Transcript High Voltage

High Voltage
Requirements
Commercial Solutions
Custom Solutions
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
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)
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
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, tubetube variation.
• Tube “conditioning”
adjustable but tubes can still
be grouped together with a
common HV value
IFR/LST Meeting Feb 26, 2003
• 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
K. Honscheid, Ohio State University
Commercial Solutions
• CAEN 527 or similar
– Too expensive
• CAEN 546
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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
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
Over-current protection (ZEUS)
6 kV
Limited streamer tube
LST Voltage
Voltage
Current
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
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
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
Block Diagram
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
Schematics (HV Regulator, Controller)
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
Schematics II (HV Distribution Channel)
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
First Prototype (5 ch)
HV Op-Amp
15 V In
Floating 5V
Supply
Current Monitor Outputs
6kV Dc/Dc
IFR/LST Meeting Feb 26, 2003
0-5 kV Out
K. Honscheid, Ohio State University
Current Monitor
Protection
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…)
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University