Imaging of an ion cloud in a Paul trap

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Imaging of an ion cloud in a Paul trap Mustapha
HERBANE
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Introduction
Motivation Precise measurement of the ?-?
angular correlation parameter during the ?-decay
of 6He. 6He?6Li?-?
W(Ee,?e?)dEed?e?W0(1a PeP?/EeE?)dEed?e?
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? detection



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Extraction Cloud imaging
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Injection
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6Li detection

• Cloud imaging measurement of
• Velocity distribution.
• Spatial distribution.

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Experimental setup

• 3 voltages V1, V3, V4
• Initial velocity Insensitivity to position.
• (Vx,Vy,Vz) ? (tof,y,z)
• Initial position Insensitivity to velocity.
• (X,Y,Z) ? (tof,y,z)

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Velocity distribution measurement



Systematic research of the best combination
of V1, V3,V4 and the position of the detector to
have the smallest incertainty on the velocity.
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• Initial positions Distributions with widths
  according to simulated trapped ions.
  ?x 0.6 mm, ?y 1.1 mm ,
  ?z 1.1 mm
• Initial velocities Grid (5?5?5).

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Transformation (Vx,Vy,Vz)f(tof,y,z)

• Approximation Linear.

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• Example Ejection of the trapped ion cloud as
  given by Simulation

• ?Vx ? 230m/s, ?Vy ?Vz ? 140m/s ? E ? 0.03eV

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Spatial distribution measurement
High voltage on electrode 1. SIMULATION Ions
with gaussian velocity distributions.
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• ?x ? ?y ? 100 ?m

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Conclusion

• Simulations demonstrate the feasibility of such
  imaging.
• Advantage suitable to all kind of ions.
• First experiments with 6Li trapped ions in the
  few next weeks (Electronic devices for pulses
  generation almost ready).