1E1 transitions  Suppresses PC transitions: E1M1, E1E2, etc. Direct measurement of SD PV effects

Rotational invariant:  Geometrically equivalent to single-photon 1 S 0 → 3 D 1 Yb experiment Asymmetry:  Odd under reversal of E or 90 o polarization rotation  Vanishes for transitions to final state with F < 3/2 Spurious asymmetry scaling:  Fewer sources of spurious asymmetry compared to 1-photon case  Additional magnetic sublevels = additional “handles”  Well-established method for elimination using additional reversals

Electric field modulation Lock-in detection can discriminate PV interference from PC signal

Sensitivity estimate: “model” atomic system Assumptions: Electric dipole matrix elements ~ ea 0 SD PV matrix element ~  ∙  10 2 Hz) Energy splittings ~ 10 2 cm -1 Transition width ~ 10 6 Hz Electric field ~ 1 kV/cm Laser light power ~ 1 kW Laser beam radius ~ mm Atomic beam width ~ 1 cm Atomic beam density ~ cm -3 Comparable to the 1 S 0 → 3 D 1 Yb experiment

Potential application to 137 Ba (I = 3/2) There should be noticeable mixing of 5d6d configuration with configuration npn ' p Configuration mixings and matrix elements needed for better estimate of SNR

Two-photon transitions we found do not offer spectacular improvement in SNR May provide better systematics control May provide access to many anapoles (see Sidney Cahn’s talk)

Parity violating 0 → 1 → 0 transitions Replaces static E & B fields with optical fields  Easier to align Interference of allowed E1M1 and PV-induced E1E1 transitions Equivalent to optical rotation on an M1 transition  More field reversals than optical rotation schemes  Better control over systematics Sensitive to neutron distributions  Isotope chain Dounas-Frazer et al., PRA 84, (2011)

Rotational invariant:  Nonzero when laser beams are collinear & polarizations are circular  Ladder-type: Polarizations need have opposite sense  Lambda-type: Polarizations need have same sense Asymmetry:  Odd under reversal of handedness or propagation vector k 2 Spurious asymmetry scaling:  E is stray electric field  Angle minimized by aligning beams over large distances

Application to Yb

Sensitivity estimate: 1 S 0 → 3 P 0 transition in Yb Experimental parameters: 399 nm light power ~ 10 mW 1280 nm light power ~ 10 W Laser beam radius ~ 2 mm Atomic beam width ~ 2 cm Atomic beam density ~ 10 9 cm -3 Asymmetry is much larger than for Bi, Pb, Tl. Statistical sensitivity similar to 1 S 0 → 3 D 1 Yb experiment

31 Full circle: Parity Nonconservation in Dy

Theory (1994): H w = 70 ± 40 Hz V. A. Dzuba et al. Phys. Rev. A 50, 3812 (1994) Experiment (1997): |H w | = | 2.3 ± 2.9 (statistical) ± 0.7 (systematic) | A. T. Nguyen et. al. Phys. Rev. A 56, 3453 (1997) Improved theory (2010): H w ≈ 2 Hz V. Dzuba and V. Flambaum ( 32 Parity Nonconservation in Dy

New apparatus... Succeeded in laser cooling of atomic beam Optimized for the  -dot experiment Measure frequency to ~1 mHz

2 nd Generation Apparatus Differentially pumped chambers 1.Oven chamber 2.Gate valve 3.Interaction chamber 2 3 AC D F E G 1 B A. Dy effusive oven B. Collimator C. Laser access port D. Two-layer magnetic shield E. 4  Optical collection system F. PMT viewport G. RF electrodes

Zeeman Crossing Spectroscopy §rf spectroscopy: 0.6 Hz sensitivity in 3 minutes l 100 mHz in 1 hour §m F =10.5 sublevels brought to degeneracy with 1.4 G magnetic field §Apply ac E-Field and look for quantum beats 35

Expected Signal (simulation) 36 m F = 10.5m F = Signature of P-odd, T-even rotational invariant: Ė  (B – B c ) New data coming soon! 

T. Peter Rakitzis IESL-FORTH and Dept. of Physics, University of Crete, Greece 5p 5 ( 2 P 3/2 )6f (J=2) 5p 5 ( 2 P 3/2 )10s (J=2)  E ≈ cm -1 (similar to Dy) Preliminary calculations (Prof. Jonathan Sapirstein) estimate 10p character of 6f state >0.01 Spectroscopic studies underway (Rakitzis group) to help evaluate the sensitivity of the 6f-10s states for PNC, EDM, and  -variation experiments Nearly degenerate Xenon 10s-6f states E= cm -1

Conclusions: The Berkeley Yb-APV experiment is making progress towards anapole 0  1 NSD-APV in 0  1 two-  transitions in Yb and other atoms (Ba, Sm,…) 0  0 NSI-APV in 0  0 two-  transitions APV in Dy and Xe*