1. IFR/LST Meeting Feb 26, 2003K. Honscheid, Ohio State University High Voltage Requirements Commercial Solutions Custom Solutions

2. IFR/LST Meeting Feb 26, 2003K. 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)

3. IFR/LST Meeting Feb 26, 2003K. 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/cm 2 expect 60nA per tube for a worst case rate of 2 Hz/cm 2 expect 640 nA

4. IFR/LST Meeting Feb 26, 2003K. 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

5. IFR/LST Meeting Feb 26, 2003K. Honscheid, Ohio State University Over-current protection (ZEUS) LST Voltage 6 kV Limited streamer tube Voltage Current

6. IFR/LST Meeting Feb 26, 2003K. 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

7. IFR/LST Meeting Feb 26, 2003K. Honscheid, Ohio State University Block Diagram

8. IFR/LST Meeting Feb 26, 2003K. Honscheid, Ohio State University Schematics (HV Regulator, Controller)

9. IFR/LST Meeting Feb 26, 2003K. Honscheid, Ohio State University Schematics II (HV Distribution Channel)

10. IFR/LST Meeting Feb 26, 2003K. Honscheid, Ohio State University First Prototype (5 ch) 6kV Dc/Dc HV Op-Amp 15 V In 0-5 kV Out Current Monitor Protection Floating 5V Supply Current Monitor Outputs

11. IFR/LST Meeting Feb 26, 2003K. 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…)