Atomic parity violation in ytterbium

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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/
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Outline

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

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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 ?N8)
• Nuclear spin-dependent PV anapole moments
  (valence neutrons)

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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 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

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Isotopic ratios and neutron distributions new
development (ArXiv)

• Neutron-skin effects in different isotopes are
  correlated

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Anapole Moments
Ya
. B. Zeldovich, V. G.
Vaks

1959
AM first introduced
V.V. Flambaum, I.B. Khriplovich

1980
-
84
O.P. Sushkov
Nuclear AM detectable in atoms

1995
E.N.Fortson and co-workers
Tl AM small

1997
C. E. Wieman and co-workers
Cs AM detected !
PNC within nucleus ! ?probe of weak meson
couplings
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Atomic Yb energy levels and transitions
5d6p
PNC amplitude ?10-9ea0 DeMille (1995)
M1?10-4 µB J.E. Stalnaker, et al, PRA 66(3),
31403 (2002)
ß?210-8 ea0/(V/cm) C.J. Bowers et al, PRA 59(5),
3513 (1999) J.E. Stalnaker et al, PRA 73, 043416
(2006)
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Stark-PV-interference Geometries and
invariants
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PV effect on line shapeseven isotopes
PV-Stark interference terms
168,170,174,176Yb
or ?
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PV effect on line shapesodd isotopes
xNSD10-11 ea0 for odd Yb isotopes x10-9 ea0 x
must be measured with 0.1 accuracy
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The Yb PNC Experiment
Electric and magnetic fields define handedness
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Optical system and control electronics
Light powers Ar 15W TiSapp (816 nm) 1
W Doubler (408 nm) 50 mW
PBC Confocal design, 25 cm Finesse 10,000
(upgrading to 40000 ??) Locking Pound-Drever-Hal
l technique
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Typical signal

• 174Yb resonance split by B?70 G E3 kV/cm
• Expected PV asymmetry 210-4/ E/(kV/cm)
• Asymmetric lineshape ? AC Stark effect

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Atoms in electric field the Stark effector
LoSurdo phenomenon
Johannes Stark (1874-1957) Nazi Fascist
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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 ???/4?
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Reversals and pseudo-reversals
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Statistical Sensitivity

• With parameters presently achieved, the shot
  noise limit is
• 10 hrs should correspond to a 0.5 measurement

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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)

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Power-buildup cavity design and characterization
C. J. Hood, H. J. Kimble, J. Ye. PRA 64, 2001
Ringdown spectroscopy
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Power-buildup cavity design and
characterization mirrors
Substrates were provided by Rainbow Research
Optics, Inc, Denver, CO
Finesse of 29000 seen with REO mirrors Photodegrad
ation is still a problem Locking electronics
needs work
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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
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Present status PV results

• About 14 hours of data collection
• Limited by shot noise and stray fields ? to be
  improved
• Systematics checks in progress

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Present status systematics
Average stray ex-field 150 mV/cm
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Progress towards measuring PV in Yb

• Completed Work
• Lifetime Measurements
• General Spectroscopy (hyperfine shifts,
  isotope shifts)
• dc Stark Shift Measurements
• Stark-Induced Amplitude (ß) 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,

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Yb the team
K. Tsigutkin A. Family
D. Dounas-Frazer post-doc
undergrad new grad.student
J. E. Stalnaker grad. student ? prof. _at_ Oberlin
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The parity violation experiment in Dy
evolved into
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Phys. Rev. Lett. 98, 040801 (2007)
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? PV with mHz sensitivity Status setting up