laser driven target at mit
DESCRIPTION
Laser Driven Target at MIT. Chris Crawford, Ben Clasie, Jason Seely, Dipangkar Dutta, Haiyan Gao. Introduction Optical pumping Spincell optimization Components of the LDT Atomic Fraction Results Preliminary Polarization Future Work. Overview. Atomic Beam Source - PowerPoint PPT PresentationTRANSCRIPT
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Laser Driven Target at MIT
Chris Crawford, Ben Clasie, Jason Seely,Dipangkar Dutta, Haiyan Gao
•Introduction
•Optical pumping
•Spincell optimization
•Components of the LDT
•Atomic Fraction Results
•Preliminary Polarization
•Future Work
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Atomic Beam Source
• Well established technology
• Can create pure spin states
• 8 x 1016 atoms/s
• 84% atomic fraction
• 80% polarization
Laser Driven Target
• Compact design
• Active pumping—higher flux
• 2 x 1018 atoms/s
• 60% atomic fraction
• 50% polarization
Overview
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Optical Pumping
At spin temperature equilibrium, the population of each spin state n(mF) is controlled by the Boltzmann equation.
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Spincell Optimization
•Developed a code to simulate recombination and depolarization
•One must minimize the Surface Area / Volume ratio, and the length of the transport tube Dimensions: 2” diameter spherical spincell with 5 cm neck
spincell neck target# wall collisions 640 96 768dwell time (ms) 6.8 0.3 3.1
spin temp time (ms) 0.075
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Target Chamber
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Polarimeter
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Sextupole Magnet
2001/9/20 Laser Driven Target http://ldt.mit.edu
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QMA Detector
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Studies of atomic fraction vs dissociator aperture diameter
50
60
70
80
90
100
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
H2 flow (sccm)
Be
st
ato
mic
fra
cti
on
(%
)
1mm,~100MHz
1mm,~160MHz
1.5mm,~100MHz
1.5mm,~160MHz
2.1mm,~100MHz
2.1mm,~160MHz
new diss,~160 MHz
Diameter and RF Can Frequency
Dissociator Trials
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Atomic Fraction
Atomic fraction at the target cell using the new dissociator.
55
60
65
70
75
80
85
90
95
20 40 60 80 100 120 140 160 180
Temp (C)
Ato
mic
Fra
ctio
n (%
)
Spincell heating up
Potassium heating up, spincell at 180C
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Negative Helicity
0
1
2
3
4
5
6
7
8
9
10
0.2
0.22
0.24
0.26
0.28
0.3
0.32
0.34
Positive Helicity
0
1
2
3
4
5
6
7
8
9
10
0.2
0.22
0.24
0.26
0.28
0.3
0.32
0.34
0.36
0.38
Preliminary Polarization
Laser transmission
Laser transmission
QMA mass 1 signal
QMA mass 1 signal
•polarization: 20% (+ helicity) and 23% (- helicity)
•polarization preserving mirrors only 87% efficient
2001/9/20 Laser Driven Target http://ldt.mit.edu
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Future Work
•Redo polarization tests with correct mirrors.
•Fine-tune operational parameters.
•Investigate the quality of the spincell coating.
•Investigate performance of sextupole filter.
•Run tests with deuterium.
•Redesign target for operation at BLAST.