1 / 28

Atomic parity violation in ytterbium

Atomic parity violation in ytterbium. Dmitry Budker University of California, Berkeley Nuclear Science Division, LBNL. PREX Workshop JLAB, August 16-18, 2008. http://socrates.berkeley.edu/~budker/. Outline. Motivation The Yb system Measurement principle Apparatus

bevis
Télécharger la présentation

Atomic parity violation in ytterbium

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Atomic parity violation in ytterbium Dmitry Budker University of California, Berkeley Nuclear Science Division, LBNL PREX Workshop JLAB, August 16-18, 2008 http://socrates.berkeley.edu/~budker/

  2. Outline • Motivation • The Yb system • Measurement principle • Apparatus • Preliminary parity-violation results • Experimental issues • Outlook (Yb and Dy)

  3. Motivation • Verification of large predicted atomic PV effect (x100 Cs; DeMille, Kozlov et al, Das et al) • Isotopic ratios and neutron distributions (6 stable isotopes; N=8) • Nuclear spin-dependent PV – anapole moments (valence neutrons)

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

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

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

  7. Atomic Yb: energy levels and transitions +5d6p PNC amplitude: 10-9e·a0 DeMille (1995) |M1|10-4 μB J.E. Stalnaker, et al, PRA 66(3), 31403 (2002) β2·10-8ea0/(V/cm) C.J. Bowers et al, PRA 59(5), 3513 (1999); J.E. Stalnaker et al, PRA 73, 043416 (2006)

  8. Stark-PV-interference Geometries and invariants:

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

  10. PV effect on line shapes:odd isotopes xNSD~10-11 ea0 for odd Yb isotopes x=10-9 ea0 x` must be measured with 0.1% accuracy

  11. The Yb PNC Experiment Electric and magnetic fields define handedness

  12. 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

  13. Typical signal • 174Yb 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. Atoms in electric field: the Stark effectorLoSurdo phenomenon Johannes Stark (1874-1957) Nazi Fascist

  15. Reversals andpseudo-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→

  16. Reversals andpseudo-reversals

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

  18. 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)

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

  20. Power-buildup cavity design and characterization: mirrors * 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

  21. The 70-Hz E-modulation schemeto avoid low-frequency noise and drift issues 20-s integration Due to bias ex  25 V/cm Different pattern and polarization dependence for PV

  22. Present status: PV results • About 14 hours of data collection • Limited by shot noise and stray fields → to be improved • Systematics checks in progress

  23. Present status: systematics Average stray ex-field: 150 mV/cm

  24. Progress towards measuring PV in Yb 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 shifts measured Almost there • Verification of PV enhancement And then… • PV in odd isotopes: NSD PV, Anapole Moments • PV in a string of isotopes; neutron distributions, …

  25. Yb: the team K. Tsigutkin A. Family D. Dounas-Frazer post-doc undergrad new grad.student J. E. Stalnaker grad. student → prof. @ Oberlin

  26. The parity violation experiment in Dy evolved into…

  27. a/a = (-2.9 ± 2.6mostly syst) x 10-15 yr-1 Phys. Rev. Lett. 98, 040801 (2007)

  28. PV with mHz sensitivity Status: setting up

More Related