1. Atomic Parity-Violation Experiments at Berkeley Dmitry Budker University of California, Berkeley Nuclear Science Division, LBNL http://socrates.berkeley.edu/~budker/ University of Texas, Austin November 2008

2. Outline APV experiments: outlook New results on Cs APV (A. Derevianko et al) APV in Yb APV in Dy

3. Atomic PV: important landmarks 1959 Ya. B. Zel’dovich: PNC (Neutr. Current)  Opt. Rotation in atoms 1974 M.-A. & C. Bouchiat heavy Z 3 enhancement  PV observable in heavy atoms 1978-9 Novosibirsk, Berkeley discovery of PV in OR(Bi) and Stark-interf.(Tl) …1995 Boulder, Oxford, Seattle, Paris Cs PV measured to 1-2% in Cs, Tl, Bi, Pb 1997 Boulder anapole moment 0.35% measurement, discovery of anapole moment Prof. Yakov B. Zel’dovich

4. New result on Cs APV Andrei Derevianko et al In agreement with SM (c.f. from HEP alone) 1000-fold increase of calculation complexity Two-fold improvement in theoretical error Result no longer theory limited

5. 5 1959 Ya. B. Zel’dovich, V. G.Vaks AM first introduced 1980-84 V.V. Flambaum, I.B. Khriplovich & O.P. Sushkov Nuclear AM detectable in atoms Anapole Moments PNC within nucleus !  probe of weak meson couplings 1997 C. E. Wieman and co-workers Cs AM detected ! 1995 E.N.Fortson and co-workers Tl AM – small…

6. 6 Some Ongoing Experimental Efforts: Fr (US, Canada, Europe) Trapped ions (Gröningen, …) Anapole in diatomic molecules (Yale) Yb and Dy (Berkeley)

7. 7 Parity Violation in Yb: motivation Atomic Physics: §Verification of large predicted atomic PV effect (x100 Cs; DeMille, Kozlov et al, Das et al) Nuclear Physics: §Nuclear spin-dependent PV – anapole moments (valence neutrons) §Isotopic ratios and neutron distributions (6 stable isotopes;  N=8)

8. 8 Isotopic ratios and neutron distributions Atomic PV calculation errors cancel in isotopic ratios Dzuba, Flambaum, and Khriplovich, Z. Phys. D 1, 243 (1986) But enhanced sensitivity to the neutron distribution  n (r) Fortson, Pang, Wilets, PRL 65, 2857 (1990) Atomic PV  Neutron distributions For 170 Yb- 176 Yb, Q W  -100;  Q W (Standard Model)  6  Q W (Neutron Skin)  3

9. 9 Isotopic ratios and neutron distributions: new development (ArXiv) Neutron-skin effects in different isotopes are correlated

10. 10 Atomic Yb: energy levels and transitions PV amplitude:  10 -9 e·a 0 DeMille (1995) +5d6p |M1|  10 -4 μ B J.E. Stalnaker, et al, PRA 66(3), 31403 (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, 043416 (2006)

11. Stark-PV-interference technique (invented by the Bouchiats in 1970s)

12. 12 Electric and magnetic fields define handedness The Yb PV Experiment

13. 13 Typical Stark-induced signal 174 Yb resonance split by B  70 G; E=3 kV/cm Expected PV asymmetry: ~ 2·10 -4 / E/(kV/cm) Asymmetric lineshape ← AC Stark effect

14. 14 Atoms in electric field: the Stark effect or LoSurdo phenomenon Johannes Stark (1874-1957) Nazi Fascist

15. m = -1 m = +1 m = 0 R0R0 R -1 R +1 1S01S0 3D13D1 Transition rates interference Compute ratio for 1st and 2nd harm. signal Ratio difference yields PV asymmetry: PV effects on rates E-field modulation

16. Fast (70 Hz) E-modulation scheme to avoid low-frequency noise and drift issues 20-s integration Different pattern and polarization dependence for PV Due to DC bias e x  43 V/cm

17. 17 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 For θ=  /4→

18. PV Result

19. About 40 hours of data collection Excess noise → to be improved Systematics checks in progress

20. 20 Reporting here  Verification of PV enhancement Near Future…  PV in odd isotopes: NSD PV, Anapole Moments  PV in a string of isotopes; neutron distributions, … 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 Progress towards measuring PV in Yb

21. 21 K. Tsigutkin A. Family D. Dounas-Frazer post-doc undergradgrad.student V. V. Yashchuk S. J. Freedman J. E. Stalnaker + C.J. Bowers, G. Gwinner, D. DeMille, E. D. Commins, J. Guzman, G. Wasik, …

22. 22 parity violation experiment The parity violation experiment in Dy evolved into…

23. 23 Phys. Rev. Lett. 98, 040801 (2007)  (-2.9 ± 2.6 mostly syst ) x 10 -15 yr -1

24. 24  PV with mHz sensitivity Status: setting up

25. Dy Laser Cooling Strong cycling transition at 421 nm but…

26. Dy Laser Cooling Strong cycling transition at 421 nm but… Many possible trap states exist

27. Dy Laser Cooling Strong cycling transition at 421 nm but… Many possible trap states exist Branching ratios are not known, but expected ~10 -4

28. Cavity-Assisted Doubling

29. Pump-Probe Experiment Probe transition at 658.1 nm 421-nm light is locked; probe is scanned

30. Pushing Dy beam with 421-nm light! Crude cooling (T trans = 3.3 K → 1 K) Next: optimize beam cooling  use in the  -dot expt Study traps; repumping? Dy MOT? Dy BEC?

32. Supplementary Slides 32

33. 33 PV effect on line shapes: even isotopes PV-Stark interference terms 168,170,174,176 Yb or θ

34. 34 PV effect on line shapes: odd isotopes  NSD ~10 -11 ea 0 for odd Yb isotopes  =10 -9 ea 0  ` must be measured with 0.1% accuracy

35. 35 Optical system and control electronics Light powers: Ar + : 15W Ti:Sapp (816 nm): 1 W Doubler (408 nm): 50 mW PBC: Confocal design, 25 cm; Finesse ~10,000 (upgrading to 40000 ??) Locking: Pound-Drever-Hall technique

36. 36 Reversals and pseudo-reversals

37. Assume stray electric and magnetic fields (non-reversing dc) and small ellipticity of laser light: PNC asymmetry and systematics give four unknowns: Reversals of B-field and polarization yield four equations  Solve for PNC asymmetry, stray fields Analysis of systematics

38. Asymmetry Scaling on DC Bias

39. Stray Fields b x /B z ~ 10 -2 e y,z ~ 1V/cm

40. 40 Statistical Sensitivity With parameters presently achieved, the shot noise limit is: 10 hrs should correspond to a 0.5% measurement…

41. 41 But there are some problems: Photo-induced PBC mirror deterioration in vacuum Slow drifts Technical noise (above shot-noise) Stray electric fields (~ up to a few V/cm)

42. 42 C. J. Hood, H. J. Kimble, J. Ye. PRA 64, 2001 Power-buildup cavity design and characterization Ringdown spectroscopy

43. 43 Power-buildup cavity design and characterization: mirrors REO set1 =408 nm REO set2 =408 nm ATF =408 nm Boulder expt =540 nm Transmission320 ppm45; 23 ppm130 ppm40; 13 S+A losses120 ppm213; 83 ppm800 ppm*<1 ppm * Substrates were provided by Rainbow Research Optics, Inc, Denver, CO Finesse of 29000 seen with REO mirrors Photodegradation is still a problem Locking electronics needs work