1. January 15, 2003Richard Talaga1 High Voltage Distribution for RPCs Simple Model of Detector & HV Specifications & Requirements Simple HV Distribution Layout Parts & Costs A Possible Alternative to Conventional System

2. January 15, 2003Richard Talaga2 Simple Model of Detector & HV Detector –300 repetitive layers –20m x 20m cross section –2m x 2m per RPC  100 RPCs per layer HV –1µA/m 2 dark current (BELLE result) mostly through noryl spacers –400 µA per layer, at best –Typical commercial HV channel provides ~1mA @10kV –HV System: 1ch/layer  300 channels for entire detector 1ch for 100 RPCs

3. January 15, 2003Richard Talaga3 Specifications & Requirements HV distribution per layer –Ability to turn on/off Any one RPC? Any of one cluster of RPCs ? –Ability to provide more than 1 value of HV per plane –Ability to track down bad RPC (high current)

4. January 15, 2003Richard Talaga4 Simple HV Distribution Layout 100 RPC/layer Assume 100 RPC connections to the outside Four HV distribution boxes per layer (25 ch/box) –100 pairs of HV connectors/layer + 8 pairs for boxes –240m of cables per quadrant  960 m/layer HV Channel Distribution box Detector cross section

5. January 15, 2003Richard Talaga5 Parts and Costs HV System: CAEN SY1527 (replaces SY 127) –Module A1526: 6 HV channels @ 1mA/15kV per channel 50 modules  300 channels (1 per layer)$250k –Crate SY1527: fits 8 Modules A1526 7 crates (6 full & 1 with two modules) $82k RG58 cable –960m/layer x 300 layers =288,000m = 950,000 ft $136/1000ft spool  $129k SHV connectors: one pair per RPC –RPC end is soldered 30,000 RPCs x $23/pair (for qty of 100) $690k Distribution boxes 1200 boxes @ ~$100/box (no connectors)$120k 10 kV connectors to PS 300 x $35 $10k Total HV M&S costs$1.28M

6. January 15, 2003Richard Talaga6 Parts and Costs: Notes CAEN HV modules –10 kV are being discontinued: SY 127 model A328 2mA @10kV ($1,400/channel) –15 kV model A1526 may be built to provide 10 kV with increased current ~1.3 mA and less potent HV connectors Note: $830/channel for standard model Connector cost –10kV connectors cost $70/pair $36 for bulkhead; $34 for cable –8kV SHV connectors cost $23/pair $9 for bulkhead; $14 cable SHV connector cost may be less because quote for qty 100

7. January 15, 2003Richard Talaga7 A Possible Alternative to Conventional System Use Cockroft-Walton HV supplies –Used in ZEUS @2kV –Each RPC has its own supply, mounted nearby (in absorber material ?) –One low voltage cable replaces HV cable & HV connectors –Reduce the possible corona discharge in long HV cables –Safer: No HV outside the detector –Cost compared to $1.3M conventional system Possibly ~$20-$30 per channel At $40/channel x 30,000 ch = $1.2M