Argon Purity: Fundamentals

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Argon Purity Fundamentals

• Where
• e electron concentration
• S concentration of electronegative impurities
• ks - attachment rate constant
• P concentration of positive ions
• kr recombination rate constant
• In practice P is negligibly small, hence
• N(t) N(0)e-t/t with t 1/(ksS)

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Argon Purity monitor
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Purity monitor signals
In practice (including shaping time of charge
amplifier)

• In principle

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Purity monitor system components
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Drift chamber geometry
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Drift chamber
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System components

• UV Light source
• Pulsed (few microsecs)
• High power
• Quartz fiber ( 1mm)
• High voltage PS (3 kV)/HV filters (3 channels)
• Low noise charge amplifier Amptek250?
• Waveform digitizer (digital scope)
• Low voltage PS (for the amplifier)
• Feed throughs fiber/signal/HV

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Accuracy/Sensitivity

• Extending the range
• long lifetimes (I wish ?) tracks, dE/dx
• Shorter lifetimes shorter detector, O2 standard
  monitors?

• k stochastic term ?? light source intensity
• h electronic noise term ? low noise, high gain
  amplifier