ifr/lst meeting feb 26, 2003k. honscheid, ohio state university high voltage requirements commercial...
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IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
High Voltage
RequirementsCommercial SolutionsCustom 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, 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
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
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
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
Over-current protection (ZEUS)
LST Voltage
6 kVLimited streamer tube
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)
6kV Dc/Dc
HV Op-Amp
15 V In
0-5 kV Out
Current MonitorProtection
Floating 5VSupply
Current Monitor Outputs
IFR/LST Meeting Feb 26, 2003
K. Honscheid, Ohio State University
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…)