Experiments towards the Efficient Trapping of Francium
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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
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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. - PowerPoint PPT Presentation
Transcript of Experiments towards the Efficient Trapping of Francium
Experiments towards the Efficient Trapping of Francium
by Seth Aubin
Parity Violation in Francium Group
Students:Eduardo GomezJoshua M. Grossman
Professors:Luis A. OrozcoGene 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
Schematic of New Apparatus
Improved Production
0
2
4
6
8
10
12
14
16
0 500 1000 1500 2000 2500 3000t (s)
Fr
pro
du
cti
on
ra
te (
mill
ion
Fr/
s)
phase transition
beam blocked
16O, 18O, 19F ~100 MeVFr+ ions
Au, Pt target
Improved Fr+ ion extraction New target design
Heated tungsten rod
Optical Trapping Efficiency1. Capture Velocity of MOT
Idea: • Accelerate MOT atoms with laser.
• Measure at what velocity atoms cannot be recaptured by MOT.
b. Velocity Calibration:a. Description
atom cloud
on resonance laser push
0
5
10
15
20
25
0 50 100 150 200 250 300
push time (microseconds)
fin
al v
elo
city
(m
/s
c. Capture Velocity (lower bound):
~18 m/s
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:
780 nm laser probe
Rb atomic beam
shutter
fast detector
Cell with coating (Rb curing)
0.74
0.76
0.78
0.8
0.82
0.84
0.86
0 10 20 30 40 50time (ms)
flu
ore
sc
en
ce
(a
. u.)
Decay Time = 6.6 ms
Monte-Carlo simulations decay time of 5.2 ms (~100 bounces)
Cell without coating
0.0375
0.04
0.0425
0.045
0 3 6 9 12 15 18 21time (ms)
fluo
resc
ence
(a.
u.)
decay time < 1 ms
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.
