Experiments towards the Efficient Trapping of Francium

1
Experiments towards the Efficient Trapping of
Francium
by Seth Aubin
Parity Violation in Francium Group Students Edua
rdo Gomez Joshua M. Grossman Professors Luis A.
Orozco Gene D. Sprouse
2
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 construction of new
production and trapping apparatus.
10,000 atom Fr MOT
3
New Apparatus for Producing and Trapping Francium

• Objective Trap 106 Fr atoms
• Parity Non-Conservation experiments
• Nuclear Anapole measurements

• Strategy
• Increase Production
• Optimize Optical Trapping efficiency
• Improve Neutralizer efficiency

4
Schematic of New Apparatus
5
Improved Production

• Improved Fr ion extraction

• New target design

16O, 18O, 19F 100 MeV
Fr ions
Au, Pt target
Heated tungsten rod
6
(No Transcript)
7
Optical Trapping Efficiency 1. Capture Velocity
of MOT Idea Accelerate MOT atoms with
laser. Measure at what velocity atoms cannot
be recaptured by MOT.
a. Description
b. Velocity Calibration
atom cloud
on resonance laser push
8
c. Capture Velocity (lower bound)
18 m/s
9
MOT
1 mm
10
Displaced MOT (External B-field)
Laser push
1 mm
11
(No Transcript)
12

• 2. Number of Bounces (Nbounces)
• Atoms rethermalize with cell walls on each
  bounce.
• NMOT?Nbounces.
• Nbounces is determined by exit holes, quality of
  dry-film coating.
• Dry-Film (SC-77) test

fast detector
780 nm laser probe
shutter
Rb atomic beam
13
Monte-Carlo simulations ? decay time of 5.2 ms
(100 bounces)
14
Comparison of Neutralizer Materials (at 5 KeV)
300 Celsius
15
Conclusion

• New apparatus for trapping 106 Fr atoms.
• Increased Fr production by a factor of 15.
• Studied neutralization process.
• Probes of capture velocity and coating quality.
• Capture velocity of at least 18 m/s.

Just converted apparatus to Francium.