Precision Spectroscopy

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Precision Spectroscopy of the 9s and 8p levels of
Francium.
by Seth Aubin
Graduate Students Eduardo Gomez Kerim
Gulyuz Jerry Sell Professors Luis A.
Orozco Gene D. Sprouse Work supported by NSF
University of Toronto
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Precision Spectroscopy in Francium
Objective Spectroscopy probes electronic
wavefunctions Lifetime ? wavefunctions far
from nucleus Hyperfine splitting ?
wavefunction near nucleus

• Importance
• Francium is the heaviest alkali (Z87).
• Test of wavefunctions in relativistic regime.
• Parity non-conservation experiments.

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A Brief History of Francium at Stony Brook
1991-94 Construction of 1st production and
trapping apparatus. 1995 Produced and Trapped
Francium in a MOT. 1996-2000 Laser spectroscopy
of Francium (8S1/2, 7P1/2,7D5/2,7D3/2, hyperfine
anomaly). 2000-2002 high efficiency trap. 2003
Spectroscopy of the 9S1/2, 8P1/2, and 8P3/2
levels.
3,000 atom Fr MOT
140,000 atom Fr MOT
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Excitation of the 9s level of 210Fr
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E1 decay channels of the 9s and 8p levels
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Lifetime Measurement

• Method Time-Correlated Single Photon Counting
• Excite atom.
• Fast turn off of excitation.
• Detect photon from spontaneous emission and
  measure its arrival time.
• The histogram of arrival times follows the
  exponential decay of the excited state.

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Optical Excitation Setup
10,000 210Fr atoms
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Timing
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Lifetime Measurements Time-correlated
Single-photon Counting
10,000 210Fr atoms
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9s lifetime data and fit
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Results for 9S1/2 Lifetime
Error Statistical 0.72 TAC/MCA
performance lt 0.04 Displacement error
from Rb lt 0.38 Quantum beats
lt 0.20 Total 0.84
Opt. Lett. 28, 2055 (2003)
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Comparison with Theory
d W. A. van Wijngaarden et al. e E. Biémont
et al. f C. E. Theodosiou et al.
a M. S. Safronova et al. b V. A. Dzuba et al.
c M. Marinescu et al.
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8p lifetimes
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8P3/2 lifetime data
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Results for 8P3/2 Lifetime
Error Statistical 1.05 Bayesian
(9S1/2) 1.44 TAC/MCA performance
lt 0.30 Contamination shift error
0.03 Total 1.8
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Bayesian Error error on ?2 due to error on ?1
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Comparison with Theory
c W. A. van Wijngaarden et al. d E. Biémont
et al. e C. E. Theodosiou et al.
a M. S. Safronova et al. b V. A. Dzuba et al.
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8P1/2 lifetime data
untilted 436 nm filter
tilted 436 nm filter
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Results for 8P1/2 Lifetime
Error Statistical
2.3 Bayesian 0.4 TAC/MCA performance
lt 0.2 Total 2.3
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Comparison with Theory
c W. A. van Wijngaarden et al. d E. Biémont
et al. e C. E. Theodosiou et al.
a M. S. Safronova et al. b V. A. Dzuba et al.
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Hyperfine Splitting (HFS)

• Scan probe laser across F11/2 and F13/2
  hyperfine levels of the 9S1/2 level.
• Record fluorescence vs. frequency

Method
With wavemeter HFS 4045.2 ? 1.5 MHz
(statistical)
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Cavity as frequency ruler
With wavemeter HFS 4044.7 ? 3.2 MHz
(statistical)
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Confirmation of Quantum Defect Theory
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SUMMARY

• Measurements of the 9S1/2 lifetime and HFS.
• Measurements of the 8P3/2 and 8P1/2 lifetimes.
• Theoretical predictions agree with lifetime
  measurements.
• Future use HFS to extract nuclear g-factor for
  210Fr.