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Experiments towards the Efficient Trapping of Francium. by Seth Aubin. Parity Violation in Francium Group Students: Eduardo Gomez Joshua M. Grossman Professors: Luis A. Orozco Gene D. Sprouse. A Brief History of Francium at Stony Brook.
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Experiments towards the Efficient Trapping of Francium by Seth Aubin Parity Violation in Francium Group Students: Eduardo Gomez Joshua M. Grossman Professors: Luis A. Orozco Gene D. Sprouse
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
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
Improved Production • New target design • Improved Fr+ ion extraction 16O, 18O, 19F ~100 MeV Fr+ ions Au, Pt target Heated tungsten rod
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
MOT 1 mm
Displaced MOT (External B-field) Laser push 1 mm
2. Number of Bounces (Nbounces) • Atoms rethermalize with cell walls on each bounce. • NMOTNbounces. • 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
Monte-Carlo simulationsdecay time of 5.2 ms (~100 bounces)
Comparison of Neutralizer Materials (at 5 KeV) ~ 300 Celsius
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.