Visualizing the Traversal of Charged Particles in a Diffusion Cloud Chamber

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Visualizing the Traversal of Charged Particles in
a Diffusion Cloud Chamber
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The Basics

• Ionization Energy
• Temperature
• Condensation
• Ideal Gas Law

• Liquid Vs. Gases
• Intermolecular Forces
• Vapor Pressure

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The Cloud Chamber?

• A sealed environment that contains supersaturated
  vapor in a non-condensing gas.
• The condensation induced by the temperature
  gradient can mark the paths traveled by charged
  particles.
• Two types Expansion and Diffusion-Continuous

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Expansion Cloud Chamber

• Invented by Charles T. Wilson (1900)
• Used in some weather balloons

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Expansion Cloud Chamber Workings

• Vapor Compression
• Charged Particle Detection
• Vapor Expansion
• Track production
• Recording of produced tracks
• Replenishing of Vapor

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Diffusion Cloud Chamber

• Invented by Alexander Langsdorf Jr. (1936)
• Provides a continuous supply of vapor for the
  detection of ions tracks.

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Diffusion Cloud Chamber Workings

• Vapor/Gas Selection
• Creation of temperature gradient
• Diffusion of Vapor
• Continuous light supply

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System in Use

• Continuous-Diffusion Cloud Chamber
• Chamber Diameter/Height 11cm/8cm
• Alpha Beta Particles Used
• Cooling Method Ice Water

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System in Use (Cont.)

• Vapor/Gas Selection 90 Ethanol (by volume), Air
• Light Source Orange LEDs (590 nm)
• Floor Temp -12 Degrees Celsius
• Ceiling Temp 23.1C

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Cloud Movie-Alpha

• Show Movie

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Cloud Movie-Beta
Show Movie
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Similarities/Differences

• Path Widths
• Path Lengths
• Path Definition
• Color

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What's Happening?

• Charged Elastic Collisions
• Ionization of Ethanol Particles
• Ion-Initiated Droplet Formation
• Gradient-Continued Droplet Formation
• Cloud Falling

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Blue Skies and Clouds

• Floating Clouds
• Rayleigh Scattering
• Mie Scattering
• Sunny Day Clouds (White)
• Rainy Day Clouds (Grey)

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Another Attempt at Visualization

• The Problem How do Charge particles move to
  produce clouds?
• Elastic Charged Collisions
• Minimum distance of Action
• Application of Measured Temperature Gradient
• Simplify problem(Model Assumptions)
• Solve Collision problems for a given path

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Setting the Stage

• Data portability and method of visualization
• What's the Minimum distance of Action?
  (Derivation)
• 3D field shape and grid-definition

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Selecting the Proper Actors

• Particle distribution (pseudo-random)
• Application of a Temp. Gradient

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Casting of Main Character

• Initial position
• Iterative collison formula (Derivation)
• Choose an Interesting path (Trial and Error)

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Special Effects

• Collision Simulation (Iterative Calculation)
• Path Tracing

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What We Did...

• Sat realistic goals for the visualization of
  physical events.
• Recognized a problem and made reasonable
  simplifications
• Picked a method for visualizing our chosen
  physical events
• Constructed models based on real physical data
• Added parts to demonstrate key physical events

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Third Attempt at Visualization

• Orientation of magnet and field lines direction
• Creation of charged particles (Electric
  Discharge)
• Direction of particles produced in field

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Thanks!!
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Acknowledgments/Sources

• Dr. Douglas Durig
• Dr. Randolph Peterson
• Comic Ray Theory. Bruno Rossi. 1941.
• A Continuously Sensitive Diffusion Cloud Chamber.
  Alexander Langsdorf, Jr. 1938
• A Theory of Diffusion Cloud Chambers. R. P.
  Shutt. 1951.