High%20Voltage

1
High Voltage

• Requirements
• Commercial Solutions
• Custom Solutions

2
Requirements

• 2076 LST tubes
• 4152 High Voltage Channels
• Up to 5 kV
• Regulated to 1
• Current monitoring
• nA resolution
• Over-current protection
• Fine granularity (individual tubes)

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Voltage and Current

• Wide HV plateau(depending on gas mixture,
  chamber construction etc)
• fixed HV for all tubes
• Operating point depends on gas mixture
  (variations), pressure, temperature, tube-tube
  variation.
• Tube conditioning
• adjustable but tubes can still be grouped
  together with a common HV value

• Current Estimates
• for a typical 0.2 Hz/cm2 expect 60nA per tube
• for a worst case rate of 2 Hz/cm2 expect 640 nA

4
Commercial Solutions

• CAEN 527 or similar
• Too expensive
• CAEN 546
• 4u crate, slots for 8 modules for a total of 96
  ch
• One HV setting per module
• Individual channel current monitor
• CAENET VME interface to slow control
• Available from CAEN by special order
• Cost estimated to 160k for 1000 channels
• Used by LVD experiment (Gran Sasso)
• 3000 channels might be available

5
Over-current protection (ZEUS)
6 kV
Limited streamer tube
LST Voltage
Voltage Current
6
Custom Solution or 4000 HV channels for less
than 200k

• OSU electronics engineers (Rush, Smith) designed
  a system similar to the CAEN 546 solution.
• single HV
• individual current monitor
• integrated protection
• pizza box design
• up to 50 ch in 1u
• stand-alone (no crate or crate controller
  required)
• Details at www-physics.mps.ohio-state.edu/klaus/
  LST/HV/HV.htm

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Block Diagram
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Schematics (HV Regulator, Controller)
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Schematics II (HV Distribution Channel)
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First Prototype (5 ch)
15 V In
Floating 5V Supply
HV Op-Amp
Current Monitor Outputs
Current Monitor Protection
0-5 kV Out
6kV Dc/Dc
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Status, Summary and the Next Steps

• Commercial Solution
• HV crate available at Padova, soon at OSU
• Test CAEN 546 system from LVD
• Integrate protection circuit (if necessary)
• Custom Solution
• Status
• Test and prototype tested and fully operational
• Based on preliminary cost estimate 4000 channels
  can be build with our budget
• Next Steps
• Complete digital part, integrate micro controller
• Test stability and reliability
• Can be ready in time for module production and QA
  test stands
• Need to decide if (and how far) OSU solution
  should be pursued
• but it is hard to beat a free system
• Start system engineering (connectors,
  distribution)